# Class D amplification can sound just as good as true A/B



## Yuck.

This could come down to how much some people's ears can really discern over others, but time spent with one or the other could reveal differences. I am open to being proven wrong, not sure how subjective it could all be however.


----------



## CBRworm

I have heard class D systems in homes and commercial settings that sound incredible. I have not been exposed to any class D full range car amplifiers that sound incredible, or I should say that didn't have flaws that detracted from the otherwise good sound. I am about 1 generation behind as far as testing. I certainly believe it is possible.


----------



## ChrisB

To the OP: call up Richard Clark and tell him you are bringing your best Class AB amplifier to test against Zed's new full range Class D offerings or a JL Audio HD series. You can come back with bragging rights saying that you won $10k of Richard Clark's money by beating his challenge AND you can brag about being able to correctly identify amplifier topologies. Just think of all the audiophile magazines that will revel in your glory!


----------



## Yuck.

Hey, just a thread spark, not the gospel. I am just trying to pool opinion. Some people say they can hear the difference or the circuit switching and that it doesn't sound natural. As for the HD's, I hear people prefer the slashes, other people say they can't tell a difference. Haven't heard anyone say the HD's sound better, but I haven't looked super hard into it. That could say something, or nothing, I don't know, but I'd like to find out what others think.


----------



## W8 a minute

I personally believe technology has reached a level that surpasses the average humans ability to distinguish the difference in a casual listening enviroment. In a sound proof/dead room you might hear a slight difference if you're lucky. But never in a moving vehicle while your driving. 

Sent from my iPhone using Tapatalk


----------



## ChrisB

I'd like to meet some of those who can pick out amplifier topologies in an automobile while it is in motion. What is the average noise floor on the most quiet of luxury vehicles? 60 decibels, give or take a few. Now let's start talking about "normal" vehicles with higher noise floors. Sure, I believe someone can hear the circuit switching while driving.


----------



## raamaudio

I have to say I have not listened to any recent class D amps but I have talked to two manf recently, one has a new line(and was one of the first to ever offer class D) and the other has a new one in the oven but has not had class D amps before. 

Both are very very good companies with great histories of quality engineered products and both are using latest chips, etc....and both said they are not as good as their A/B amps. 

Of the class D I tried years ago, I could easily tell the difference but then again, my system was light years ahead of 99.999% of what others would put into a vehicle and yes, while parked it was much easier to hear it though I could while driving as well (200 hours of sound deadening, solid as a rock, always going to have some road noise left so crank it up LOUD and drone it out but that is not fun either)

And I only played reference quality material.

I have also talked with a couple of home audio manf lately about the different classes, they preferred AB over D as well, even for subs and make both. 

How many have actually done the RC test? How was it setup, quality of the systems, source material, etc.....? I have not read the test material for years, not going to either. But I am open to the idea that D class has gotten good enough but I will not believe it until I hear it, why I have some on order and have the ability to properly listen here. 

Rick


----------



## sqshoestring

I've talked to people in the industry such as a master technician, and they say today's class D will meet any spec you want just as well as a class AB. They say class D are in everything from TVs to HT. That said they can have a different response curve, the ones I heard for cars were not new and they sounded more flat or some would say cold. Myself I prefer more 'warm' sounding amps such as older AB amps tend to be, but in reality with all the EQ processing today it is not much of an issue. They also can sound different when they clip. But, those two issues should not be confused with THD or other sound quality issues. Most agree class D is taking over everything and will be the common type of amp in the future.


----------



## normalicy

I can't vouch for the newer classes myself, but I can say that in the older Class D stuff I could definitely hear something that was off. I've heard some really good things from many audiophiles (the even the snobby types) that the newer Class D varieties are very listenable.

I think though that it works out pretty well with Class D though. What you need Class D for the most is high current applications (subwoofers) where this topology excels & have minimal distortion (even the older ones). No reason to really use a Class D amp on higher frequency drivers when you can get a reasonably sized amp & relative low draw amp to push them.


----------



## Sarthos

I run a class D full range amplifier in my car. Planet Audio BB150.2. Very high quality MB Quart speakers and a really good Eclipse headunit. Could never tell the difference between it and any A/B amps I'd used, other than power output. If you notice a difference, it's likely at the very high end of the treble, which not all people can hear, especially in a car environment.


----------



## coyote-1

The environment is everything.

Most folk don't sit in their car to listen to music; even under best conditions, an automobile is not an optimal listening environment. I have pretty good ears.... I'm trusting that my new Sony Xplod amp (class D) will not show itself to be audibly flawed when I install it in spring.


----------



## raamaudio

Just a general statement, not intended to say much except:

I much prefer the sweet sound of a good tube amp over any transistor amp ever made

Possibly the specs of the class D might be there but the way a transistor works may be kinder to my ears, as a tube amps is compared to a transistor one???

How about this, set up a true listening test in your own vehicle, level matched, playing the best recordings you have, switching as seamlessly as possible from a great AB amp to a D class.......parked, dark out, lights off, etc.......

Then do the best you can while driving, it would be much harder to hear the difference if any but you might. 

---------------------

I do wonder how many have actually heard a world class system with a true audiophile recording as not that many have actually been built and tuned well. Speaking of tuning, I have beaten a world champion on my own build and tune, by a good margin then had Eric at ID tune it for me and absolutely blow away my tune. I fear not many of us can begin to approach that level of tuning. I would love to hear the amp test with such a system and tune, it does matter, hard to fully understand until you hear it, harder to explain.

(I have to admit, I seldom played the system while driving, it was just to good while parked. I did however love to show it off to anybody I could because it blew them away. Best was some very very musically experienced people from outside the mobile realm, that was the most fun

Rick


----------



## mokedaddy

Anybody in the DFW is more then welcome to listen to my car and see if they can tell the difference. I have Zed built Class a/bs and the new Zed class ds at my disposal.

FWIW the class D's are staying put in my car.


----------



## Sarthos

What about other classes of amps? Specifically G, H, or T?


----------



## raamaudio

Switching them in and out seamlessly while playing would be the ultimate way to do this. 

I have many test disks but if I want to really see what a system can do I use the Alan Parsons Sound Check disk, be careful with it, makes sure the gains are such you cannot overdrive anything, a butt load of energy on that disk 

(for those nit pickers out there I am using the term energy as a general term


----------



## raamaudio

I am very impressed with the G class amps I have in my Vette, enough so I am putting 3 in my truck to save space for our huge doggies, Akita and Irish Wolfhound. 

Rick


----------



## Yuck.

Sarthos said:


> What about other classes of amps? Specifically G, H, or T?


G and H use switching with MOSFETS, it's two amps in one chassis with a common switching rail (I believe). I had a clarion xh5410 but sold it before using it, it's G/H.


----------



## Yuck.

raamaudio said:


> I have to say I have not listened to any recent class D amps but I have talked to two manf recently, one has a new line(and was one of the first to ever offer class D) and the other has a new one in the oven but has not had class D amps before.
> 
> Both are very very good companies with great histories of quality engineered products and both are using latest chips, etc....and both said they are not as good as their A/B amps.
> 
> Of the class D I tried years ago, I could easily tell the difference but then again, my system was light years ahead of 99.999% of what others would put into a vehicle and yes, while parked it was much easier to hear it though I could while driving as well (200 hours of sound deadening, solid as a rock, always going to have some road noise left so crank it up LOUD and drone it out but that is not fun either)
> 
> And I only played reference quality material.
> 
> I have also talked with a couple of home audio manf lately about the different classes, they preferred AB over D as well, even for subs and make both.
> 
> How many have actually done the RC test? How was it setup, quality of the systems, source material, etc.....? I have not read the test material for years, not going to either. But I am open to the idea that D class has gotten good enough but I will not believe it until I hear it, why I have some on order and have the ability to properly listen here.
> 
> Rick


Thanks for the added info Rick, and for the roll of Raamat shipped to Fairfield drive in Flourtown PA, musta been 8-9 years ago when I was 17. I don't live there anymore, but PM for my new address to send more, for free


----------



## ChrisB

I am currently using a Clarion DPX1851 to power my JL Audio 13w6v2. Truthfully, that was the best BNIB amplifier deal for the money at $150 shipped from Crutchfield.


----------



## Sarthos

I know how G and H work, I meant anyone with actual experience to the sound? Can A/B sound like G or H?

Class D, by its nature, may never produce sine waves exactly like A and B will. That doesn't mean it can't sound as good, technology can surpass our ability to measure it with our ears.


----------



## sqshoestring

Hybrids are a class AB with a variable rail voltage, so they should work like any other class AB in theory. The rail voltage is reduced at low demand to lessen the loss from high rail with low output. The H is a variable rail, the G is a tiered voltage rail that switches. The H is a little better. A class AB output transistor has a loss in efficiency when you ask it to provide a fraction of available power, so if you lower the supply when you don't need it you raise efficiency, you cut the differential between supply and output. It is complex to have the power supply mimic the needs of the amplifier, but electronics get better all the time to make this stuff viable.

Electronic amplifier - Wikipedia, the free encyclopedia


----------



## t3sn4f2

General question, not directed at any one individual.........

What is it that makes Class D sound inferior?


----------



## normalicy

Errors in the power supply switching can directly affect the output stage, unlike in other designs.


----------



## t3sn4f2

normalicy said:


> Errors in the power supply switching can directly affect the output stage, unlike in other designs.


And in what form does that manifest itself in the AC waveform that leaves the amp terminals?


----------



## rugdnit

mokedaddy said:


> Anybody in the DFW is more then welcome to listen to my car and see if they can tell the difference. I have Zed built Class a/bs and the new Zed class ds at my disposal.
> 
> FWIW the class D's are staying put in my car.


While I agree with this I got alot of pushback here on this last year. Something about how the bass / midbass was good, but the highs were lacking and had " artifact ". Your not a cool guy here unless you bash Mantz.


----------



## normalicy

I'll admit that I'm no master on the subject, but I'll throw out what I think I understand.

It can manifest itself in many forms depending on where a design flaw could be. It really is impressive that good sounding Class D even exists considering how much more complex they are over other designs.

Turn on/off pops are an initial issue.

Power supply rejection will feed any audible noise through the filter (since it's only designed to filter high frequency noise) from the power supply straight to the output section causing very audible distortion. 

Various types of distortion due to numerous possible modulation irregularities.

Also, there's difficulty getting a flat frequency response at high frequencies due to the need for said output filtering.

There can also be huge EMI issues (I've had a few Class D amps that completely eliminated the ability of a radio to tune any FM band radio stations).

Of course, most of these issues can be dealt with today with complex circuits & good engineering.


----------



## squeak9798

Is this where we mention Richard Clark...... ?

Doh! Rick already did it.



raamaudio said:


> How many have actually done the RC test?


According to RC, hundreds to thousands IIRC. I believe he had it setup at some conventions and/or gatherings in which tests were conducted by the dozens over the course of a weekend or week. 



> How was it setup, quality of the systems, source material, etc.....?


Anything the test taker wanted, as long as it the source material was music and not test tones. You could pack up your own system and take it with you if you so chose.

Setup of the system was outlined in the rules;
Amplifier Comparison Test Conditions

1. Amplifier gain controls - of both channels - are matched to within +- .05 dB.

2. Speaker wires on both amps are properly wired with respect to polarity. (+ and -)

3. That neither amp has signal phase inversion. If so correction will be made in #2 above.

4. That neither amp is loaded beyond its rated impedance.

5. That all amplifiers with signal processors have those features turned off. This includes bass boost circuits, filters, etc. If frequency tailoring circuits cannot be completely bypassed an equalizer will be inserted in the signal path of one of the amps (only one and the listener can decide which) to compensate for the difference. Compensation will also be made for input and output loading that affects frequency response. Since we are only listening for differences in the sonic signature of circuit topology, the addition of an EQ in only one amps signal path should make the test even easier.

6. That neither amp exhibits excessive noise (including RFI).

7. That each amp can be properly driven by the test setup. Not normally a problem but it is theoretically a problem.

8. That the L and R channels are not reversed in one amp.

9. That neither amp has excessive physical noise or other indicators that can be observed by the listener.

10. That neither amp has DC OFFSET that causes audible pops when its output is switched.

11. That the channel separation of all amps in the test is at least 30 dB from 20Hz to 20kHz.


----------



## normalicy

Oh & for those wondering, I'm not saying that Class D amps don't sound good. I was just pointing out what can happen if poorly designed.


----------



## GRIFTER9931

Right now i have a 450/4 slash amp in my car and it sounds pretty awesome. In my next build i will try some ZED amps 
I know ... rough life


----------



## Dangerranger

This argument as well as the tube vs transistor argument will likely go on and on and on until the end of time. 

Class A/B amplifiers were once seen as just as bad a "violation" to audio snobs as Class D full range amplifiers are today. Back in the day if it wasn't a Class A or Tube amplifier then it just wasn't good enough for their needs. Class A amplifiers were gigantic, extremely expensive, a poor value, they were inefficient, and they put off a TON of heat. So Class A/B amplifiers were seen as a solution. 

Is full range class D a more radical transition than the transition from Class A to A/B? Yes and No. When A/B was first implemented, engineers went to the extremes. A lot of the reason for tube amplifier purists and a lot of the transistor amplifier myths were generated due to engineers taking extreme measures in the design process. The field just wasn't as well known those days. The reality is that given equivalent design, a transistor amplifier can do anything that a tube amp can do and do it more reliably, efficiently, for less money. 

I feel that in any REPRODUCTION of music, you don't want extreme levels of distortion. By that I mean you don't want an amplifier to clip under any circumstances. It's better to have much, MUCH more power than you need than to overdrive an amp. If I'm given the option of a $500 amplifier that has .01% THD and puts out 200Wx2 into a 4 ohm load, versus a $500 amplifier that has .000000000001% THD and puts out 75Wx2 into a 4 ohm load, I'm choosing option #1. Even for SQ use. 

If I'm choosing an amp for PRODUCING music, then I'm going to choose an amplifier that has more pleasing overload characteristics and for this I can see where tube amplifiers have merit. So for guitar amps where you intend to drive them into clipping, or in the recording process, I would prefer to use tubes in any situation where there may be an overload. 

Yes, a full range class D (or any other switching mode amp) is more "complicated" than a design that runs in linear mode. But the field of audio and the field of electronics is much more well known than it was in the past (say when transistor amps took over tube amps). PWM is a very widely used, well known and well implemented process as well as a reliable one. And as far as amplifiers, it has been prominent until the 1990s, it just takes a long time for car audio to get the trickle down from anything because the retail car audio market is trash.

If the amplifiers in question are designed competently, then there is not going to be a noticeable difference. Full range Class D amplifiers have distortion that is comparable to A/B and both are well below the threshold of audibility. And just to cover it, topology is not to blame for an amplifier not being designed competently. There are violators of all types of amp topologies.


----------



## Oliver

Dangerranger said:


> Is full range class D a more radical transition than the transition from Class A to A/B? Yes and No. When A/B was first implemented, engineers went to the extremes. A lot of the reason for tube amplifier purists and a lot of the transistor amplifier myths were generated due to engineers taking extreme measures in the design process. The field just wasn't as well known those days. The reality is that given equivalent design, a transistor amplifier can do anything that a tube amp can do and do it more reliably, efficiently, for less money.


For the average joe , the bottom line is all that matters.

billionaires 1 per every 40,000,000 average joes - [ who would your market be ?]

Handmade exotic things or production line average things ?

A Harley or a Honda?

Prime Rib or McDonalds ?

etcetera ....


----------



## Dangerranger

Oliver said:


> For the average joe , the bottom line is all that matters.
> 
> billionaires 1 per every 40,000,000 average joes - [ who would your market be ?]
> 
> Handmade exotic things or production line average things ?
> 
> A Harley or a Honda?
> 
> Prime Rib or McDonalds ?
> 
> etcetera ....


True but really the biggest offenders are the extreme sides of the market. The extreme low end overrates and lies about their product. The extreme high end...overrates and lies about their product. 

"Handmade" really isn't what it's cracked up to be. In most cases and most products, machines and computers just flat out do it better. A LOT better and they do it consistently. Except, of course, testing. I'd want a very competent person testing the equipment before it heads out the door.

Harley vs Honda is a good example. Realistically (as much as I like Harley and their pedigree) the Honda is the superior bike. In every facet. For less money. Harley is all about their image. Until recently their bikes were absolutely terrible (aside from the Porsche designed V-rod powertrain which is pretty damn good by any standard) And to cater to the wealthy, image is 95% of what you need to sell things. Image is there when the knowledge of the particular market by the person (and we all have things we're just not familiar with) isn't. The $30,000 millionaires buy Bose. They think $1200 is a lot of bread for a home audio system. Even though Bose is complete garbage, they still make tons of money because of the marketing and "reputation". So realistically, I'd choose to cater to the "billionaires". And market well.


----------



## wheelieking71

my feelings are that input stages, and processing have a much greater effect on the sound of an amp than the topology.


----------



## W8 a minute

...There's real gas in these tubes....


----------



## sqshoestring

I actually prefer an moderate power amp that clips nicely, keeps me in line. Unfortunately the few I see are old school amps or something like a McIntosh. I'm really not sure why in 2010 everyone builds amps that clip.


----------



## raamaudio

I have forgotten more about electronics that I remember but I am fine with it, I know what I like, willing to listen to new things and if I like them will try them.......

BUT, I do recall at least the basic reasons why tube amps are still the best if you want to enjoy a nice audio system at home. It is how the electrons flow, actually flow, not through a switch which all transistor amps are, more like a valve(why they that term is used all over in the tube amp world.

What does this mean? It means I can listen to music for hours on end and my ears do not become fatigued or irritated and my mood is better as much more relaxed even playing music I may not even care for as much as some. 

Tube amps, worse specs, more natural sounding, love them..

-----------

Hybrid tube/transistor mobile audio amps, some very fine ones have been made, I have not owned them, have heard them, liked them a great deal. 

High end A/B amps, I have owned and loved McIntosh amps but when I rebuilt and wanted more power I went with Arc amps and was not let down in the least, Robert Zeff does not how to engineer a great amp

Class H and G, I have a Class H on my home sub, a monster of a sub, I have used a D class on it, went right back to the H. I also have a 2KW Crown A/B amp to try out once I find the right crossover/EQ, analog is all I am interested in as I have a very fine audio signal coming in I need to spit off to the mains and sub, I am not going to run that through any processor and end up with a lessor signal. I do need it to be active as I only have 10 watts out of the tube amp and do not want any losses in a giant passive network(though I know how to design them, why I know I do not want to)

Class D, I tried many but it was some time ago, even RZ's best work of the day just were not what I liked hearing, a very audible difference. 

Current class D amps, I just have not tried any but going to for mobile use that is, the most current chips, well engineered, etc......but I just cannot imagine liking them well enough to switch from my RZ engineered tiny little G class amps I am more than happy with now in my Vette, ones I recommend to other Vette owners regularly and they all love them so far

The main thing that concerns me is not the specs, it is the sound and there are many aspecs that are harder to quantify with most test gear, all the low level aspects that make a musical instrument sound musical, at what point do they get chopped off due to the processors involved? 

Even though I have some of the finest CD's ever recorded, some quite costly, I have heard, some time in the past, the same exact recordings on Vinyl and it reminded me why that medium was better yet, by quite a margin. BUT, I gave up on Vinyl as I do not have the time to fool with it, once CD's became decent. Now I have a very fine transport that will play the best digital recordings exceptionally well, home audio system that is, and wish I could AB test it against a great Vinyl setup, just for fun

-------------

I might even try a home audio class D amp for my sub, give them another chance sort of thing but would rather borrow, rent, etc than buy as most likely do not really want to use one but I will not know unless I try

------------

Rick


----------



## Allan74

Class D needs to get the monkey off it's back that it is a '_Compromise_' class, built not on it's own, but as a more efficient alternative to Class A/B, that is known traditionally to sacrifice SOME SQ in the process. If you ask 10 people what Class D means to them, I bet 9 of them will mention something like that.

Class D needs a 'Public Relations' revamp more than a technological one...lol


----------



## raamaudio

As I mentioned, in my past, I tried very expensive class D amps designed by one of the best engineers ever and was disapointed in them. That was many years ago so I need to take a listen again but when the guys that are making them tell me they are not as good as their AB amps it makes me think they are not that great even though the latest technology is being used. These are friends of mine, not just somebody I called and squeezed and answer out of. 

So, I am going to try some and then decide, I actually hope to like them, really

But it not I will trust my own ears, they have been around long enough to trust. 

Rick


----------



## Allan74

raamaudio said:


> As I mentioned, in my past, I tried very expensive class D amps designed by one of the best engineers ever and was disapointed in them. That was many years ago so I need to take a listen again but when the guys that are making them tell me they are not as good as their AB amps it makes me think they are not that great even though the latest technology is being used.


I think you more or less just hinted at one of the problems right there.

A traditional Class A/B Builder/Designer/Manufacturer might not have the same luck jumping into the Class D marketplace ?

For instance (yes, I know)...Notice how Audison are not bringing much Class D to the table to head their lineups yet ? Secondary and suplimentary items....but nothing leading the way for them.

Wouldn't that be like asking a Typewriter Company to create a Desktop Computer and have it be competitive in the marketplace right away ?


----------



## raamaudio

"I tried very expensive class D amps designed by one of the best engineers ever and was dissapointed in them. That was many years ago"

.......same company now

I have raced bicycles and cars on and off for decades. I built the lightest known full suspension mountain bike 12 or so years ago, 20.4 lbs and very strong.....I drove an under 1,800 lb 510 Datsun for many years way back in the 70's and thus love light weight, compact engineering. So, I want to find a very low weight, great power and efficiency design amp, class D would be perfect for my needs, for the time being I am running and very happy with some really little G class amps

I hope that changes when I test some of the current crop of D class amps.

Rick


----------



## sqshoestring

I'd like to hear that infinity kappa 4.

A tube amp will round the wave like compression when it clips, soft clipping more or less, sure is nicer it does not have all those ugly harmonics. Kinda hard to run tubes in a car though.

Class D was difficult to make work well, one of the first years back was Tripath they put the class D section on an IC chip. Eventually they went out of biz. The current ICE power amps are similar and seem to work quite well. The Alpine PDX, the Pioneer PRS full range class D are ICE, and there are others. The one issue is for midrange and highs it really does not matter, the power usage in a car is nominal unless maybe you are running midbass hard. A sub amp can suck the life out of your headlights easy enough, so with subs it really helps power usage....but with mid/highs not that big a deal. They do run cooler though, so they can be built smaller. Also be careful of mini amps many of them are not class D even though the seller says so (like sonicelectronix/etc). You look up the factory manual and it says nothing about class D (the full range mini amps).


----------



## Dangerranger

raamaudio said:


> BUT, I do recall at least the basic reasons why tube amps are still the best if you want to enjoy a nice audio system at home. It is how the electrons flow, actually flow, not through a switch which all transistor amps are, more like a valve(why they that term is used all over in the tube amp world.


In a vacuum, electrons will accelerate continuously in an electric field according to Newton's second law of motion (until they reach a relativistic speed). This is known as ballistic transport, which basically means that the medium has little electrical resistivity from scattering and such. That really has more of a benefit with super high frequency operation which is why tubes are still the choice for things like TV broadcasting. But with the exception of the SET tube amp, they are typically coupled either capacitively or inductively so that bandwidth capability is limited anyway.

In a solid (such as transistors), if the electrons must move only a very short distance, quasi-ballistic transport is possible. 

On the downside:

1:Tubes are very poor devices for low impedance loads and no matter what you have to use an output transformer to be the load in place of the resistor. It's a severe compromise. The impedance of the transformer primary in operation is substantially higher than the DC resistance of it's windings. High performance transformers add a lot of cost as well compared to a direct-coupled transistor design. The output impedance of a tube amplifier is almost always going to be higher than solid state and the damping factor is going to be very low. Many to the point of it being audible which not many amplifiers accomplish.

2: Tube stages are coupled with components rated to withstand several hundred volts, typically a capacitor, occasionally a coupling transformer. The phase shifts introduced by coupling networks can become problematic in circuits that have feedback. Fortunately lots of tubes (particularly triodes) have good open loop linearity so you can get away with designs with little or no negative feedback. It pretty much demands a competently designed amplifier and quality parts though.

3: Where it is possible to have complementary devices in silicon land, with tubes it isn't. Push-pull tube topologies typically require a transformer.

Modern higher power tube amplifiers still use push-pull as it's configuration and necessitate a phase splitter to get a differential/balanced signal from a single-ended input. Shunt regulated push pulls are a good example because the output stage serves as the phase splitter.

Realistically there are as many tube amplifier topologies as there are in solid state and a lot of good and bad designs out there. You can get good results with either. With tubes, you're going to spend a lot more money and have a lot more maintenance to deal with though.


----------



## Allan74

Dangerranger said:


> In a vacuum, electrons will accelerate continuously in an electric field according to Newton's second law of motion (until they reach a relativistic speed). This is known as ballistic transport, which basically means that the medium has little electrical resistivity from scattering and such. That really has more of a benefit with super high frequency operation which is why tubes are still the choice for things like TV broadcasting. But with the exception of the SET tube amp, they are typically coupled either capacitively or inductively so that bandwidth capability is limited anyway.
> 
> In a solid (such as transistors), if the electrons must move only a very short distance, quasi-ballistic transport is possible.
> 
> On the downside:
> 
> 1:Tubes are very poor devices for low impedance loads and no matter what you have to use an output transformer to be the load in place of the resistor. It's a severe compromise. The impedance of the transformer primary in operation is substantially higher than the DC resistance of it's windings. High performance transformers add a lot of cost as well compared to a direct-coupled transistor design. The output impedance of a tube amplifier is almost always going to be higher than solid state and the damping factor is going to be very low. Many to the point of it being audible which not many amplifiers accomplish.
> 
> 2: Tube stages are coupled with components rated to withstand several hundred volts, typically a capacitor, occasionally a coupling transformer. The phase shifts introduced by coupling networks can become problematic in circuits that have feedback. Fortunately lots of tubes (particularly triodes) have good open loop linearity so you can get away with designs with little or no negative feedback. It pretty much demands a competently designed amplifier and quality parts though.
> 
> 3: Where it is possible to have complementary devices in silicon land, with tubes it isn't. Push-pull tube topologies typically require a transformer.
> 
> Modern higher power tube amplifiers still use push-pull as it's configuration and necessitate a phase splitter to get a differential/balanced signal from a single-ended input. Shunt regulated push pulls are a good example because the output stage serves as the phase splitter.
> 
> Realistically there are as many tube amplifier topologies as there are in solid state and a lot of good and bad designs out there. You can get good results with either. With tubes, you're going to spend a lot more money and have a lot more maintenance to deal with though.


Holly......
Looks like someone just got their Electrical Engineering Degree and wants to share


----------



## raamaudio

I actually know more than I posted but the bottom line is, how do the sound and how long can you listen to them at a time and not get your ears worn out? Specs be damned, I want to enjoy the music and I do and my system did not cost all that much, even if it was at retail no more than $7-8K but I have half of that in it. I have been to high end audio stores, Alexis Park at CES, etc........I have heard systems costing ten times what I have in mine that I did not even care for, at all. 

Tube/Transistors/Chip Amps/ I really do not care what they are made with, I care about how they sound, period

Rick


----------



## thehatedguy

The JL Audio HD amps are very very nice. Mine remind me of my Brax amps, only a ton smaller. I do have some of IMO finest car amps made- HSS Fidelity all tube class A, Monolithic A501s, Marantz 750A, and assorted Brax. The HSS and Monolithics are my favorites, but don't have a lot of power. The JL HDs are every bit as nice as my Brax.

I can't speak about other full range class D amps since I really haven't used them...but the JL HDs changed how I think about class D amps.


----------



## raamaudio

Nice class D review, simple, basic info, but from somebody that has tried many great amps, thanks

I know of some that are in the works from a very fine company that I am quite interested in trying but no idea when they may come out.


----------



## stills

NAD Electronics :: M2 Direct Digital Amplifier


my next home amp


----------



## W8 a minute

thehatedguy said:


> The JL Audio HD amps are very very nice. Mine remind me of my Brax amps, only a ton smaller. I do have some of IMO finest car amps made- HSS Fidelity all tube class A, Monolithic A501s, Marantz 750A, and assorted Brax. The HSS and Monolithics are my favorites, but don't have a lot of power. The JL HDs are every bit as nice as my Brax.
> 
> I can't speak about other full range class D amps since I really haven't used them...but the JL HDs changed how I think about class D amps.



Now I know why you're hated. You're gonna make me spend money on one of these amps aren't ya? Lol

Sent from my iPhone using Tapatalk


----------



## Dangerranger

Allan74 said:


> Holly......
> Looks like someone just got their Electrical Engineering Degree and wants to share



Objective information is pretty useful in, say, a forum dedicated to dispelling myths. Being a douchebag isn't.


----------



## instalher

grab a blade se.2.0 amp from 1990 and compare its class d and sounds fricken wicked.. well all blade se amps were georgeous and way ahead of the time.. yes class d can sound incredible.. that is if amps had a signiture.


----------



## Chaos

All I know is that I have a five channel class D sitting here ready to install and power the entire system. I have never used class D for highs before, so this ought to be an interesting experience.

Theoretically (i.e., according to published specs) it should provide three times the power than the unregulated class A/B amp that it is replacing. 

Will I hear a difference? I sure as hell hope so. Will it sound "better"? I don't know, but if I notice anything worth mentioning, I'll post about it soon.




That being said, experience and common sense dictate that there are bound to be some compromises. Whether or not the amp produces acceptable performance in spite of this is the real question.


----------



## instalher

the class d design is just a more efficient means of transfering a low signal into a larger signal, thats it. you should be ok with the sound quality of your system with the class d amps..


----------



## Flyinbanana

This is the thread I was looking for and wound up posting in another subforum...

I've been fascinated by my relatively inexpensive but amazing little Virtue amps for home use; sweet sounding, compact-- I've really had no complaints. I love the idea of this hiss-free performance in an automotive environment but realize that (correct me if I'm wrong) much of that pleasing sound is dependent on power supply. 

In any event, great read thus far...


----------



## torontooddysey

I think that technology is getting to the point where the human ear will not be able to discern between the two.. maybe another few years down the line


----------



## SoulFly

i'd be interested in hearing Class T and Z amps, both are patented licensed out but their still just a variety of class d. 
The only thing i don't like about some class d amps is the interference they cause with radio stations.


----------



## GranteedEV

The biggest issue with Class D (PWM) amps in general is the high output impedance. They don't deal well with drivers that have rising impedance. Tubes actually have the same problem.

You can look at some behaviour hear:

Sonic Tripath

The other issue is that they often have a rising or drooping top end that might be a couple db down or up by 20hz. 

This isn't as a rule though. This is with your average class D amp. Well engineered class D definitely exists. Now if someone made a car amp for a hypex module, it might sound just as transparent as a true class A amp. Some PWM technology has hit a point where it sounds absolutely excellent to the point where you don't have to worry about it being class D or T or what have you. Just not most of it.

In the same way, there's some class ab amps that have lots of crossover distortion (audible 3rd and 5th harmonics) and there's many class AB amps that measure and sound the same as a class A amp.


----------



## SoulFly

GranteedEV said:


> Now if someone made a car amp for a hypex module, it might sound just as transparent as a true class A amp.


can you elaborate further and why don't more amp makers do this? i thought hypex was a DSP chip of some sort.


----------



## InCarAudioVideo

I've been wanting to test a full range class D myself. Especially the newly released TD5X from Earthquake. Anyone heard of it?

From my readings of the digital amplifiers, isn't it meant to bring in efficiency more than anything else? Especially in the 12 volts industry, where power is very limited and thus high efficiency is required. 

An average class D amplifier would have approximately 85% efficiency, whereas an average class A/B would be on the 50% mark. (correct me if I'm wrong).

So I'm really looking forward to test the TD5X soon, and I'll give you my 2 cents on the sound quality then...


----------



## GranteedEV

SoulFly said:


> can you elaborate further and why don't more amp makers do this? i thought hypex was a DSP chip of some sort.


Hypex is a company which manufacturers DIY and OEM electronics. They do offer a DSP plate amp for Home Hi Fi speakers which lets you bi-amp (and tri-amp if you've got powered subs). I've never tried it, but only heard good things about it.

Their UCD modules are made to address many of the issues with classic class D amps, you can read about it here:

UcD

I'm pretty sure it's patented, so you couldn't just copy what they're doing. You'd have to purchase the OEM modules from them in bulk.

Back to their UCD modules, I don't know if any vendor has ever really bothered to try it in a car. As a DIYer you could probably make your own Hypex car amp if you know what you're doing. I'd personally wait til someone else does it first to see where they made a mistake and messed up  :laugh:

Commercially, thing about UCD is, while I'm pretty sure it's the superior technology, Bang and Olufsen has marketing behind it. I'm pretty damn sure there's a few car audio amp manufacturers that use ice power modules, and I suspect JL audio is one of them.


----------



## St. Dark

JL actually licenses something different from PowerPhysics in SoCal. 

But yes, a number of companies have listed the ICE Power on their amps going back to some big Eclipses 8-9 years ago.


----------



## sjg5359

I would think is a car going over 30 mph it would be hard to tell the difference


----------



## sqshoestring

Bang and Olufsen is ICEpower, Alpine PDX and Pioneer PRS (were prs), and I would guess others. I have an alpine sub box with the typhany driver with a B&O amp in it.


----------



## envisionelec

Yes, it certainly can. I just finished a design that uses an old throwback (Tripath) to produce 160W per channel from a paperback novel-sized chassis that is as sweet and clean as any A/B amp I've ever designed. 

However, it requires *much* *more attention* to layout than anything in the linear audio classes if you ever hope to acquire CE or FCC approval. And yes, it does. 

As it's a commercial design that is in beta testing, I can't show pictures. But I can tell you the company - Virtue Audio.


----------



## jim walter

sqshoestring said:


> Bang and Olufsen is ICEpower, Alpine PDX and Pioneer PRS (were prs), and I would guess others. I have an alpine sub box with the typhany driver with a B&O amp in it.


Alpine no longer uses ICEpower for PDX, we now have our own custom (and patent pending) design with our own chips. This new tech is in both PDX and the new MRX, and is a HUGe step up in performance compared to where we were before.


----------



## The Baron Groog

jim walter said:


> Alpine no longer uses ICEpower for PDX, we now have our own custom (and patent pending) design with our own chips. This new tech is in both PDX and the new MRX, and is a HUGe step up in performance compared to where we were before.


In the Uk you never owned up to the ICEpower link, thanks for just confirming it


----------



## briansz

I've never had issue with the sonics of a Tripath Blaupunkt PA-2150 car amp that I own, but it's the only full range amp I've used in a car that isn't class A or AB.

I'm very happy with the $50 Sure Electronics Class-D module (especially for the cost) that I picked up from Parts Express. I'm feeding it with a decent 24V SMPS and an old 45-pound Sony CDP-707ESD CD transport ($1.8K in the late 1980's) and it is quite pleasing, I hear new things and nuances on recordings all the time. I do not find it as refined or lifelike as the best home systems I've heard, but for a hundred bucks invested it's damn good.

'Pleasing' is not to be confused with what I heard from a system at the Audio Fest a couple years ago - Class D Channel Islands Audio monoblocks and DAC, Oracle CD transport, Von Schweikert Unifield 3 loudspeakers. When the chorus came in on 'O Holy Night' from the Cantate Domino recording, it was electric goosebumps. The huge cathedral and dozens of voices were _there._

Similar experience with a Genesis system driven by class D amplification with some Stevie Ray Vaughan tracks.

I find the home systems I enjoy the most to include high end switching amps upwards of 75% of the time.


----------



## sqshoestring

jim walter said:


> Alpine no longer uses ICEpower for PDX, we now have our own custom (and patent pending) design with our own chips. This new tech is in both PDX and the new MRX, and is a HUGe step up in performance compared to where we were before.


I should have said the first PDX my bad. Well that is cool, I suspect at some point it will mostly be done on a processor.


----------



## Hillbilly SQ

I'll run a D amp on subs but never on my fronts. Maybe it's because I can fit really big amps in my install without ever knowing they're there


----------



## 14642

We did a demo at CES 15 years ago that pitted an Infinity Beta 100 against a Krell 250. I must have played that demo (using an old pair of Kappa 9 home speakers, which were regarded at the time as being one of the most difficult loads to drive--in fact, Adcom had a "kappa9" mod for their amps) for 100 people and there were only two people who could reliably tell the difference.


----------



## t3sn4f2

Hmmm..........no benefit in sound when compared to modern class D versus added weight, current draw, heat, and space needed? 

That's a tough one :thinking:


----------



## Petter

Was or is Anaview involved in the design of the new PDX/MRX amps or did they only do the old ones?




jim walter said:


> Alpine no longer uses ICEpower for PDX, we now have our own custom (and patent pending) design with our own chips. This new tech is in both PDX and the new MRX, and is a HUGe step up in performance compared to where we were before.


----------



## jsun_g

I have been running full-range class D amps for about a year and the only differences I notice are that they do sound a little "cold"/flat compared to the amplifiers they replaced, and at high volumes they seem to suffer from compression. To be fair, these class D amps are also rated at half the power of the amps they replaced (at 1/4 of the size)...perhaps this "compression" is their form of clipping? It doesn't sound distorted, they just lose their oomph. If listening at sane levels, the detail is very much there and pleasing.


----------



## Cablguy184

I run class A/B amps in my Sound Quality vehicle ... Love them ... 
At low volumes, moderate volumes, high volumes, or full tilt ... no problems at all !!! 
Sounds great !!! My demos have just about every kind of music you can think of and I play them at all volumes !!! I will be glad to pull up to any class D system and compare notes ... Not issueing any chalenges of anything, but would like to really compare the differences ... thanks, Randal ...


----------



## 03blueSI

I have to agree that the JL HD amps are an amazing amp. I have used a bunch of class A/B and class D amps over the years including the original JL Slash, DLS A-series, Memphis Belle, JL HD, Tru and a few others. I would rate them as HD and DLS right at the top with a similar sound, the Tru, the Memphis and the JL Slash. The Slash was lifeless. The HD I would classify as warm. Every bit as good as the Dynaco ST-70 I have at home except better able to drive difficult loads and has a ton more power.


----------



## subwoofery

InCarAudioVideo said:


> I've been wanting to test a full range class D myself. Especially the newly released TD5X from Earthquake. Anyone heard of it?
> 
> From my readings of the digital amplifiers, isn't it meant to bring in efficiency more than anything else? Especially in the 12 volts industry, where power is very limited and thus high efficiency is required.
> 
> *An average class D amplifier would have approximately 85% efficiency, whereas an average class A/B would be on the 50% mark. (correct me if I'm wrong).*
> 
> So I'm really looking forward to test the TD5X soon, and I'll give you my 2 cents on the sound quality then...


Class A/B nowadays avarages around 65% whereas 15 years ago (old school Zapco and PPI) would be around 50%. 

Class D is the answer to today's car audio needing more and more power but most newest cars have stronger alternator which can accept 1200rms of class A/B power. 

Kelvin


----------



## atxtrd

The missing link is 2nd and 3rd order harmonics.


----------



## sqshoestring

Some of the newer class AB are pretty good, I tested a 2x150 kenwood that was quite good though only at 10A draw. I ran a bunch of amps at 10A on a meter that one was louder the 7201, but full output efficiency could be different. Class D are always louder.

I have no idea why I should run class AB on subs, I can't tell any difference. I like them on highs because they clip nicer, but I don't need need that with subs they already play far louder than the highs. In fact the class D on subs seem to clip better than class AB in my experience, providing you run small enough amp where you dare to clip it. I clipped my kicker to clamp the amp and it still didn't sound bad, the subs were good for 150% of the amp's ratings.


----------



## 2MuchRiceMakesMeSick

interesting discussion. Is there a good company that makes class D and class A/B amplifiers that look the same? Hifonics is the only one that I can think of and I really dont want to put those on an all focal system


----------



## Petter

Focals previous FP serie had both a/b and d amps in same design. 
There smaller 2, 4 and 5 channels amps works in AB while there 1.800 sub amp do D-class.


----------



## subwoofery

2MuchRiceMakesMeSick said:


> interesting discussion. Is there a good company that makes class D and class A/B amplifiers that look the same? Hifonics is the only one that I can think of and I really dont want to put those on an all focal system


If you're talking about front A/B and sub D then there's quite a few: 
- Audison LRx, SRx and SR 
- DLS Reference 
- Soundstream REF, STL and RUB 
- JBL Px series 
- Rockford Power 
- Precision Power (don't remember which) 

Kelvin


----------



## tyroneshoes

And the memphis belle 

The first pdx's had numerous problems but the kenwoods, I couldnt tell from A/B.

I just put back in a "high end" a/b amp and I prefer the sound. I also have more power. Its not black and white. Not all amps are created equal.


----------



## paulf1

Is anyone making Tube Amps for the auto industry.......or would they suck too much power.


----------



## ChrisB

paulf1 said:


> Is anyone making Tube Amps for the auto industry.......or would they suck too much power.


There are some, but they generally are NOT true tube amplifiers. The majority of them put the tubes in the preamp stage. Some of them will still play even if you pull the tubes, which makes me question their motives and suspect the tubes were nothing more than a marketing tactic.


----------



## rugdnit

paulf1 said:


> Is anyone making Tube Amps for the auto industry.......or would they suck too much power.


I fell for this trick once...... ONCE.


----------



## subwoofery

paulf1 said:


> Is anyone making Tube Amps for the auto industry.......or would they suck too much power.


You have deep pockets? Coz real car audio tube amps are expensive... 
There are a few... 

Kelvin


----------



## mht_v10

such as tru tech copper AT , milbert ?


----------



## subwoofery

mht_v10 said:


> such as tru tech copper AT , milbert ?


Yep, also look at DD, HSS Fidelity & Abyss 

Kelvin


----------



## andrave

I could definitely hear the difference between class D amps last time I messed with them. I didn't like them so I got rid of them and have been class AB ever since. Class D and "H" and "t" and hybrids WILL be the way of the future in the some was mosfets killed tubes. Audiophiles still pay lots for big ass inefficient tube amps, but the future of all electronics is lower amp draws, driven by more expensive energy. low draw LEDS for lighting and new chips using class D technology for audio. The real question is when cars switch to a 24 or 32 volt electrical system so they can more efficiently power the new electric power steering, electric air conditioning, oem 10 speaker 1000 watt sound systems, heated seats, and etc, and do so without adding a ton of expensive and heavy copper wiring.


----------



## GranteedEV

briansz said:


> 'Pleasing' is not to be confused with what I heard from a system at the Audio Fest a couple years ago - Class D Channel Islands Audio monoblocks ........ When the chorus came in on 'O Holy Night' from the Cantate Domino recording, it was electric goosebumps. The huge cathedral and dozens of voices were _there._


Channel islands uses the same hypex modules that I mentioned earlier, that could be "ported" over to car application.


----------



## garysummers

Using 5 Alpine PDX amplifiers in my 06' C230 5.1 system! Posted the highest Mecca SQ score for 2011! You decide!


----------



## garysummers

Just another note: Mark Eldridge posted 2nd highest SQ score and he uses the JL Audio Class D amps! Again you decide!


----------



## Mic10is

Todd Luliak is using JL HD amps and won MECA Finals in Extreme Class


----------



## tnbubba

again take a clas d and hook it to a decent home system .. they suck...
I have about 30k worth of good gear and a system that has not changed for 10 yrs until this year.

No musician ever liked the class d amps on anything but subs on the studio monitoring system or my home system..
even the vauted crown peavy qsc whatever.. my bryston or coda's win every time..
I have a 20,000 A/h forklift batter packj rewired for 12v to run all auto stuff on so we can test auto amps on the same system no contest the SS class A and other win hands down over the class D I wont tell you which two amps my 10 yrs old, who has much better hearing than any of us picked, but one is a car amp and it's in my car...


----------



## Mic10is

tnbubba said:


> again take a clas d and hook it to a decent home system .. they suck...
> I have about 30k worth of good gear and a system that has not changed for 10 yrs until this year.
> 
> No musician ever liked the class d amps on anything but subs on the studio monitoring system or my home system..
> even the vauted crown peavy qsc whatever.. my bryston or coda's win every time..
> I have a 20,000 A/h forklift batter packj rewired for 12v to run all auto stuff on so we can test auto amps on the same system no contest the SS class A and other win hands down over the class D I wont tell you which two amps my 10 yrs old, who has much better hearing than any of us picked, but one is a car amp and it's in my car...



you should maybe google who Gary Summer is in the Music Industry.
He isnt sponsored by any company yet he still chose to run the PDX amps...


----------



## Sarthos

A 10 year old may have better ability to hear certain notes, but that doesn't make them a better judge of quality...


----------



## garysummers

Ok, I thought we were talking about car audio amplifiers! My McIntosh MC207 does sound better than the PDX's. Just for clarification, I chose the PDX's because I was designing a fully active 5.1 system and required 14 separate channels of amplification. Try to do that with conventional Class A/B amps and still keep your spare tire.


----------



## garysummers

View attachment 31361


This is what was required! FYI


----------



## t3sn4f2

tnbubba said:


> again take a clas d and hook it to a decent home system .. they suck...
> I have about 30k worth of good gear and a system that has not changed for 10 yrs until this year.
> 
> No musician ever liked the class d amps on anything but subs on the studio monitoring system or my home system..
> even the vauted crown peavy qsc whatever.. my bryston or coda's win every time..
> I have a 20,000 A/h forklift batter packj rewired for 12v to run all auto stuff on so we can test auto amps on the same system no contest the SS class A and other win hands down over the class D I wont tell you which two amps my 10 yrs old, who has much better hearing than any of us picked, but one is a car amp and it's in my car...


And put a blind fold on and you're back to square one. A lot of money, a lot of heat, a lot of wasted power, but the same sound.


----------



## MadeByMonkey

As long as class ab exists, this argument will continue. I see it as a good thing that amplifiers are moving towards class d. They are getting smaller and sound just as good as, if not better than, the over sized, not so efficient, class ab relics they replaced.


----------



## WLDock

tnbubba said:


> again take a clas d and hook it to a decent home system .. they suck...
> I have about 30k worth of good gear and a system that has not changed for 10 yrs until this year.
> 
> No musician ever liked the class d amps on anything but subs on the studio monitoring system or my home system..
> even the vauted crown peavy qsc whatever.. my bryston or coda's win every time..
> I have a 20,000 A/h forklift batter packj rewired for 12v to run all auto stuff on so we can test auto amps on the same system no contest the SS class A and other win hands down over the class D I wont tell you which two amps my 10 yrs old, who has much better hearing than any of us picked, but one is a car amp and it's in my car...


I am one that believes that people don't all hear things the same....musicians generally are more critical when it comes to sound (Hell, some even have perfect or relative pitch!). So I am not suprised to hear that a musician like a class A amp over a class D amp. But, newer designed Class D amps like the JL Audio HD's are getting closer to quality sound when compaired to a Class A/B amp. Not all amps sound the same *under all conditions* regardless of the topology.

Regardless, for a touring rig, car audio, subwoofers, etc.....Class G, H, D just makes SO much more sense.

P.S. - Maybe you 10 year old is a future musician/amplifier design engineer? A Golden Ear Elite?


----------



## garysummers

I will not profess to be an expert here on this subject as I am not a person with a lot of technical knowledge! In my profession, my tool is my ears, that is what I use daily! I will say this for sure. I was originally running the first generation Alpine PDX amps in my 5.1 setup! When the new PDX came out I decided to replace all 5 amps at once! I mapped each speaker driver in the car for frequency response and amplitude using my RTA employing 4 mic timed spacial averaging. The new amps were installed and the gains were matched to the measured levels as before! With out question these amps sonically out preformed the original. We use all kinds of words to describe sound quality and sometimes it helps us understand what we hear! all I can equate the difference to is a visual correlation! It was like looking at a conventional DVD and then watching the same movie with a blue-ray! So IMHO the technology is improving! Is it perfect or as good as the best Class A/B amps, I am not qualified to say! I only know what my ears say and that is it was significantly better with respect to SQ!


----------



## BuickGN

The only word I can use to describe the HD amps on Dyn speakers is "real". I love the setup and I love the fact that they're both under the seats so wire runs are short and no space is taken up, no need for a false floor or to lose the spare tire. There's no way that could be accomplished with an A/B that puts out 150w/ch or 100wx4 + 500 for a sub.


----------



## ChrisB

BuickGN said:


> The only word I can use to describe the HD amps on Dyn speakers is "real". I love the setup and I love the fact that they're both under the seats so wire runs are short and no space is taken up, no need for a false floor or to lose the spare tire. There's no way that could be accomplished with an A/B that puts out 150w/ch or 100wx4 + 500 for a sub.


Were you as surprised to find how clean the JL Audio HD sounded after hooking it up? It shocked me because my prior experience with full-range class d was with the first generation Alpine PDX. To be honest, I was expecting a marginal improvement over the PDX but thinking I would "hear" something that didn't sound quite right. Unless I get power hungry again, that 900/5 is there to stay in my vehicle.


----------



## Sarthos

My experience with Full Range Class D is old Planet Audio "Big Bang" amps. I've kinda forgotten how the system sounded with an A/B amp, and I never had EQ or time alignment or anything tuned right when I had one. Does this mean that I'd be likely to notice a sonic difference swapping in my rebuilt/"upgraded" Hifonics amp? Maybe slightly. Am I gonna do it? When I get off my butt sure.


----------



## cleansoundz

My Arc Audio class G/H amps work well for me in both of my vehicles.


----------



## BuickGN

ChrisB said:


> Were you as surprised to find how clean the JL Audio HD sounded after hooking it up? It shocked me because my prior experience with full-range class d was with the first generation Alpine PDX. To be honest, I was expecting a marginal improvement over the PDX but thinking I would "hear" something that didn't sound quite right. Unless I get power hungry again, that 900/5 is there to stay in my vehicle.


I was surprised at the lack of a noise floor even with the gains all the way up. With the 900/5 on the tweeters I turned the gains all the way up just to see where I could begin to hear a hiss and if you listen carefully with the engine off and the gain all the way up you can hear it. Anything below full gain or with the engine running it's just pure clean power. I've got the gains set to around halfway right now but it's nice to know all of it is usable if needed. Obviously the sub channel has no noise and I was surprised coming from a 1,000w amp how powerful the sub channel is. I'm finally happy in with every aspect of these amps. For once I'm happy with my purchase, I'm not wishing I would have gotten something different.


----------



## rc10mike

I liked my JL HD600/4, he was a cool little dude, until he started bitching about my sub amps power supply and shouting it through my tweeters.


----------



## BuickGN

tvrift said:


> I liked my JL HD600/4, he was a cool little dude, until he started bitching about my sub amps power supply and shouting it through my tweeters.


Was that the one that didn't play nicely with any sub amp you tried?


----------



## rc10mike

BuickGN said:


> Was that the one that didn't play nicely with any sub amp you tried?


I tried many different sub amps, even a 2nd HD600/4. Ill stay away until they get the interference bugs worked out.


----------



## gnesterenko

Well, I can't find the paper on this topic now, but there was a rather extensive research done into why exactly people tend to think that Class A/B amps sound better then Class D amps, especially considering that both are capable of accurate frequency reproduction.

The conclusion was the emphasis of the different amplifier structures on harmonic distortion. Class A/B amps emphasized second and fourth order harmonics (and to a far lesser extent, sixth), similar to tube amps. Listeners generally describe this sound as 'warm' or 'natural'. Class D amps however emphasize the first and thrid order harmonic distotrions (and to far lesser extent 5th). Listeners generally describe this sound as 'harsh' or opposite of natural. That said, class D amp technology has come a long way and the top end models are designed to avoid the above generalizations to varying degrees of success. I can't tell you why or how this is the case as I can't find the link to the paper, but that was the takeaway for me. That said, I'm runnin a JL HD 600/4 for my front stage and it sounds pretty warm to me. Sure I could do better, but theres a budget to consider. One day however, when money is less of a concern, my build will be all class A/B - perhaps even a tube in there somewhere >. By that day I'm sure that class D will sound even better, but I'm a retro kind of dude, and the cool factor of these amps is just through the roof for me 

Posting from work, so need this disclaimer:
"The views expressed here are mine and do not reflect the official opinion of my employer or the organization through which the Internet was accessed."


----------



## ChrisB

gnesterenko said:


> Well, I can't find the paper on this topic now, but there was a rather extensive research done into why exactly people tend to think that Class A/B amps sound better then Class D amps, especially considering that both are capable of accurate frequency reproduction.
> 
> The conclusion was the emphasis of the different amplifier structures on harmonic distortion. Class A/B amps emphasized second and fourth order harmonics (and to a far lesser extent, sixth), similar to tube amps. Listeners generally describe this sound as 'warm' or 'natural'. Class D amps however emphasize the first and thrid order harmonic distotrions (and to far lesser extent 5th). Listeners generally describe this sound as 'harsh' or opposite of natural. That said, class D amp technology has come a long way and the top end models are designed to avoid the above generalizations to varying degrees of success. I can't tell you why or how this is the case as I can't find the link to the paper, but that was the takeaway for me. That said, I'm runnin a JL HD 600/4 for my front stage and it sounds pretty warm to me. Sure I could do better, but theres a budget to consider. One day however, when money is less of a concern, my build will be all class A/B - perhaps even a tube in there somewhere >. By that day I'm sure that class D will sound even better, but I'm a retro kind of dude, and the cool factor of these amps is just through the roof for me
> 
> Posting from work, so need this disclaimer:
> "The views expressed here are mine and do not reflect the official opinion of my employer or the organization through which the Internet was accessed."


Wasn't that paper written by Stephen Mantz aka Zed Audio? If so, the reason you can't find it is because...

wait for it... 

His new amplifiers are full range Class D.


----------



## sqshoestring

The harmonics should be in clipping. I see no reason to not use class D on subs, it would take a lot to make an amp crappy enough to matter given the average amp. The full range seem to be getting better now the kappa I run sounds very clean. In the end run what you want, I have bunch of old school class AB I plan to try on highs....which I really need to do so I can get rid of what I don't need.


----------



## tnbubba

lets put it thsi way.. the foirst time head heard SMOKE on the Water fornthe made in japan album.. he nailed Ians vocal almost perfect.. and he play s acoustic guitar in church band

he damn sure didn't get his musical talent from his da!!!! so when I think I hear a difference i just ask him!


----------



## zoomer

Bang and Olufsen market a high end class D amp called ICE Power. it is used in many high end audio amps, some costing thousands of dollars. Many reviews rate them very very sweet sounding. 
you can read some reviews here:
How a Class D "Digital" Amplifier Works — Reviews and News from Audioholics
Seymour AV Ice Block 5001 500watt Monoblock Amplifier Review — Reviews and News from Audioholics
Attack of the Clone Amplifiers — Reviews and News from Audioholics
Pioneer Elite SC-55 & SC-57 9.1 Channel A/V Receivers Preview — Reviews and News from Audioholics
Pioneer Elite SC-07 A/V Receiver Review — Reviews and News from Audioholics


----------



## cvjoint

gnesterenko said:


> Well, I can't find the paper on this topic now, but there was a rather extensive research done into why exactly people tend to think that Class A/B amps sound better then Class D amps, especially considering that both are capable of accurate frequency reproduction.
> 
> The conclusion was the emphasis of the different amplifier structures on harmonic distortion. Class A/B amps emphasized second and fourth order harmonics (and to a far lesser extent, sixth), similar to tube amps. Listeners generally describe this sound as 'warm' or 'natural'. Class D amps however emphasize the first and thrid order harmonic distotrions (and to far lesser extent 5th). Listeners generally describe this sound as 'harsh' or opposite of natural. That said, class D amp technology has come a long way and the top end models are designed to avoid the above generalizations to varying degrees of success. I can't tell you why or how this is the case as I can't find the link to the paper, but that was the takeaway for me. That said, I'm runnin a JL HD 600/4 for my front stage and it sounds pretty warm to me. Sure I could do better, but theres a budget to consider. One day however, when money is less of a concern, my build will be all class A/B - perhaps even a tube in there somewhere >. By that day I'm sure that class D will sound even better, but I'm a retro kind of dude, and the cool factor of these amps is just through the roof for me
> 
> Posting from work, so need this disclaimer:
> "The views expressed here are mine and do not reflect the official opinion of my employer or the organization through which the Internet was accessed."


You can hear harmonics under .05%? Look at the XD -the cheaper JL amp- test:

http://mobile.jlaudio.com/pdfs/XD%20Review/XD_Review.pdf

Unless driven near the edge, amplifiers (including class D) have ridiculously low harmonics. As far as I know only the sharpest ears can pick up harmonics under 1%, and even then, to go bellow .7 is unheard of. (pun intended) If you are going to hear any distortion from amplifiers odds are it would be that tube amp you want, that or you drive them constantly between 90% and clipping.


----------



## chefhow

I think cars like Mark Eldridge's NASCAR and Highly's GTi debunk any and all notion that class D is inferior to A/B.


----------



## ErinH

cvjoint said:


> You can hear harmonics under .05%? Look at the XD -the cheaper JL amp- test:
> 
> http://mobile.jlaudio.com/pdfs/XD Review/XD_Review.pdf
> 
> Unless driven near the edge, amplifiers (including class D) have ridiculously low harmonics. As far as I know only the sharpest ears can pick up harmonics under 1%, and even then, to go bellow .7 is unheard of. (pun intended) If you are going to hear any distortion from amplifiers odds are it would be that tube amp you want, that or you drive them constantly between 90% and clipping.


More so, the drivers used exhibit distortion much higher than an amplifier making them the weak link. Not the amp. Unless the amp is fudged up.


----------



## WLDock

While I do think that amps can sound different near the point of audible distortion. Class D amps like the JL HD's are very efficient and have great specs. Both are going to go a long way in helping produce great sound in a 12 Volt based car audio system. 

While I think the HD's are good enough to use on mids and tweets...I will continue to use a Class A/B on my mids and tweets because the 14.12" x 8.25" size of my amp is not that much larger than the 10.74" x 8.29" size of the HD amps. 

Now my 8 Ohm long stroke low efficiency midbasses, and dual 3 Ohm huge underhung vocecoil 15" sub is makes so much sense to put the HD900/5 on those drivers. IMO, I will have the best of both worlds....

...Heck, my 4 ch Class A/B amp's input stage was updated/modified and the bias was individually set for each channel with a distrotion analyser at normal listening levels...so in effect the output stage runs at Class A at low levels.

I think the hybrid approach is the way to go...(The Audison LRx 5.1k is the epitome of the concept) But I will create my own hybrid approach utilizing 2 small amps, 7 channels, 1280 watts, Class A, A/B, D operation. I don't see a reason to choose one topology over the other? Use both! OR three or four!


----------



## cvjoint

WLDock said:


> While I do think that amps can sound different near the point of audible distortion. Class D amps like the JL HD's are very efficient and have great specs. Both are going to go a long way in helping produce great sound in a 12 Volt based car audio system.
> 
> While I think the HD's are good enough to use on mids and tweets...I will continue to use a Class A/B on my mids and tweets because the 14.12" x 8.25" size of my amp is not that much larger than the 10.74" x 8.29" size of the HD amps.
> 
> Now my 8 Ohm long stroke low efficiency midbasses, and dual 3 Ohm huge underhung vocecoil 15" sub is makes so much sense to put the HD900/5 on those drivers. IMO, I will have the best of both worlds....
> 
> ...Heck, my 4 ch Class A/B amp's input stage was updated/modified and the bias was individually set for each channel with a distrotion analyser at normal listening levels...so in effect the output stage runs at Class A at low levels.
> 
> I think the hybrid approach is the way to go...(The Audison LRx 5.1k is the epitome of the concept) But I will create my own hybrid approach utilizing 2 small amps, 7 channels, 1280 watts, Class A, A/B, D operation. I don't see a reason to choose one topology over the other? Use both! OR three or four!


We can easily prove A/B uses more juice to get the same output. Can we just as easily prove A/B or A sounds better? Where is the proof? How do you know that efficiency is traded away for something other than zilch? With efficiency comes smaller footprint. Smaller footprint means more room in the mobile environment. You can go from a 10" to a 12" or gain more storage space. The benefits of class D are very tangible, where are those of class A/B?


----------



## cvjoint

bikinpunk said:


> More so, the drivers used exhibit distortion much higher than an amplifier making them the weak link. Not the amp. Unless the amp is fudged up.


Yeah it's something like a factor of 10 or more. Huge. Amps are also easier in that you can get a larger amplifier, more watts per channel, with no loss of accuracy. Getting a larger woofer usually means more inductance, poorer decay, worse dispersion, just to reduce THD. If you double the woofers you get comb filtering and localization problems. Bridging amps is by comparison easy as pie.


----------



## WLDock

The benefits of Class A/B in the 12 volt environment have been proven ages ago. The topology can sound good, some designs have efficiency in the 67% range, and some are not that large. With the emergence of so many good sounding Class G/H, & D amps there is really no need to use all class A/B amps or use Class A/B at all. But just because Class D has gotten better does not mean that all of a sudden Class A/B needs justification. Even JL still offers A/B amps....for now.

I will let the golden ears folks decide if A/B sounds better than class D. In the in the meantime.....*MY* system will have two amps, 7 channels, utilizing 380 watts of Class A/B and 900 watts of Class D. We all know that getting quality sound in a vehicle has a HELL of a lot more to do with other factors than just the topology of your amps.

I think we just need to leave things at..."Class D can sound good and is getting better...digital cameras took a similar path when compared to film."


----------



## subwoofery

Ok... I'll try once more  

Can someone please try answer my below quoted post? (more infos in the link posted)


subwoofery said:


> ...To be honest, I wouldn't be able to tell you why I prefer one amp over another. I'm actually planning to sell my LRx3.1k coz when compared to my DLS A7, it seems like it has less headroom even though it puts out more power... I just let my ears and my brain do the work.
> 
> Everytime we talk about amp and debate over the sound, people always think about what is being said in my signature: "all amps that measure the same, sound the same" <-- I understand that and agree.
> 
> HOWEVER  How can you make 2 amps have the same distortion figures over the whole bandwith? Remember, for it to sound the same, gain, power, frequency response, noise or *distortion* needs to be close enough to go indistinguishable...
> Note the emphasis on distortion coz I've posted on numerous threads about my findings yet nobody, yes *NOBODY* wanted to tackle it:
> http://www.diymobileaudio.com/forum/1425818-post366.html
> http://www.diymobileaudio.com/forum/1361402-post74.html
> http://www.diymobileaudio.com/forum/1414387-post22.html
> http://www.diymobileaudio.com/forum/1358739-post31.html
> 
> People always turn around and say that if I sit in their car, I wouldn't be able to know which brand he's using and all that blah blah blah - but I'm just asking for a reply to my findings... Scared to actually find that the brain can in fact distinguish one amp from another coz the difference can be as high as 50dB (comparing Mosconi and DLS @ 3kHz) ; *50dBs*
> I know some people will argue that we can't distinguish distortion as high as 3% or for some even higher - however that doesn't mean that the brain and ears can't tell at all. Patrick Bateman states that when listenning to a low distortion set of speakers (like his Summas) he listens to it at a much higher volume than one with more distortion
> www.diymobileaudio.com/forum/1464136-post559.html
> The brain translates distortion as being louder and offensive (or if not too much distorsion, pleasing...) I do believe that the brain CAN hear distortion without us really knowing it
> 
> Ok I'm done


Kelvin


----------



## cvjoint

What does the 50db stand for? 

If you can find one study out there, one, that can show someone can hear distortion at .05% I'll buy it. Even so, I can show you A/B class amps that are cleaner than class D over some watt region and the other way around. I don't see the class mattering much, but the variation comes entirely from near clipping, or the first few watts operation. From 10% power to 90% power I couldn't tell you what class amplifier it is by looking at THD vs Watts. If there is variation among classes it has to come from somewhere other than THD.


----------



## subwoofery

cvjoint said:


> What does the 50db stand for?
> 
> If you can find one study out there, one, that can show someone can hear distortion at .05% I'll buy it. Even so, I can show you A/B class amps that are cleaner than class D over some watt region and the other way around. I don't see the class mattering much, but the variation comes entirely from near clipping, or the first few watts operation. From 10% power to 90% power I couldn't tell you what class amplifier it is by looking at THD vs Watts. If there is variation among classes it has to come from somewhere other than THD.


I'm actually not talking about the "Total Harmonic Distortion" numbers (0.xxx%) but about the distorsion over the whole bandwith... 
I gladly accepted (even though it took me some time ) that all amps can sound the same as long as gain, power, frequency response, noise or distortion are close enough to go indistinguishable. 

I took the Mosconi graph and the DLS graph as an example, @ 3kHz the difference is as much as 50dB. 50dB is what? *10 times as loud*, right? since 10dB is approx twice as loud... 
Meaning from 1 amp to the next, distorsion can be 10 times louder at a frequency we are particularly sensitive (mid band) - I'm *sure* the brain can pick that up... In the audio world, 50dB more sure is *A LOT*... 
A lot of people believe that one amp brand (can) sounds warmer than another - I'm pretty sure those people (and myself) are not totally wrong. 


Sorry I posted in the wrong thread - felt I needed to since I did not get the answer I was looking for in the other threads I posted :blush:
I'm actually not debating that Class D can sound just as good as Class A/B or A, I'm just debating that all amps won't sound the same if *ONLY* levels are set within 0.1dB... Remember: gain, power, frequency response, noise or distortion. 

Kelvin


----------



## cvjoint

subwoofery said:


> I'm actually not talking about the "Total Harmonic Distortion" numbers (0.xxx%) but about the distorsion over the whole bandwith...
> I gladly accepted (even though it took me some time ) that all amps can sound the same as long as gain, power, frequency response, noise or distortion are close enough to go indistinguishable.
> 
> I took the Mosconi graph and the DLS graph as an example, @ 3kHz the difference is as much as 50dB. 50dB is what? *10 times as loud*, right? since 10dB is approx twice as loud...
> Meaning from 1 amp to the next, distorsion can be 10 times louder at a frequency we are particularly sensitive (mid band) - I'm *sure* the brain can pick that up... In the audio world, 50dB more sure is *A LOT*...
> A lot of people believe that one amp brand (can) sounds warmer than another - I'm pretty sure those people (and myself) are not totally wrong.
> 
> 
> Sorry I posted in the wrong thread - felt I needed to since I did not get the answer I was looking for in the other threads I posted :blush:
> I'm actually not debating that Class D can sound just as good as Class A/B or A, I'm just debating that all amps won't sound the same if *ONLY* levels are set within 0.1dB... Remember: gain, power, frequency response, noise or distortion.
> 
> Kelvin


Ohhh, I see what you are saying. The plot you are interested in is hz vs. thd. In reality we should have a multidimensional plot power vs frequency vs harmonics. In effect that is all captured in "given distortion is the same." The real question is, what is the baseline? if the harmonics are -130db vs -80db then no, 50 db difference won't matter. In the majority of comparisons I presume that is the case.

Here are the JL Class D:

http://mobile.jlaudio.com/pdfs/XD%20Review/XD_Review.pdf

Note that indeed the 4 channel is much cleaner than the 6 channel, presumable due to tighter arrangement. Will you be able to tell a difference? Doubt it. At it's worse the 6 channel is way bellow .1% THD. There is almost a 70db difference but I doubt it makes an audible difference, it's just that low. 

The new PPI class D also looks very good:
http://www.pasmag.com/car-audio/test-reports/1805-test-report-precision-power-p9004-amplifier-

It's -70 at it's worst, or .03THD. Even if the JL 4 channel can muster -130 does it really matter? A resonating door panel is like a million times worse distortion wise. You're better off laying 1 square inch of dynamat on the doorpanel then spending the extra $100 on an amplifer.


----------



## subwoofery

EUREKA!!!!! I got my answer... 

Your post made me think especially with this sentence: _"The real question is, what is the baseline?" _

That's why I looked at my .pdf files and use google translate for the little comment below the plots. From my understanding, the baseline is the noise floor. It's when distortion is above the noise floor that it affects the sound... 

Below is the measured (from the mag) S/N ratio (called background noise) and the translated comment for each amp: 
Mosconi - 96dB 
_Typical distortion spectrum for an amplifier in Class A operation_
Zapco - 93dB 
_Quite discordant distortion spectrum with low background noise_
Brax - 90dB 
_clean harmonic distortion falling, K3 higher than K2_
Sinfoni - 95dB 
_Homogeneous decaying distortion content, K2, K4, K6, as high as K3, K5, K7_
DLS RA - 98dB
_Very low noise floor, slightly increases K2 harmonic distortion that extremely harmoniously inclined_
Audison - 90dB
_Constant sloping THD, low background noise_
Focal - 79dB
_Elevated background noise, which is mainly due to the use of a DSP chip_
DLS TA2 - 88dB 
_Relatively low background noise in relevant range, higher straight harmonic distortion_

From my understanding, the plot shows harmonic distorsion where K2, K4, K6 is even and K3, K5, K7 is odd. 

You can clearly see that on the Mosconi, Sinfoni, DLS RA & Audison ; harmonic distortion is clearly above the noise floor. 

Kelvin 

PS: Was not able to translate the below-plot-comment on the XD400/4 but here's for the XD600/6: _Very restless distortion spectrum, typical of a Class D amplifier._ 
Dunno if it's due to a not-so-good design or as you stated due to tighter arrangement...


----------



## ErinH

I'm digging these test links. Keep em coming. 

George, has anyone benched the HD vs XD that you know of?


----------



## WLDock

subwoofery said:


> EUREKA!!!!! I got my answer...
> Your post made me think especially with this sentence: _"The real question is, what is the baseline?" _ That's why I looked at my .pdf files and use google translate for the little comment below the plots. From my understanding, the baseline is the noise floor. It's when distortion is above the noise floor that it affects the sound...


Wow, that discussion took me back to thinking about the technology used in the old Blaupunkt Velocity V7000 amp I had years ago. They used a technology taken from the pro sound company Rocktron: HUSH® Noise Reduction and *THD*L Distortion Limiting circuitry to deal with some of the factors that all amps exhiibit.

*HUSH® Noise Reduction*
Originally developed for pro audio use, the HUSH® noise reduction system is capable of reducing noise from all audio sources, AM, FM, tape, and even background noise on analog recorded CD's. HUSH® will also reduce noise that plagues car audio systems, such as alternator whine and noise from automobile computers. The HUSH® feature comes with a variable threshold level that can be fine-tuned at any time with the optional RM-1 remote control.










*Distortion Limiting (THDL)*
WHAT IS AN AMPLIFIER?...
An amplifier, by definition, is a device that receives a small audio signal on its input and reproduces it with larger voltages (or current) on its output. Ideally there should be no internal modifications of the signal other than voltage or current level. If there are any changes in the signal character it is considered a “distortion” of the input signal. 

A perfect amplifier will be able to reproduce any output voltage regardless of input signal level, but this is impossible due to upper limits created by the voltages found in a car, typically 12 - 15 volts DC. The amplifier’s output stage cannot swing voltages that exceed the upper limit commonly referred to as the voltage “rails”, as in locomotive train tracks. If the input signal is driven to high levels, the outputs try to follow this path but crash into the “rails” thus turning musical sine waves into very unmusical square waves. Here is where your new Blaupunkt VELOCITY amplifier is uniquely impressive.

The Blaupunkt VELOCITY series of amplifiers have a very unique feature called Distortion Limiting (*THD*L) which tolerates high input voltage levels but prevents ugly sounding distortion products common to nearly all other amplifiers. An input voltage sensing network looks at the incoming signal and adjusts the feed-through gain of the amplifier so quickly that high level bass notes cannot drive the amp into distortion yet lower signal level mid and high frequencies pass throu without gain modification. This is done within milliseconds, so “gain pumping” acoustical byproducts of inexpensive audio limiters are never encountered. Below is a visual description of a high level audio signal passing through a typical car audio amplifier and then through the new Blaupunkt VELOCITY amplifiers: 

*THD*L monitors the input signal, and adjusts the feed-through gain levels automatically, regardless of bass, treble, loudness, or gain settings on the amp. The amplifier is not allowed to clip off the tops of sine waves, which create unwanted harmonic frequencies. This operation, much like a rev-limiter on a high performance car engine, allows the amp to be run up to a certain level, then holds, or "limits", the gain. There is no detrimental effect; just wide-open sound levels without the distortion.










http://autosound21.co.kr/shop/board_data/automanual/blaupunkt-amp-v7000-manual.pdf

I think amps that do better at dealing with these variables are going to sound different. While magazine tests are not the authority on reality, I have to say that the Velocity V7000 was highly touted for its overall multi-channel power output, features, price, etc. in a comparison test years ago in CA&E mag. The other amps in the test were the a/d/s 850MX, Audio Art 340.6XE, Blade SE-56, Earthquake PA-6050C and the McIntosh MC440. 



> The Blaupunkt V7000 has everything most car audio systems would ever need. Effective noise reduction at low levels and effective distortion limiting at high levels makes it sound better with imperfect sources AND when pushed beyond its limits. You can't ask for more than that.


I think the fact that that old Blaupunkt Velocity dealt with some of the variables that make amps sound different made it stand out from the crowd.


----------



## cvjoint

subwoofery said:


> EUREKA!!!!! I got my answer...
> 
> Your post made me think especially with this sentence: _"The real question is, what is the baseline?" _
> 
> That's why I looked at my .pdf files and use google translate for the little comment below the plots. From my understanding, the baseline is the noise floor. It's when distortion is above the noise floor that it affects the sound...
> 
> Below is the measured (from the mag) S/N ratio (called background noise) and the translated comment for each amp:
> Mosconi - 96dB
> _Typical distortion spectrum for an amplifier in Class A operation_
> Zapco - 93dB
> _Quite discordant distortion spectrum with low background noise_
> Brax - 90dB
> _clean distortion components falling, higher than K3 K2_
> Sinfoni - 95dB
> _Homogeneous decaying distortion content, K2, K4, K6, as high as K3, K5, K7_
> DLS RA - 98dB
> _Very low noise floor, slightly increases K2 harmonic distortion that extremely harmoniously inclined_
> Audison - 90dB
> _Constant sloping THD, low background noise_
> Focal - 79dB
> _Elevated background noise, which is mainly due to the use of a DSP chip_
> DLS TA2 - 88dB
> _Relatively low background noise in relevant range, higher straight harmonic distortion_
> 
> From my understanding, the plot shows harmonic distorsion where K2, K4, K6 is even and K3, K5, K7 is odd.
> 
> You can clearly see that on the Mosconi, Sinfoni, DLS RA & Audison ; harmonic distortion is clearly above the noise floor.
> 
> Kelvin
> 
> PS: Was not able to translate the below-plot-comment on the XD400/4 but here's for the XD600/6: _Very restless distortion spectrum, typical of a Class D amplifier._
> Dunno if it's due to a not-so-good design or as you stated due to tighter arrangement...


Close. I think the proper way to interpret those is in reference to the fundamental, not the noise level. Noise is tested in different plots. Think of 0db as the pure test tone reproduced. If you feed the amplifier 50hz signal at 120db it will also reproduce harmonics. The second harmonic would be 100hz and it be -50db in reference to the fundamental (here 70db). The power in watts must be fixed in these HD vs. Frequency plots I just can't find what it is. It's a 2 dim graph of a 3dim problem but anywho, better than nothing. 



bikinpunk said:


> I'm digging these test links. Keep em coming.
> 
> George, has anyone benched the HD vs XD that you know of?


That German magazine talked about testing the HD previously but I couldn't find it. I imagine it's the same as XD with maybe slightly better noise readings and extra 200w on one of the channels (5 channel). You have to really be indifferent to spending $400 vs $800 to want the HD.


----------



## cvjoint

WLDock said:


> Wow, that discussion took me back to thinking about the technology used in the old Blaupunkt Velocity V7000 amp I had years ago. They used a technology taken from the pro sound company Rocktron: HUSH® Noise Reduction and *THD*L Distortion Limiting circuitry to deal with some of the factors that all amps exhiibit.
> 
> *HUSH® Noise Reduction*
> Originally developed for pro audio use, the HUSH® noise reduction system is capable of reducing noise from all audio sources, AM, FM, tape, and even background noise on analog recorded CD's. HUSH® will also reduce noise that plagues car audio systems, such as alternator whine and noise from automobile computers. The HUSH® feature comes with a variable threshold level that can be fine-tuned at any time with the optional RM-1 remote control.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> *Distortion Limiting (THDL)*
> WHAT IS AN AMPLIFIER?...
> An amplifier, by definition, is a device that receives a small audio signal on its input and reproduces it with larger voltages (or current) on its output. Ideally there should be no internal modifications of the signal other than voltage or current level. If there are any changes in the signal character it is considered a “distortion” of the input signal.
> 
> A perfect amplifier will be able to reproduce any output voltage regardless of input signal level, but this is impossible due to upper limits created by the voltages found in a car, typically 12 - 15 volts DC. The amplifier’s output stage cannot swing voltages that exceed the upper limit commonly referred to as the voltage “rails”, as in locomotive train tracks. If the input signal is driven to high levels, the outputs try to follow this path but crash into the “rails” thus turning musical sine waves into very unmusical square waves. Here is where your new Blaupunkt VELOCITY amplifier is uniquely impressive.
> 
> The Blaupunkt VELOCITY series of amplifiers have a very unique feature called Distortion Limiting (*THD*L) which tolerates high input voltage levels but prevents ugly sounding distortion products common to nearly all other amplifiers. An input voltage sensing network looks at the incoming signal and adjusts the feed-through gain of the amplifier so quickly that high level bass notes cannot drive the amp into distortion yet lower signal level mid and high frequencies pass throu without gain modification. This is done within milliseconds, so “gain pumping” acoustical byproducts of inexpensive audio limiters are never encountered. Below is a visual description of a high level audio signal passing through a typical car audio amplifier and then through the new Blaupunkt VELOCITY amplifiers:
> 
> *THD*L monitors the input signal, and adjusts the feed-through gain levels automatically, regardless of bass, treble, loudness, or gain settings on the amp. The amplifier is not allowed to clip off the tops of sine waves, which create unwanted harmonic frequencies. This operation, much like a rev-limiter on a high performance car engine, allows the amp to be run up to a certain level, then holds, or "limits", the gain. There is no detrimental effect; just wide-open sound levels without the distortion.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> http://autosound21.co.kr/shop/board_data/automanual/blaupunkt-amp-v7000-manual.pdf
> 
> I think amps that do better at dealing with these variables are going to sound different. While magazine tests are not the authority on reality, I have to say that the Velocity V7000 was highly touted for its overall multi-channel power output, features, price, etc. in a comparison test years ago in CA&E mag. The other amps in the test were the a/d/s 850MX, Audio Art 340.6XE, Blade SE-56, Earthquake PA-6050C and the McIntosh MC440.
> 
> 
> 
> I think the fact that that old Blaupunkt Velocity dealt with some of the variables that make amps sound different made it stand out from the crowd.


The noise block I don't understand. 

The second feature is nothing more than a clip protection. These vary by manufacturer, JLs reduces volume while others cut it completely. If you don't run your amp near the edge this won't matter. The picture is also wrong in that at any wattage level every amp still produces harmonics, it doesn't have to be clipping or running near the edge.

I think the biggest difference in amplifiers is first marketing second performance.


----------



## ChrisB

cvjoint said:


> I think the biggest difference in amplifiers is first marketing second performance.


A HUGE X2 on this statement! You'd be amazed what one will hear if they believe the marketing jargon because I once did myself. Sadly, I discovered the truth after performing many extensive listening tests, in my house, on a test bench. With the exception of certain old school brands that intentionally colored the sound through equalization and distortion, most decent amplifiers were impossible to tell apart after performing proper level matching.


----------



## subwoofery

cvjoint said:


> Close. I think the proper way to interpret those is in reference to the fundamental, not the noise level. Noise is tested in different plots. Think of 0db as the pure test tone reproduced. If you feed the amplifier 50hz signal at 120db it will also reproduce harmonics. The second harmonic would be 100hz and it be -50db in reference to the fundamental (here 70db). The power in watts must be fixed in these HD vs. Frequency plots I just can't find what it is. It's a 2 dim graph of a 3dim problem but anywho, better than nothing.


Hmm... Not sure what I'm supposed to think... 

I know that you need the fundamental in order to have harmonics but in the translated part, they do talk about the *background noise* = *S/N ratio* and about the harmonics - no mentioning of the fundamentals... 

I'm still confident that those plots explain why people hear differences between amps... 
Sure 80% of todays amps don't produce harmonics high enough to be noticeable and could probably be made to sound the same with proper gain settings - while the remaining 20% do sound different. 

Found a good read from searching over the internet for "distortion spectrum": 
Distortion Feedback (starts page 4) 

Those of us that are using horns, differences can really be heard and a more powerful amp doesn't always mean the best sounding... From experience, that's what I believe. 

Kelvin


----------



## cvjoint

subwoofery said:


> Hmm... Not sure what I'm supposed to think...
> 
> I know that you need the fundamental in order to have harmonics but in the translated part, they do talk about the *background noise* = *S/N ratio* and about the harmonics - no mentioning of the fundamentals...
> 
> I'm still confident that those plots explain why people hear differences between amps...
> Sure 80% of todays amps don't produce harmonics high enough to be noticeable and could probably be made to sound the same with proper gain settings - while the remaining 20% do sound different.
> 
> Found a good read from searching over the internet for "distortion spectrum":
> Distortion Feedback (starts page 4)
> 
> Those of us that are using horns, differences can really be heard and a more powerful amp doesn't always mean the best sounding... From experience, that's what I believe.
> 
> Kelvin


You need a fundamental frequency to produce a harmonic...

I'm ready for you to show me some amplifiers tests that have bad enough distortion to be in the audible range, without clipping.


----------



## ErinH

To discuss THD audibility, we need to have some meaningful number as to what levels down non-linear distortion can be heard.
If you take the Klippel auralization test you'll find (at the end) the typical value of audible distortion is near the -12dB mark. Past that, the success value of hearing distortion drops significantly. I've pretty much benchmarked my studies for distortion audibility at -30dB. 
Furthermore, the ability to detect distortion varies with frequency itself so we have to be careful of using a single number to describe audible distortion. Then as you become accustomed to the sound you also become a better listener and you can pick out distortion more easily.

I've seen numbers as low as 1% published as the threshold. However, I don't recall seeing frequency bands attributed to it. I've also seen reports stating as high as 4% with "piano music" and x% with all other types (whatever that really encompasses). 

Then there's FR which is an animal of itself. Luckily, most amps don't seem to stray far from a pretty flat 20-20khz reproduction.

There's a whole lot of misc data out there and I really wish I had the time to gather it all up and present it to you guys so you could draw your own conclusions. Sadly, I barely have enough time to post this reply anymore.

- Erin


----------



## ChrisB

cvjoint said:


> You need a fundamental frequency to produce a harmonic...
> 
> I'm ready for you to show me some amplifiers tests that have bad enough distortion to be in the audible range, without clipping.


I measured a few with Rightmark through my Countryman Direct Box:

First off, this is how the Countryman measures:









Here was a Zapco Z100S2:









Rockford Fosgate Power 351S:









And a mystery amp that has a cult like following where the users swear they hear stuff in their music that they never noticed before:









At first, I thought it was a mistake, but multiple runs with the mystery amplifier revealed distortion that crossed the audible threshold along with a nice little EQ curve. Now I know why everyone swears by the "sound" of this particular brand of amplifier.


----------



## subwoofery

bikinpunk said:


> To discuss THD audibility, we need to have some meaningful number as to what levels down non-linear distortion can be heard.
> If you take the Klippel auralization test you'll find (at the end) the typical value of audible distortion is near the -12dB mark. Past that, the success value of hearing distortion drops significantly. I've pretty much benchmarked my studies for distortion audibility at -30dB.
> Furthermore, the ability to detect distortion varies with frequency itself so we have to be careful of using a single number to describe audible distortion. Then as you become accustomed to the sound you also become a better listener and you can pick out distortion more easily.
> 
> I've seen numbers as low as 1% published as the threshold. However, I don't recall seeing frequency bands attributed to it. I've also seen reports stating as high as 4% with "piano music" and x% with all other types (whatever that really encompasses).
> 
> Then there's FR which is an animal of itself. Luckily, most amps don't seem to stray far from a pretty flat 20-20khz reproduction.
> 
> There's a whole lot of misc data out there and I really wish I had the time to gather it all up and present it to you guys so you could draw your own conclusions. Sadly, I barely have enough time to post this reply anymore.
> 
> - Erin


Found that: Human Hearing - Distortion Audibility Part 3 — Reviews and News from Audioholics 

Kelvin


----------



## ErinH

first off:
you're gonna have to come off the name of the mystery amp

secondly:
What I really would like to see is measurements at incremental gain adjustments. 

Real world:
I'd love to see these same measurements in #2 with ALL channels loaded down.


----------



## ErinH

subwoofery said:


> Found that: Human Hearing - Distortion Audibility Part 3 — Reviews and News from Audioholics
> 
> Kelvin


Yep! I need to save that off while I'm thinking about it. 


My post above still stands. Now we just have the site to back it up.


----------



## subwoofery

ChrisB said:


> And a mystery amp that has a cult like following where the users swear they hear stuff in their music that they never noticed before:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> At first, I thought it was a mistake, but multiple runs with the mystery amplifier revealed distortion that crossed the audible threshold along with a nice little EQ curve. Now I know why everyone swears by the "sound" of this particular brand of amplifier.


Wonder what it takes to achieve THD as high as the principles (like in that last pic)... High bias towards Class B? 

Kelvin


----------



## cvjoint

Great post! The Rockford looks terrible, and of course so does the mystery amp. 
What power did you test these at? I mean if it's 1/1000 watt or at clipping it still doesn't prove anything. Looking good so far. Do you think magazines don't post the bad ones? Because I haven't seen one.


----------



## ChrisB

cvjoint said:


> Great post! The Rockford looks terrible, and of course so does the mystery amp.
> What power did you test these at? I mean if it's 1/1000 watt or at clipping it still doesn't prove anything. Looking good so far. Do you think magazines don't post the bad ones? Because I haven't seen one.


It's whatever Rightmark syncs at through the Countryman which is hard to pin point during the initial testing. I guess I could take an average reading of the synchronization pulses at the amplifier outputs with a DMM since I know the resistance. Only problem, the mystery amp is back with its rightful owner and the Zapco was recently sold.


----------



## ChrisB

bikinpunk said:


> first off:
> you're gonna have to come off the name of the mystery amp


I would, but I would just be accused of bashing, yet again while being biased. I bet I could video the test and still be accused of doing something to skew the results by the nuthuggers. 



bikinpunk said:


> secondly:
> What I really would like to see is measurements at incremental gain adjustments.


That's tough to pull of since Rightmark is so precise with the calibration signal. Raise amplifier gain, lower input gain, pray you don't see clip lights on the MobilePre when the test runs. If I see clip lights, start over again. 



bikinpunk said:


> Real world:
> I'd love to see these same measurements in #2 with ALL channels loaded down.


All channels are always loaded down, even though Rightmark only measures one. What I do is flip things around to measure the other one.

Dang, you just made me think of another test to try. Bridged mono to see if THD changes on the graph.


----------



## gnesterenko

cvjoint said:


> If you are going to hear any distortion from amplifiers odds are it would be that tube amp you want


That is what I was getting at, actually. For some reason or another, the human ear perceives the harmonics produced by tube amps as, as I said, "warm" - whatever THAT means. I guess my impression was that class A/B's come closer to tubes in this respect then D's?

Either way, other points made here are good points - in a car environment there are a multitude of factors that have a far greater impact on the overall sound quality, thus worrying about A/B vs D distinctions is a bit moot?


----------



## WLDock

cvjoint said:


> The noise block I don't understand.


The HUSH circuitry was actually pretty effective at cleaning up low level noise without messing up the original signal. Like a noise gate but a little more effective and natural. Also, the fact that you could adjust the level with a remote was a plus.




cvjoint said:


> The second feature is nothing more than a clip protection. These vary by manufacturer, JLs reduces volume while others cut it completely. If you don't run your amp near the edge this won't matter. .


Not all amps have clipping cicutry. I know that JL's Single Cycle Control tracks the input signal and makes corrections. Also, the SLASH amps have the Absolute Symmetry Circuit that keeps distortion low. _"Some of them have a soft-clipping circuit... but all of them will clip when overdriven, like any other amp.The only way to protect against clipping is via a limiter.".. _ Those are direct words from Manville Smith. Still, lets not kid ourselves...car audio amps get abused. Many run their amps near the edge. 



cvjoint said:


> The picture is also wrong in that at any wattage level every amp still produces harmonics, it doesn't have to be clipping or running near the edge..


I think the point of the graph was that at normal levels harmonics are small.(Even you said: " _I'm ready for you to show me some amplifiers tests that have bad enough distortion to be in the audible range, without clipping.") _However, at clipping the levels jump up quite a bit. 



cvjoint said:


> I think the biggest difference in amplifiers is first marketing second performance..





ChrisB said:


> A HUGE X2 on this statement! You'd be amazed what one will hear if they believe the marketing jargon because I once did myself. Sadly, I discovered the truth after performing many extensive listening tests, in my house, on a test bench. With the exception of certain old school brands that intentionally colored the sound through equalization and distortion, most decent amplifiers were impossible to tell apart after performing proper level matching.


I think you guys missed the point I was making in that the Blaupunkt Velocity amps date back 17 years. The amp was compared to other class A/B amps and it stood out over amps like the McIntosh that has its own "Power Guard Circuit" that prevents clipping. The features of the Velocity amps were not marketing gimmicks and they actually worked. Having tested the HUSH circuit while listening to FM radio and cassettes it did a good gob on low level noise. Also, having maxed out a system listening to House Music and Rap CD's, I can say that the distortion limiting circuit was effective. While many amps today have digital circuits that do this type of thing....many still don't!

While most amps sound the same at normal levels..we know that not all amps sound the same under all circumstances. Amps that better deal with the artifacts that make amps sound different are going to sound different...or better. That is why the JL class D amps sound better than some other class D amps...and why some companies realized this years ago with class A/B amps like the Blaupunkt & McIntosh.

During a indoors listening session with others present we heard a difference between two amps in regards to staging, imaging and overall quality of the sound. Maybe our setup approach was not scientfic enough? Therefore, I am convinced that in a car there are going to be many other factors that will effect the sound given the tough environment. Therefore, amps that better deal with noise and distortion are going to sound better...and as we have all seen...results vary!

So amp classes/topology is probably not as important as in-vehicle frequency response and distortion at high output, etc...


----------



## tnbubba

yep cars suck.. my orginal comment was I use my home system to judge the SQ of ANY 12V amp before it goes into my vehicle.. and to see how it compare to very good 120/240V systems. FYI ALL my HOME amps are run off 240! My sub amp is a hyrbrid Crown K2 .. ther rest are all class A or A/B.. most are biased Class A to 25 W or more so plenty to boogie with. Do any of the 12V amps compare... Very Very few.!!! I have not had the chance to listen critically to all amps but having been in the music businees and knowing score of musicians who still use my system for eval... I'm not changing amps until I can afford the HALCRO's! and I've had everything from Krells to mccormacks to ayre's... I've heard the new JL and they are not bad.. but certianlly not in A/B class on my system and not up to many of the A/B 12v amps I've heard. Now granted my system is 4 way active.. so the amps have an easy load to drive.. and it's kinda hard to find (3) Macs to test all at once so we usually replace one amp at a time and evaluate. just FYI


----------



## cvjoint

ChrisB said:


> That's tough to pull of since Rightmark is so precise with the calibration signal. Raise amplifier gain, lower input gain, pray you don't see clip lights on the MobilePre when the test runs. If I see clip lights, start over again.


That troubles me. The wattage at which you are testing is a must known parameter. Amplifier distortion skyrockets on the last few watts even before clipping. How do you know you are not testing one amp at 1 w and another at 99% of its capabilities? Really not comparable. It may explain what happened to the mystery amp, different calibration. 



gnesterenko said:


> That is what I was getting at, actually. For some reason or another, the human ear perceives the harmonics produced by tube amps as, as I said, "warm" - whatever THAT means. I guess my impression was that class A/B's come closer to tubes in this respect then D's?
> 
> Either way, other points made here are good points - in a car environment there are a multitude of factors that have a far greater impact on the overall sound quality, thus worrying about A/B vs D distinctions is a bit moot?


The big picture is that if you look at anywhere in the audible range all classes are usually so squeaky clean you couldn't hear harmonics (even order are generally warm from what I gather). If there are class differences the patterns are not obvious or important in harmonic distortion. Caveat don't stress your amp near the limits, buy more power than you need. 

Now, I did find one test where there would be an audible difference between an average Class D and the rest of the classes but I'll hold up on revealing it for now. 




WLDock said:


> The HUSH circuitry was actually pretty effective at cleaning up low level noise without messing up the original signal. Like a noise gate but a little more effective and natural. Also, the fact that you could adjust the level with a remote was a plus.
> 
> 
> Not all amps have clipping cicutry. I know that JL's Single Cycle Control tracks the input signal and makes corrections. Also, the SLASH amps have the Absolute Symmetry Circuit that keeps distortion low. _"Some of them have a soft-clipping circuit... but all of them will clip when overdriven, like any other amp.The only way to protect against clipping is via a limiter.".. _ Those are direct words from Manville Smith. Still, lets not kid ourselves...car audio amps get abused. Many run their amps near the edge.
> 
> I think the point of the graph was that at normal levels harmonics are small.(Even you said: " _I'm ready for you to show me some amplifiers tests that have bad enough distortion to be in the audible range, without clipping.") _However, at clipping the levels jump up quite a bit.
> 
> 
> I think you guys missed the point I was making in that the Blaupunkt Velocity amps date back 17 years. The amp was compared to other class A/B amps and it stood out over amps like the McIntosh that has its own "Power Guard Circuit" that prevents clipping. The features of the Velocity amps were not marketing gimmicks and they actually worked. Having tested the HUSH circuit while listening to FM radio and cassettes it did a good gob on low level noise. Also, having maxed out a system listening to House Music and Rap CD's, I can say that the distortion limiting circuit was effective. While many amps today have digital circuits that do this type of thing....many still don't!
> 
> While most amps sound the same at normal levels..we know that not all amps sound the same under all circumstances. Amps that better deal with the artifacts that make amps sound different are going to sound different...or better. That is why the JL class D amps sound better than some other class D amps...and why some companies realized this years ago with class A/B amps like the Blaupunkt & McIntosh.
> 
> During a indoors listening session with others present we heard a difference between two amps in regards to staging, imaging and overall quality of the sound. Maybe our setup approach was not scientfic enough? Therefore, I am convinced that in a car there are going to be many other factors that will effect the sound given the tough environment. Therefore, amps that better deal with noise and distortion are going to sound better...and as we have all seen...results vary!
> 
> So amp classes/topology is probably not as important as in-vehicle frequency response and distortion at high output, etc...


Good points on the Blaupunkt. For the average Joe in car audio a trick clip protection is very valuable indeed. But for the few of us who understand that being remotely close to clipping is no good it's really not a variable. I always buy more power than I'll ever need.

The noise gate I still don't understand how it works. My guess is it trades off efficiency at low output for a good S/N, if so, brilliant! A good S/N ratio is probably the second most important aspect of an amplifier after meeting good power benchmarks on the test bench. 

If class differences do exist, they would be exhibited in the tests if they are comprehensive enough. That's a big IF, and my biggest holdout on not buying class D. Having said that, I might switch to class D soon, most of the modern class D amp tests meet all of RC's conditions for sounding the same.


----------



## sqshoestring

To simplify a noise gate just turns off the signal when it is under a certain dB, a very low dB, in other words when no signal is present but noise it turns it off. Once you have a signal you usually can't hear the noise under it. There are also filters that cut low dB 'noise' sounds. With digital music this is not really an issue anymore, unless your amps are gained up so much they make noise. Analog recordings of course had problems with this.

Someone once told me customers don't like limiting, because amps clip way sooner than they think, and that is why most amps don't have it.

Tube amps soft clip, it rounds off the peak and has much different harmonics. Some other amps can simulate this, many amps just don't worry a lot about it since you are above the capability of the amp anyway....buy a larger amp. Limiting has been used in pro audio for a long time.


----------



## cvjoint

sqshoestring said:


> To simplify a noise gate just turns off the signal when it is under a certain dB, a very low dB, in other words when no signal is present but noise it turns it off. Once you have a signal you usually can't hear the noise under it. There are also filters that cut low dB 'noise' sounds. With digital music this is not really an issue anymore, unless your amps are gained up so much they make noise. Analog recordings of course had problems with this.
> 
> Someone once told me customers don't like limiting, because amps clip way sooner than they think, and that is why most amps don't have it.
> 
> Tube amps soft clip, it rounds off the peak and has much different harmonics. Some other amps can simulate this, many amps just don't worry a lot about it since you are above the capability of the amp anyway....buy a larger amp. Limiting has been used in pro audio for a long time.


Great post. I see now why it comes with an adjustment knob. I suppose I would set it to where it cuts noise only when there is absolutely no signal present. Otherwise I can see how this can cut program material that is rather subdued. I imagine you would also want to set it at the lowest setting with very sensitive drivers.


----------



## GS3

subwoofery said:


> Wonder what it takes to achieve THD as high as the principles (like in that last pic)... High bias towards Class B?
> 
> Kelvin


anyone know what is the mystery amp. he is referring to? i'm curious to know.


----------



## subwoofery

GS3 said:


> anyone know what is the mystery amp. he is referring to? i'm curious to know.


Just try to search for some threads that ChrisB created. The information might still be there. 

Kelvin 

PS: to everyone, no need to PM me... I won't tell


----------



## GS3

subwoofery said:


> Just try to search for some threads that ChrisB created. The information might still be there.
> 
> Kelvin
> 
> PS: to everyone, no need to PM me... I won't tell


if thats the case, then i have a strong sense of what amp it is. lol


----------



## WLDock

ChrisB said:


> I would, but I would just be accused of bashing, yet again while being biased. I bet I could video the test and still be accused of doing something to skew the results by the nuthuggers.





subwoofery said:


> Just try to search for some threads that ChrisB created. The information might still be there.
> Kelvin
> PS: to everyone, no need to PM me... I won't tell


I did...and only found more mystery amp posts. So....what is the mystery all about? Is this brand owned by some bad guys that will hunt you down and take you out for posting measurments of their amps? ChrisB, if you really feel that way....why show the names of any of the amps? I guess you are not bothered by Rockford and its nut hugging crew....oh wait! They are not an esoteric mega buck brand....sorry! Forget I said that.


----------



## adrenalinejunkie

So... What's the mystery amp?


----------



## ErinH

I'm gonna start posting driver data and not telling you guys what it is.


----------



## ChrisB

I've been labeled a basher and hater of the mystery amp brand along with the modification BS snake oil sold by the tech that maintains them. I'd be plum crazy to say anything more about the ear candy that intentionally colors the sound. 

If you can't figure it out from the hint I just dropped, well, that's all you are getting out of me.


----------



## ErinH

Do you have any idea what I went through when I started testing speakers? Data is data. Post it up if it makes us smarter. Otherwise don't post anything. Don't let a company dictate what you do. As long as you can validate your measurements you have nothing to worry about.


----------



## ChrisB

bikinpunk said:


> Do you have any idea what I went through when I started testing speakers? Data is data. Post it up if it makes us smarter. Otherwise don't post anything. Don't let a company dictate what you do. As long as you can validate your measurements you have nothing to worry about.


Only issue is I no longer have access to the amplifier to perform further testing. The owner sold it shortly after the test because he didn't like the built-in eq curve. 

Making matters worse, it took a lot of futzing to get the measurements as good as I posted them. Carrying over the settings from the Power 351s on the M-Audio USBMobilePre with the same dummy loads resulted in a worse distortion profile out of the modified 1502IQ. The EQ curve was essentially the same at all output levels but we had to keep dropping the gain to get the distortion lower. In speaking with another engineer, he told me that distortion profile is there to emulate tube saturation and said it was perfectly normal to have it above the signal threshold. Furthermore, he stated that is why many like the sound of that particular brand. 

On the flip side, I now know why the brand as a whole had a different sound and why the cult followers swear that they hear details in their music that they never heard before. It's because the amplifier is adding those details! Oh well, at least I can chalk it up as a life lesson of making a mistake and learning from it.


----------



## Hillbilly SQ

ChrisB said:


> Only issue is I no longer have access to the amplifier to perform further testing. The owner sold it shortly after the test because he didn't like the built-in eq curve.
> 
> Making matters worse, it took a lot of futzing to get the measurements as good as I posted them. Carrying over the settings from the Power 351s on the M-Audio USBMobilePre with the same dummy loads resulted in a worse distortion profile out of the modified 1502IQ. The EQ curve was essentially the same at all output levels but we had to keep dropping the gain to get the distortion lower. In speaking with another engineer, he told me that distortion profile is there to emulate tube saturation and said it was perfectly normal to have it above the signal threshold. Furthermore, he stated that is why many like the sound of that particular brand.
> 
> On the flip side, I now know why the brand as a whole had a different sound and why the cult followers swear that they hear details in their music that they never heard before. It's because the amplifier is adding those details! Oh well, at least I can chalk it up as a life lesson of making a mistake and learning from it.


You just described the amp I have on my frontstage right now but it ain't ell pee. I'd love to get this thing tested to see if the objective data shows what my subjective ears are hearing. I'm serious. Erin are you set up for that? ChrisB already said he didn't want the responsibility.


----------



## envisionelec

Hillbilly SQ said:


> You just described the amp I have on my frontstage right now but it ain't ell pee. I'd love to get this thing tested to see if the objective data shows what my subjective ears are hearing. I'm serious. Erin are you set up for that? ChrisB already said he didn't want the responsibility.


You just want a frequency response curve? 

I have a $15,000 spectrum analyzer in my office that was calibrated this week. 

PM me if you're interested.


----------



## envisionelec

ChrisB said:


> Only issue is I no longer have access to the amplifier to perform further testing. The owner sold it shortly after the test because he didn't like the built-in eq curve.
> 
> Making matters worse, it took a lot of futzing to get the measurements as good as I posted them. Carrying over the settings from the Power 351s on the M-Audio USBMobilePre with the same dummy loads resulted in a worse distortion profile out of the modified 1502IQ. The EQ curve was essentially the same at all output levels but we had to keep dropping the gain to get the distortion lower. In speaking with another engineer, he told me that distortion profile is there to emulate tube saturation and said it was perfectly normal to have it above the signal threshold. Furthermore, he stated that is why many like the sound of that particular brand.
> 
> On the flip side, I now know why the brand as a whole had a different sound and why the cult followers swear that they hear details in their music that they never heard before. It's because the amplifier is adding those details! Oh well, at least I can chalk it up as a life lesson of making a mistake and learning from it.


From the Ell Pee's that I have tested - most had copious amounts of crossover distortion and one had the lowest performing crosstalk measurements I'd ever seen. Crossover distortion is even order, not at all "tube like" which is primarily odd-order.

The amplifier was functioning properly and the bias was set correctly - it was just bad design.


----------



## WLDock

ChrisB said:


> I've been labeled a basher and hater of the mystery amp brand along with the modification BS snake oil sold by the tech that maintains them. I'd be plum crazy to say anything more about the ear candy that intentionally colors the sound.
> 
> If you can't figure it out from the hint I just dropped, well, that's all you are getting out of me.


Oh, Linear Power...that is all you had to say!

As far as amp modifications....I'm sure if one did a side-by-side, in some cases differences might be seen. other than that....it might be hard to tell if there is a long time diffeence between listening sessions.

Myself, I picked up a used Genesis Series III Four Channel on ebay. The amp needed work so I had it refurbed by the Gordon(former Genesis head guru) a.k.a The Amp Doctor. In the process he asked if I wanted the input stage upgraded and the bias accurately set. I went ahead and had it done at an additional cost of about $65. This is all that was done to my amp:




Gordon - The Amp Doctor said:


> Hi Walter,
> I will upgrade the preamp for you and set the bias individually for each channel of the power amp. The standard chips are TL074's, a nice smooth sounding chip, however the LME49740 we replace them with is a step up in every aspect - lower distortion, better dynamics and lower noise, more detail.
> 
> Setting the bias with a distortion analyser minimises distortion at normal listening levels by running the output stage in Class A at low levels with a gradual transition to class AB. The amp chassis runs a little warmer however only by 20 degrees C or so.


Did it make a difference? I dont know? But I did compared the amp to a PG Xenon 4 ch powering a set of fullrange drivers, which by the way is a very nice amp. All I will say is that the amps sounds really good...and there were some slight differences compared to the Xenon. I can't wait to get my system finished...as I stated previously I will add a JL HD900/5 for a hybrid combo. IMO, I have the best of both worlds and will have just under $1k invested in two amps. Unless these puppies die and can't be repaired, or I have too many issue wih EMI/RFI from the HD, I don't see changing amps for a very long time.


----------



## ChrisB

envisionelec said:


> From the Ell Pee's that I have tested - most had copious amounts of crossover distortion and one had the lowest performing crosstalk measurements I'd ever seen. Crossover distortion is even order, not at all "tube like" which is primarily odd-order.
> 
> The amplifier was functioning properly and the bias was set correctly - it was just bad design.


Thanks for correcting me on that one. I think I may have screwed the engineer speak up because I was on beer number 5 or 6 when we had the conversation. The point he may have been trying to make was that some people just like the Linear Power distortion similar to how audiophiles like tube distortion. I tend to remember something else thrown in there about the power supply falling on its face near clipping causing the amp to "cut out" sound and that may have been what he meant about the "tube like" soft clipping sound. I'd have to call him again and ask prior to Abita Springs time, lol.

On the flip side, all testing is usually performed alcohol free. I could tell the story about where I let one of my friends reverse polarity his amp after drinking a few too many, but that's another story for another thread.:laugh:


----------



## Hillbilly SQ

envisionelec said:


> You just want a frequency response curve?
> 
> I have a $15,000 spectrum analyzer in my office that was calibrated this week.
> 
> PM me if you're interested.


I'm wanting a distortion test too. I may or may not be getting artifacts in the sound as well. I recently replaced my old sun baked with hardened glue around the surround and cone for icing x2's with a fresh set of x2's. Can't believe the old ones lasted as long as they did with the record breaking summer we had down here. Two years in the dash! Shipping would cost a fortune but if I ever get really curious I'll sure let you know and thanks for the offer.


----------



## sqshoestring

Ah the LPs. Some spread it on thick these days. Great amp for some things, not so great for others. If you want clean accurate SQ I suggest you run maybe a SS D200 for mids and 100 or 60 on highs, whatever on sub. The LP were always good on sub compared to similar amps at the time, a LP2002 would hammer a SS D200 for plain power output. But back then many amps without T03 were considered junk because they just didn't perform. Of course they got better in the 90s, and it may not have had that much to do with what kind of transistors they used it just seemed that way.

I never used IQs but the older T03 LP always sounded tube-like to me, maybe more so when operated with alcohol lol.

Some amps did use a weak power supply on purpose, to protect the outputs. Actually I often thought it worked better than massive clipping.


----------



## AKheathen

omg, i just wasted so much time reading about home audio, and other NOT MOBILE AUDIO OR CLASS-D disc in this thread...and i only got to page 3....... well, if it's been posted, i'm sorry, but i'm going to skip to my pov on the subject, since i spent the time to search this thread out to discuss. plain and simple, class-d is specifically a class of the output stage, not the power supply, or signal processing. commonly, there is also other things used, adn i've even seen it reffered to as the same in a post ("class d blah blah, and it's pwm"......) well hold it right there. pwm is a whole other factor all in it's own., we shall call it "class between a/b and d" the biggest myth problem comes from the classification going from describing the power supply type, to describing the output type. now, i'm also getting tired of hearing about dick clark's stupid fixed contest, but he would probably agree thet the following should happen to see if you can tell the difference on a sub between class d and pre-class-d output circutry. build it modular. one un-regulated or otherwise sable well-built power supply that does not effect the rail voltage to a point that the output is actually effected. then, the same sound processing to feed the different output drives/processors with the same clean signal. then build 2 different ouptout sections to swap out. both having the same rms rating, and signal sensitivity. same sub, and no higher than 200hz, which is well above what i consider sub-duty hz i, too would put money down that you could not hear any difference that class d square-wave pulsed technology makes. i have played with, owned, and heard many, many class-d(and others) amps, and yes, there are several, mostly made from 2003-somewhat recent that i could pick up the "dirty" rail voltage fluctuations, and also several stable ones from the beginning of mainstream class-d -on, that were absolutely awesome and very musical, with the only tale being how much current it would hog.


----------



## slipchuck

this is what I found on an electronics website 
Amplifier Classes



> You should remember:
> Class A amplifiers are very inefficient and produce lots of heat because there is a large amount of current flowing through the output transistors even with no audio signal.
> Class B amplifiers are more efficient but will have a 'notch' distortion.
> Class AB amplifiers are moderately efficient (depending on bias current) but notch distortion is eliminated by the idle (bias) current.
> Class D amplifiers are very efficient but are generally used for non high fidelity or subwoofer applications


hope this helps

randy


----------



## t3sn4f2

slipchuck said:


> this is what I found on an electronics website
> Amplifier Classes
> 
> 
> 
> hope this helps
> 
> randy


This is better........

http://www.diymobileaudio.com/forum/car-audio-truth-myths-industry-dogma/93704-class-d-amplification-can-sound-just-good-true-b.html


----------



## BuickGN

slipchuck said:


> this is what I found on an electronics website
> Amplifier Classes
> 
> 
> 
> hope this helps
> 
> randy


That sounds a little outdated, class D is used in full range high fidelity systems.


----------



## cvjoint

These threads are a disaster. There is probably enough information in any one of them to reach the conclusion that class D can even be better than class AB if designed well enough. However, there is always new blood peddling misconceptions and skipping over lots of insightful posts. There won't be any convergence on the truth until class A/B will be gone from the market completely. 

I'm personally looking forward not only to the extinction of A/B, tube, and A class amps but to the day where the entire signal chain will be digital. No more of this analog bs and A/D, D/A conversions.


----------



## cvjoint

AKheathen said:


> omg, i just wasted so much time reading about home audio, and other NOT MOBILE AUDIO OR CLASS-D disc in this thread...and i only got to page 3....... well, if it's been posted, i'm sorry, but i'm going to skip to my pov on the subject, since i spent the time to search this thread out to discuss. plain and simple, class-d is specifically a class of the output stage, not the power supply, or signal processing. commonly, there is also other things used, adn i've even seen it reffered to as the same in a post ("class d blah blah, and it's pwm"......) well hold it right there. pwm is a whole other factor all in it's own., we shall call it "class between a/b and d" the biggest myth problem comes from the classification going from describing the power supply type, to describing the output type. now, i'm also getting tired of hearing about dick clark's stupid fixed contest, but he would probably agree thet the following should happen to see if you can tell the difference on a sub between class d and pre-class-d output circutry. build it modular. one un-regulated or otherwise sable well-built power supply that does not effect the rail voltage to a point that the output is actually effected. then, the same sound processing to feed the different output drives/processors with the same clean signal. then build 2 different ouptout sections to swap out. both having the same rms rating, and signal sensitivity. same sub, and no higher than 200hz, which is well above what i consider sub-duty hz i, too would put money down that you could not hear any difference that class d square-wave pulsed technology makes. i have played with, owned, and heard many, many class-d(and others) amps, and yes, there are several, mostly made from 2003-somewhat recent that i could pick up the "dirty" rail voltage fluctuations, and also several stable ones from the beginning of mainstream class-d -on, that were absolutely awesome and very musical, with the only tale being how much current it would hog.


The RC challenge is stronger than than your comparison. Simply put it identifies the parameters that have audible consequences and looks across not only topologies but preamps and so on to show that only those parameters matter. Armed with that knowledge and raw data on the parameters of interest you can buy amps that differ not only in topologies but across many other design criterias. The scope of the RC challenge was much greater, and imo decently well done.


----------



## ZAKOH

Such a long thread and not a one link to someone who has done a simple A/B comparison of more recent 4-channel Class A/B and Class D amps for a 2-way active front stage duty..


----------



## kyheng

Can a class D JL Audio HD600/4 sounds better than an Alpine F#1 MRV-F900?
Or can a Lightning Audio LA4200 sounds better than JL Audio HD600/4?
Do we have a fair way to do a comparison for amps on different classes? Nope, we don't... The only way to do a fair comparison are when a company can come out an amp model with 2 different classes....


----------



## t3sn4f2

kyheng said:


> Can a class D JL Audio HD600/4 sounds better than an Alpine F#1 MRV-F900?
> Or can a Lightning Audio LA4200 sounds better than JL Audio HD600/4?
> *Do we have a fair way to do a comparison for amps on different classes? Nope, we don't... The only way to do a fair comparison are when a company can come out an amp model with 2 different classes.*...


----------



## sqshoestring

Its not that complex. In the first class D they could not modulate the outputs fast or well enough to make high frequency in good quality, this is much like a low rate mp3. So they made a lot of sub amps in class D because the modulation was much easier for them. Today electronics are far advanced and anyone can make a class D or buy the technology to make full range sound as good as any other amp. If the rest of the amp is that good is up to the maker, as the class D is only the part that runs the ouputs and filters the output; the rest of the amp and its tonal qualities/build quality are still up to the maker as with any other amp. Class D can meet better specs than a human can hear, if the maker chooses. In fact likely a much more important factor is cost rather than technology. In_ technology_ even a brand new model full range class D amp today is much like a dinosaur turd compared to a common cell phone we've had for many years.


----------



## cvjoint

kyheng said:


> Can a class D JL Audio HD600/4 sounds better than an Alpine F#1 MRV-F900?
> Or can a Lightning Audio LA4200 sounds better than JL Audio HD600/4?
> Do we have a fair way to do a comparison for amps on different classes? Nope, we don't... The only way to do a fair comparison are when a company can come out an amp model with 2 different classes....


If and only if the same "company" means the same everything else. That's a big if when you think how common designs get labeled under different company names and within a company they may adopt a variety of designs. About the only thing the same company guarantees is a matching heatsink nowadays. 

There are of course many ways to have fair comparisons despite that.


----------



## envisionelec

sqshoestring said:


> Its not that complex. In the first class D they could not modulate the outputs fast or well enough to make high frequency in good quality, this is much like a low rate mp3. So they made a lot of sub amps in class D because the modulation was much easier for them. Today electronics are far advanced and anyone can make a class D or buy the technology to make full range sound as good as any other amp. If the rest of the amp is that good is up to the maker, as the class D is only the part that runs the ouputs and filters the output; the rest of the amp and its tonal qualities/build quality are still up to the maker as with any other amp. Class D can meet better specs than a human can hear, if the maker chooses. In fact likely a much more important factor is cost rather than technology. In_ technology_ even a brand new model full range class D amp today is much like a dinosaur turd compared to a common cell phone we've had for many years.


You're really oversimplifying the design aspect here. It's not that today's electronics are more advanced - it's just better understood how to build a quality full range Class D amp. Unfortunately, there are still a lot of very poorly designed units out there - and the car audio manufacturers are often a primary offender. They just do stupid things like mount all four (4 channel amp) inductors parallel to each other causing measurably poor crosstalk. Or they don't pay much attention to the quality of the modulator so distortion numbers suffer.

MP3 is a compression algorithm and is not a good analog to an early Class D amp. It's not as simple as increasing bandwidth - you just can't switch big, high voltage MOSFETs that fast without a dramatic loss in efficiency. Until someone invents a low capacitance 600V MOSFET, you won't be seeing 2kW full range Class D amps.


----------



## cvjoint

envisionelec said:


> You're really oversimplifying the design aspect here. It's not that today's electronics are more advanced - it's just better understood how to build a quality full range Class D amp. Unfortunately, there are still a lot of very poorly designed units out there - and the car audio manufacturers are often a primary offender. They just do stupid things like mount all four (4 channel amp) inductors parallel to each other causing measurably poor crosstalk. Or they don't pay much attention to the quality of the modulator so distortion numbers suffer.
> 
> MP3 is a compression algorithm and is not a good analog to an early Class D amp. It's not as simple as increasing bandwidth - you just can't switch big, high voltage MOSFETs that fast without a dramatic loss in efficiency. Until someone invents a low capacitance 600V MOSFET, you won't be seeing 2kW full range Class D amps.


If I may ask, what are your words of wisdom on the impact of class D filtering on the damping factor? A recent review of the Alpine PDX amplifiers states that they have made major improvements by partially bypassing in some way and gaining better control of the driver. Should I worry at all about >50 df?


----------



## envisionelec

cvjoint said:


> If I may ask, what are your words of wisdom on the impact of class D filtering on the damping factor? A recent review of the Alpine PDX amplifiers states that they have made major improvements by partially bypassing in some way and gaining better control of the driver. Should I worry at all about >50 df?


I would have to read up on the particular design Alpine has implemented. It's possible they decided to use delta-sigma post-inductor feedback. A Class D amp with exceptionally low DF is probably an open-loop design.

I wouldn't worry about DF being greater than 50 (>50). Did you mean <50?? A DF of 100 or greater is generally considered the minimum for direct-coupled solid state amps. But anything over 20 is considered adequate. A low damping factor simply causes a variation in frequency response depending on the type of load connected.


----------



## cvjoint

envisionelec said:


> I would have to read up on the particular design Alpine has implemented. It's possible they decided to use delta-sigma post-inductor feedback. A Class D amp with exceptionally low DF is probably an open-loop design.
> 
> I wouldn't worry about DF being greater than 50 (>50). Did you mean <50?? A DF of 100 or greater is generally considered the minimum for direct-coupled solid state amps. But anything over 20 is considered adequate. A low damping factor simply causes a variation in frequency response - it doesn't cause loose or flabby-sounding bass as the term might imply.


I've seen some class D amps having just over 100 df. I assume that's 4 ohm and it goes down to near 50 at 2 ohm? Ultimately I just want to know if paying to get a higher df than 100 is going to make any difference. When you say the FR is impacted do you mean depending on the source material or full time? If the FR is within 1 db over the audible range when bench tested is that the whole story? 

Here is the part of the interview that talks about the new design, probably not enough to tell you what you want to know:
_JK: For example, back in the day Clark & Navone and others argued that damping factor doesn’t matter, etc. But internally that relates to stability. Tight damping means no impedance modulation, not reactive to kickback from the load.

EG: More a pure voltage source. So even if not a big deal to hear a difference in a steady state, the design implication is that the sound will be better with real music, not directly due to the damping factor but indirectly because of the design.
JK: You can hear it. Take a straight up Class D mono amp with maybe some error correction at the FETs, damping factor will be around 80. Compare to the new generation PDX at over 1000 and you can hear an amazing difference in control. Could be other things as well but the damping is one of them. Especially Class D, since they all have an output filter between the amp and the load. Besides degrading damping, it causes frequency response modulation with dynamic impedances (speakers) if not corrected. That’s where our global modulation core comes in.

EG: So your feedback loop actually extends out past the filter?
JK: Yeah, it includes everything in the correction all the way out to the terminals, that’s a big big difference versus others.
EG: What if you ditch the output filter? The whole switching frequency output voltage would go across the load, but some argue that since speaker’s impedance is very high at those frequencies, the speaker won’t really heat up much. They argue you’d be better off, since you could avoid the huge high frequency peaks those filters always cause with real speakers
JK: Only if you’d want a high power radio transmitter wiping out all reception for blocks! That’s what I’m talking about; our PDX topology doesn’t have the typical Class D high frequency peaks due to the global feedback. Filter resonance has been totally suppressed with zero overshoot. That’s an area of big improvement versus the previous generation PDX. We achieved high frequency bandwidth, perfect transient response, and much lower noise. We also focused on low distortion in the one to ten watt range where fullrange amplifiers usually operate._

Alpine's New PDX and Its Technology - Amplifier Reviews - Car Audio and Electronics


----------



## envisionelec

cvjoint said:


> I've seen some class D amps having just over 100 df. I assume that's 4 ohm and it goes down to near 50 at 2 ohm? Ultimately I just want to know if paying to get a higher df than 100 is going to make any difference. When you say the FR is impacted do you mean depending on the source material or full time? If the FR is within 1 db over the audible range when bench tested is that the whole story?
> 
> Here is the part of the interview that talks about the new design, probably not enough to tell you what you want to know:
> _JK: For example, back in the day Clark & Navone and others argued that damping factor doesn’t matter, etc. But internally that relates to stability. Tight damping means no impedance modulation, not reactive to kickback from the load.
> 
> EG: More a pure voltage source. So even if not a big deal to hear a difference in a steady state, the design implication is that the sound will be better with real music, not directly due to the damping factor but indirectly because of the design.
> JK: You can hear it. Take a straight up Class D mono amp with maybe some error correction at the FETs, damping factor will be around 80. Compare to the new generation PDX at over 1000 and you can hear an amazing difference in control. Could be other things as well but the damping is one of them. Especially Class D, since they all have an output filter between the amp and the load. Besides degrading damping, it causes frequency response modulation with dynamic impedances (speakers) if not corrected. That’s where our global modulation core comes in.
> 
> EG: So your feedback loop actually extends out past the filter?
> JK: Yeah, it includes everything in the correction all the way out to the terminals, that’s a big big difference versus others.
> EG: What if you ditch the output filter? The whole switching frequency output voltage would go across the load, but some argue that since speaker’s impedance is very high at those frequencies, the speaker won’t really heat up much. They argue you’d be better off, since you could avoid the huge high frequency peaks those filters always cause with real speakers
> JK: Only if you’d want a high power radio transmitter wiping out all reception for blocks! That’s what I’m talking about; our PDX topology doesn’t have the typical Class D high frequency peaks due to the global feedback. Filter resonance has been totally suppressed with zero overshoot. That’s an area of big improvement versus the previous generation PDX. We achieved high frequency bandwidth, perfect transient response, and much lower noise. We also focused on low distortion in the one to ten watt range where fullrange amplifiers usually operate._
> 
> Alpine's New PDX and Its Technology - Amplifier Reviews - Car Audio and Electronics



Ok, so it's exactly as I expected. 

The damping factor has to be very low to affect FR in any significant way. Probably 5 or less to be audible. FR variation from low DF is source independent and a function of output impedance only.


----------



## subwoofery

Have a question since you're here _*envisionelec*_

I see some amps have really low input impedance: 
Adcom GFA - 8.5 K Ohms 
Alpine PDx (v.1) - 10 K Ohms 
Brax Graphic - 10 K Ohms
DLS Ultimate A - 10 K Ohms 
Steg MSK - 11 K Ohms 
Harman Kardon TC - 20 K Ohms 

While others have higher numbers: 
Zed Class D - 37 K Ohms
Diamond Audio - 40 K Ohms
Sinfoni - 48 K Ohms 

^ What does it tell you? Maybe it's nothing but I really don't know what the above means :blush: 

Kelvin


----------



## envisionelec

subwoofery said:


> Have a question since you're here _*envisionelec*_
> 
> I see some amps have really low input impedance:
> Adcom GFA - 8.5 K Ohms
> Alpine PDx (v.1) - 10 K Ohms
> Brax Graphic - 10 K Ohms
> DLS Ultimate A - 10 K Ohms
> Steg MSK - 11 K Ohms
> Harman Kardon TC - 20 K Ohms
> 
> While others have higher numbers:
> Zed Class D - 37 K Ohms
> Diamond Audio - 40 K Ohms
> Sinfoni - 48 K Ohms
> 
> ^ What does it tell you? Maybe it's nothing but I really don't know what the above means :blush:
> 
> Kelvin


_*Input *_impedance has _no effect _on output impedance of an amplifier (or anything else, for that matter). It simply states how much of a load it will put on your source (headunit, EQ, etc). 

If you parallel amps with simple splitters, the effective input impedance decreases just like paralleled resistors ([1/R1+1/R2+1/R3]^-1...). Once you hit an effective impedance that equals the output impedance of the source, you've hit the limit for expecting unity gain. Say if your source output impedance is 200 ohms, you can join 50, 10k ohm inputs in parallel without a loss in gain.

10k isn't *really low*.


----------



## subwoofery

envisionelec said:


> _*Input *_impedance has _no effect _on output impedance of an amplifier (or anything else, for that matter). It simply states how much of a load it will put on your source (headunit, EQ, etc).
> 
> If you parallel amps with simple splitters, the effective input impedance decreases just like paralleled resistors ([1/R1+1/R2+1/R3]^-1...). Once you hit an effective impedance that equals the output impedance of the source, you've hit the limit for expecting unity gain. Say if your source output impedance is 200 ohms, you can join 50, 10k ohm inputs in parallel without a loss in gain.
> 
> 10k isn't *really low*.


Thanks a lot :thumbsup: 

I guess that's a spec I don't have to worry about then... 

Kelvin


----------



## rc10mike

What about amps with adjustable damping factor? What does this actually do? Helix A1 for example..


----------



## envisionelec

rc10mike said:


> What about amps with adjustable damping factor? What does this actually do? Helix A1 for example..


I had to do some research on the amp, because my knee-jerk reaction was similar to this tidbit from Andy Wehmeyer:

http://www.diymobileaudio.com/forum/1466181-post4.html

I think the marketing department has gotten their stupid little hands on the amp and have made this feature something it is NOT.

From what I can tell, the "damping factor" adjustment is _*nothing more than the "Q" adjustment on an equalizer*_. If you look at the amp, the "damping factor" knob is located near the Gain, Frequency and Phase controls. Upon closer inspection, the surrounding circuitry is your basic EQ - not a hint of anything exotic like a transconductance stage that would indicate they are screwing around with the output impedance of the amplifier.

Funny stuff.


----------



## cvjoint

envisionelec said:


> Ok, so it's exactly as I expected.
> 
> The damping factor has to be very low to affect FR in any significant way. Probably 5 or less to be audible. FR variation from low DF is source independent and a function of output impedance only.


Refreshing piece of information. Thanks! 

The impedance curve of a speaker is more or less fixed I think even if the coil warms up. For someone that tunes the car to a certain target curve to begin with even low DF is probably not an issue.


----------



## sqshoestring

envisionelec said:


> You're really oversimplifying the design aspect here. It's not that today's electronics are more advanced - it's just better understood how to build a quality full range Class D amp. Unfortunately, there are still a lot of very poorly designed units out there - and the car audio manufacturers are often a primary offender. They just do stupid things like mount all four (4 channel amp) inductors parallel to each other causing measurably poor crosstalk. Or they don't pay much attention to the quality of the modulator so distortion numbers suffer.
> 
> MP3 is a compression algorithm and is not a good analog to an early Class D amp. It's not as simple as increasing bandwidth - you just can't switch big, high voltage MOSFETs that fast without a dramatic loss in efficiency. Until someone invents a low capacitance 600V MOSFET, you won't be seeing 2kW full range Class D amps.


I agree, I was getting at how they can make a good class D amp...and if they don't it is just like any other amp; it was because they choose not to.

You know much more about it than I, IIRC in the past they could not get the switching right at high frequency so quality suffered. I was not sure what component caused the most issues. But today they can. 2K full range? Wow, I can't see much use for over 150rms/ch for the typical market and they are just now becoming common (good sound quality amps).

I said mp3 because that tends to chop up the top end too, but right not by the same means.


----------



## envisionelec

sqshoestring said:


> I agree, I was getting at how they can make a good class D amp...and if they don't it is just like any other amp; it was because they choose not to.
> 
> You know much more about it than I, IIRC in the past they could not get the switching right at high frequency so quality suffered. I was not sure what component caused the most issues. But today they can. 2K full range? Wow, I can't see much use for over 150rms/ch for the typical market and they are just now becoming common (good sound quality amps).
> 
> I said mp3 because that tends to chop up the top end too, but right not by the same means.


My intent wasn't to flaunt my experience, but to correct the thread in case someone else reads this later. Naw, that _never_ happens.


----------



## Tnutt19

I have ran a ton of both ab and d class amps and there is a big difference. Class ab does a lot better in several areas from bass response to detail in the midrange and high frecuencies. Of course a lot will depend on the speakers you are using and other variables of your install. If your goal is sq you will want ab. That is not to say class d cannot sound good.
I have a huge list of amps I have tried all dropped in the same install and honestly you can tell a difference even between class ab amps, the biggest difference was between class d and ab though. Even in the subs it was very noticeable changing from d to ab and viceversa.
The Richard Clark theory is a great idea but it's wrong especially when getting into serious high end gear.


----------



## BuickGN

I have to disagree. I couldn't tell a difference between my McIntosh and JL HD amps. The only difference I've ever heard is in power. I'm running the Dynaudio Esotars, they tend to pick up everything.


----------



## Tnutt19

We did a comparison with jl hd amps and audison lrx on focal k2p and we notice a big difference.
I am currently running focal no7 and last I ran scan speak and we compared about 8 to 12 amps. Are finding were that there is a big difference


----------



## ChrisB

Tnutt19 said:


> We did a comparison with jl hd amps and audison lrx on focal k2p and we notice a big difference.
> I am currently running focal no7 and last I ran scan speak and we compared about 8 to 12 amps. Are finding were that there is a big difference


What were the parameters of the test? Did you know which amplifier was playing while performing the test? Was proper level matching performed at a certain volume level keeping both amplifiers well within the constraints of their operating abilities and keeping power relatively the same?

Why am I being a jerk about this? Because all I need is 15 minutes with your car and your gear and I can make it sound different too! A few tweaks to the crossover points and/or the gains, and you'd swear that it was a totally different setup. Before you dismiss what I am saying, keep in mind, I've done that exact thing before!

[Begin long story] 

A friend of mine has some Alpine F1 Status components installed and tuned by a local shop and they connect some MTX amplifier (I forget the model) to it with the gains all the way on the floor (but I didn't know this up front). This was in a 350z with the stock Bose setup, and only the door speakers being changed. He brings the car over to my house, and I was either going to install my Soundstream Reference 700s in his car or the modified Linear Power LP150 that I had on hand. Needless to say, he was blaming the amp for his crappy sound. 

After I start digging, I notice that his setup was tuned like ****. What had happened was the shop left the gains all the way down so that the factory speakers overpowered the replacement door speakers and they set the crossover stupid high, like 250 Hz. It didn't take long to find the reason for his disappointment with the sound. I spent 15 minutes tweaking the setup while my buddy stayed in the house watching TV, then had him come out and have a listen. His first comment/question "Wow, that sounds amazing! Which amp did you end up using?" Imagine the look on his face when I showed him his SAME MTX amplifier! 

[/End long story]


----------



## TOOSTUBBORN2FAIL

For what its worth, i plan to set up a test sometime this year, maybe at a diyma get together. Going to build a couple things, that will allow almost no lag time in between amp swaps, since i believe thats a big deal. Of course level matched, and you wont know what amp your listening to. Ill post more later when im not on a nook, but my opinion is you wont be able to tell.


----------



## Tnutt19

We had processor setting flat and went back and forth with amp setting on both turned up, both sets got very loud and sounded very good, the lrx amp just had much better midbass and higher end. I'm sure you could tune it to make the difference less noticeable but to us we noticed a difference. We were not doing an official test to prove it to anyone else though so I'm just here expressing my opinion. A few years back we also did a test on an avionixx class t amp and ppi dcx amp, speakers were mb quart pce and the biggest difference was in warmth and midbass between those two amps. 
All my other testing has been in running subs though. In my last years setup we ran a ton of different amps and the class ab always sounds a little better.

That is just my opinion through my testing, I'm sure it is possible to tune the setup and make them sound very very close I just prefer ab after that. 
The class d amps are getting better but I would have to think that likewise the ab amps are making advances at the same time.


----------



## Tnutt19

TOOSTUBBORN2FAIL said:


> For what its worth, i plan to set up a test sometime this year, maybe at a diyma get together. Going to build a couple things, that will allow almost no lag time in between amp swaps, since i believe thats a big deal. Of course level matched, and you wont know what amp your listening to. Ill post more later when im not on a nook, but my opinion is you wont be able to tell.


I will be interested to hear more on this. My very good friend and I are about to do a side by side with two focal utopia be no7 sets, my set will be run with audison vrx 2.250 cs and 4.300 cs, my friends will be run by mosconi as200.4 and as100.4. I think this will be an interesting comparison also.


----------



## Yuck.

As the OP, I gotta make these 2 observations:

1) Psychoacoustics will probably be impossible to fully understand until we can further profile "hearing ability" as well as how individual brains decipher said sound

2) haven't heard anyone say they _prefer_ class D yet, but I have heard a fair amount of people say they prefer A/B, for what it's worth.


----------



## dragonrage

Yuck. said:


> 2) haven't heard anyone say they _prefer_ class D yet, but I have heard a fair amount of people say they prefer A/B, for what it's worth.


It's worth absolutely nothing.

For the test, it has to be a double-blind ABX test or it is statistically worth much less.


----------



## TOOSTUBBORN2FAIL

Not only that, but the tests have to be performed with as small of breaks while switching amps as possible. Even a minute or two, is too long.


----------



## Yuck.

dragonrage said:


> It's worth absolutely nothing.
> 
> For the test, it has to be a double-blind ABX test or it is statistically worth much less.


Again though, IMO logic tells me some people will not be able to "tell the difference" and other will be able to tell and go with one or the other (I predict more will like the A/B but some will prefer the D). There are so many unknowns with the properties of sound, as well as the perception of sound and what sounds appealing, that I have a feeling this test will not show much except different opinions. 

You want the amplification source to be the variable, ok, but if you have more than one person listening than you've now just added many more variables and some totally unknown, and the experiment has become unhinged. 

But still, I want to see this happen and I wish the whole process well in coming up with a general consensus, I just don't see it being conclusive.

But, I guess that means I started this thread for redundancy's sake, ha :smash:


----------



## Tnutt19

Yuck. said:


> Again though, IMO logic tells me some people will not be able to "tell the difference" and other will be able to tell and go with one or the other (I predict more will like the A/B but some will prefer the D). There are so many unknowns with the properties of sound, as well as the perception of sound and what sounds appealing, that I have a feeling this test will not show much except different opinions.
> 
> You want the amplification source to be the variable, ok, but if you have more than one person listening than you've now just added many more variables and some totally unknown, and the experiment has become unhinged.
> 
> But still, I want to see this happen and I wish the whole process well in coming up with a general consensus, I just don't see it being conclusive.
> 
> But, I guess that means I started this thread for redundancy's sake, ha :smash:


You guys are over thinking it. It is simple, if you do not think there is a big difference or any at all, then run with the class D. As for me, I could tell a big difference every time so I will always run class AB or A. This forum is a great place to pick up some great used amps though to try out, I would suggest that and if you like them (class D, ab what have you) then keep them, if you are yearning to try something else then resell and try the next thing. At the end of the day it can be as simple or profound as you want, id suggest simplifying it a little so you do not drive your self insane.


----------



## Yuck.

Tnutt19 said:


> You guys are over thinking it. It is simple, if you do not think there is a big difference or any at all, then run with the class D. As for me, I could tell a big difference every time so I will always run class AB or A. This forum is a great place to pick up some great used amps though to try out, I would suggest that and if you like them (class D, ab what have you) then keep them, if you are yearning to try something else then resell and try the next thing. At the end of the day it can be as simple or profound as you want, id suggest simplifying it a little so you do not drive your self insane.


I did simplify it for myself, said I know what works well from my experience and went all AB. Had a JBL BPX Crown 500.1 on my sub stage for a little bit, giving me a solid 250 watts or so, didn't like the robotic (IMO) sound on anything but kick drums listening to metal, went back to my 150 stereo A/B watts and couldn't be happier with the trade off. If I didn't like that amp, which was a nice class D amp when it was released, then I figured I wouldn't use anything D on my stuff unless I'm doing something 2kw and up. But I know very little about amplifier design, so I'm open to seeing how improved technology has closed the gap.


----------



## TOOSTUBBORN2FAIL

Ill say this, my views and my dads views are very different.

My dad is an objective person by trade. His job is to design power supplies for everything from ordinary things to the power supply that is in things that absolutely can't fail. 

From an engineering stand point, he feels that class d is the way to go, for efficiency reasons. However, he also believes it may be possible to hear things that we don't have the ability to measure. He wont say that he can, he just says its a possibility. He also says its possible that some people can hear a difference, and others can't. So his view is that from a distortion and noise reduction point of view, class a would be best. He is currently working on designing from scratch a class d amp for the sub in his truck, and possibly a set of class a monoblocks for his passive mids and highs. Depending on where he mounts them, they may end up as class ab with a high class a bias, if there's not enough room for them to stay cool. 

My view is that there is probably a threshold under which no one can hear a difference. I also feel that if you comparing amps in a car, that took 20 mins or so to swap out, any differences you hear are more of a placebo effect and psychoacoustics than a real difference, unless the amps measure drastically different. Your brain just can't compare things with that much of a gap in between listening.

My plan is to build a couple of small amps, maybe something like a 25 watt dual mono design. I would need to build a class a, ab, and d. From there, they would be mounted behind a wall, with a set of reference speakers in front of the wall. All three amps would be powered up at the same time, and all would have speaker wires with banana plugs ready to go. Each one would get constant signal, so the only delay would be switching from one set of speaker wires to the next. Then test and see what the results were.


----------



## subwoofery

TOOSTUBBORN2FAIL said:


> Ill say this, my views and my dads views are very different.
> 
> My dad is an objective person by trade. His job is to design power supplies for everything from ordinary things to the power supply that is in things that absolutely can't fail.
> 
> From an engineering stand point, he feels that class d is the way to go, for efficiency reasons. However, he also believes it may be possible to hear things that we don't have the ability to measure. He wont say that he can, he just says its a possibility. He also says its possible that some people can hear a difference, and others can't. So his view is that from a distortion and noise reduction point of view, class a would be best. He is currently working on designing from scratch a class d amp for the sub in his truck, and possibly a set of class a monoblocks for his passive mids and highs. Depending on where he mounts them, they may end up as class ab with a high class a bias, if there's not enough room for them to stay cool.
> 
> My view is that there is probably a threshold under which no one can hear a difference. I also feel that if you comparing amps in a car, that took 20 mins or so to swap out, any differences you hear are more of a placebo effect and psychoacoustics than a real difference, unless the amps measure drastically different. Your brain just can't compare things with that much of a gap in between listening.
> 
> My plan is to build a couple of small amps, maybe something like a 25 watt dual mono design. I would need to build a class a, ab, and d. From there, they would be mounted behind a wall, with a set of reference speakers in front of the wall. All three amps would be powered up at the same time, and all would have speaker wires with banana plugs ready to go. Each one would get constant signal, so the only delay would be switching from one set of speaker wires to the next. Then test and see what the results were.


^ if you have a really good friend at a shop, you can do that. I did a comparison between a PDx, a DLS RA40, a Sinfoni 50.4 and a Milbert :worried: and now know what to think about this thread...  

Kelvin 

PS: sorry I couldn't invite anyone coz it's probably too far for you guyz since I live in Tahiti, French Polynesia


----------



## Yuck.

TOOSTUBBORN2FAIL said:


> Ill say this, my views and my dads views are very different.
> 
> My dad is an objective person by trade. His job is to design power supplies for everything from ordinary things to the power supply that is in things that absolutely can't fail.
> 
> From an engineering stand point, he feels that class d is the way to go, for efficiency reasons. However, he also believes it may be possible to hear things that we don't have the ability to measure. He wont say that he can, he just says its a possibility. He also says its possible that some people can hear a difference, and others can't. So his view is that from a distortion and noise reduction point of view, class a would be best. He is currently working on designing from scratch a class d amp for the sub in his truck, and possibly a set of class a monoblocks for his passive mids and highs. Depending on where he mounts them, they may end up as class ab with a high class a bias, if there's not enough room for them to stay cool.
> 
> My view is that there is probably a threshold under which no one can hear a difference. I also feel that if you comparing amps in a car, that took 20 mins or so to swap out, any differences you hear are more of a placebo effect and psychoacoustics than a real difference, unless the amps measure drastically different. Your brain just can't compare things with that much of a gap in between listening.
> 
> My plan is to build a couple of small amps, maybe something like a 25 watt dual mono design. I would need to build a class a, ab, and d. From there, they would be mounted behind a wall, with a set of reference speakers in front of the wall. All three amps would be powered up at the same time, and all would have speaker wires with banana plugs ready to go. Each one would get constant signal, so the only delay would be switching from one set of speaker wires to the next. Then test and see what the results were.


Well, for one thing you Dad is cool, haha. But this is a great idea and I wish you the best.


----------



## TOOSTUBBORN2FAIL

Lol, ill probably figure out how to set this all up, and then bring it out at a diyma meetup sometime this summer.

The biggest reason I want to do this, is since the amps going in my car will be built however I want them, id like to figure out exactly what I want.


----------



## nickalways4u

Well i dont think,Class D amps can be as musical as Class D,if you use them to power components,well if used for Subwoofers then i am not sure


----------



## AKheathen

why not just build a signal, and output switching device? then you can seamlessly switch between all 3 amps.... just need some relays, inter-connects, switch, and possibly some pots for level-matching flexability. just make sure the source is hot-swappable.


----------



## ChrisB

AKheathen said:


> why not just build a signal, and output switching device? then you can seamlessly switch between all 3 amps.... just need some relays, inter-connects, switch, and possibly some pots for level-matching flexability. just make sure the source is hot-swappable.


In other words, don't use a Pioneer HU containing a Pico fuse as the source. :laugh:


----------



## sqshoestring

ChrisB said:


> In other words, don't use a Pioneer HU containing a Pico fuse as the source. :laugh:


Lol, I am not sure but think if you used an opamp that would detach the HU from it, could use small transistors to move the signal. The hard part would be soldering it together. Mind you I'm no amp designer.


----------



## TOOSTUBBORN2FAIL

My plan was to use a denon r1 as the source, with each amp continuously receiving signal from it using a custom build rca distribution block. This way, the only thing that would have to be switched is the speaker wires. Each amp would also have its own set of speaker wires, so you would simply unplug one amps wires from the speakers and plug the next amps wires in. This would allow swapping in less than 5 seconds, and no complaining that constantly swapping one set of wires around was "degrading the signal".


----------



## Coral_PRX

coyote-1 said:


> The environment is everything.
> 
> Most folk don't sit in their car to listen to music; even under best conditions, an automobile is not an optimal listening environment. I have pretty good ears.... I'm trusting that my new Sony Xplod amp (class D) will not show itself to be audibly flawed when I install it in spring.


email the Admin, ask them to delete your account on this forum 

set yourself free and be happy


----------



## ChrisB

Coral_PRX said:


> email the Admin, ask them to delete your account on this forum
> 
> set yourself free and be happy


Why? What he wrote was 100% correct. Between reflections, refractions, non-equidistant placement of drivers, extraneous noise variables beyond one's control, a 12 volt DC power source, and a whole slew of other limiting factors, this by default makes the car the worst environment for reproduction of sound. 

In the end, it all boils down to what level of compromise the car audio aficionado is willing to accept. With car audio, it is what it is... PERIOD!


----------



## Spectrum (WI)

I was reading about a company that seems to know a lot about Class D amplifiers. Anthem just released a new class D amp that apparently addresses a lot of "issues" with Class D amplification.

YouTube clip from CES 2012
CES 2012 ANTHEM M1 1000 W AMP - YouTube 

Looking on their website for more info about this M1 amp they explain a lot of generalizations on the problems with class D amplification. I believe this information would apply to car audio as well. It makes me wonder what technology exists in a JL Audio Class D amp compared to Anthem's........

Website info:
M1 Monaural Amplifier - Welcome to the New Official Anthem® Audio Video Website.


----------



## AKheathen

Spectrum (WI) said:


> It makes me wonder what technology exists in a JL Audio Class D amp compared to Anthem's........


the unstable kind, imo

If you were to go the op-amp rout, might as well be using a line driver wiyh output switching devise. Simple is better. However, simple relay array on the speaker leads might work well, and save on physically going to switch wires. I immagine using banana plugs if you want to switch wires. Iirc, you can get them in binded pairs for even quicker physical swaps, like under 2sec. And gold plating would be sure to eliminate any contact resistance variation, since gold will naturally stick to itself and resist corrosion and oxidation layer formation, which you cannot physically see.


----------



## sqshoestring

I guess if you use the same speakers, it would be better to switch them to various amp outputs. Seems like you could find a 'selector' switch to do that though I've never looked.


----------



## AKheathen

sqshoestring said:


> I guess if you use the same speakers, it would be better to switch them to various amp outputs. Seems like you could find a 'selector' switch to do that though I've never looked.


pretty endless options for switches, there is even home use selectors made for just that.


----------



## ern2112

Have tested full range D against ZR 1000 A/B. Sorry....but the D sounds at least as good...and sometimes smoother on the top. Once you are in the car.....forget trying to tell. Don't bet your life on being able to tell the difference. But hey...some can hear grass grow too.


----------



## cleansoundz

A few weeks ago, I replaced my Arc Audio KS 1000.1 and KS 300.4 with the Alpine PDX M 12 and F 4. I couldn't tell a difference in the sound at all.


----------



## avanti1960

ZAKOH said:


> Such a long thread and not a one link to someone who has done a simple A/B comparison of more recent 4-channel Class A/B and Class D amps for a 2-way active front stage duty..


Exactly my thinking too- and here it is a few pages later still no luck.


----------



## avanti1960

After being away from upgraded mobile audio for too long, I am now on my second Class D amp in less than 3 months. The first was a Pioneer class D. It sounded like complete garbage- and I attributed it to class D, having never owned one before. 
Now I have a JL 900 HD. It sounds very good, worlds better than the Pioneer. I am hearing things in the music that I have never heard before. Unfortunately they are not good things. 
I have several sources of music that sound downright awful- even at low and moderate volume. It's music that has some intended distortion effects or is a little edgy. The effect in my car can be described as harsh, abrasive, gritty, broken up. With the right music, this amp can sound absolutely amazing- acoustic, female vocals, horns, etc. I can't imagine what it would sound like if I liked death metal- I would probably rip it out and chuck it into the ditch. 
But with the wrong music, I hear things that demand I try to fix it. 
Check out this clip- listen to the guitar refrain at 2:14.
"Unmade bed" - YouTube 
In my car at moderate volume it makes me hear fingernails on glass. Harsh, fatiguing, whatever- it sounds unacceptable. In the house, not so. Sounds like it was intended. I have others to sample if anyone is interested.
My rep at my electronics dealer says it is class D's fault. He is quite a smart and knowledgeable dude. He runs Audison and will never run class D, although he believes the JL HDs and newer PDXs are not as bad as older product. They are almost not carrying class AB any longer. Most just want gobs of power in a small efficient package- SQ be damned. 
I will soon be running the 900HD on the rear speakers and sub exclusively and have a JL 300\4v2 on order. I will then post up my findings. 

Regarding the concept that the measured distortion is not audible by human hearing, I would ask the distortion of what? Is it a small percentage of fixed frequency tone bursts as measured by a scope? 
What happens when there are multiple frequencies playing at once? How does this translate into distortion specs? There has to be more to the quality of an amplifiers sound than can be assumed by a percentage of distortion specification. 
I'll soon find out. I know something ain't right because I can hear it over and over again.


----------



## W8 a minute

avanti1960 said:


> Exactly my thinking too- and here it is a few pages later still no luck.


What are you looking for? There are probably 100's of posts on the internet comparing the two. Every one is as different as the person doing the comparison.


----------



## metanium

avanti1960 said:


> After being away from upgraded mobile audio for too long, I am now on my second Class D amp in less than 3 months. The first was a Pioneer class D. It sounded like complete garbage- and I attributed it to class D, having never owned one before.
> Now I have a JL 900 HD. It sounds very good, worlds better than the Pioneer. I am hearing things in the music that I have never heard before. Unfortunately they are not good things.
> I have several sources of music that sound downright awful- even at low and moderate volume. It's music that has some intended distortion effects or is a little edgy. The effect in my car can be described as harsh, abrasive, gritty, broken up. With the right music, this amp can sound absolutely amazing- acoustic, female vocals, horns, etc. I can't imagine what it would sound like if I liked death metal- I would probably rip it out and chuck it into the ditch.
> But with the wrong music, I hear things that demand I try to fix it.
> Check out this clip- listen to the guitar refrain at 2:14.
> "Unmade bed" - YouTube
> In my car at moderate volume it makes me hear fingernails on glass. Harsh, fatiguing, whatever- it sounds unacceptable. In the house, not so. Sounds like it was intended. I have others to sample if anyone is interested.
> My rep at my electronics dealer says it is class D's fault. He is quite a smart and knowledgeable dude. He runs Audison and will never run class D, although he believes the JL HDs and newer PDXs are not as bad as older product. They are almost not carrying class AB any longer. Most just want gobs of power in a small efficient package- SQ be damned.
> I will soon be running the 900HD on the rear speakers and sub exclusively and have a JL 300\4v2 on order. I will then post up my findings.
> 
> Regarding the concept that the measured distortion is not audible by human hearing, I would ask the distortion of what? Is it a small percentage of fixed frequency tone bursts as measured by a scope?
> What happens when there are multiple frequencies playing at once? How does this translate into distortion specs? There has to be more to the quality of an amplifiers sound than can be assumed by a percentage of distortion specification.
> I'll soon find out. I know something ain't right because I can hear it over and over again.


There are definitely some harsh intentional artifacts in recordings that just hurt. With that said, music that has been digitally compressed can also produce some harsh unintentional artifacts, due to lowering the bit rate. Are you listening to well-recorded/well-mastered music. Has it been compressed into another digital format?

I think the rep is feeding you incorrect information on AB vs D. While I never used any of the early PDX's or other full-range class D's that had reported noise & SQ issues, I have begun using full-range Class D in JL's HD and XD lines. I haven't detected any issues that you've described comparing to past experiences with several Class AB JL Audio (slash series) and Audison amps (LRx & SRx) I've owned.

I really believe that the differences are not able to be discerned by human hearing.


----------



## The Baron Groog

I've not had any noise issues with any of the FR Class D we've fitted for customers, Alpine PDX-5 are pretty quick sellers for me and the Kenwood XR4's have done pretty well too..


----------



## adrenalinejunkie

Thinking of going with a JL Audio 600/4HD for a pair of HAT 6 1/2 Clarus *Active, but was told that the amp isn't good at higher frequencies. This is my first time hearing something like this, is it true?


----------



## [email protected]

No, this is not right!
Just look in this forum how many people use the HD600/4 (me to).

Regards Barney



Send with Tapatalk


----------



## adrenalinejunkie

[email protected] said:


> No, this is not right!
> Just look in this forum how many people use the HD600/4 (me to).
> 
> Regards Barney
> 
> 
> 
> Send with Tapatalk



I do realize that many people use the amp. I haven't heard a 600/4HD my self, but this person said that "SQ" guys can't tell since we go with a "flat" sound. Thanks for your feedback.


----------



## avanti1960

metanium said:


> There are definitely some harsh intentional artifacts in recordings that just hurt. With that said, music that has been digitally compressed can also produce some harsh unintentional artifacts, due to lowering the bit rate. Are you listening to well-recorded/well-mastered music. Has it been compressed into another digital format?
> 
> I think the rep is feeding you incorrect information on AB vs D. While I never used any of the early PDX's or other full-range class D's that had reported noise & SQ issues, I have begun using full-range Class D in JL's HD and XD lines. I haven't detected any issues that you've described comparing to past experiences with several Class AB JL Audio (slash series) and Audison amps (LRx & SRx) I've owned.
> 
> I really believe that the differences are not able to be discerned by human hearing.


I'm listening with purchased CDs. I can hear the harsh gritty abrasive overtones on probably 1 out of 5 CDs. 
Before having a class D amp I have never experienced this before. The same CDs played on my home stereo will not sound so objectionable. It is a harsh, almost sharpness to the sound. 
I would blame it on the Focal tweeters but I have swapped out about 5 different tweeters before I bought the Focals.

If ANYONE was sitting in the car with me I could easily get them to notice the harshness. It is completly audible. 
As soon as my class AB amp shows up I will pop it in and be able to tell in 10 minutes if this fixes the issue. 
I honestly do not know what else it could be- I bought the best dam HU on the market to try and fix it, and what I thought were very good speakers and amplifier. 
Bottom line- it is NOT ACCEPTABLE TO ME.


----------



## t3sn4f2

"2011 MECA World Champion Extreme SQ"

http://www.diymobileaudio.com/forum/build-logs-project-install-gallery/116323-highlys-mk4-vw-gti-2011-comp-build.html

Blind testing anyone?


----------



## atxtrd

"The sound quality of an audio amplifier is largely determined
by its performance in term of distortion (e.g. THD) and noise
(e.g. PSRR). One of the problems with open-loop Class D
amplifier is the susceptibility of the PWM or output stage to
non-linearity and noise [2-4]. The non-linearity and noise
will as a result lead to poor THD and PSRR performance in
an open-loop Class D amplifier. In a linear amplifier, these
problems can be easily mitigated by feeding the nonlinearities
at the Class D output back to the input. However,
the application of negative feedback in Class D amplifier is
not straight forward due to the high switching frequency
carrier and time delay in the feedback loop. To improve the
stability and dynamic range of the input signal, a low pass
filter is generally employed to provide sufficient attenuation
to the amplitude of the high frequency carrier in the feedback
loop. As a result of low pass filtering, the THD of the
closed-loop Class D amplifier usually suffer from poorer
THD performance at higher frequency (e.g. 3kHz)."

Class D amps tend to have alaising errors where the sample clock demodulates high frequencies present in the input audio and they get tossed back into the audio band...distortion.


----------



## TOOSTUBBORN2FAIL

^thats great and all, and completely true, however, can you hear it? That is what this thread is about. 

With modern class d amps, were past the technical difficulties of the past that made those problems audible.


----------



## TOOSTUBBORN2FAIL

t3sn4f2 said:


> "2011 MECA World Champion Extreme SQ"
> 
> http://www.diymobileaudio.com/forum/build-logs-project-install-gallery/116323-highlys-mk4-vw-gti-2011-comp-build.html
> 
> Blind testing anyone?


Not only that car, but I believe Mark Eldridge was the runner up, and also using JL HD's. I also believe Scott Buwalda also just switched to HD's in his G35. And Gary Summers, 2010 Modex National Champion, (also a 4 time oscar and one time emmy winner for his sound mastering skills in blockbuster motion pictures such as Saving Private Ryan), users Alpine PDX's. I listened to his car right after listening to the Magic Bus, which runs class a/b, and I noticed no electrical noise or audible distortion in either vehical.


----------



## ChrisB

While I used to be passionate about this topic, I've come to realize that it is just car audio, and the JL Audio HD amplifiers were more than adequate to meet my needs.

About the ONLY place I noticed a difference was when I drove the HD into clipping... I find that many of my Class AB amplifiers were more forgiving at clipping. Solution: Don't crank the volume all the way to the right OR use more power than you need so that your speakers will catch on fire before the amplifier clips.


----------



## subwoofery

Just to steer it up  

To those that don't hear a difference... Good for you that you found the "holy grail". Won't be able to prove you wrong. 

But to those that can hear a difference. Like me: "try to prove me wrong..." lol 

Kelvin


----------



## atxtrd

TOOSTUBBORN2FAIL said:


> ^thats great and all, and completely true, however, can you hear it? That is what this thread is about.
> 
> With modern class d amps, were past the technical difficulties of the past that made those problems audible.



I've done some comparison and in those situations I was able to tell the difference, but thats not to say that I couldnt ever be fooled. A large part of it boils down to euphonics, after about an hour of listening the brain will likely suffer listener fatigue. Digital lacks certian harmonics that render it sterile for lack of a better term, this is not pleasing to the brain. That sterile sound is due to the higher end distortion and a lack of certain harmonics. Personally I prefer analog gear, then again we build analog gear for recording studios...my point of reference is based on years of working in recording studios. I know what a snare drum sounds like or how a stand up bass sounds from feet away...sustain, release, decay and the vibrations in my bone structure. Kids that have grown up on digital may only have that as a point of reference, where I've listened to master recordings in the studio through monitors that cost more than my house and logged many hours playing in bands and working in the studio with them. Then there is the crazy relationship between the sense of hearing and the brain, we all process sound in different ways, some folks like George Martin are said to be able to hear things very few other can...they call guys like that "golden ears". Sound is also a subjective thing, what I like may not be what others like. My desire is to hear an accurate reproduction of an instrument, the sound of a grand piano hitting a low note carries vibrations and characteristics that can be felt and they affect the brain in a certain way, even a good recording of that sound played back through a digital amp is not the same as the real thing sonically. A good signal is the first thing you must have but what happens to that signal from source to the ears/brain makes a lot of difference, by the very nature of digital amps they will never be the same as an analog piece of gear, they strip away the good distortion/harmonics. Accurate does not mean that the signal carries all the characteristics that give the brain that warm fuzzy feeling, what may look good on a scope is not always pleasing to the brain, specs don't tell the whole story! But if it sounds good to a person I say go for it and have fun. FWIW my mobile gear includes a few pieces of digital gear though I don't care for much of it that I've heard that is on the market. Manufacturers have done a great job of marketing it to their benefit, lots of power in a small box for less money. Can't say I know anyone in the recording industry that uses digital amps for reference playback though. I will say I am biased because of my background, I think the digital age has done terrible things to the music industry as a whole and I know many talented people who suffer the fallout daily...but that is a whole other topic. If your point of reference is an MP3 at 128kbps on crappy headphones (beats by Dre perhaps)..then you will probably not care. On the other hand a critical listener who has a better point of reference will most likely find themselves squirming after a while. Even the most talented recording engineers I know send their mixes off to be mastered, because the mastering guys usually have supreme ears and can pick apart a recording like surgeons. Some of us drive around all day and never actually "listen" to the music and some of us ***** about the production and engineering of a CD, we are not all the same when it comes down to how we listen or how we really hear. I often find myself picking out a certain instrument in a song and humming along to that part, I hear them all and can recite guitar or bass parts by memory...some don't hear that stuff nor do they care.


----------



## cleansoundz

atxtrd said:


> I've done some comparison and in those situations I was able to tell the difference, but thats not to say that I couldnt ever be fooled. A large part of it boils down to euphonics, after about an hour of listening the brain will likely suffer listener fatigue. Digital lacks certian harmonics that render it sterile for lack of a better term, this is not pleasing to the brain. That sterile sound is due to the higher end distortion and a lack of certain harmonics. Personally I prefer analog gear, then again we build analog gear for recording studios...my point of reference is based on years of working in recording studios. I know what a snare drum sounds like or how a stand up bass sounds from feet away...sustain, release, decay and the vibrations in my bone structure. Kids that have grown up on digital may only have that as a point of reference, where I've listened to master recordings in the studio through monitors that cost more than my house and logged many hours playing in bands and working in the studio with them. Then there is the crazy relationship between the sense of hearing and the brain, we all process sound in different ways, some folks like George Martin are said to be able to hear things very few other can...they call guys like that "golden ears". Sound is also a subjective thing, what I like may not be what others like. My desire is to hear an accurate reproduction of an instrument, the sound of a grand piano hitting a low note carries vibrations and characteristics that can be felt and they affect the brain in a certain way, even a good recording of that sound played back through a digital amp is not the same as the real thing sonically. A good signal is the first thing you must have but what happens to that signal from source to the ears/brain makes a lot of difference, by the very nature of digital amps they will never be the same as an analog piece of gear, they strip away the good distortion/harmonics. Accurate does not mean that the signal carries all the characteristics that give the brain that warm fuzzy feeling, what may look good on a scope is not always pleasing to the brain, specs don't tell the whole story! But if it sounds good to a person I say go for it and have fun. FWIW my mobile gear includes a few pieces of digital gear though I don't care for much of it that I've heard that is on the market. Manufacturers have done a great job of marketing it to their benefit, lots of power in a small box for less money. Can't say I know anyone in the recording industry that uses digital amps for reference playback though. I will say I am biased because of my background, I think the digital age has done terrible things to the music industry as a whole and I know many talented people who suffer the fallout daily...but that is a whole other topic. If your point of reference is an MP3 at 128kbps on crappy headphones (beats by Dre perhaps)..then you will probably not care. On the other hand a critical listener who has a better point of reference will most likely find themselves squirming after a while. Even the most talented recording engineers I know send their mixes off to be mastered, because the mastering guys usually have supreme ears and can pick apart a recording like surgeons. Some of us drive around all day and never actually "listen" to the music and some of us ***** about the production and engineering of a CD, we are not all the same when it comes down to how we listen or how we really hear. I often find myself picking out a certain instrument in a song and humming along to that part, I hear them all and can recite guitar or bass parts by memory...some don't hear that stuff nor do they care.


Very well said. I would say this is a good place to end this thread. Some people prefer full range class D and some don't prefer full range class D. I guess it took 10 pages of responses to get to this point.


----------



## avanti1960

i'm not sure it's ready to end yet. 
i have arguably one of the best class D amps available (JL 900HD)
one of the best, cleanest source units (pioneer dex-p99rs)
and some nice speakers (focal 165v30)

what i'm hearing in a good amount of the music i listen to- is not subtle, is not "golden ears", is not hard to hear- 
It is flat out objectionable and irritating- lacking in quality and it is obvious. 
I can demonstrate it to anyone with ears. 

When I install the JL class AB amp I have on order and these objectionable qualities are eliminate or significantly reduced I would have to reach the conclusion that class AB sounds significantly better. 
If not, I'll at least say I tried and have some extra channels to run active!


----------



## avanti1960

when we hear about competition winners running class D amps, could it be that competition program material is very specific and limited to clean recordings that would not bring out the worst in class D attributes?


----------



## [email protected]

Did you ever thought the sound with the JL is the "true" sound how it should be?
Maybe your old a/b amp made whitewash (is this the right slang ?)


Regards Barney


----------



## TOOSTUBBORN2FAIL

atxtrd said:


> I've done some comparison and in those situations I was able to tell the difference, but thats not to say that I couldnt ever be fooled. A large part of it boils down to euphonics, after about an hour of listening the brain will likely suffer listener fatigue. Digital lacks certian harmonics that render it sterile for lack of a better term, this is not pleasing to the brain. That sterile sound is due to the higher end distortion and a lack of certain harmonics. Personally I prefer analog gear, then again we build analog gear for recording studios...my point of reference is based on years of working in recording studios. I know what a snare drum sounds like or how a stand up bass sounds from feet away...sustain, release, decay and the vibrations in my bone structure. Kids that have grown up on digital may only have that as a point of reference, where I've listened to master recordings in the studio through monitors that cost more than my house and logged many hours playing in bands and working in the studio with them. Then there is the crazy relationship between the sense of hearing and the brain, we all process sound in different ways, some folks like George Martin are said to be able to hear things very few other can...they call guys like that "golden ears". Sound is also a subjective thing, what I like may not be what others like. My desire is to hear an accurate reproduction of an instrument, the sound of a grand piano hitting a low note carries vibrations and characteristics that can be felt and they affect the brain in a certain way, even a good recording of that sound played back through a digital amp is not the same as the real thing sonically. A good signal is the first thing you must have but what happens to that signal from source to the ears/brain makes a lot of difference, by the very nature of digital amps they will never be the same as an analog piece of gear, they strip away the good distortion/harmonics. Accurate does not mean that the signal carries all the characteristics that give the brain that warm fuzzy feeling, what may look good on a scope is not always pleasing to the brain, specs don't tell the whole story! But if it sounds good to a person I say go for it and have fun. FWIW my mobile gear includes a few pieces of digital gear though I don't care for much of it that I've heard that is on the market. Manufacturers have done a great job of marketing it to their benefit, lots of power in a small box for less money. Can't say I know anyone in the recording industry that uses digital amps for reference playback though. I will say I am biased because of my background, I think the digital age has done terrible things to the music industry as a whole and I know many talented people who suffer the fallout daily...but that is a whole other topic. If your point of reference is an MP3 at 128kbps on crappy headphones (beats by Dre perhaps)..then you will probably not care. On the other hand a critical listener who has a better point of reference will most likely find themselves squirming after a while. Even the most talented recording engineers I know send their mixes off to be mastered, because the mastering guys usually have supreme ears and can pick apart a recording like surgeons. Some of us drive around all day and never actually "listen" to the music and some of us ***** about the production and engineering of a CD, we are not all the same when it comes down to how we listen or how we really hear. I often find myself picking out a certain instrument in a song and humming along to that part, I hear them all and can recite guitar or bass parts by memory...some don't hear that stuff nor do they care.


Let me ask this, were your tests blind? Did you know know which amps you were listening to? If you knew which amps you were listening to, the tests were invalid. Even the best of us is biased. I know that the best class a will always measure better than the best class d. But if you were blindfolded, and had them swapped out multiple times in a row, could you reliably tell the difference?


----------



## atxtrd

TOOSTUBBORN2FAIL said:


> Let me ask this, were your tests blind? Did you know know which amps you were listening to? If you knew which amps you were listening to, the tests were invalid. Even the best of us is biased. I know that the best class a will always measure better than the best class d. But if you were blindfolded, and had them swapped out multiple times in a row, could you reliably tell the difference?


No, there was no blind test. Lets put it this way....sometimes while listening to an ipod, with source material of 128kbps, I find myself getting this tense irritable feeling and I will quicly turn the music off. I have learned that my brain does not prefer the sound of music that is not reproduced in a natural manner, i.e. music that contains the good distortion/harmonics. Mind you it was not until this happened many times that I figured out what was going on.

"Scientific evidence shows that digital music just doesn’t stack up to the real thing—and we have the brain scans to prove it.

A recent study in PLoS One had music lovers listen to two different Chopin recordings while having their brains scanned in real time. An expert musician played one performance. For the other, a computer played the same melody, notes, and volumes on the same piano—but lacked the subtlety of the expert.

Brain regions involved in emotion lit up on the scan when the pianist performed, but the computer left subjects brains’ mostly dark. Watch the scan in action here."

emotion Movie V2

A few years ago Rupert Neve handed me a study done in Japan that also showed the effects of various types of source material on the brain, he asked me to read it as he felt it was highly relevant to my position as his employee. In case you have never heard of Mr Neve lets just say he is the king of all things audio, from technical Grammy awards to the Audio Engineering Society's man of the century...he has been the benchmark for pro audio for a very long time. If you have listened to the radio or music for more than 30 minutes in your entire life you have heard music that was produced using his designs. My bias against digital is not just an opinion, my brain and my ears made the decision and they do not lie to me, they have been well conditioned and trained for many years. Distortion defines the modern guitar sound, most desired guitar amps are tube amps that are overdriven to achieve that sound, when recorded well and played back on a worthy piece of gear they sound very good right? Give SRV's Riviera Paradise a listen, part of the way through you can hear his overdriven Fender amp humming in the background...but the song sounds frigging amazing with the right source and right gear. From a scientific approach digital is a very different animal than a good analog piece of gear...period. Does anyone really think that most car audio manufacturers are putting the integrity of sound ahead of their ability to make more profit? Anyone ever wonder why we seek out "oldschool" gear or designs by certain engineers from years ago? It is because they frigging sound better than the **** farmed out of overseas build houses! 

A few years ago there were great strides being made in the digital realm, DSD and Sony's work with SACD's were groundbreaking and the stuff sounded amazing as far a material goes. But it seems that the "industry" has choosen to abandon those technologies in favor of lesser quality and cheaper alternatives. We have gone from SACD to MP3's, most people use an iPod or a PC for their listening now, radio stations no longer have racks of CD's to store or keep track of...and in the end those of us who really give a **** are left in the dark. Ever notice how Best Buy went from 25% of the store being the music/cd section to now just a couple of rows of CD's? FWIW the brain is analog.

"...let me also back up a bit and explain the difference between digital and analog, even though this is probably well known to most readers. An analog system is one that encodes information as a continuum. There is no inherent limit to values that can be assigned at any point. For example, if you consider a ruler without that is just a blank strip of wood one foot long, without any markings. You can line the ruler up along some thing you are measuring and then mark the length on the ruler. This would be an analog measure, because you can make the mark anywhere along the continuum.

A digital system is one in which information has discrete values. So a digital ruler would be one where you have to indicate the measured distance as 8 3/16 inches, and there is no way of indicating a measurement between 8 3/16 and 8 4/16."


----------



## TOOSTUBBORN2FAIL

The study involving the brain scans doesnt count. NOTHING compares to real live music. Nothing has the dynamic range, impact, etc. It isnt an accurate comparison to the class a/class ab/class d argument.

I still doubt the majority of the people on the planet could tell the difference between the best class a and the best class d amps, if listening blind. If not listening blind, then it simply just doesnt count. Your preconseived notions of what each amp sounds like are larger than the actual measureable differences in each if you know what you are listening to.


As for studys, there are just as many studies refuting what you state as there are studies supporting it. My dad once said you can engineer a study to show whatever you want it to. For some background on that statement, has has a masters in physics, and earned a 4.0 through his whole masters program. Having kids was the only thing that kept him from going back for his doctorate. 

The only thing that really means anything, is can you tell the difference, blind.



Something else to add, can you hear the difference knowing that the room, speakers, and your position in the room change the sound more than an amp ever possibly could?


----------



## atxtrd

TOOSTUBBORN2FAIL said:


> The study involving the brain scans doesnt count. NOTHING compares to real live music. Nothing has the dynamic range, impact, etc. It isnt an accurate comparison to the class a/class ab/class d argument.
> 
> I still doubt the majority of the people on the planet could tell the difference between the best class a and the best class d amps, if listening blind. If not listening blind, then it simply just doesnt count. Your preconseived notions of what each amp sounds like are larger than the actual measureable differences in each if you know what you are listening to.
> 
> 
> As for studys, there are just as many studies refuting what you state as there are studies supporting it. My dad once said you can engineer a study to show whatever you want it to. For some background on that statement, has has a masters in physics, and earned a 4.0 through his whole masters program. Having kids was the only thing that kept him from going back for his doctorate.
> 
> The only thing that really means anything, is can you tell the difference, blind.
> 
> 
> 
> Something else to add, can you hear the difference knowing that the room, speakers, and your position in the room change the sound more than an amp ever possibly could?


My ears, brain and I can tell the difference, don't know how to make it much more clear. Don't know how to get much better listening environment than behind a mixing console surrounded by the best gear in the world. Fact is I know what I know and I hear what I hear. Here is a little sample of our design work, we kinda know what we're doing.


----------



## TOOSTUBBORN2FAIL

I understand what your saying, all im saying is without blind testing, its not fully valid. Knowing what your listening to can change how you hear things as much as small differences such as the differences in distortion between a high end class a and high end class d. If you can ID different amps without seeing them, then that would be a different.

There are a lot of people who really know what they are doing that would agree with you, and a lot of people that really know what they are doing that disagree.

There was a study where high definition audio was dropped down to cd format (SACD to 16 bit 44.1K), none of the tested subjects could tell when the signal was switched.


----------



## metanium

atxtrd said:


> My ears, brain and I can tell the difference, don't know how to make it much more clear. Don't know how to get much better listening environment than behind a mixing console surrounded by the best gear in the world. Fact is I know what I know and I hear what I hear. Here is a little sample of our design work, we kinda know what we're doing.


Awesome. Now how about the listening environment behind the wheel of a car? I'm sure many others along with their ears and brains could discern between class D and A/B in a studio environment, but does any of that matter at 60 mph?


----------



## Wesayso

avanti1960 said:


> I'm listening with purchased CDs. I can hear the harsh gritty abrasive overtones on probably 1 out of 5 CDs.
> Before having a class D amp I have never experienced this before. The same CDs played on my home stereo will not sound so objectionable. It is a harsh, almost sharpness to the sound.
> I would blame it on the Focal tweeters but I have swapped out about 5 different tweeters before I bought the Focals.
> 
> If ANYONE was sitting in the car with me I could easily get them to notice the harshness. It is completly audible.
> As soon as my class AB amp shows up I will pop it in and be able to tell in 10 minutes if this fixes the issue.
> I honestly do not know what else it could be- I bought the best dam HU on the market to try and fix it, and what I thought were very good speakers and amplifier.
> Bottom line- it is NOT ACCEPTABLE TO ME.


I'm quite curious if swapping the amp will solve your problem but take more than the 10 minutes to be sure! I have experienced the harshness you describe, tried different tweeters and switched to a class AB amp. Every time I changed something I thought I had fixed it. But in regular use over a week it popped up again. I heard the offending parts on different equipment like headphones etc but somehow in the car I could never forget about it while I would'nt think about it on different gear. 
In short, I believe I was the biggest part of the problem, not the equipment.
I'm thinking in my case it is position related but I was able to solve (tame) it with TA and EQ.


----------



## atxtrd

metanium said:


> Awesome. Now how about the listening environment behind the wheel of a car? I'm sure many others along with their ears and brains could discern between class D and A/B in a studio environment, but does any of that matter at 60 mph?


To some people it may not matter, to me it does. Specs, blind tests, and the fact that a car is a less than ideal listening environment are all great arguements to toss into the mix...but the bottom line is - "how does it sound"? I happen to love my old Carver TFM amp for home stereo listening, sure there are more expensive amps, amps with better looking specs ect...but I "like" the way it sounds over others. I actually own a Zed Deuce and will be trying it out on my subs (bridged running at 4ohms) in the next couple of weeks, I will let my ears decide as to whether or not I like it. Google "listener fatigue" and you will find class D mentioned often, psychoacoustics do play a part in this.


----------



## avanti1960

[email protected] said:


> Did you ever thought the sound with the JL is the "true" sound how it should be?
> Maybe your old a/b amp made whitewash (is this the right slang ?)
> Regards Barney


whitewash, yeah i get what you mean. nice analogy. in this case i may like the whitewash!


----------



## avanti1960

Wesayso said:


> I'm quite curious if swapping the amp will solve your problem but take more than the 10 minutes to be sure! I have experienced the harshness you describe, tried different tweeters and switched to a class AB amp. Every time I changed something I thought I had fixed it. But in regular use over a week it popped up again. I heard the offending parts on different equipment like headphones etc but somehow in the car I could never forget about it while I would'nt think about it on different gear.
> In short, I believe I was the biggest part of the problem, not the equipment.
> I'm thinking in my case it is position related but I was able to solve (tame) it with TA and EQ.


i'm curious too- and trust me i will give it plenty of time.

my new JL slash amp came today and i will install it this week-end. man the thing weighs a metric tonne compared to the JL HD! It seems like it weighs 3X as much. It HAS to sound better!


----------



## W8 a minute

Maybe it's the enviroment and not the equipment?


----------



## t3sn4f2

avanti1960 said:


> i'm curious too- and trust me i will give it plenty of time.
> 
> my new JL slash amp came today and i will install it this week-end. man the thing weighs a metric tonne compared to the JL HD! It seems like it weighs 3X as much. * It HAS to sound better*!


And with that.........

:inout:


----------



## cleansoundz

I just re-installed my Arc Audio KS 300.4 & KS 1000.1 and I can hear a difference between the KS 300.4 and Alpine F4. Guess which way?


----------



## MarkZ

Wait... I don't get it. Are people trying to call class D digital and class B analog? Or is this just an analogy?

Anyway, could you link to the specific plos one study? The conclusions you drew from the results you described seem a bit odd. Just because there are differences in brain activity between two stimuli does not mean that we USE those differences to form our percept. For example, neurons in primary visual cortex will generally respond directly to monitor refresh rates pretty strongly, even though we tend to filter those things out perceptually.

So it doesn't really matter if a particular portion of the nervous system is reliably representing the difference between two stimuli. The only thing that matters is whether or not we perceive that difference. So, sure, you can easily demonstrate that the spectral content of an mp3 is different from the wav or from the analog source... and you may also be able to show that the cochlea responds differentially to it ... and maybe even the ACC. But show me that a human being can reliably distinguish between the given stimuli, and _then_ you've got something. The other tests are just distractions. 



> FWIW the brain is analog.


The brain is not analog. The brain is a giant distortion machine.  The entire point of the brain is to represent "stuff" in a usable filtered version important for achieving goals. That means manipulating the incoming sensory information into representations that ultimately serve perception, action, and memory. To imply that it shares some kind of kinship with analog sources is to imply that fidelity is a goal of the nervous system, and it isn't.


----------



## atxtrd

MarkZ said:


> Wait... I don't get it. Are people trying to call class D digital and class B analog? Or is this just an analogy?
> 
> Anyway, could you link to the specific plos one study? The conclusions you drew from the results you described seem a bit odd. Just because there are differences in brain activity between two stimuli does not mean that we USE those differences to form our percept. For example, neurons in primary visual cortex will generally respond directly to monitor refresh rates pretty strongly, even though we tend to filter those things out perceptually.
> 
> So it doesn't really matter if a particular portion of the nervous system is reliably representing the difference between two stimuli. The only thing that matters is whether or not we perceive that difference. So, sure, you can easily demonstrate that the spectral content of an mp3 is different from the wav or from the analog source... and you may also be able to show that the cochlea responds differentially to it ... and maybe even the ACC. But show me that a human being can reliably distinguish between the given stimuli, and _then_ you've got something. The other tests are just distractions.
> 
> 
> 
> The brain is not analog. The brain is a giant distortion machine.  The entire point of the brain is to represent "stuff" in a usable filtered version important for achieving goals. That means manipulating the incoming sensory information into representations that ultimately serve perception, action, and memory. To imply that it shares some kind of kinship with analog sources is to imply that fidelity is a goal of the nervous system, and it isn't.


What I should have said is the human brain/ear hears in the analog format. The human brain interprets sound from the vibrations that amplified waves produce in the air, which then cause in the ear drum to vibrate. An analog system is one that encodes information as a continuum. There is no inherent limit to values that can be assigned at any point. A digital system is one in which information has discrete values. Here is an interestin read regarding just how the brain reacts to high Freq content. We may not be consciously aware of it but the brain apparently is. http://jn.physiology.org/content/83/6/3548.full.pdf+html


----------



## MarkZ

But that was my point... it doesn't matter if early stages in the brain encode a stimulus in a certain way. If we don't perceive it, then it's irrelevant information that's been filtered out.

Again, I don't think that the fact that the physical world is _analog_ has any bearing here. I'm not sure what point you're trying to make about that. Nobody's claiming that digital transmission is occurring between the sound source and the brain. The sound that a digital source ultimately produces is _analog_. That's what a DAC does.  The only question is whether the artifacts produced during that encoding/decoding process are audible. Those digital artifacts mostly exist in the analog domain (e.g. distortion from the conversion comes from the dithering or interpolation process).


----------



## Pimpnyou204

Going from a SS rubi to a sundown and then to a arc ks i def was upgrading in sound personally or atleast more power before i was clipping and clarity. I think D is ok as long as its top quality because lets face it our ears arent the most keen.


----------



## TOOSTUBBORN2FAIL

To add to what markz said, to know whether we truly perceive something in the audio realm, it needs to be a back to back blind test. Multiple studies have shown that knowing what your listening to can change what you think of the sound, even if there is no actual change (ie telling someone they are listening to a class a amp when ots really a class d inside the case).

This is why taste tests are done blind. Your eyes can mess with your taste just as much as the actual taste does. The same holds true for audio.


----------



## Wesayso

avanti1960 said:


> i'm curious too- and trust me i will give it plenty of time.
> 
> my new JL slash amp came today and i will install it this week-end. man the thing weighs a metric tonne compared to the JL HD! It seems like it weighs 3X as much. It HAS to sound better!


Read this quote below,



TOOSTUBBORN2FAIL said:


> To add to what markz said, to know whether we truly perceive something in the audio realm, it needs to be a back to back blind test. Multiple studies have shown that knowing what your listening to can change what you think of the sound, even if there is no actual change (ie telling someone they are listening to a class a amp when ots really a class d inside the case).
> 
> This is why taste tests are done blind. Your eyes can mess with your taste just as much as the actual taste does. The same holds true for audio.


The second quote here from TOOSTUBBORN2FAIL will explain to you that your sound will improve . You're allready expecting it to be different/better.
Only time will tell if it really has changed.


----------



## subwoofery

I actually feel that the brain is powerful enough to discern certain things the ear or eyes cannot - the other way around is quite true too... 

At CES, you walk around and listen to a lot of speakers (home audio) in different rooms. Then you enter one particular room and from the very first note, you get goose bumps and ask yourself: "what is THAT?" 
That has been my experience and although some speakers sounds right down awful... There are some really nice speakers that sounds natural (MBL, Magico, YG, Thiel, Dynaudio, etc...) but only a handful can make hair on the back of the head stand up (for me it was Raidho Acoustics C1.1 this year and the TAD Cr-1 when I first heard it in a proper demonstration sound room) 

^ my opinion of course  

Kelvin


----------



## MarkZ

subwoofery said:


> I actually feel that the brain is powerful enough to discern certain things the ear or eyes cannot - the other way around is quite true too...


What does this mean? The eyes and ears don't "discern" things. The brain does. The eyes and ears are just sensory organs.

All this discussion about the brain is a red herring. What we really care about is perception, which is easily measurable with established psychophysical approaches. If you want to know whether sound A is distinguishable from sound B, you don't throw a person in a scanner and see if a brain region lights up more strongly for one than for the other. Instead, you demonstrate directly that a person can discriminate sound A from sound B.

The studies that show the MRI data were performed to address other issues, like providing mechanistic descriptions for sensory discrimination.


----------



## avanti1960

I'm reading all this theory about perception vs. belief and expectations, and it sounds an awful lot like placebo effect to me. 
Today on the way home I listened to Mark Lennegan's new CD (highly recommended BTW) and I made a note on my handy deck of post-its that on track no. 9, Mark's voice is noticeably overly raspy and tinged with some harshness that is not acceptable. Call it unacceptably rough around the edges, tainted with a wash of breakup. 
I made a list of all such songs so that when I install the new slash amp I can go directly to them and do a quick sampling to see if the class AB cures some of the harsh ills. 

Quite honestly I hope that I am objective enough not to have my perception colored by expectation. Maybe it will be, but temporarily, because placebo effect can only last for so long.


----------



## t3sn4f2

Schema (psychology) - Wikipedia, the free encyclopedia


----------



## atxtrd

subwoofery said:


> I actually feel that the brain is powerful enough to discern certain things the ear or eyes cannot - the other way around is quite true too...
> 
> At CES, you walk around and listen to a lot of speakers (home audio) in different rooms. Then you enter one particular room and from the very first note, you get goose bumps and ask yourself: "what is THAT?"
> That has been my experience and although some speakers sounds right down awful... There are some really nice speakers that sounds natural (MBL, Magico, YG, Thiel, Dynaudio, etc...) but only a handful can make hair on the back of the head stand up (for me it was Raidho Acoustics C1.1 this year and the TAD Cr-1 when I first heard it in a proper demonstration sound room)
> 
> ^ my opinion of course
> 
> Kelvin


I think I may have mentioned the problems with class D and HF distortion, then there is the limiting of hfc on many modern recordings in the digital realm. Taken from the link I posted above. 

"We pay special attention to the fact that FRS is accompanied
by an intensification of the pleasure with which the sound is
perceived, and envisage the participation of the neuronal pathways
in connection with reward-generating systems (Cooper
1991; Olds and Milner 1954; Wise 1980), which effectively
control various aspects of human behavior. The present PET
result does not seem to be contradictory to this view. The brain
stem contains distinct neuronal groups that are the major
source of monoaminergic projections to various parts of the
brain (Nieuwenhuys et al. 1988; Role and Kelly 1991). These
monoaminergic systems are thought to be the primary sites for
the action of many stimulants and antipsychotic drugs (Kandel
1991). The rCBF in this area was reported to increase after oral
amphetamine challenge (Devous et al. 1995). These fibers lie
in the medial forebrain bundle, which is considered to be
intimately connected with registering pleasurable sensations
(Thompson 1988). The monoaminergic neurons or the opioidpeptidergic
neurons in the deep-lying brain structures are characterized
by long neurotransmitter residence times at synaptic
junctions and the participation of an intracellular messenger in
the postsynaptic neurons (Hartzell 1981; Kehoe and Marty
1980; Schwartz and Kandel 1991). These characteristics seem
to support the delay and persistence of the hypersonic effect
observed in the present EEG experiments. The activation of the
thalamus may reflect its function as part of the limbic system,
which also plays an important role in the control of emotions
(LeDoux 1993; Vogt and Gabriel 1993). It might also reflect
the role of the thalamus in gating sensory input to the cortex
(Andreasen et al. 1994). We speculate that changes of activity
in the deep-lying structure may introduce some modulatory
effects on the perception of audible sounds and thus control
some aspects of human behavior. We have incorporated these
features in the two-dimensional sound perception model: sound
frequencies in the audible range function as a message carrier
and frequencies above the audible range, together with those in
the audible range, function as a modulator of sound perception
through the brain systems, including the reward-generating
system. Further investigations are clearly required to examine
this hypothetical model.
In conclusion, our findings that showed an increase in alpha-
EEG potentials, activation of deep-seated brain structures, a
correlation between alpha-EEG and rCBF in the thalamus, and
a subjective preference toward FRS, give strong evidence
supporting the existence of a previously unrecognized response
to high-frequency sound beyond the audible range that might
be distinct from more usual auditory phenomena. Additional
support for this hypothesis could come from future noninvasive
measurements of the biochemical markers in the brain such as
monoamines or opioid peptides."

Warm fuzzies anyone?


----------



## subwoofery

MarkZ said:


> What does this mean? The eyes and ears don't "discern" things. The brain does. The eyes and ears are just sensory organs.
> 
> All this discussion about the brain is a red herring. What we really care about is perception, which is easily measurable with established psychophysical approaches. If you want to know whether sound A is distinguishable from sound B, you don't throw a person in a scanner and see if a brain region lights up more strongly for one than for the other. Instead, you demonstrate directly that a person can discriminate sound A from sound B.
> 
> The studies that show the MRI data were performed to address other issues, like providing mechanistic descriptions for sensory discrimination.


Guess I didn't use the right word... seems like I need to brush up my english more :blush: lol 

My point is, we all have different perception of things. Some people hear things better than others (women and youngsters), some people trained their ears in order to listen to subtle things in recordings, while others just plain don't care... 
And even those that don't care can still have goose bumps when they hear something natural and above all "Believable". That's the brain at work there. 

I've named a few speaker brands that sounds natural and tonally correct, "almost perfect" and would give them 10/10 everytime I hear it - until I hear Raidho or Tad... 

I have a lot of test that shows the freq response of Audison amps and it is flat from 20Hz to 20kHz - yet people keep saying that they have a warm sound to it. If all amps sound the same, where did the rumor start? Did someone posted once and everybody followed like a sheep? People's brain must have discern a little something because I've never once in my life heard someone say that his Audison was analitical sounding... 

In another thread, we talked about comb filtering. Searched about it and found out that some people do hear it while others don't. Even found some articles about people saying that we don't hear it. 


> Richard,
> 
> It may be a lot easier to hear if you cover one ear. Your brain filters out a lot of nonsense when you can hear with both ears.
> 
> It sounds something like a very tight EQ cut being swept up and down in frequency. Try doing that on a mixer with full parametric EQ and then you'll have an idea what to listen for.


 (from another forum)
^ some people might really hear it while others really don't - brain at work? 

Kelvin


----------



## MarkZ

Where else do you think we perceive sound? The kidney? 

I agree with you that there are some things that some people hear more readily than others. This should be obvious. The point is that all of this is fairly easily testable by every individual. And by "tests" I don't mean "hey dude, swap out your amp and tell me if it sounds different." You have to be a little more rigorous than that.

If you're trying to figure out why your Audison amp sounds different from another amp, you need to do a better job characterizing the differences in the signals that they're producing. Saying that it has a flat amplitude response from 20-20k is very incomplete. I'm pretty sure you don't believe that there are magical forces outside the realm of acoustics that are responsible for the differences, so you need to figure out what is the source of the electrical differences between the amps that's responsible for it. It's hard to draw meaningful conclusions otherwise.


----------



## subwoofery

MarkZ said:


> Where else do you think we perceive sound? The kidney?
> 
> I agree with you that there are some things that some people hear more readily than others. This should be obvious. The point is that all of this is fairly easily testable by every individual. And by "tests" I don't mean "hey dude, swap out your amp and tell me if it sounds different." You have to be a little more rigorous than that.
> 
> If you're trying to figure out why your Audison amp sounds different from another amp, you need to do a better job characterizing the differences in the signals that they're producing. Saying that it has a flat amplitude response from 20-20k is very incomplete. I'm pretty sure you don't believe that there are magical forces outside the realm of acoustics that are responsible for the differences, so you need to figure out what is the source of the electrical differences between the amps that's responsible for it. It's hard to draw meaningful conclusions otherwise.


Agreed entirely  Even the kidney joke :mean:

Kelvin


----------



## nubz69

Hypex Ncore


----------



## trumpet

subwoofery said:


> I have a lot of test that shows the freq response of Audison amps and it is flat from 20Hz to 20kHz - yet people keep saying that they have a warm sound to it. If all amps sound the same, where did the rumor start? Did someone posted once and everybody followed like a sheep? People's brain must have discern a little something because I've never once in my life heard someone say that his Audison was analitical sounding...


I would really like to know if there is actually something about Audison amplifiers that lends to a characteristic sound. I've read many times that it's a whole different league of sound quality when you step up to Audison, McIntosh, and the like. The cynical side of me wants to say, "That's absurd, it's expectation bias after spending so much money!".


----------



## MarkZ

trumpet said:


> I would really like to know if there is actually something about Audison amplifiers that lends to a characteristic sound. I've read many times that it's a whole different league of sound quality when you step up to Audison, McIntosh, and the like. The cynical side of me wants to say, "That's absurd, it's expectation bias after spending so much money!".


I think the more likely scenario, if there is indeed a difference in sound, is that the Audison amp is designed to color the sound in a particular way. I say this because it's incredibly cheap and simple to use established designs to produce a perfect reproduction of the input signal. As Doug Self calls it, a "blameless amplifier."


----------



## Mooresound

In my opinion the difference in how one amplifier sounds vs another IE Audision,Mcintosh, Rockford fosgate, or ZED are undeniable. I have used a leviathin and loved its midbass and highs yet found the PDX to be fatiguing and unatural. I also have my RF power amps that arent warm and remind me more of the PDX yet they are A/B. I also recently bought a Class T arc amp and find it to be a a bit darker than the PDX. or RF amps. 

I also think that taste in amplifier has to do with what speakers they are played on. For example. I used my leviathin on a diamond audio silk tweeter, vs a FR89EX with my pdx. I also used the rockford onboth the diamond Silk(HEX) and the FR89. ... Rockford sounded very bright on both. tended to scream.... leviathin sounded smoother on the silk. With my cuurent set-up I like the arc Class t on my aluminum mids/Tweet(Dayton) because it takes away the fatiguing nature of the aluminum drivers. 


My point is both technologies are different just as manufactures are... And theyh can be implemented to their strengths/weakness in a correctly planned system.


----------



## avanti1960

Well I was all set to install the JL 300/4V2 this week-end for my front stage and have it go head to head against the 900HD in a class AB vs. D comparison.
Unfortunately the package for the JL RCA twisted pair cables had the wrong length from what I ordered. They are too short and will not reach my head unit. The perils of online ordering from a third rate vendor I guess.


----------



## BuickGN

trumpet said:


> I would really like to know if there is actually something about Audison amplifiers that lends to a characteristic sound. I've read many times that it's a whole different league of sound quality when you step up to Audison, McIntosh, and the like. The cynical side of me wants to say, "That's absurd, it's expectation bias after spending so much money!".


I was surprised when I couldn't tell a difference between my McIntosh, Interfire, JLa6450, and Leviathan. There were differences in the way they sounded as they approached their limits and noise floor and all of that but not so much during normal operation. That's when I started putting more emphasis on other factors like power and how they would work in my particular install.


----------



## ChrisB

BuickGN said:


> I was surprised when I couldn't tell a difference between my McIntosh, Interfire, JLa6450, and Leviathan. There were differences in the way they sounded as they approached their limits and noise floor and all of that but not so much during normal operation. That's when I started putting more emphasis on other factors like power and how they would work in my particular install.


I may have said it before in this thread, but when it came to all the amplifiers that I went through, differences in power were easier to determine between switching out various amplifiers, versus amplifiers that output relatively the same amount of power. 

The only caveat were those couple of amplifiers that intentionally colored the sound. They sounded "better" at first, but after getting many hours of seat time, I could tell that their "better" didn't sound right on certain tracks because certain notes weren't being produced correctly. When you mess with my Pink Floyd audio reproduction or shut off trying to reproduce electronic music, I take it personally!:laugh: Rather than get into all that, you can search this forum and see my meltdown. I'm sure it is still somewhere around here.:blush:


----------



## avanti1960

Well after listening exclusively to my JL 900 HD (class D) amp for the past several months and hearing some notable grit, harshness, edgy break up in about a fifth of the music I listen to I finally was able to install my new JL 300/4 V2 (class A-B) amp over the week-end in a quest to eliminate the harsh overtones that should NOT be present in a good high quality mobile audio system. 

After listening for the past (2) days and playing all of the "troublesome" CDs that I took note of I can with absolute certainty that the JL 300/4 V2 amplifier running my front stage has ELIMINATED THE GRITTY EDGY BREAKUP and HARSHNESS that the JL 900 HD exhibited. 
The music that contains some challenging material, e.g. intended fuzziness, intended raw and grittiness or distortion effects- sounds like it was intended to sound- in there for effect and tolerable- not compounded by the class D circuitry which made these recordings unacceptable. 
I am so very happy to have a solution and a true SQ system in my car. 
I see no reason to ever run a class D amp for the mids and tweeters ever again. 

WITHOUT A SHADOW OF A DOUBT, IN A WELL DOCUMENTED COMPARISON BEWEEN CLASS D AND CLASS A-B AMPLIFIERS FROM THE SAME MANUFACTURER- CLASS A-B SOUNDS SIGNIFICANTLY BETTER AT REPRODUCING MIDRANGE AND HIGH FREQUENCIES THAN DOES CLASS D. 

As soon as my amp was installed I just learned of a new version of my amp, the JL 300/4 V3-
JL Audio Slash 300/4v3 4-channel car amplifier — 75 watts RMS x 4 at Crutchfield.com 

I wonder how that one compares to my V2, although I got mine for just above half the cost of the V3. 

I am confident that I could reproduce the results for anyone with ears. As soon as I told you what to listen for you would hear it forever and ditch the class D as soon as you could.


----------



## envisionelec

avanti1960 said:


> WITHOUT A SHADOW OF A DOUBT, IN A WELL DOCUMENTED COMPARISON BEWEEN CLASS D AND CLASS A-B AMPLIFIERS FROM THE SAME MANUFACTURER- CLASS A-B SOUNDS SIGNIFICANTLY BETTER AT REPRODUCING MIDRANGE AND HIGH FREQUENCIES THAN DOES CLASS D.


Please point us to your documentation. I am genuinely interested in learning how you intercepted the data between your ears and brain and were able to translate that into a human-readable file. Failing that, I want to see your written notes detailing what you've perceived as better.

My doubts overshadow the claim.


----------



## avanti1960

Over the course of several months I documented which CDs and tracks sounded objectionable per the qualities described previously. I did this so that I eventually could play them once the A-B amp was installed and see if it showed the same objectionable characteristics. 
The class A-B does not reproduce anything objectionable when playing back the songs on my documented list. I could demonstrate this to anyone.

I would be happy to provide a list of artist, CD and track no. if you wish do do your own comparison.


----------



## envisionelec

BuickGN said:


> I was surprised when I couldn't tell a difference between my McIntosh, Interfire, JLa6450, and Leviathan. There were differences in the way they sounded as they approached their limits and noise floor and all of that but not so much during normal operation. That's when I started putting more emphasis on other factors like power and how they would work in my particular install.


Thank you for being objective.


----------



## envisionelec

avanti1960 said:


> Over the course of several months I documented which CDs and tracks sounded objectionable per the qualities described previously. I did this so that I eventually could play them once the A-B amp was installed and see if it showed the same objectionable characteristics.
> The class A-B does not reproduce anything objectionable when playing back the songs on my documented list. I could demonstrate this to anyone.
> 
> I would be happy to provide a list of artist, CD and track no. if you wish do do your own comparison.


OK, but I would need to have your speakers, cabling, electrical system, installation, interior, head unit and everything else to do a fair comparison. Oh, and a means to switch between the amplifiers immediately and imperceptibly...you know, to eliminate any psychological perception that one is better than the other. The (discontinued) QSC ABX comparator would be ideal.


----------



## t3sn4f2

avanti1960 said:


> Well after listening exclusively to my JL 900 HD (class D) amp for the past several months and hearing some notable grit, harshness, edgy break up in about a fifth of the music I listen to I finally was able to install my new JL 300/4 V2 (class A-B) amp over the week-end in a quest to eliminate the harsh overtones that should NOT be present in a good high quality mobile audio system.
> 
> After listening for the past (2) days and playing all of the "troublesome" CDs that I took note of I can with absolute certainty that the JL 300/4 V2 amplifier running my front stage has ELIMINATED THE GRITTY EDGY BREAKUP and HARSHNESS that the JL 900 HD exhibited.
> 
> The music that contains some challenging material, e.g. intended fuzziness, intended raw and grittiness or distortion effects- sounds like it was intended to sound- in there for effect and tolerable- not compounded by the class D circuitry which made these recordings unacceptable.
> I am so very happy to have a solution and a true SQ system in my car.
> I see no reason to ever run a class D amp for the mids and tweeters ever again.
> 
> WITHOUT A SHADOW OF A DOUBT, IN A WELL DOCUMENTED COMPARISON BEWEEN CLASS D AND CLASS A-B AMPLIFIERS FROM THE SAME MANUFACTURER- CLASS A-B SOUNDS SIGNIFICANTLY BETTER AT REPRODUCING MIDRANGE AND HIGH FREQUENCIES THAN DOES CLASS D.
> 
> As soon as my amp was installed I just learned of a new version of my amp, the JL 300/4 V3-
> JL Audio Slash 300/4v3 4-channel car amplifier — 75 watts RMS x 4 at Crutchfield.com
> 
> I wonder how that one compares to my V2, although I got mine for just above half the cost of the V3.
> 
> I am confident that I could reproduce the results for anyone with ears. As soon as I told you what to listen for you would hear it forever and ditch the class D as soon as you could.


NwAvGuy: What We Hear


----------



## Wesayso

avanti1960 said:


> I'm reading all this theory about perception vs. belief and expectations, and it sounds an awful lot like placebo effect to me.
> Today on the way home I listened to Mark Lennegan's new CD (highly recommended BTW) and I made a note on my handy deck of post-its that on track no. 9, Mark's voice is noticeably overly raspy and tinged with some harshness that is not acceptable. Call it unacceptably rough around the edges, tainted with a wash of breakup.
> I made a list of all such songs so that when I install the new slash amp I can go directly to them and do a quick sampling to see if the class AB cures some of the harsh ills.
> 
> Quite honestly I hope that I am objective enough not to have my perception colored by expectation. Maybe it will be, but temporarily, because placebo effect can only last for so long.


It can last for two days , just saying...


----------



## TOOSTUBBORN2FAIL

avanti1960 said:


> Over the course of several months I documented which CDs and tracks sounded objectionable per the qualities described previously. I did this so that I eventually could play them once the A-B amp was installed and see if it showed the same objectionable characteristics.
> The class A-B does not reproduce anything objectionable when playing back the songs on my documented list. I could demonstrate this to anyone.
> 
> I would be happy to provide a list of artist, CD and track no. if you wish do do your own comparison.


I'm curious if you listened to Todd Luliaks 2011 Meca National Extreme Class winning car, using 2 JL HD900/5's, on the midbass, mids and highs, if you would still think it was the amps fault. Same with Mark Eldridge's car, or Scott Buwalda's G35, both also using JL HD amps. Or Gary Summers car, which uses Alpine PDX amps, and was the 2010 Meca Modex champion. 

Not saying competition is the end all of this, but I bet you wouldnt be able to tell a difference in their cars, and I bet if you did a blind test in yours, you couldnt tell either, unless you were clipping it.


----------



## avanti1960

TOOSTUBBORN2FAIL said:


> I'm curious if you listened to Todd Luliaks 2011 Meca National Extreme Class winning car, using 2 JL HD900/5's, on the midbass, mids and highs, if you would still think it was the amps fault. Same with Mark Eldridge's car, or Scott Buwalda's G35, both also using JL HD amps. Or Gary Summers car, which uses Alpine PDX amps, and was the 2010 Meca Modex champion.
> 
> Not saying competition is the end all of this, but I bet you wouldnt be able to tell a difference in their cars, and I bet if you did a blind test in yours, you couldnt tell either, unless you were clipping it.


I do not disagree that the HD900s can sound good. They can. In fact there are probably some things they do better. 
I would also have a strong hunch that competition source material is predetermined and is probably very high quality. 
I am talking about music that can bring out the worst in an amp, unfortunately lots of the music I listen to- a singer with a gravelly voice (Eddy Vedder, Mark Lannegan, even Dave Grohl) the edge on these guys vocals can wring out the worst in class D amplifiers tendencies- giving it a break up, a sharp edge, a grit that is all too obvious, I have witnessed it for months and it drove me crazy to think that I spent so much money on a system only to have it occasionally sound irritating.
The Class A-B amp flat out does not do that. This is significant. Issue gone.


----------



## avanti1960

Here is my new amp.

In all fairness my first class D amp was a real cheapie- a pioneer GMD9500F- and it exhibited far worse harsh tendencies surrounding "challenging" source material than the HD900 does. 
This led to my being able to hone in on these tendencies, to really understand what it sounds like and be able to spot it in an instant. 

Unfortunately I did not place the blame on the pioneer amp- i swapped speakers, head units, and eventually the HD900 in an effort to get rid of that irritating sound. 
When I bought the HD900 it did sound a lot better. However, it was not long before I picked up on the occasional harshness and grittines.

In hindsight I could have saved a lot of time and money and been satisfied with a good 4-channel A-B amp and a good class D mono amp.


----------



## avanti1960

envisionelec said:


> OK, but I would need to have your speakers, cabling, electrical system, installation, interior, head unit and everything else to do a fair comparison. Oh, and a means to switch between the amplifiers immediately and imperceptibly...you know, to eliminate any psychological perception that one is better than the other. The (discontinued) QSC ABX comparator would be ideal.


The harshness is so obvious once you know what to look for that you do not need an immediate comparison- 

it is ingrained in my skull!


----------



## TOOSTUBBORN2FAIL

avanti1960 said:


> I do not disagree that the HD900s can sound good. They can. In fact there are probably some things they do better.
> I would also have a strong hunch that competition source material is predetermined and is probably very high quality.
> I am talking about music that can bring out the worst in an amp, unfortunately lots of the music I listen to- a singer with a gravelly voice (Eddy Vedder, Mark Lannegan, even Dave Grohl) the edge on these guys vocals can wring out the worst in class D amplifiers tendencies- giving it a break up, a sharp edge, a grit that is all too obvious, I have witnessed it for months and it drove me crazy to think that I spent so much money on a system only to have it occasionally sound irritating.
> The Class A-B amp flat out does not do that. This is significant. Issue gone.


I listen to a wide variety of music. In that is some of the most difficult music to reproduce. Yes, even death metal (the good well recorded stuff). I've listened on JL HD's before and heard none of the problems youve brought up. Comparisons without a blind a/b comparison with little to no lag between switching amps is unfortunately, useless.


----------



## TOOSTUBBORN2FAIL

avanti1960 said:


> The harshness is so obvious once you know what to look for that you do not need an immediate comparison-
> 
> it is ingrained in my skull!


Sorry, but the red text is exactly why most comparisons have no credibility. If you dont listen to them back to back, with as little lag as possible, the "testing" is worthless as a test of whats better.


----------



## W8 a minute

I've proved all this to be tom foolery before. Once by using Pyramid amps and telling everyone they were Phoenix Gold (or PPI?) and another time by placing pictures of people playing instruments on my dashboard. Everyone thought the Pyramid amps sounded great. Commenting on the low distortion and great dynamic range. During the soundstage experiment people all thought the bass player was on the left if the picture was on the left and right if the picture was on the right. All of this while playing the same song. You hear what you WANT to hear.

And for the record the Pyramid amp was a PB900G Gold series. Not the rebadged PPI Super Pro amps.


----------



## avanti1960

TOOSTUBBORN2FAIL said:


> I listen to a wide variety of music. In that is some of the most difficult music to reproduce. Yes, even death metal (the good well recorded stuff). I've listened on JL HD's before and heard none of the problems youve brought up. Comparisons without a blind a/b comparison with little to no lag between switching amps is unfortunately, useless.


the comparison is useless??? that's more harsh than my amp is!


----------



## avanti1960

W8 a minute said:


> I've proved all this to be tom foolery before. ..... You hear what you WANT to hear.
> 
> But i did not WANT to hear the class D sound harsh and gritty but it did not listen to me.....


----------



## TOOSTUBBORN2FAIL

Sorry, just brutal honesty. You claim the amp was absolutely the cause of your problems, but you dont really know that. All you have is a opinion flawed by inadequate testing procedure. Unless you have both amps hooked up, with a way to seemlessly switch between the two, with someone else doing the switching, and both amps level matched to within a db, you cant claim anything about differences between the two as fact. Anything else just isnt good enough.

Reguardless of how you wanted the class d to sound, you expected the class a/b to sound better, which whether consciously or not, makes you biased towards thinking its better.


----------



## vrdublu

avanti1960 said:


> W8 a minute said:
> 
> 
> 
> I've proved all this to be tom foolery before. ..... You hear what you WANT to hear.
> 
> But i did not WANT to hear the class D sound harsh and gritty but it did not listen to me.....
> 
> 
> 
> I hate to jump on the bandwagon here, but I'm afraid I have to agree with most people's comments. Could be something as simple as improperly set gains, which most of the times it is. Great article BTW, thanx for the link.
Click to expand...


----------



## minbari

TOOSTUBBORN2FAIL said:


> Sorry, but the red text is exactly why most comparisons have no credibility. If you dont listen to them back to back, with as little lag as possible, the "testing" is worthless as a test of whats better.


complettely agree. if you are doing blind A/B testing, then you have to switch it with less than 1 sec of lag or the mind forgets what it was hearing. and honestly if you switch it instantly and there is no difference, this adds to the argument.


----------



## Wesayso

avanti1960 said:


> W8 a minute said:
> 
> 
> 
> I've proved all this to be tom foolery before. ..... You hear what you WANT to hear.
> 
> 
> 
> But i did not WANT to hear the class D sound harsh and gritty but it did not listen to me.....
Click to expand...

When did you run auto EQ? I stubled on a post 2 days ago of you mentioning auto EQ. If you did run that after the amp switch it could be another reason for the change.

If you had any doubt with the class D, purely by reading about it on here that would be reason enough to have an influence.


----------



## envisionelec

minbari said:


> complettely agree. if you are doing blind A/B testing, then you have to switch it with less than 1 sec of lag or the mind forgets what it was hearing. and honestly if you switch it instantly and there is no difference, this adds to the argument.


It's closer to 50 milliseconds and it can't be interrupted.


----------



## envisionelec

Think about this from JL's point of view. Why would they design or, in this case, license a unique technology that would be in any way inferior to their A/B lineup? What would be their motivation?

When I saw that they had licensed the SCC control method, I nearly fell out of my chair. It is the current state-of-the art. I do not hesitate to recommend it to anyone interested in their amplifiers.


----------



## envisionelec

avanti1960 said:


> I am talking about music that can bring out the worst in an amp, unfortunately lots of the music I listen to- a singer with a gravelly voice (Eddy Vedder, Mark Lannegan, even Dave Grohl) the edge on these guys vocals can wring out the worst in class D amplifiers tendencies- giving it a break up, a sharp edge, a grit that is all too obvious


I take issue with this statement. This implies that you know something about Class D's weaknesses, which you have yet to connect to your single-ended statements. What is the mechanism in a Class D amplifier (that is not inherent in any other design) that you believe is causing these flaws? The switching? The filters? Keep in mind that the JL switching occurs well WELL above human hearing. 

Let me try to make this more clear: If you can't tell that FM stereo's audio signal is literally switched left to right at 38KHz (didn't know that, did you?) then you can't hear a Class D amplifier "switching" to produce an approximation of a sine wave - especially after it has been filtered to produce an exceptional, yet greatly amplified, facsimile of the original signal. AND the JL uses post-filter feedback to correct for distortions that occur as a result of phase shift all in the infinite response of the analog domain.

The very fact that you keep responding shows me that you'd actually like a viable explanation for what is happening. The truth is: We can't tell you, because none of us are hearing what you experience in your vehicle. We're trying to explain that it's faulty reasoning to compare amplifiers without an ABX test. *We're not trying to find fault with you or your experience*, but we are pointing out the inconsistencies and trying to educate you about how this stuff really works.


----------



## TOOSTUBBORN2FAIL

^best reponse of the whole thread.


----------



## Cooluser23

Mobile Electronics AU | Alpine PDX-F6 4 Channel Amplifier


----------



## simplicityinsound

i think there are two questions here:

1. Can a class D full range sound good - and the answer is surely yes, as proven by Eldridge, Bulwada etc..


2. Can a class D full range sound as good as a class AB, budget not a limiting factor.

here is where the debate is.


so my question to yall is this.

if say Scott, and Mark,after this season, instead of being supported and sponsored by JL, instead was sponsored by a company that makes ultra high end class AB and class A amps...

so both of them make a swtich to these types of amps, while keeping everythign else the same.

do you think they themselves can hear an audible difference versus before? namely, an improvement versus before.

i think that is the key factor here...and what should really matter to people debating this topic, at the end of the day, no one cares what other people may or may not think about the car, its you who hears it on a daily basis and you who gets to right away, tell the differences, so the key is will YOU hear a difference by going to a class AB....if it does, regardless what anyone else says, its worth it to you


----------



## kyheng

12 pages of debates, well done....


----------



## oilman

Subscribed


----------



## avanti1960

vrdublu said:


> avanti1960 said:
> 
> 
> 
> I hate to jump on the bandwagon here, but I'm afraid I have to agree with most people's comments. Could be something as simple as improperly set gains, which most of the times it is. Great article BTW, thanx for the link.
> 
> 
> 
> I am on my second class D amp- I went from worst to (argualby) first and although the harsh tendencies have been greatly reduced, they are nonetheless still present as to be objectionable an unacceptable.
> I worked for months on each one tuning night and day, adjusting gains, swapping headunits and drivers, adjsting EQ to try and cut the objectionable frequencies- and when it was all said and done I could not satisfactorily eliminate the harsh tendencies in the class D amp for mid and high frequencies.
> I did it in one day by running the 300/4 v2 and nearly a week later it still sounds sweet.
Click to expand...


----------



## avanti1960

Wesayso said:


> When did you run auto EQ? I stubled on a post 2 days ago of you mentioning auto EQ. If you did run that after the amp switch it could be another reason for the change.
> 
> If you had any doubt with the class D, purely by reading about it on here that would be reason enough to have an influence.


again, i ran the HD 900 for months and eq'd, tuned, adjusted, swapped etc. and could not come to a satisfactory sound considering the investment I made on my system in both time and fincial resources. 

i came to satisfaction in one day by running the 300/4 v2.


----------



## avanti1960

envisionelec said:


> I take issue with this statement. This implies that you know something about Class D's weaknesses, which you have yet to connect to your single-ended statements. What is the mechanism in a Class D amplifier (that is not inherent in any other design) that you believe is causing these flaws? The switching? The filters? Keep in mind that the JL switching occurs well WELL above human hearing.
> 
> Let me try to make this more clear: If you can't tell that FM stereo's audio signal is literally switched left to right at 38KHz (didn't know that, did you?) then you can't hear a Class D amplifier "switching" to produce an approximation of a sine wave - especially after it has been filtered to produce an exceptional, yet greatly amplified, facsimile of the original signal. AND the JL uses post-filter feedback to correct for distortions that occur as a result of phase shift all in the infinite response of the analog domain.
> 
> The very fact that you keep responding shows me that you'd actually like a viable explanation for what is happening. The truth is: We can't tell you, because none of us are hearing what you experience in your vehicle. We're trying to explain that it's faulty reasoning to compare amplifiers without an ABX test. *We're not trying to find fault with you or your experience*, but we are pointing out the inconsistencies and trying to educate you about how this stuff really works.


I make no claims about understanding the mechanism behind the observed sound quality. 
The written statements of why there shouldn't be any issues with sound quality in these class D amplifiers are not enough to eliminate them from my particular perception in my particular experience. 
I would argue that my reasoning behind my findings- that I have witnessed similar harsh sound reproduction tendencies in (2) class D amplifiers- and that despite efforts above and beyond to cure these tendencies over the course of several months I was unable to satisfactorily resolve these issues- and that they were completely eliminated in one day by switching to the class A-B amplifier- 
I would argue that while the reasoning may not be valid as a rigorous, indisputable scientific experiment- it is far from worthless and without value. The findings are significant enough as to point in a direction to suggest that there may be something here that could very well be proven if subjected to controlled scientific study. The findings do have merit. 
When we start talking all mythical about perception bias and hearing what we want to hear, that is where people seem to really be grasping for straws. Seriously, as much as I want the sky to be neon green at high noon on Sunday, I will look at it and have to admit that unless there are some serious cosmic events in process it will most likely still be blue. 

Ask yourself this- why is there so much energy here behind the idea that Class A-B can still sound better than class-D? Why is it such a difficult idea to swallow?


----------



## MarkZ

avanti1960 said:


> Ask yourself this- why is there so much energy here behind the idea that Class A-B can still sound better than class-D? Why is it such a difficult idea to swallow?


Because some of us who understand how class D amplification works, and how it's generally implemented in car audio, are having trouble understanding what the problem might be, because there's no reason that it should sound inferior to class A/B or B.

If I wasn't moving in a couple weeks, I'd offer to test and benchmark this amp for you and post the results on the forum, to see if there's something peculiar about this particular amp that could be giving rise to this objectionable sound. Maybe someone else reading this can volunteer to do it?


----------



## envisionelec

avanti1960 said:


> I make no claims about understanding the mechanism behind the observed sound quality.
> The written statements of why there shouldn't be any issues with sound quality in these class D amplifiers are not enough to eliminate them from my particular perception in my particular experience.
> I would argue that my reasoning behind my findings- that I have witnessed similar harsh sound reproduction tendencies in (2) class D amplifiers- and that despite efforts above and beyond to cure these tendencies over the course of several months I was unable to satisfactorily resolve these issues- and that they were completely eliminated in one day by switching to the class A-B amplifier-
> I would argue that while the reasoning may not be valid as a rigorous, indisputable scientific experiment- it is far from worthless and without value. The findings are significant enough as to point in a direction to suggest that there may be something here that could very well be proven if subjected to controlled scientific study. The findings do have merit.
> When we start talking all mythical about perception bias and hearing what we want to hear, that is where people seem to really be grasping for straws. Seriously, as much as I want the sky to be neon green at high noon on Sunday, I will look at it and have to admit that unless there are some serious cosmic events in process it will most likely still be blue.
> 
> Ask yourself this- why is there so much energy here behind the idea that Class A-B can still sound better than class-D? Why is it such a difficult idea to swallow?


You're the only one getting mythical about this. We're presenting scientific facts and I am presenting the facts as they exist around the design of Class D amplifiers (with which I have actual design experience). We're not talking about any Class D, but the specific JL HD version which incoporates specific technology designed to reduce distortion through and beyond the listening bandwidth.

Do you always resort to the straw man in your logic? 

Your question deserves an answer. Early and poorly designed Class D amps can sound harsh due to an uncompesated, rising frequency response of the passive filter. This is not the case here with the JL.


----------



## W8 a minute

Is this 900/5 for sale? If it sounds this bad I should be able to get it really cheap.


----------



## avanti1960

W8 a minute said:


> Is this 900/5 for sale? If it sounds this bad I should be able to get it really cheap.


Sorry- not for sale- it's running my sub and rear passives. 
Please understand I am not bashing this amp- it sounds great as a sub amp- the infrasonic filter does wonders to tighten up the bass of both versions of my 12W3V3- either ported or sealed. It sounds MUCH better either way with that filter turned on. 
It also sounded very good if not great with most music for the full range stage. 
It's just that an occasional harshness cropped up in about 1/5th of the music I listen to that I could not get rid of. 
There is nothing wrong with the amp. 
Peace to all if I was coming off as confrontational or insulting.


----------



## adrenalinejunkie

My JL 300-2v1 took a crap an I'm considering the JL 600-4HD since it seems that i cant go wrong with it from what i have read Thanks for the info 


Sent from your mom's WiFi using Tapatalk


----------



## jgustin

I have an Eclipse XA4000 and I have experienced the same thing as avanti1960. It's been driving me crazy since I stopped using my JL 500/5. There is a harshness that starts to hurt my ears in some music. I thought the harshness was coming from the speakers, but since then I've tried several different speakers and they all have the same problem. I just haven't been able to switch back to an A/B amp yet.


----------



## envisionelec

jgustin said:


> I have an Eclipse XA4000 and I have experienced the same thing as avanti1960. It's been driving me crazy since I stopped using my JL 500/5. There is a harshness that starts to hurt my ears in some music. I thought the harshness was coming from the speakers, but since then I've tried several different speakers and they all have the same problem. I just haven't been able to switch back to an A/B amp yet.


I can tell you that you're clipping the amp. Class D amps often exhibit hard clipping which can sound like white noise rather than a buzzing that A/B amps will exhibit.

You need a more powerful amp for your listening habits, plain and simple.


----------



## jgustin

I have to disagree. 
First off, how do you even know what my listening habits are? 
Secondly, why do you assume that I don't know how to tune my system properly?
I assure you that I am not clipping my amp.
It really concerns me that you would make such a blanket statement with so little information.
How many readers would be off shopping for a more powerful amp because they believe you?


----------



## TOOSTUBBORN2FAIL

Let me play devils advocate, how do you know that its a problem with class d amps? There is no real evidence that states you can hear the difference between well designed class ab and class d. In fact, every scientific study ive seen says you cant hear the difference when not pushed to clipping.


----------



## TOOSTUBBORN2FAIL

Let me play devils advocate, how do you know that its a problem with class d amps? There is no real evidence that states you can hear the difference between well designed class ab and class d. In fact, every scientific study ive seen says you cant hear the difference when not pushed to clipping. Are you sure your not clipping it? You cant be sure without checking with an oscope.


----------



## jgustin

To be fair, I can't say that I know definitively that it is a problem with class D.
I was attracted to them based on their efficiency, footprint and price tag. But, I suspected that you don't get these advantages without giving up something, so I read and read all about them.
I dismissed the rants from the old school AB purists and chose to go with D. And, I regret it.


----------



## ChrisB

I don't know why I found this funny, but I read TOOSTUBBORN2FAIL's posts as "Let me play doubles advocate":laugh:

Ok, carry on now...


----------



## jgustin

I set the voltage to 5V to match the 5V outs from my head unit. While tuning, at 100% volume on the head unit the clipping indicator occasionally flickers. I never turn the volume past 80% while listening.
I get the science argument, guys. I'm just saying that there is more to it. You can't pick speakers from their test graphs, some guys still swear by tube amps, Jesus came back to life after three days. Not everything can be explained by science.
I just wanted to share my experience to support the argument that our ears know what makes them happy. They don't need everybody telling them how they are supposed to be hearing it.


----------



## ErinH

Well, on the flip side, a lot of peoples' ears tell them there is nothing wrong with Class D amps. A lot of people fail to understand the importance of double blind testing and rely on their on their psyche to influence their decisions. It's actually a science as well. 

At the end of the day, emotion is tied to music. I'm fine with a purchase decision or choice rationale based on emotion. However, few will acknowledge the impact of emotion and psychoacoustics and instead default to making generic statements and conclusions to only fan the flames of those who are uniformed and gullible. 


Sent from my iPhone. Pardon the grammar.


----------



## MarkZ

jgustin said:


> But, I suspected that you don't get these advantages without giving up something


This, I think, sums up most people's reluctance to embrace new technology. You're basically saying, "what's the catch?" It's not really a rational way of looking at things.


----------



## TOOSTUBBORN2FAIL

ChrisB said:


> I don't know why I found this funny, but I read TOOSTUBBORN2FAIL's posts as "Let me play doubles advocate":laugh:
> 
> Ok, carry on now...


Lol, stupid phone double post.


----------



## envisionelec

jgustin said:


> I have to disagree.
> First off, how do you even know what my listening habits are?
> Secondly, why do you assume that I don't know how to tune my system properly?
> I assure you that I am not clipping my amp.
> It really concerns me that you would make such a blanket statement with so little information.
> How many readers would be off shopping for a more powerful amp because they believe you?


I can assume anything. It's the internet.
Your abilities to "tune your system" were never called into question.
Are you certain? 
_That_ concerns you? Wow.
I don't know. Maybe because I've designed both Class D and A/B amps and know their tendencies/behavior at clipping?

You are probably clipping your amp more often than you think.


----------



## envisionelec

jgustin said:


> They don't need everybody telling them how they are supposed to be hearing it.


Then why post at all? You're contradicting yourself by setting the stage for an argument.


----------



## jgustin

"You need a more powerful amp for your listening habits, plain and simple."

What do you recommend?


----------



## envisionelec

jgustin said:


> "You need a more powerful amp for your listening habits, plain and simple."
> 
> What do you recommend?


Wrong thread.

This isn't about recommendations - it's about the perceived differences between the JL Audio HD amps and a typically well-regarded A/B amplifier.

Look, I'm not being a dick about this. Maybe I should have asked some questions, but your post basically stated "Oh yeah, those Class D amps are harsh - I can hear it with all different types of speakers". So my reply, being one-sided and judgmental really shouldn't be taken offensively because it's the same tack you used. Try a different approach like "I have a XXX amplifier and hear harshness on X and Y music, but not Z. Are the XXX brand amplifier the same technology?"


----------



## jgustin

> Early and poorly designed Class D amps can sound harsh due to an uncompesated, rising frequency response of the passive filter


Is that the problem with the Eclipse XA4000?


----------



## envisionelec

jgustin said:


> Is that the problem with the Eclipse XA4000?


I was going to write a big technical response, but I've decided a simple "Yep." is enough. It gets complex very fast. The feedback/filter mechanism is the biggest contributor to its issues with load variance. I think if you ran an active system with tweeters that had a relatively flat impedance profile, you'd never hear that harshness. But I still think you're clipping - and depending on how the clip indicator is designed, it probably isn't responding well to clipping in the upper midrange/treble.

You can clip an amplifier below the 100% mark on your headunit if the source material is above your reference level when you set the system up.


----------



## jgustin

I really thought I was leaving enough head room so that I would NEVER clip. I set it up so that it BARELY clipped at 100%. I don't see how it would be clipping at 80%, running components with passive crossovers. I use the loudest/best recordings I have when I set it up to account for source levels.


----------



## jgustin

envisionelec said:


> Wrong thread.
> 
> This isn't about recommendations - it's about the perceived differences between the JL Audio HD amps and a typically well-regarded A/B amplifier.
> 
> Look, I'm not being a dick about this. Maybe I should have asked some questions, but your post basically stated "Oh yeah, those Class D amps are harsh - I can hear it with all different types of speakers". So my reply, being one-sided and judgmental really shouldn't be taken offensively because it's the same tack you used. Try a different approach like "I have a XXX amplifier and hear harshness on X and Y music, but not Z. Are the XXX brand amplifier the same technology?"


I do apologize for offending anyone. I just re-read my original post and I can see how it could be offensive. I really did not mean it that way - lesson learned to be more sensitive while I type.


----------



## envisionelec

jgustin said:


> I really thought I was leaving enough head room so that I would NEVER clip. I set it up so that it BARELY clipped at 100%. I don't see how it would be clipping at 80%, running components with passive crossovers. I use the loudest/best recordings I have when I set it up to account for source levels.


But that's not how you set up a system. You can't generally hear the onset of clipping on normal source material, so you have to run the amp into a dummy load (resistor) and play a 0dB signal while monitoring the speaker output on an oscilloscope or HD meter. Turn the headunit up until it clips (amp gain all the way down), then turn the amp gain up until it clips. Ideally you want all sources and amps to clip at the same point.

Keep in mind, though, that most source material will sound "too quiet" on a system that is ideally set up - even at max headunit volume. So this is why you have to be cognizant of what clipping sounds like on your system without attributing non-linearities to a particular class of amplifier.


----------



## envisionelec

jgustin said:


> I do apologize for offending anyone. I just re-read my original post and I can see how it could be offensive. I really did not mean it that way - lesson learned to be more sensitive while I type.


You didn't offend me. No worries, mate! 

Double post? Yep...not sure how.


----------



## envisionelec

jgustin said:


> I do apologize for offending anyone. I just re-read my original post and I can see how it could be offensive. I really did not mean it that way - lesson learned to be more sensitive while I type.


You didn't offend me. No worries, mate!


----------



## jgustin

envisionelec said:


> Look, I'm not being a dick about this.





envisionelec said:


> You didn't offend me. No worries, mate!


Okay good!  
But, I might offend you now...
I just have to say, you _were_ being _kind of_ a dick earlier.
I appreciate your knowledge, now that I have asked for it. But, as for earlier, maybe you can take some of your own advice on how to phrase things better


----------



## jgustin

envisionelec said:


> But that's not how you set up a system.


Well, that's what I get for trusting a bunch of guys from DIYMA! 




envisionelec said:


> Keep in mind, though, that most source material will sound "too quiet" on a system that is ideally set up - even at max headunit volume.


I'm sorry, but I don't follow this at all. Can you please explain it more?


----------



## t3sn4f2

jgustin said:


> Well, that's what I get for trusting a bunch of guys from DIYMA!


The same bunches that talk down on quality cheap cables, ipods, 25% CLD dampening, not using linedrivers for SQ, etc.? You're following the wrong crowd, need to start looking for that science thing.


----------



## jgustin

It's so hard to know who to listen to. I am fairly intelligent, and I read and read, falling asleep at my desk most nights. I never trust something the first time I read it. I make sure I verify it from multiple sources. So many people sound like they know what they are talking about, and sometimes it even makes sense


----------



## jgustin

garysummers said:


> I was originally running the first generation Alpine PDX amps in my 5.1 setup! When the new PDX came out I decided to replace all 5 amps at once!
> With out question these amps sonically out preformed the original.
> So IMHO the technology is improving!


Gary,
What was the time period between the older and the new amps?


----------



## envisionelec

jgustin said:


> It's so hard to know who to listen to. I am fairly intelligent, and I read and read, falling asleep at my desk most nights. I never trust something the first time I read it. I make sure I verify it from multiple sources. So many people sound like they know what they are talking about, and sometimes it even makes sense


Well, if you look through my posts, you'll see that I don't get into fights about amplifiers based on anything but scientific principles. When people ask me which amp to buy, I say stuff like "Get the one that color-matches your installation" and "Buy as much power as you can afford, not based on your speaker's rated power handling (which is almost meaningless)."

What I am saying about playing "normal source material" is that you'll likely find your system doesn't get "loud enough" when playing normal music if you've set your system to clip at 0dB. Most well-recorded music doesn't peak at 0dB, so that can be misleading. Maybe set your max levels at -10dB source and make _that_ your limit. 

If you want to find out if you are clipping when you hear that harshness, grab a storage oscilloscope and look at the output during that passage (and level) that you hear it. To find the upper limit, crank the gain up until the waveform amplitude stops increasing and the tops of the waveforms are chopped off. Make note of that level...Set the capture levels to grab anything over 90% of that peak voltage and see what you get. 

The amp could be faulty. The only way to know _that_ is to perform a standard THD test, but you need specialized equipment for that like an Audio Precision or HP 8903b (I have the HP). You'd then capture the harmonic distortion over frequency response and compare to the specification.


----------



## avanti1960

Update 5/4/12 Re: Swapping out the class D JL HD900/5 for the class A-B JL 300/4 V2: 

It has been 3-weeks of running the JL class A-B on the front stage and the occasional but offensive harshness found in the JL class D has yet to be observed in the new amp. 
I am willing to bet dollars to donuts that if I go out right now and swap RCA connectors and speaker leads to bring the HD900/5 back online for the front stage- I could insert those CDs and play those tracks that I have recorded in my log notes as being objectionably harsh- and duplicate the sound tendencies once again. 
But I won't do it. I'm perfectly happy letting the 900 play bass and rear fill, although I have been tempted to bridge (2) channels just for the front mids!


----------



## TOOSTUBBORN2FAIL

1- The lag between switching the rca's and putting the cd's in would be more than your (or anyones) brain can accurately remember.

2- Your expecting the harshness to come back, so it will.


----------



## subwoofery

TOOSTUBBORN2FAIL said:


> 1- The lag between switching the rca's and putting the cd's in would be more than your (or anyones) brain can accurately remember.
> 
> 2- Your expecting the harshness to come back, so it will.


For #1, what happens if you take notes on a piece of paper of what you hear and feel? 

Kelvin


----------



## TOOSTUBBORN2FAIL

Every study I've read states that your brain cant accurately remember what it heard a few seconds ago, let alone a few minutes.


----------



## ChrisB

TOOSTUBBORN2FAIL said:


> Every study I've read states that your brain cant accurately remember what it heard a few seconds ago, let alone a few minutes.


Please explain this to my wife for me.:laugh:


----------



## TOOSTUBBORN2FAIL

This isnt completely scientific, but you could try this. I'm not sure if you can do this, but if you have the gear to do it, try it.

Play a song for your wife. Afterwards, go to where the amps are, and "mess with some settings", but dont really. Then get back in, and tell her that there should be more bass this time, that it wasnt set right the first time. Ask her to listen again, and see if she agrees.

Or, you can do the opposite. Play the song, then use the remote knob out of her view to slightly or raise the bass, try to make a 2-3 db change. You'll probably have to practice to get it right. Ask her if she heard anything wrong with it, and then play it again, and see if she notices.


----------



## ChrisB

TOOSTUBBORN2FAIL said:


> This isnt completely scientific, but you could try this. I'm not sure if you can do this, but if you have the gear to do it, try it.
> 
> Play a song for your wife. Afterwards, go to where the amps are, and "mess with some settings", but dont really. Then get back in, and tell her that there should be more bass this time, that it wasnt set right the first time. Ask her to listen again, and see if she agrees.
> 
> Or, you can do the opposite. Play the song, then use the remote knob out of her view to slightly or raise the bass, try to make a 2-3 db change. You'll probably have to practice to get it right. Ask her if she heard anything wrong with it, and then play it again, and see if she notices.


No, I meant from the perspective of when she tells me to do something and I don't do it.:laugh: I'm blaming it on the fact that I can't remember what I heard seconds or minutes ago.


----------



## TOOSTUBBORN2FAIL

Ahh, haha. Ya, i know all about that.


----------



## avanti1960

TOOSTUBBORN2FAIL said:


> 1- The lag between switching the rca's and putting the cd's in would be more than your (or anyones) brain can accurately remember.


I can agree with this to a certain extent- some may not accurately recall very subtle differences a few moments after the fact. I would argue that some people are better than others at recalling sound qualities. 
However the opposite end of the spectrum- meaning sound qualities of more obvious distinction- most certainly can be recalled seconds if not years later. For example, I will play track (1) of a sound effects CD on May 5th 2012. It is the sound of a gong crashing at full effect. I will then play track (2) and it will feature the sound of a seagull chirping. I should be able to discern many many years later that I know the difference between the sound of a gong and a seagull and would strongly argue to that effect that I would remember the difference if an amplifier sounded like a gong or a seagull. The differences in sound qualities between a gong and a seagull are obvious and distinctive and therefore easy to recall in one's mind. 
So where do you draw the line for the threshold of distinction where people can no longer recall sound characteristics with accuracy? Gong vs. seagull? loud vs. soft? slight changes in pitch?
I will again argue that the differences I heard when playing the (2) amplifiers of different class architectures were by no means subtle with certain program material. The differences were obvious. I remember them and would testify as such.


----------



## subwoofery

TOOSTUBBORN2FAIL said:


> Every study I've read states that your brain cant accurately remember what it heard a few seconds ago, let alone a few minutes.


I remember some poster saying the same thing. Am too lazy to search for those studies but agree  
However, what happens if you take notes on a piece of paper of all the distinctive notes that you hear and feel? Wouldn't that be a pretty good way to compare two things? Objectively of course... 

Kelvin


----------



## Wesayso

subwoofery said:


> I remember some poster saying the same thing. Am too lazy to search for those studies but agree
> However, what happens if you take notes on a piece of paper of all the distinctive notes that you hear and feel? Wouldn't that be a pretty good way to compare two things? Objectively of course...
> 
> Kelvin


Probably not if you expect to hear a difference?


----------



## ChrisB

Wesayso said:


> Probably not if you expect to hear a difference?


I'm sure I said it somewhere else in this thread if not somewhere else on the forum... I spent many HOURS listening to my HD 900/5 when I had my Mustang, just waiting for that one note that it would produce wrong. I'd hook up my Iota DLS55 to the battery, put the car in accessory mode, and just sit there and listen with my eyes closed. I did CD, I did iPod, I did every genre known to man, and to be honest, it was a totally unfair test for the JL Audio amplifier because I NEVER treated any other amp that way since going scientific. After about 2 or 3 weeks of doing this, I concluded that the JL Audio full range class d amplifier was good enough to meet my needs in the automotive environment.

Then again, I can't hear grass grow or scream when cut, nor can I hear the electrical pulses running through the wiring in my house. In other words, take what I just wrote with a grain of salt because I make no claims of being a golden ear God among man.


----------



## MarkZ

You guys are totally overthinking this. But fortunately you won't remember that I said that, because your brain is only capable of storing it for a few seconds.


----------



## envisionelec

ChrisB said:


> I can't hear grass grow or *scream when cut*


Oooh, that's a good excuse to not cut the grass. :wings:


----------



## rc10mike

Not all brains are created equal.....

Some people can watch a movie once and remember the whole thing, and recall every scene months later...me, I forget the entire movie a day later...

I have to see a movie at least 3 times to remember anything about it...some people dont have to do this.


----------



## W8 a minute

rc10mike said:


> Not all brains are created equal.....
> 
> Some people can watch a movie once and remember the whole thing, and recall every scene months later...me, I forget the entire movie a day later...
> 
> I have to see a movie at least 3 times to remember anything about it...some people dont have to do this.


I do this. Every time I see a movie it's new to me whether I've seen it or not.


----------



## trumpet

It seems this aural memory discussion has gone awry. Of course we can remember what a cow sounds like or what breaking glass sounds like. That's not what blind ABX testing is for comparing.


----------



## avanti1960

trumpet said:


> It seems this aural memory discussion has gone awry. Of course we can remember what a cow sounds like or what breaking glass sounds like. That's not what blind ABX testing is for comparing.


Where is the line for what most people can remember accurately with their ears? 

Cow and breaking glass- differences are easy to remember- very obvious. 
Why can't you recall something obvious in the sound quality on a specific track number at a specific time during that song between (2) different amplifiers? 
What specifically is not obvious enough to remember with accuracy? Whether a speaker has good bass or weak bass (easy for me), whether an amp sounds distorted or clean? Whether a car has a bright or laid back soundstage?


----------



## 14642

The clipping discussion has gone awry too. We don't hear clipping on transients until it approaches 20%. Steady-state signals that include distortion are much nastier. We're much more sensitive to things like zero crossiing distortion, so if you're setting your system so that it never clips, you're probably eliminating 10dB of fun. 

Rather than using a sine wave recorded at 0sB, try one at -10dB. That provides a much better experience. 

I also suggest that when you hear a difference between amplifiers, you attempt to qualify the difference with some kind of objective measurement. That's the way to understand the difference. It's sloppy to listen and to then attribute the differences to AB vs. D, one brand vs another, tubes vs. transistors. That's mythology...


----------



## envisionelec

Andy Wehmeyer said:


> *Rather than using a sine wave recorded at 0sB, try one at -10dB.*



Yep, I said that here

:heart:


----------



## slowpoke

rc10mike said:


> Not all brains are created equal.....
> 
> Some people can watch a movie once and remember the whole thing, and recall every scene months later...me, I forget the entire movie a day later...
> 
> I have to see a movie at least 3 times to remember anything about it...some people dont have to do this.



i wish i had your problem. after seeing a movie once it becomes to annoying to watch it again since the excitement is gone from not knowing whats going to happen next.


----------



## avanti1960

Today I swapped my tweeter channels that were being powered by the 300/4 V2 and connected the spare channels on the HD900/4. 
Immediately I noticed the highs were not as crisp or bright as they were with the 300/4 V2. I had been playing 2 CDs all week long and was familiar with how they sounded. 
In the process I bridged the channels on the 300/4 V2 to the front mid-bass drivers. 
Basically I went from 150 / channel to 250 / channel on the front stage. The added power and dynamics sound incredible. Any harshness, lack of brightness or other concerns from the Class D will be trumped by the additional power to the front stage. 
I know 1200 clean watts is modest compared to what many run with but after adding the 100 per channel today I know why power is king in this game.


----------



## KSpan

avanti1960 said:


> Today I swapped my tweeter channels that were being powered by the 300/4 V2 and connected the spare channels on the HD900/4.
> Immediately I noticed the highs were not as crisp or bright as they were with the 300/4 V2. I had been playing 2 CDs all week long and was familiar with how they sounded.
> In the process I bridged the channels on the 300/4 V2 to the front mid-bass drivers.
> Basically I went from 150 / channel to 250 / channel on the front stage. *The added power and dynamics sound incredible. Any harshness, lack of brightness or other concerns from the Class D will be trumped by the additional power to the front stage. *I know 1200 clean watts is modest compared to what many run with but after adding the 100 per channel today I know why power is king in this game.


Excuse the confusion, but do the bolded sentences indicate that you now feel like more Class D power overcomes the deficiencies you've previously described in the HD900?


----------



## avanti1960

KSpan said:


> Excuse the confusion, but do the bolded sentences indicate that you now feel like more Class D power overcomes the deficiencies you've previously described in the HD900?


let me try to sum it up-
Previous setup:
Front mids and tweeters run at 75 watts per channel from the class A-B, 4-channels driven. I added the class A-B amp to overcome occasional harshness and break up with certain program material when running the fronts with the HD900. It worked. 
Rear passive comps. run from 2-channels of the HD900, 100 watts per channel (no issue).
Subwoofer run from the 5th channel of the HD900 (no issue)
HD900 has (2) free channels. 

New setup-
Bridged the 300\4 V2 (class A-B) to drive the front mids at 150 watts per channel.
Used the open channels on the HD900 to drive the tweeters.

Front stage now has 250 watts / channel vs the previous 150 per. 
Class A-B driving the midwoofers, class D driving the tweeters. 
Left everything else the same. 

I have not yet replayed the CDs/tracks that I noted to cause the harshness on when the front stage was driven by the HD900. 

So far, the added power sounds much better and more dynamic that it could make up for any harshness I would encounter from the tweeters being driven by the class D. Time will tell but so far it was worth the risk.


----------



## ChrisB

I learned a long time ago that power is king. That is why I ran 240 watts underrated per door in my 1997 Civic to my passive speakers that were only capable of handling 90 watts RMS.


----------



## Spasticteapot

Class D amps can distort very heavily when they approach peak output. Of course, the peak output is often so much higher than a comparably priced class A/B amp that you'll never notice. 

That said, there's no dome tweeter ever made that can cope with over 100W. You'll melt the voice coil if you get even close.


----------



## minbari

Spasticteapot said:


> Class D amps can distort very heavily when they approach peak output. Of course, the peak output is often so much higher than a comparably priced class A/B amp that you'll never notice.
> 
> That said, there's no dome tweeter ever made that can cope with over 100W. You'll melt the voice coil if you get even close.


The class of amp has nothing to do with distortion once you reach peak. Class A/B will do the same thing

Sent from my Motorola Electrify using Tapatalk 2


----------



## thomasluke

minbari said:


> The class of amp has nothing to do with distortion once you reach peak. Class A/B will do the same thing
> 
> Sent from my Motorola Electrify using Tapatalk 2


Ya, Your right but to me the class d sounds gets really nasty really quick.
With the amps they tend to give you a little more warning.
But that is just what i hear from what i've heard.


----------



## ErinH

thomasluke said:


> Ya, Your right but to me the class d sounds gets really nasty really quick.
> With the amps they tend to give you a little more warning.
> But that is just what i hear from what i've heard.


No offense but why are you repeating something you've heard and don't even have confidence in repeating? 
You seem
To be contradicting yourself ... Or your reply was poorly worded. 
Not trying to be a jerk. I'm just perplexed by what you're saying. It doesn't really make sense. 


Sent from my iPhone. Pardon the grammar.


----------



## avanti1960

avanti1960 said:


> let me try to sum it up-
> Previous setup:
> Front mids and tweeters run at 75 watts per channel from the class A-B, 4-channels driven. I added the class A-B amp to overcome occasional harshness and break up with certain program material when running the fronts with the HD900. It worked.
> Rear passive comps. run from 2-channels of the HD900, 100 watts per channel (no issue).
> Subwoofer run from the 5th channel of the HD900 (no issue)
> HD900 has (2) free channels.
> 
> New setup-
> Bridged the 300\4 V2 (class A-B) to drive the front mids at 150 watts per channel.
> Used the open channels on the HD900 to drive the tweeters.
> 
> Front stage now has 250 watts / channel vs the previous 150 per.
> Class A-B driving the midwoofers, class D driving the tweeters.
> Left everything else the same.
> 
> I have not yet replayed the CDs/tracks that I noted to cause the harshness on when the front stage was driven by the HD900.
> 
> So far, the added power sounds much better and more dynamic that it could make up for any harshness I would encounter from the tweeters being driven by the class D. Time will tell but so far it was worth the risk.


After running the tweeters on the class D HD900/5 for the past (2) weeks I have not once observed the objectionable harshness or garbled sound that I heard on occasion when running the entire front stage on the class D. 
This is leading me to believe that the harshness in the class D was evident only in the midrange frequencies- at or below the 5Khz crossover point. 
This kind of runs contrary to popular thinking regarding class D amplifier tendencies- but it does make sense because the harshness was definitely well within vocal range frequencies. 
So far I am really liking the sound of having the mid bass drivers running with 150 clean watts per- a snappy increase in midbass, sound quality and clarity at high volume.


----------



## thomasluke

bikinpunk said:


> No offense but why are you repeating something you've heard and don't even have confidence in repeating?
> You seem
> To be contradicting yourself ... Or your reply was poorly worded.
> Not trying to be a jerk. I'm just perplexed by what you're saying. It doesn't really make sense.
> 
> 
> Sent from my iPhone. Pardon the grammar.


Poorly worded. Heard as in the past tense form of hear. Not heard as in thats what the guy at the local shop said.
I heard my polk audio go from sounding great to completly **** in one click of the volume. Same thing with the xd. 
Only two amps i've ever experienced this with and both were class d.
All the others and by all the others i mean every other amp i've ever owned that was not full range class d gave me more to play with before going full on balls out clipped to hell and back distorted.
I would in no way just state things that i've "heard" or read like it was truth.
Also, I'm not saying class d sounds bad. I'm still using my polk right now and it sounds great. 
But on some dynamic peeks it falls apart and HARD!


----------



## cubdenno

thomasluke said:


> Poorly worded. Heard as in the past tense form of hear. Not heard as in thats what the guy at the local shop said.
> I heard my polk audio go from sounding great to completly **** in one click of the volume. Same thing with the xd.
> Only two amps i've ever experienced this with and both were class d.
> All the others and by all the others i mean every other amp i've ever owned that was not full range class d gave me more to play with before going full on balls out clipped to hell and back distorted.
> I would in no way just state things that i've "heard" or read like it was truth.
> Also, I'm not saying class d sounds bad. I'm still using my polk right now and it sounds great.
> But on some dynamic peeks it falls apart and HARD!


Wouldn't that be a function of that particular amp build than what class it is? How many high end home audio amps use class D? I could pull out a ****ty Class AB designed amp and then claim that class AB amps are inferior because my amp fails at producing quality sound under all circumstances.


----------



## MarkZ

Sounds like some of you guys need to invest in bigger amps. I can't comment on how harsh my class D and class B amps sound during clipping, because I don't clip them as often as you guys.


----------



## minbari

cubdenno said:


> Wouldn't that be a function of that particular amp build than what class it is? How many high end home audio amps use class D? I could pull out a ****ty Class AB designed amp and then claim that class AB amps are inferior because my amp fails at producing quality sound under all circumstances.


exactly! equaly designed and quality built. I bet 99% of people couldnt pass a double blind test between class A/B and class D. they way they function up to the output section is exactly the same.


----------



## avanti1960

minbari said:


> exactly! equaly designed and quality built. I bet 99% of people couldnt pass a double blind test between class A/B and class D. they way they function up to the output section is exactly the same.


I guess I'm in the 1-percent.


----------



## minbari

avanti1960 said:


> I guess I'm in the 1-percent.


you like to beleive so 

you have never done a double blind test though, so even you dont know for sure.


----------



## oilman

I don't need to do a blind test. I ran two different well known class D's in my active setup driving to and from work for a week. By weeks end I was picking it apart and already thinking how much I could sell them for. 
I don't have golden ears and I'm not saying anything bad about class d. I'm just sharing my experience with them in my situation. Maybe one day I'll try them again as I haven't listen to the new JL amps for any length of time or heard a verity of music on them. A set down double blind test isn't going to prove anything.


----------



## minbari

oilman said:


> I don't need to do a blind test. I ran two different well known class D's in my active setup driving to and from work for a week. By weeks end I was picking it apart and already thinking how much I could sell them for.
> I don't have golden ears and I'm not saying anything bad about class d. I'm just sharing my experience with them in my situation. Maybe one day I'll try them again as I haven't listen to the new JL amps for any length of time or heard a verity of music on them. A set down double blind test isn't going to prove anything.


it will prove you cant tell the difference.


----------



## t3sn4f2

oilman said:


> *I don't need to do a blind test*. I ran two different well known class D's in my active setup driving to and from work for a week. By weeks end I was picking it apart and already thinking how much I could sell them for.
> I don't have golden ears and I'm not saying anything bad about class d. I'm just sharing my experience with them in my situation. Maybe one day I'll try them again as I haven't listen to the new JL amps for any length of time or heard a verity of music on them. A set down double blind test isn't going to prove anything.


_Yes_ you do . Click on my sig, read it all, and learn something new.


----------



## TOOSTUBBORN2FAIL

oilman said:


> I don't need to do a blind test. I ran two different well known class D's in my active setup driving to and from work for a week. By weeks end I was picking it apart and already thinking how much I could sell them for.
> I don't have golden ears and I'm not saying anything bad about class d. I'm just sharing my experience with them in my situation. Maybe one day I'll try them again as I haven't listen to the new JL amps for any length of time or heard a verity of music on them. A set down double blind test isn't going to prove anything.


Driving to work for two weeks with an amp doesnt prove anything.


----------



## minbari

t3sn4f2 said:


> _Yes_ you do . Click on my sig, read it all, and learn something new.


amazing article! really speaks to the issue at hand.



> An amusing story: About 14 years ago Zed Audio was building subwoofer amplifiers for a large well known speaker company in Chatsworth California. One of the projects involved a high pass active preamplifier whose output was to be 6dB/octave high pass crossover (same as the circuit above) with some simple elegant electronics. The BIG question came up from management and sound gurus whether one could tell the difference between various high quality film capacitors. I said "no" and I got hammered for this comment. I set up a test where I said they could not even hear a cheap electrolytic, never mind a film type. "You are crazy, full of you know what" were some of the comments I received. So we set up a double blind test. We had a fancy turntable, Audio Research tube preamplifiers and power amplifiers, speaker cable as thick as your arm and all the other high end toys needed for a sound system. Between the preamplifier and power amplifier a two pole switch was inserted and the switch was to select either a dead short or this one penny electrolytic capacitor. I soldered the capacitor to the switch but unbeknownst to the audio boffins, I wired a short across the capacitor so in either switch position they were listening to the same thing – a dead short, a piece of wire! This was going to be fun – I knew that.
> 
> The gurus put their favourite album on the turntable and away we went. One of their technicians was flipping the switch at the listeners' command. Back and forth we went for over ten minutes with all saying "Yes that's the capacitor, no that's the wire". So we stopped and I called all these gurus over to the switch and showed them the dead short across the capacitor. Red faces, curses etc and I was a bad boy and they were fools. Most of this "component" sound is in one's head. You have to hear the difference after you have spent $55.00 on your new coupling capacitors!


that is another example, pulled from Zed audio's Stephen Mantz


----------



## thomasluke

cubdenno said:


> Wouldn't that be a function of that particular amp build than what class it is? How many high end home audio amps use class D? I could pull out a ****ty Class AB designed amp and then claim that class AB amps are inferior because my amp fails at producing quality sound under all circumstances.


Yes, Thats why i switched to a different amp. Another class d amp but made by a different company.
It also has a higher power rating and seems to be a better match for me.
Not necessarily a better amp. The two i've tryed have both been made by respectable, well know company's.
Everything else the same the one with more power sounds better to me.
But both shared the same characteristic.


----------



## cubdenno

thomasluke said:


> Yes, Thats why i switched to a different amp. *Another class d amp but made by a different company*.
> It also has a higher power rating and seems to be a better match for me.
> Not necessarily a better amp. The two i've tryed have both been made by respectable, well know company's.
> Everything else the same the one with more power sounds better to me.
> But both shared the same characteristic.


Maybe and maybe not. The number of amp brands that are the same board with a different heat sink/nameplate. Drop the name brands that you were using.

In the end though, I think it doesn't matter. If you have a predisposed belief that class D is inferior or whatever, you will dislike Class D. a lot of ism's and phobia's follow this. You like what you like and dislike what you dislike. Only issue I have with it is the lack of any sort of reasoning and repeatability. And honestly this is not a shot at you. You are just an example based on your two amp story. There is zero chance of us or you to go back and test WHY you felt you heard a difference. Then we could quantify the reasons as to what was heard and discuss that. or rather, It is what it is.


----------



## thomasluke

cubdenno said:


> Maybe and maybe not. The number of amp brands that are the same board with a different heat sink/nameplate. Drop the name brands that you were using.
> 
> In the end though, I think it doesn't matter. If you have a predisposed belief that class D is inferior or whatever, you will dislike Class D. a lot of ism's and phobia's follow this. You like what you like and dislike what you dislike. Only issue I have with it is the lack of any sort of reasoning and repeatability. And honestly this is not a shot at you. You are just an example based on your two amp story. There is zero chance of us or you to go back and test WHY you felt you heard a difference. Then we could quantify the reasons as to what was heard and discuss that. or rather, It is what it is.


Not takig any of this personal man, I started out with jl xd then moved on to the polk 4000.4. 
Dont get me wrong the amp doesnt sound bad at all within it's limits.
But when pushed hard the level of distortion increased fast and hard. Both did this.
I had no predetermined belief that either of the two would do this or i would not have purchased them. I dont have any sort of space restrainment or any other reason. 
They both just fit my needs. Also i'm ot saying that they sound/sounded bad.
But i am looking around for another solution though. 
Not a change in amps but a new hu like the 80prs.
The x995 works great but i need the eq of 80.


----------



## geogena

I recently installed 2 class-d full range amps, 3-way + sub, full active using Alpine H800. And it sounded very good if not excellent, these class D amps replaced a Genesis 475SE, a class A/AB and I cannot hear the difference only the price!


----------



## HiloDB1

According to someone local to me there is no way class D can sound anywhere near a good as class A/B



> ********. Where or who has proven that a good class D amp was up to par sonically with a good A/B amp? If this were true then there would be basically no need for A/B amps anymore


And the only way it would be possible would be if all the "high end" manufacturers scrapped their product line and only product class D



> Take a sq car with top quality a/b amps and do a straight swap to some class D amps and let me know what you notice. Better yet lmk when Sinfoni, Brax or maybe even Mac decide to scrap their whole product lineup and build only class D


----------



## TOOSTUBBORN2FAIL

You should listen to Gary Summers, Scott Buwalda, Todd Luliak's cars and tell me what you notice, all are national champion sound quality cars, all class d.


----------



## oilman

^ I knew someone would say that. The amps they use we're not run of the mill class d amps. They cost as much if not more than most good class ab. 


Sent from my iPhone using Tapatalk


----------



## t3sn4f2

oilman said:


> ^ I knew someone would say that. The amps they use we're not run of the mill class d amps. They cost as much if not more than most good class ab.
> 
> 
> Sent from my iPhone using Tapatalk


What's your point? That class d can sound the same as long as the amp is competently designed? That's the point of the thread. 

And any class can sound as ****ty as the next, class has nothing to do with sound quality.


----------



## HiloDB1

TOOSTUBBORN2FAIL said:


> You should listen to Gary Summers, Scott Buwalda, Todd Luliak's cars and tell me what you notice, all are national champion sound quality cars, all class d.





t3sn4f2 said:


> What's your point? That class d can sound the same as long as the amp is competently designed? That's the point of the thread.
> 
> And any class can sound as ****ty as the next, class has nothing to do with sound quality.


He was pretty adamant with his argument. I stopped arguing with him after a couple of back and forth comments. Apparently he has "golden ears" so he would be able to discern between the two.


----------



## TOOSTUBBORN2FAIL

oilman said:


> ^ I knew someone would say that. The amps they use we're not run of the mill class d amps. They cost as much if not more than most good class ab.
> 
> 
> Sent from my iPhone using Tapatalk


There all actually stock commercially available amps. In fact, after showing my dad the jl hds, he said there were actually cheaper than hed expect for everything it does. Thats coming from someone who designs power supplies for the military and nasa, and is weeks away from having a scratch designed microprocessor controlled class d amp built.


----------



## PerformanceAudioLVNV

Some really good points being made. I know in my 99 Tacoma (Certainly not the quietest vehicle on the planet regardless of how much work I've poured into it to make improvements), As soon as I turn the key.... I'm sure you get the point. For the temporary setup that is in the truck it does sound nice. But much better with the engine off. I demo the truck to potential clients running & off so they have a realistic idea of what to expect. In many cases people own a much quieter vehicle than mine. This may be a little off topic but not really.


----------



## tnbubba

Class D/H/G wtf ever proaudio and car amps ..absolute blind test..
I've said before my 10 yr old is oblivious to all the BS, never heard or seen of the audio forums he just listens.. at home when he is with me.. and good quality older kuntry some rock some jazz analog and digital stuff ( he plays acoustic guitar)
I've have tried so many times to trick him swapping out only the midrange amp in my 4way active system.. Daddy what did you do to the stereo? it sounds like crap!

He is finally starting to catch on that I use him for a tester..lol
In EVER CASE I replaced my Bryston 4BSST with crown/ qsc/peavy/JL/Dayton/Alpine/DLS and god knows what amps have been in here for "evaluation" and every one he says sounds like crap is a digital amp. now I know a 10 yr old hearing is a ****load better than any of ours on here. but dammit it is a blind test he doesn't even know the amps have been swapped!!! I only see him every other weekend.. and I'm only swapping the mid/tweet amp.. he did say some of the car a/b amp sounded crappy too.. mainly the old skool stuff (lol) like Linear, one old Alpine, a carver, a HK too. liked the old concord amp.. so im out of amps to test I swapped the bryston for a crown K2 picked it out immediately this weekend.

SO if ya want a true blind test.. there ya go! yea I have a very good 0.5omv capable tectronics analog 50mhz scope (2225) so the levels r checked to about .01mv ( so no level change argument either)

just my $0.02 worth


----------



## ChrisB

tnbubba said:


> Class D/H/G wtf ever proaudio and car amps ..absolute blind test..
> I've said before my 10 yr old is oblivious to all the BS, never heard or seen of the audio forums he just listens.. at home when he is with me.. and good quality older kuntry some rock some jazz analog and digital stuff ( he plays acoustic guitar)
> I've have tried so many times to trick him swapping out only the midrange amp in my 4way active system.. Daddy what did you do to the stereo? it sounds like crap!
> 
> He is finally starting to catch on that I use him for a tester..lol
> In EVER CASE I replaced my Bryston 4BSST with crown/ qsc/peavy/JL/Dayton/Alpine/DLS and god knows what amps have been in here for "evaluation" and every one he says sounds like crap is a digital amp. now I know a 10 yr old hearing is a ****load better than any of ours on here. but dammit it is a blind test he doesn't even know the amps have been swapped!!! I only see him every other weekend.. and I'm only swapping the mid/tweet amp.. he did say some of the car a/b amp sounded crappy too.. mainly the old skool stuff (lol) like Linear, one old Alpine, a carver, a HK too. liked the old concord amp.. so im out of amps to test I swapped the bryston for a crown K2 picked it out immediately this weekend.
> 
> SO if ya want a true blind test.. there ya go! yea I have a very good 0.5omv capable tectronics analog 50mhz scope (2225) so the levels r checked to about .01mv ( so no level change argument either)
> 
> just my $0.02 worth


Send him to take Richard Clark's challenge NOW!:laugh:


----------



## Ampman

I've only personally heard class D as a sub amp never any full range class D's. I think it all comes down to what your willing to pay to get the best sound, if you buy an amp with cheap AD to DA converters then the sound you get is going to be just that CHEAP. Wether my old school amps pull a ton of current or not I'll stay with class AB their SQ's don't change from one program material to the next their basically the same no matter what kind of music I feed them that's my thoughts on the matter and as always my thoughts don't count y'all have a good one


----------



## oilman

HiloDB1 said:


> He was pretty adamant with his argument. I stopped arguing with him after a couple of back and forth comments. Apparently he has "golden ears" so he would be able to discern between the two.


I'm pretty sure I've only made 3 comments and one clearly stated I didn't have experience with the newer high end class d amps. I could only comment on the others I've owned and they didn't do it for me. I've heard good things about the HD amps from people I trust. 

Sorry but I don't remember arguing with anyone on this topic, I must of missed that part, I could have been sleep foruming, I don't know... anyway who am I to argue with anyone on this forum. I'm not a rocket science or a world champ, just a guy that likes the challenge of getting my car to sound as good as I can get it. However, when those class 4D amps come out that have the hologram of the band playing on your dash  look out. 

If the definition of golden ears are the small details in music that I expect to hear, and don't want to hear. Then I'm very happy to have them, though I must say they do get heavy at times. 




Sent from my iPhone using Tapatalk


----------



## Chaos

tnbubba said:


> Class D/H/G wtf ever proaudio and car amps ..absolute blind test..
> I've said before my 10 yr old is oblivious to all the BS, never heard or seen of the audio forums he just listens.. at home when he is with me.. and good quality older kuntry some rock some jazz analog and digital stuff ( he plays acoustic guitar)
> I've have tried so many times to trick him swapping out only the midrange amp in my 4way active system.. Daddy what did you do to the stereo? it sounds like crap!
> 
> He is finally starting to catch on that I use him for a tester..lol
> In EVER CASE I replaced my Bryston 4BSST with crown/ qsc/peavy/JL/Dayton/Alpine/DLS and god knows what amps have been in here for "evaluation" and every one he says sounds like crap is a digital amp. now I know a 10 yr old hearing is a ****load better than any of ours on here. but dammit it is a blind test he doesn't even know the amps have been swapped!!! I only see him every other weekend.. and I'm only swapping the mid/tweet amp.. he did say some of the car a/b amp sounded crappy too.. mainly the old skool stuff (lol) like Linear, one old Alpine, a carver, a HK too. liked the old concord amp.. so im out of amps to test I swapped the bryston for a crown K2 picked it out immediately this weekend.
> 
> SO if ya want a true blind test.. there ya go! yea I have a very good 0.5omv capable tectronics analog 50mhz scope (2225) so the levels r checked to about .01mv ( so no level change argument either)
> 
> just my $0.02 worth



That is actually a pretty interesting observation.


----------



## HiloDB1

oilman said:


> I'm pretty sure I've only made 3 comments and one clearly stated I didn't have experience with the newer high end class d amps. I could only comment on the others I've owned and they didn't do it for me. I've heard good things about the HD amps from people I trust.
> 
> Sorry but I don't remember arguing with anyone on this topic, I must of missed that part, I could have been sleep foruming, I don't know... anyway who am I to argue with anyone on this forum. I'm not a rocket science or a world champ, just a guy that likes the challenge of getting my car to sound as good as I can get it. However, when those class 4D amps come out that have the hologram of the band playing on your dash  look out.
> 
> If the definition of golden ears are the small details in music that I expect to hear, and don't want to hear. Then I'm very happy to have them, though I must say they do get heavy at times.
> 
> 
> 
> 
> Sent from my iPhone using Tapatalk


I was referring the person local to me who I quoted in my previous post. I dont believe your are that person so you must have mistaken what I wrote.


----------



## tnbubba

don't get me started on dheads challenge..
been there done that cept he wouldn't come to nashville

that was when I could hear

hey u want to know what some sounds like? ask a kid.. they have no biased opions n most have damn good hearing.. hasn't been destroyed but too many concerts, gunshots, topfuel drag races, shiot like that!

amazing I can still hear up to 15-16K at 50 yrs old.


----------



## TOOSTUBBORN2FAIL

Without back to back blind tests with no lag between switching amps, having a kids hearing is pointless. The test could be affected by THOUSANDS of other factors unless there is a near instantaneous and seemless to the ear switch between amps.


----------



## SSSnake

tnbubba said:


> Class D/H/G wtf ever proaudio and car amps ..absolute blind test..
> I've said before my 10 yr old is oblivious to all the BS, never heard or seen of the audio forums he just listens.. at home when he is with me.. and good quality older kuntry some rock some jazz analog and digital stuff ( he plays acoustic guitar)
> I've have tried so many times to trick him swapping out only the midrange amp in my 4way active system.. Daddy what did you do to the stereo? it sounds like crap!
> 
> He is finally starting to catch on that I use him for a tester..lol
> In EVER CASE I replaced my Bryston 4BSST with crown/ qsc/peavy/JL/Dayton/Alpine/DLS and god knows what amps have been in here for "evaluation" and every one he says sounds like crap is a digital amp. now I know a 10 yr old hearing is a ****load better than any of ours on here. but dammit it is a blind test he doesn't even know the amps have been swapped!!! I only see him every other weekend.. and I'm only swapping the mid/tweet amp.. he did say some of the car a/b amp sounded crappy too.. mainly the old skool stuff (lol) like Linear, one old Alpine, a carver, a HK too. liked the old concord amp.. so im out of amps to test I swapped the bryston for a crown K2 picked it out immediately this weekend.
> 
> SO if ya want a true blind test.. there ya go! yea I have a very good 0.5omv capable tectronics analog 50mhz scope (2225) so the levels r checked to about .01mv ( so no level change argument either)
> 
> just my $0.02 worth


Not to try and be argumentative but is it possible that the Bryston has some EQ curve implemented? The reason I ask is because if your son is used to hearing a specifically tailored freq response he would be able to easily discern the difference when you swap amps. Also you only mention level matching not EQ. For this to be a fair test you would have to ensure the freq response was consistent after the swap. 

In the interest of full disclosure I run class d amps and love them.


----------



## W8 a minute

I'm gonna have to call BS on some of these stories. I think there's a lot of internet "one upping" concerning how good people can hear while other stories are just out right fabricated. Some people just fear change.


----------



## Shinju

I run class D on my 3 way front stage.. And I am not looking back nor do I hear any change from A A/B to D.


----------



## bobwires

A good class D sounds fantastic.

One key problem is that they lose the sq a bit as they get pushed harder. Hybrid Audio's G36 had a 750 watt amp going to each of the L3 mids........ they didn't have to work very hard, and Scott's got the biggest trophy...... Again.


----------



## tnbubba

dude seriously .. are you familiar with Bryston or Coda or Crown or Levinson or Krell or Macincrap or ...???..the Brystons amps measure ruler flat with distortion #'s in the 3 digits zero's on the right side of the decimal place..still have the birth sheet on my sst in file cabinet..
ya'll need to get out the car world and into some real recording studios or mutli-thousand dollar professional systems..
there is no eq on the amps.. and if the amp doesn't measure flat I don't bother trying it. 
I want to ask anybody..when is the last time you have had your hearing "professionally" checked. Seriously.. like i stated before i knwo mine and i know my left n right ear curves are substantially different!
I know several recording engineers who do it at a minimum of yearly! so what ever.. test ya own ears first!
ya ever thought that maybe the ****ty ass power supplies in a digital amp may be FN up the other amps making an audible difference huh?? omg bet nobody paid atten that my system is 4 way ACTIVE!!!! if it is doing that it means its still a ****ty amp!
im not saying it is or isn't.. just most people don't think or analyze... just a point..


----------



## TOOSTUBBORN2FAIL

You need to disassociate the word digital from class d. They are NOT the same thing. Class d simply means the power supply switches on and off. Can you hear 400,000hz? Because thats the frequency the JL HD switches at. On top of that its attenuated by a low pass filter. 

My hearing is checked every year. Its mandatory where i work. I show no hearing loss, despite less than ideal testing locations (a portable "quiet" room, with running trash trucks parked outside). I wear earplugs at all times at work, even though my job is below the noise level specified as safe by osha. Listening back to back to the magic bus with high class a biased class ab amps, and gary summers classd powered car, i could hear no difference that could be attributed to the amps.


----------



## ChrisB

This thread has lots of passion and emotion against Class D amplifiers. I'm going to remember that as the trend of 12 volt electronics continues towards smaller and more efficient class d amplifiers. I predict that within the next 5 to 10 years, there will be MORE class d offerings and less class ab choices on the market.


----------



## The Baron Groog

^ very true, cost/size/weight/component count are all in D's favour-with price being the ultimate deciding factor for most consumers the main "feature" that will sell them will be cheapness from economies of scale...


----------



## SSSnake

tnbubba said:


> dude seriously .. are you familiar with Bryston or Coda or Crown or Levinson or Krell or Macincrap or ...???..the Brystons amps measure ruler flat with distortion #'s in the 3 digits zero's on the right side of the decimal place..still have the birth sheet on my sst in file cabinet..
> ya'll need to get out the car world and into some real recording studios or mutli-thousand dollar professional systems..
> there is no eq on the amps.. and if the amp doesn't measure flat I don't bother trying it.
> I want to ask anybody..when is the last time you have had your hearing "professionally" checked. Seriously.. like i stated before i knwo mine and i know my left n right ear curves are substantially different!
> I know several recording engineers who do it at a minimum of yearly! so what ever.. test ya own ears first!
> ya ever thought that maybe the ****ty ass power supplies in a digital amp may be FN up the other amps making an audible difference huh?? omg bet nobody paid atten that my system is 4 way ACTIVE!!!! if it is doing that it means its still a ****ty amp!
> im not saying it is or isn't.. just most people don't think or analyze... just a point..


I currently own two Crowns and previously owned Krells. I have never owned a Levinson but I have heard them many times. My comment stands. 

BTW - the last visualization center I designed and implemented had a $1,000,000 AV budget (gotta love DoD) Most of that was spent on the video side because that is where we could gain performance by spending more. We ran multiple crown amps that all had great measurements when installed On my last visit, approximately one year after installation, we had to replace one of the crowns because the sound was off. It still worked but sounded different. I forget what was wrong as this was roughly a decade ago but my point is things happen, equipment breaks and or drifts out of spec over time. For someone to pick the correct amp EVERY single time would indicate a large change not the minuscule differences among quality amplifiers. You've got to remember our hearing changes as well. IMO - this represents just too many variables to reliably pick out an amp unless something is off. 

IMO - audio frequency amps have been well understood and correctly implemented for multiple decades. 

Again IMO - spending Levinson type dollars on an amp has only two benefits - durability and psychoacoustic. If you are willing to pay a premium for those benefits, carry on but I am not. 

BTW - my hearing is checked annually. A little less hf sensitivity than I would like but not bad for a 44 yr old.


----------



## subwoofery

I'll use a full-range Class D when Brax releases one  

Kelvin


----------



## MarkZ

SSSnake said:


> IMO - audio frequency amps have been well understood and correctly implemented for multiple decades.


This.

Not. Rocket. Science. 

Amplification is what you teach _beginners_ in electronics because it's conceptually the easiest-to-understand circuit.

I know we're all "audiophiles" to some degree around here, but let's try not to let our egos get too audio-centric. The sun doesn't rise and set with amplifiers. Electrical engineers don't care about amplifier research anymore because it's boring and there's very little room for advancement. We're the niche group of weirdos that think it's important.


----------



## SSSnake

MarkZ said:


> This.
> 
> Not. Rocket. Science.
> 
> Amplification is what you teach _beginners_ in electronics because it's conceptually the easiest-to-understand circuit.
> 
> I know we're all "audiophiles" to some degree around here, but let's try not to let our egos get too audio-centric. The sun doesn't rise and set with amplifiers. Electrical engineers don't care about amplifier research anymore because it's boring and there's very little room for advancement. We're the niche group of weirdos that think it's important.


Very true statement. My son is following in Dad's footsteps as an EE. He is taking his first analog circuit design course. He came home this week all excited because the first real circuit designs they are doing are audio freq amps. Given that the audio bug bit him too he is stoked. He wants to use his design in his car. I hated to rain on his parade and tell him he will likely end up with a design that costs far more for him to build than buying a commercially available amp with the same capabilities so I kept my mouth shut. No need to kill the dream. Besides he will likely learn a lot before he gets to pricing everything. Some things are better discovered independently.


----------



## MarkZ

Better off starting with a home rig anyway so you don't have to deal with the SMPS. Which can be more difficult for a beginner, not because of "SQ" but because of stability.


----------



## tnbubba

class D, G H SMPS issues and powe line contamination..
Class D digital artifacts or phase issues related to filters..
nasty ultrasonics..

now a properly designed calls D CAN be made to sound good. but 
as any EE will tell you it cost 3-4 x as much to prpperly design a class D as an equivelent AB
(way more parts due to the filters and more compicated SMPS sheilding and filtering)

so consider that when you have $500 to spend on an amp!!!


now id say in 10 yrs or less we will have class D sounding ok..
kinda like it took 20+ ys to figure out cd's starting at the ADC's..


----------



## TOOSTUBBORN2FAIL

I really hope your not saying you can tell the difference between different ADC and DAC's. That's already pretty scientifically been shot down. In fact, the testers couldnt even tell when an additional ADC and DAC were added into the line, let alone that it was dropping the signal from 24 bit to 16 bit. 

Again, what digital artifacts? Just because its a class d, doesnt mean that its a digital amp. And what do ultrasonics have to do with hearing a difference?


If you or your kid can repeatedly and accurately pick out modern well designed class d from modern well designed class a/b, you should seriously consider finding a university near you with a good accoustics program. I'm sure theyd want to study your hearing, as EVERY scientific study ever conducted on this has shown otherwise. This isnt just to pick on you, but for anyone that thinks they can pick out class d from class a/b.


----------



## BEAVER

Loving my Class D amp. Makes gobs of power, doesn't take up much space and sounds as good as anything I've ever owned. 


Sent from my iPhone using Tapatalk


----------



## MarkZ

tnbubba said:


> now id say in 10 yrs or less we will have class D sounding ok..


Why? What will time buy?


----------



## avanti1960

Logging in again after many months of comparing JL HD 900/5 vs. JL 300/4 V2

HD 900/5 Class D-

Very dynamic.
Very bright presence
Overly harsh midrange at times
Midrange breakup and harshness at times- not from over driving

300/4 V2 Class A-B

Not as bright or dynamic as the HD 900
No midrange harshness
No midrange garble or breakup
Bass is very punchy, impactful, quick. 

Conclusion- 
Using Class A-B for midbass duty
Using Class D for tweeter duty

Neither is perfect but I would prefer hands down the 300/4 if I had to pick just one.


----------



## minbari

...........Thinking you can tell the difference, priceless

Sent from my phone using digital farts


----------



## tnbubba

If you or your kid can repeatedly and accurately pick out modern well designed class d from modern well designed class a/b, you should seriously consider finding a university near you with a good accoustics program. I'm sure theyd want to study your hearing, as EVERY scientific study ever conducted on this has shown otherwise. This isnt just to pick on you, but for anyone that thinks they can pick out class d from class a/b. 

please cite studies.. I have others that prove otherwise.. and i cited my test conditons very accurrate..I never said hed picked out any amp by name ..only it sounded different or crappy.. as a matter of fact before you make blanket statements like EVERY STUDY//please read ALL of Floyd toole's publications and AES papers.!
we are not talking adc or dac we are talking amps..
quick without going to net tell me how much power an amp should have to not clip when a recording has a 50db peak over average!!!

BSMET/ASEE/ASCE/ASAE


----------



## tnbubba

I know we're all "audiophiles" to some degree around here, but let's try not to let our egos get too audio-centric. The sun doesn't rise and set with amplifiers. Electrical engineers don't care about amplifier research anymore because it's boring and there's very little room for advancement. We're the niche group of weirdos that think it's important. 

hmm funny and they said CD were perfect sound forever 30 yrs ago...
much to be learned young padawan. when we reach 0.0000000000% distortion then I will say amplifier design has reached the room for little advancement!


----------



## tnbubba

A class-D amplifier or switching amplifier is an electronic amplifier where all power devices (usually MOSFETs) are operated as binary switches. They are either fully on or fully off. Ideally, zero time is spent transitioning between those two states.
I think binary would be considered digital


----------



## minbari

tnbubba said:


> A class-D amplifier or switching amplifier is an electronic amplifier where all power devices (usually MOSFETs) are operated as binary switches. They are either fully on or fully off. Ideally, zero time is spent transitioning between those two states.
> I think binary would be considered digital


since DACs function this way too, would that make all music digital that has ever been through a DAC or any system that has a DAC or DSP in it?


----------



## tnbubba

depends on how u look at it remember the c part stands for conversion..
so analog to digital then digital to analog.. in the end the signal get to us analog..
until they can plug a cable into our ears and attach to our auditory nerves directly..

guess we got a long way to go huh>?


----------



## minbari

tnbubba said:


> depends on how u look at it remember the c part stands for conversion..
> so analog to digital then digital to analog.. in the end the signal get to us analog..
> until they can plug a cable into our ears and attach to our auditory nerves directly..
> 
> guess we got a long way to go huh>?


the output filters on a Class D make the "digital" waveforms into analog as well.

alot of the conversion in a DAC is in our ears as well. the tiny steps made that form the analog waveforms can be seen on a scope. just a matter of what resolution. once you get the steps small enough, it dosent matter anymore.


----------



## chad

tnbubba said:


> class D, G H SMPS issues and powe line contamination..


A: If you want to have any credibility you may want to post in a manner people can understand, or one that does not make you appear as a 13 year old girl.

B: Explain what I quoted. Because I don't think you can.


----------



## TOOSTUBBORN2FAIL

The point was you are mistakenly calling class d digital. Its not.

Your question reguarding how much power needed for a 50db peak above average is too open ended to answer with a numeric power rating, as you never stated what average power was required for your listening requirements, but youd need about 110,000 times as much power for that peak in watts vs average. Let me ask you, what does that have to do with anything here? I would also love to see a cd with a 50db peak. The question is can a well designed class d amp be picked out from a well designed class ab. The answer is no.


----------



## MarkZ

tnbubba said:


> hmm funny and they said CD were perfect sound forever 30 yrs ago...
> much to be learned young padawan. when we reach 0.0000000000% distortion then I will say amplifier design has reached the room for little advancement!


I'm curious: why did you choose 0.0000000000%? (sic)

Why not 0.0001% instead?

Or 0.01%?

You understand there's a point where reducing distortion (however you want to define it) leads to inaudible improvements, right? Or are you suggesting that our brains are capable of distinguishing infinitesimal differences in distortion?

This is an important point. And I'm not sure you understand it, padawan.




> I think binary would be considered digital


And you'd probably be surprised to learn that there's a lot more to "digital" than binary. Schrodinger's cat wasn't digital.

Whether or not class D is "digital" is a red herring. I can see the argument either way. What's important -- _really, the only thing that's important_ -- is whether our auditory systems have the capabilities to resolve minute differences in sound, and whether a given amplifier can exceed those capabilities.


----------



## minbari

MarkZ said:


> And you'd probably be surprised to learn that there's a lot more to "digital" than binary. Schrodinger's cat wasn't digital.
> 
> Whether or not class D is "digital" is a red herring. I can see the argument either way. What's important -- _really, the only thing that's important_ -- is whether our auditory systems have the capabilities to resolve minute differences in sound, and whether a given amplifier can exceed those capabilities.


exactly my point is bringing up DACs. they are still digital in nature, but the steps are so small that you cant hear it. it sounds analog.

for that matter, most amplifiers, no matter what class use PWM power supplies. those are only on or off too. but they switch very fast and with the filtering of the supply you dont see it turning on and off.


----------



## ChrisB

This thread is making me want another JL Audio HD900/5!


----------



## subwoofery

And I'm about ready to play with a Zuki Class D 5 lol 

Kelvin


----------



## tnbubba

if ya got a good scope you do!

as the thread said

"can "

give it 10 yrs


----------



## tnbubba

You understand there's a point where reducing distortion (however you want to define it) leads to inaudible improvements, right? Or are you suggesting that our brains are capable of distinguishing infinitesimal differences in distortion?


Prove it.. and no not abx..already been proved it's not useful in audio comparison..
only a/b testing.. and no we are not going there
read my previous posts on abx and stress testing .statistics don't mean **** because they cant account for stress induced test errors so don't go there wither.

This is an important point. And I'm not sure you understand it, padawan.

yes i do understand it very well. Prove someone can't hear something!!! 
them not being able to PASS and abx test does not prove they cant hear it!
my favorite argument of my ex ahhhhhhhhhhhhhh btw who's PHD paper was on the very subject and debunks a lot of sensory abx testing.
we all no no one can tell a digital print from 35 mm right? 

oh yea gedlee had something his testing of audio subjects showed up along that line too

so when a amplifier reaches 0% distortion then and only then can you say its inaudible!

I understand it very well..so prove it's inaudible to 100% of the population then i will buy it.. but hen again the Aborigines don't have electricity yet.

Well being an engineer I'm not settling for 0.1 or 0.01% distortion because it has been proven that that is an audible difference and that moving the decimal
one more place left results in an audible difference.. on yea i think Halcro had a white paper on that.. never finished reading that one.
do some aes reading.

again I will state..Every amp designer ( from Audio to RF) that i have ever talked too says the same thing
it takes 2-3x the part count and cost to make a Digital amplifier equal any Class a (a/b) amp.
so when I spend $500 on a "digital" amp I'm thinking god what kind of amp am i getting when an equivalent a/b is $500 too??????

Btw I do have some "digital" amps in my system if you read previously.. but only a select few have made it to that stage and none of the current crop!
that I have "listened to or tested.


----------



## TOOSTUBBORN2FAIL

Your might as well give up on audio then. If your not happy with 0.001% distrotion from an amp, you must be horrified of the 1% distortion MINIMUM your speakers are putting out. And, as any engineer will tell you, there will NEVER be a distortion free amp. But lets get past that and ask what you consider distortion. Is a singers live voice distorted to you, since the air, room, and all multitudes of other things change its sound before it reaches your ears?


----------



## MarkZ

tnbubba said:


> You understand there's a point where reducing distortion (however you want to define it) leads to inaudible improvements, right? Or are you suggesting that our brains are capable of distinguishing infinitesimal differences in distortion?
> 
> 
> Prove it.. and no not abx..already been proved it's not useful in audio comparison..
> only a/b testing.. and no we are not going there
> read my previous posts on abx and stress testing .statistics don't mean **** because they cant account for stress induced test errors so don't go there wither.
> 
> This is an important point. And I'm not sure you understand it, padawan.
> 
> yes i do understand it very well. Prove someone can't hear something!!!
> them not being able to PASS and abx test does not prove they cant hear it!
> my favorite argument of my ex ahhhhhhhhhhhhhh btw who's PHD paper was on the very subject and debunks a lot of sensory abx testing.
> we all no no one can tell a digital print from 35 mm right?
> 
> oh yea gedlee had something his testing of audio subjects showed up along that line too
> 
> so when a amplifier reaches 0% distortion then and only then can you say its inaudible!
> 
> I understand it very well..so prove it's inaudible to 100% of the population then i will buy it.. but hen again the Aborigines don't have electricity yet.
> 
> Well being an engineer I'm not settling for 0.1 or 0.01% distortion because it has been proven that that is an audible difference and that moving the decimal
> one more place left results in an audible difference.. on yea i think Halcro had a white paper on that.. never finished reading that one.
> do some aes reading.
> 
> again I will state..Every amp designer ( from Audio to RF) that i have ever talked too says the same thing
> it takes 2-3x the part count and cost to make a Digital amplifier equal any Class a (a/b) amp.
> so when I spend $500 on a "digital" amp I'm thinking god what kind of amp am i getting when an equivalent a/b is $500 too??????
> 
> Btw I do have some "digital" amps in my system if you read previously.. but only a select few have made it to that stage and none of the current crop!
> that I have "listened to or tested.



You're a "throw the baby out with the bathwater" kinda guy, huh?

We know an incredible amount about how the human auditory system works. We know about the mechanisms of audition, we know about psychophysical evaluation of sensory capabilities, and we understand the pitfalls of some of the interpretations of the data. The field is roughly 150 years old, beginning with the pioneering work of Helmholtz; continuing through the early to mid twentieth century with the work at Bell labs; SS Stevens brilliant insight about 60 years ago (whose book from the 70s I highly recommend); and existing today as a major field of study in which practically every institution with a graduate or medical school has active ongoing research.

So, no, I don't buy a word you say.

We understand how to conduct sensory experiments and know a great deal about the human auditory system. And some people even understand the limitations of the interpretations of the data, and can debate them rationally and effectively without dumping it all in the trash can. If you don't understand these concepts, that's fine. But don't assume that it's the "dark matter" of psychology just because it's difficult.

As for amplifier design, no one is really arguing that class D amps are the better value. In fact, Andy mentioned that his line of class D amps are more expensive than the class A/B counterparts. So, yes, if you're trying to save money, and the added efficiency/power isn't much of a benefit to you, then maybe a class A/B amp is the better solution. But that's not what the thread is about.

Also, re: parts count, it's well-known that improved designs generally require high parts counts. Not just in terms of adding output devices and switching transistors for robustness, but also in terms of adding circuits to the input stage and VA stage to improve things like PSRR, THD performance, S/N, thermal tracking, and stability. [See Doug Self's book, for example] So why are higher parts counts a damning attribute in your view?


----------



## ErinH

tnbubba said:


> Well being an engineer I'm not settling for 0.1 or 0.01% distortion because it has been proven that that is an audible difference and that moving the decimal
> one more place left results in an audible difference..


this isn't how real engineering works, though. not unless you design systems that save peoples' lives (like I do) and every effort is put in to making the product operate to it's highest capacity in whatever regard that is, rather than focusing on cost vs performance. otherwise, it's a trade-off but the real engineering isn't in the product design as much as it is in the research and analysis that drives the design. So, you saying you're an engineer and you design amplifiers to measure 0.01% THD seems a bit overzealous. If I'm your project manager and you come to me with a proposal saying you'll have to spend an extra $xxx to get you from 0.1% to 0.01% THD, you better have a really good explanation why. Your ambitions are affecting the bottom line and I need to know your reasons are justified.

Furthermore, you should know that stating a THD value really should come with a condition, such as "at xxx watts" or the like. In speaker testing, you are given a fundamental SPL to compare the harmonic components to, so you understand that if a speaker is driven to X output, this is what you can expect the non-linear distortion to be. In the amplifier world, you often see specs stating a drive level with a given THD percentage. Otherwise, one could simply claim 0.002% THD and not tell the user that value is given at 1w, while driving the voltage up to provide 100w results in THD of 1.5%. So, like I said, providing a value isn't really meaningful unless we know the conditions that got you there. 


That said, please provide proof that 0.01% THD is audible. You say it's been proven, so it should be easy to provide the proof. The best I've found is studies that say JDD limits are *no lower than 1%*... and that's with some folks that are trained to listen for it. On average, 3-5% THD is the norm for distortion audibility. 
Here's some reading on it:
Human Hearing - Distortion Audibility Part 3 — Reviews and News from Audioholics

If you've got data/white papers to back up your 0.01% distortion claim, I'd honestly really like to see it. I've searched high and low on the topic and have never come across anything remotely mentioning that level of audibility.


Now, consider the speakers' contribution to the THD. It's MUCH higher than any halfway decently made electronic component is or ever will be. I've yet to measure an amplifier that tested poorly in any regard, but it's EASY to drive a speaker to a level of distortion that is completely audible if you aren't mindful of what you're doing. Short of clipping an amp, I'll just step out on a limb and say that worrying about distortion is meaningless *as long as you trust the manufacturer (which, some, I do not)*. More attention should be paid to the choice of components; linear distortion is top dog yet people will buy a $10k amp to power a speaker with an FR of +5/-5dB. It's bewildering.


----------



## TOOSTUBBORN2FAIL

^the last two posts sum it up. 

Like Erin said, the best I've ever found to be audible is 1%. I'll even give you 0.1%, and a large majority of amplifiers would be adequate. 

And definately agreed on what Erin posted reguarding the engineering of these things. While I'm not an engineer, my dad and his girlfriend are, both design parts that absolutely cant fail, as Erin does. Both have a masters in physics, his girlfriend a doctorate. Even then, my dad states that he questions the accuracy of rating an amplifier at 0.0005% THD as McIntosh does. Anything with that many zeros has an inherent tolerance that may or may not be greater than the measurement. 

Boutique brands are the only ones that care about anything past 0.1% or so, and they generally target the "audiophile" crowd. The type of people willing to spend $4000-12000 on an amp. Not that theres anything wrong with that, as long as your truthful with yourself about it.


----------



## ChrisB

subwoofery said:


> And I'm about ready to play with a Zuki Class D 5 lol
> 
> Kelvin


If that Zuki SPL 5 isn't 27" long, I may consider it. If it is over 15" in any dimension, it is a no go.


----------



## tnbubba

hmm funny yea i've only designed a few hundred million dollars worth of assembly and test equipment over the last 30 yrs.. some for the audio industry most for automotive and medical. and throw 10+yrs in designing race engine components too.

did I mention I was a speaker designer for panasoninc here in the US for 4 yrs

yea don't know **** i guess

again find halcros white paper on their distortion listening tests..
btw you know all those tests u cite are using single test tones and not music content
and nobody has answered my 50 db power question yet!

and yes I know how real engineering works... sorry bikini.. been doing it way longer than you .. yes it's always a cost vs performance trade off.. but when cost is no object and ultimate performance is desired then.....
go formula one racing is all i can say or build a space shuttle..
you are commend for your work here and on other things but never say I don't know how engineering works!!!

yea some of your points taken but I'm not gonna waste time rehashing 30 yrs worth of studies..and many including your post above have many glaring errors of omission..its not what studies tell you it's what they leave out that they don't tell you... got my ass in big trouble an booted form an AES convention when I questions someone if they even bothered to test their subjects hearing before using them in abx testing results that we obviously skewed..lol

oh yea parts count .. simple... parts cost money duh!!! remember KISS
the best designs are usually the simplest

and nobody has answered my 50 db power question yet!


----------



## tnbubba

you guys need to go to skool..
speaker dist is calculated in acousitic power.. not electrical
convert those distortion #'s to equivelent electrical power..

this is the simpliest explination i had handy.. had to show this to another EE who forgot his physics 

THD Measurement and Conversion

now let me ask you non EE guys this

what is the absolute threshold of hearing and what is the distortiuon attenuation of 0.01%thd..
let you guys chew on that for a while


----------



## ChrisB

tnbubba said:


> what is the absolute threshold of hearing and what is the distortiuon attenuation of 0.01%thd..
> let you guys chew on that for a while


Let me answer your question with a question: Why does .01% THD+N matter when the amplifier is installed in a motorized vehicle that can have anywhere between 60 dB to 100+ dB of road noise while actually driving the thing?

EDIT: To keep things relevant... it's down to the Zuki SPL 5, Kenwood XR-5s x 2, JL Audio HD900/5, or Alpine PDX-V9 for my up and coming install.


----------



## tnbubba

Chris.. the post was class D can sound as good as A/B 
here is a question..
what if the car is not moving?


----------



## TOOSTUBBORN2FAIL

Like i said before, your 50db power question was open ended, and could be any multitude of answers since you didnt specify the average power. I gave you an approximation of what it would take without putting a number out there, since you didnt give a number to start with.

0.01% distortion would be about 40db down from the fundamental. At that point, you wouldnt be able to accurately test if it could be heard, as the speaker would be the main distortion producing device.


----------



## ChrisB

If I am going to sit there and listen to music, I'd rather be in my house where I can place the speakers in equidistant locations relative to the listening position. Besides, my last vehicle encountered sub bass cancellation just merely sitting there idling with the exhaust out of the Borla Stingers. I'm quite certain that boxer rumble of my Subaru will cause similar problems, but it's too damn hot to start installing gear.

I find humor that there is so much passion regarding the worst reproduction environment known to man, the automobile. I guess it is karma, irony, or whatever you want to call it because I used to be one of those who thought sonic bliss could be achieved in the car. I bought into the hype of class ab amplifiers modified for better sound and every other audiophool marketing tactic known to man. In fact, at first, I thought this amplifier sounded awesome until I had some extended listening time and noticed that it introduced distortion at higher volume levels:










Regardless, what I learned through my jaunt of swapping out amplifiers to the tune of 53 amps in a 4 year period is that changing speakers will have a far greater impact on sound than changing amplifiers will. I also won't recommend swapping unless it is for double the power OR a smaller, more efficient, footprint.


----------



## ErinH

Yes, I realize most of the testing is with tones. Which, is quite ironic because tones are easier to spot distortion...
The data I've seen for real music tests shows 3-5% as the norm, and that can vary even with the music type selected. 

Here, this is done with real music (you're an engineer, so you should be able to do the math on dB vs THD %). 










You can see the majority of audibility is in the -12dB to -18dB range. -45dB (0.56% THD) is the best.
The testing done with various types of speakers (ie: headphones, component, etc) vary as well. Frankly, that's the best set of data I've seen yet. Most of the data I've seen from the auralization test show lower levels of audibility with music.
http://www.klippel.de/uploads/media/Speaker_Auralization-Subjective_Evaluation_of_nonlin_Dist_01.pdf
HTML Report - Klippel GmbH


Here's a post I made a while back elsewhere:


ErinH said:


> Of course, it seems like the more recent studies seem to dismiss distortion as not being as important... at was once thought. Meh... I disagree. However, the issue isn't "does it matter". The issue is "how susceptible are you to it". The best 'research' I've found is to do my own testing on Klippel's site. Once you complete this testing you'll find a summary of results from others' tests. I've found that the majority of the test summaries show a level of -30dB to be approximately the point where distortion becomes inaudible because this is where the majority of testers fell within (94%). Now, do we make up any of the remaining 6% who tested better? There are some who have tested, apparently, to a higher threshold but you'll find the CLEAR majority of results is in the -12 to -18dB range. For my purposes, though, I'll stick with the -30dB value. It's something that I can refer to.
> 
> Here's some results from a test I took with my computer speakers:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> To me, this kind of testing is more valuable than HD tests. IMD testing is more like real music listening. Multi tones. The klippel machine's method of measuring distortion is one that uses a fixed bass tone and sweeps a voice tone, or vice versa. HD sweeps with a sine wave are good for showing you trends, but the more I"ve studied the topic the more it is clearly evident: IMD testing > HD testing.
> 
> 
> Go HERE:
> Listening Test
> 
> Take the test. Play around with Bl and Cms, Le, and Two-Tone distortion altering as well. That's where we can get the best feel for what we can hear.


I invite you to take the test as well and post your results. It's not a challenge. 

So, back to the 0.01% THD, again, I'm not looking to argue for the sake of it. I'm genuinely wanting to see the research you're referring to. That impacts my own analysis. 0.01% is an attenuation of 80dB and I've not seen anything, anywhere, suggesting that capability of humans... maybe in some individuals with excellent hearing, but certainly not in the general public (as evidenced by all the above).


As for the real engineering comment, I stand by it. It doesn't matter if you've been engineering you're entire life, the basis is still the same.


----------



## MarkZ

tnbubba said:


> hmm funny yea i've only designed a few hundred million dollars worth of assembly and test equipment over the last 30 yrs.. some for the audio industry most for automotive and medical. and throw 10+yrs in designing race engine components too.
> 
> did I mention I was a speaker designer for panasoninc here in the US for 4 yrs
> 
> yea don't know **** i guess


That's nice. But you have to consider that other people here are experienced engineers and scientists as well, so let's all throw our credentials in the closet and avoid the pissing match.



> oh yea parts count .. simple... parts cost money duh!!! remember KISS
> the best designs are usually the simplest


The _cheapest_ designs are sometimes the simplest. The best designs use the best circuitry to achieve the highest-performing results. That means take your typical run of the mill amp, replace all the pulldown resistors with current sources; replace your input stage with a mirrored design (which literally _doubles_ the parts count of the IPS); add one of the many improved thermal tracking circuits to reduce OPS distortion; use an SMPS instead of a linear; add advanced protection circuitry, etc.

If you want evidence of support for any of those points above, I'll point you to Randy Sloan's book on the subject.




> what is the absolute threshold of hearing and what is the distortiuon attenuation of 0.01%thd..


You're asking two unrelated questions. Human sensory systems are notoriously nonlinear. You can't easily derive jnd's from detection thresholds.


----------



## t3sn4f2

I wish it would go deeper. And no, that is not what _she_ said. 

I estimate my threshold on this test to be around -55dB (*.*17%), which is still 5dB short of *.*1%.


----------



## avanti1960

minbari said:


> ...........Thinking you can tell the difference, priceless
> 
> Sent from my phone using digital farts


 I'm willing to bet that in my car I could get you to hear the difference. 

I'm also willing to suggest that environment, speaker drivers and source material contribute to a stack-up of conditions that meet head on with the sonic tendencies of the class D amp to occasionally reveal the harsh attributes. In other words, an environment that reflects and amplifies midrange octaves- combined with source material that does the same- e.g. harsh vocals and distorted guitar- combined with speaker drivers that are playing in their higher distortion frequencies, e.g. 4Khz or so for a 6.5" midbass driver- combined with the sonic characteristics of the amplifier's reproduction tendencies- all add together in a stack-up of "collisions" that lead to the previously stated observations. 

this theory would support the idea that listening comparison tests between amplifier classes revealed that there were no significant distinguishable differences- when the testing was conducted in an indoor environment using benign source material.


----------



## MarkZ

avanti1960 said:


> I'm willing to bet that in my car I could get you to hear the difference.
> 
> I'm also willing to suggest that environment, speaker drivers and source material contribute to a stack-up of conditions that meet head on with the sonic tendencies of the class D amp to occasionally reveal the harsh attributes. In other words, an environment that reflects and amplifies midrange octaves- combined with source material that does the same- e.g. harsh vocals and distorted guitar- combined with speaker drivers that are playing in their higher distortion frequencies, e.g. 4Khz or so for a 6.5" midbass driver- combined with the sonic characteristics of the amplifier's reproduction tendencies- all add together in a stack-up of "collisions" that lead to the previously stated observations.
> 
> this theory would support the idea that listening comparison tests between amplifier classes revealed that there were no significant distinguishable differences- when the testing was conducted in an indoor environment using benign source material.


Could you elaborate on what you mean when you say that the midrange is more enhanced in the car than elsewhere? I don't really follow that observation. Tuned flat is tuned flat. You're right about reflections, but the car tends to be fairly "hard" and so the reflections extend well into the high frequencies. It's also not clear to me why reflections would improve discriminability. The opposite should be true.

What you're suggesting is pretty profound. And it should mean that all the guys in Stereophile and other magazines should be evaluating their equipment in very small confined spaces with lots of reflective surfaces, which is pretty opposite to what the current viewpoint is.


----------



## tnbubba

i give up
human threshold of hearing is 5 - 15 db depending on age and how it measured
ascendign or descending... google it.. or whatever tons of studies out there I read 3 and took the range..

0.01% is -80 db..
+50 db in power is 1E5 multiplier.. 


the reason i bring this up is two fold..

you can hear at a 100 db signal a -80 db harmonic fundamental if your not def!!!

ok so who gives a **** if your speakers produce 3% dammint they are acoustic transducers or multipliers.. so they multiply or amplify the distortion too.. along with adding their own. but it you use the same speaker and reduce the distortion by a factor of 10!!!! then the speaker will still output that reduced distortion.. you do the thd graphs and figure it out 
oh yea don't forget to change acoustic power to electrical or vice versa when you add the speakers contribution
to the total power thd computation!!

so yes you can hear i just mathematically proved it ..
10db threshold of hearing plus 90 db mean sound pressure of music..
falls with in the -80 db range of 0.01% thd!! DUH!!! the longer the signal and the louder the more audible the distortion guess by your logic we don't need amplifier with better than -60db SNR (.1%)

yea I read 10 ms signal is considered minimum for auditory memory but anything over 50 ms is good.. oh yes did I mention that deaf people can hear.. they can actually hear distortion of bass notes using test tones!!


ok so back to the 50 db question

google tannoy scissor recording
it has a 50 db peak over average( forgot the duration) for a freaking scissor snip!!!! so if you are listening at 1 w average
mr geniuses tell me how many watts you need to produce that 50db peak.. yea.. maybe you will start seeing what I'm getting at. you are listening to a lot of clipping
oh material with lots of transients

btw I do gunshot recordings for fun.. want to guess what has the highest peak to average levels?? and they don't come close to that scissor snip!


----------



## tnbubba

As for the real engineering comment, I stand by it. It doesn't matter if you've been engineering you're entire life, the basis is still the same.


ok so what is the basis of real engineering.... guess that depends on what skool you went to>??
cant wait to trun all the engineers at ORNL and Los alamos loose on this one!!!


----------



## TOOSTUBBORN2FAIL

Just because you can hear 20db, doesnt mean you can hear it while something else is going on at 100db. By your analogy, you should be able to have your music cranked in one room, while following a conversation in the next room.

Id love to get you in a room with my dad, who btw, since you brought it up, had 3 power supplies of his design in the space shuttle, among other aerospace projects.

Im done, this thread isnt worth the time.


----------



## HiloDB1

Well as the saying goes just cause you've been doing something your entire life doesn't mean you've been doing it right.


----------



## chad

tnbubba said:


> hmm funny yea i've only designed a few hundred million dollars worth of assembly and test equipment over the last 30 yrs.. some for the audio industry most for automotive and medical. and throw 10+yrs in designing race engine components too.
> 
> did I mention I was a speaker designer for panasoninc here in the US for 4 yrs
> 
> yea don't know **** i guess
> 
> ....... sorry *bikini*.. been doing it way longer than you ..
> 
> 
> .........you are commend for your work here and on other things but never say I don't know how engineering works!!!
> 
> 
> ........and nobody has answered my 50 db power question yet!


Out of those 44 years, how long have you been insecure?

Or a reader..... because it B-I-K-I-N-P-U-N-K

The reason nobody has answered your question is because nobody is taking you seriously anymore. Hell, I stopped when I felt as if I was reading a text from a 13 year old girl.


----------



## TOOSTUBBORN2FAIL

Chad, i gave up when he told people to go back to skool.


But, for future reference, if anyone thinks they can hear 0.01% thd, id suggest the following. Schedule a hearing test. Ask them to play the first subharmonic of each test tone at the loudest volume they can, wgile testing each tone. So for the 8000hz test, they would play 4000hz at 100db or so. Then tell me you can hear a 20db sound while listening to 100db of other noise. 

Of course, id also like to see a cd with actual music with 50db of dynamic range. I could give a **** how a pair of scissors sounds on my stereo.


----------



## MarkZ

tnbubba said:


> i give up
> human threshold of hearing is 5 - 15 db depending on age and how it measured
> ascendign or descending... google it.. or whatever tons of studies out there I read 3 and took the range..
> 
> 0.01% is -80 db..
> +50 db in power is 1E5 multiplier..


You didn't read what I wrote. :/ That's kinda annoying.

You're trying to estimate how well we can detect distortion in a noisy signal based on how well we can detect the presence of a sound in silence. You don't understand the difference? If I tell you I can hear a pin drop, does that mean that I can also hear the pin drop while the phone is ringing?

Here are some links that might help you.

Auditory masking - Wikipedia, the free encyclopedia
Just-noticeable difference - Wikipedia, the free encyclopedia
Sensory threshold - Wikipedia, the free encyclopedia

HTH


----------



## chad

MarkZ said:


> You didn't read what I wrote.


Give it 10 years.


----------



## ErinH

chad said:


> Give it 10 years.


Never. When someone already knows they're right, why waste time considering others' input.


----------



## minbari

TOOSTUBBORN2FAIL said:


> Just because you can hear 20db, doesnt mean you can hear it while something else is going on at 100db. By your analogy, you should be able to have your music cranked in one room, while following a conversation in the next room.
> 
> Id love to get you in a room with my dad, who btw, since you brought it up, had 3 power supplies of his design in the space shuttle, among other aerospace projects.
> 
> Im done, this thread isnt worth the time.


lol, none of this makes any sense. if you have something in the audio that is 10db lower than a whisper while 100db content is happening, you couldnt hear it. I bet you would have a near impossible time measuring it!

good for your dad, what does space shuttle power supplies have to do with audio.

my dad has been biulding kitchen cabinets for 50 years, doesnt make him an expert on sub enclosures.


----------



## ChrisB

TOOSTUBBORN2FAIL said:


> Of course, id also like to see a cd with actual music with 50db of dynamic range.


Speaking of CDs, have you ever analyzed the wave forms of modern produced music compared to stuff from the 80s and 90s? Holy ****balls, they record stuff HOT these days!


----------



## chad

ChrisB said:


> Speaking of CDs, have you ever analyzed the wave forms of modern produced music compared to stuff from the 80s and 90s? Holy ****balls, they record stuff HOT these days!


They have always recorded hot, in fact hotter than now because there's actually an absolute limit now. (You can bang the living **** out of 2" tape)

Difference is that for some stupid reason the bubblegum token consumers feel that everything needs to be louder than balls and the engineers squeeze the **** out of it.


----------



## chad

minbari said:


> my dad has been biulding kitchen cabinets for 50 years, doesnt make him an expert on sub enclosures.


No, but the wood shop alone is worth making said person worthy of thinking they are for the benefits of use.


----------



## minbari

chad said:


> No, but the wood shop alone is worth making said person worthy of thinking they are for the benefits of use.


I am not saying he couldnt build it if you gave him the design and the structural considerations.

but he couldnt design one and if you didnt tell him how well braced it needs to be or if the face needs to be double thick, etc.

my point being just because you are an expect in one field doesnt make you one in another.


----------



## The Baron Groog

ChrisB said:


> Speaking of CDs, have you ever analyzed the wave forms of modern produced music compared to stuff from the 80s and 90s? Holy ****balls, they record stuff HOT these days!





chad said:


> They have always recorded hot, in fact hotter than now because there's actually an absolute limit now. (You can bang the living **** out of 2" tape)
> 
> Difference is that for some stupid reason the bubblegum token consumers feel that everything needs to be louder than balls and the engineers squeeze the **** out of it.


Loudness wars I have heard that the engineers are backing off now, saw a link on facebook-but can no longer find it!

EDIT: http://www.cepro.com/article/loudness_wars_coming_to_an_end


----------



## chad

minbari said:


> my point being just because you are an expect in one field doesnt make you one in another.


Totally got that, just making small talk.


----------



## trumpet

TOOSTUBBORN2FAIL said:


> I could give a **** how a pair of scissors sounds on my stereo.


I don't know why but this made me laugh my ass off. :laugh: Is there a story behind that?


----------



## TOOSTUBBORN2FAIL

minbari said:


> lol, none of this makes any sense. if you have something in the audio that is 10db lower than a whisper while 100db content is happening, you couldnt hear it. I bet you would have a near impossible time measuring it!
> 
> good for your dad, what does space shuttle power supplies have to do with audio.
> 
> my dad has been biulding kitchen cabinets for 50 years, doesnt make him an expert on sub enclosures.


You misunderstood my quote, my point was that you cant hear it. The other posters logic would say that you can, which is absurd.

He made a comment about building a space shuttle, otherwise i would have never posted. He wanted a pissing match of credentials, as much as it doesnt matter. I agree with you on that.


----------



## TOOSTUBBORN2FAIL

trumpet said:


> I don't know why but this made me laugh my ass off. :laugh: Is there a story behind that?


In post 447, the poster talks about a recording of scissors snipping, said that it had a 50db peak. He keeps asking how much power it takes for a 50db peak, when most music doesnt have peaks of more than 20db, and modern music is lucky to have peaks of 10db.

Chris, i frequent the dr loudness database often before buying cds, a lot of times this leads me to avoid remasters as lately many decently recorded cds have been remastered compressed to hell. Of course there are some genres i listen to that you just cant get away from compressed cds, but i try to avoid it when i can.


----------



## chad

TOOSTUBBORN2FAIL said:


> In post 447, the poster talks about a recording of scissors snipping, said that it had a 50db peak. He keeps asking how much power it takes for a 50db peak, when most music doesnt have peaks of more than 20db, and modern music is lucky to have peaks of 10db.
> .


I have some very un mastered classical recordings here. I'm willing to wager a bet that......


----------



## TOOSTUBBORN2FAIL

I would actually love to hear those. Not that i doubt it if their unmastered, just that the best i usually find commercially is around 20db. My Telarc Tchaikovsky disks max at 21db. They sound good, but no where close to the dynamics of the real thing.


----------



## ErinH

I'm just curious what it takes to record something with that much of a swing. In other words, is it a bit depth thing or something that generally requires higher resolution? I realize outputting that is hard but is recording it equally as tough when the mic is exposed to highish levels of SPL from the general recording itself?


----------



## chad

bikinpunk said:


> I'm just curious what it takes to record something with that much of a swing. In other words, is it a bit depth thing or something that generally requires higher resolution? I realize outputting that is hard but is recording it equally as tough when the mic is exposed to highish levels of SPL from the general recording itself?


We usually do 24/96. Also found we like 88.2 when going to CD. 

These are some very quiet rooms. Also remember the definition of RT60.


----------



## chad

TOOSTUBBORN2FAIL said:


> I would actually love to hear those. Not that i doubt it if their unmastered, just that the best i usually find commercially is around 20db. My Telarc Tchaikovsky disks max at 21db. They sound good, but no where close to the dynamics of the real thing.


It would be something that I would have to look into the legalities of. But I'm wondering what can be done under the stipulations of "education." the performances don't belong to me in other words.


----------



## TOOSTUBBORN2FAIL

Completely understood, just something that would be very interesting to hear if possible.


----------



## chad

TOOSTUBBORN2FAIL said:


> Completely understood, just something that would be very interesting to hear if possible.


Let me look into it. Having un-mastered stuff is pretty unique. Makes you appreciate proper mastering. Pisses you off at the same time.


----------



## avanti1960

MarkZ said:


> Could you elaborate on what you mean when you say that the midrange is more enhanced in the car than elsewhere? I don't really follow that observation. Tuned flat is tuned flat. You're right about reflections, but the car tends to be fairly "hard" and so the reflections extend well into the high frequencies. It's also not clear to me why reflections would improve discriminability. The opposite should be true.
> 
> What you're suggesting is pretty profound. And it should mean that all the guys in Stereophile and other magazines should be evaluating their equipment in very small confined spaces with lots of reflective surfaces, which is pretty opposite to what the current viewpoint is.


The attached pic shows an RTA of my car with zero EQ. Notice the 10db plateau @ 1.3Khz. This creates an overbearing midrange sound. Prior to this I had the Pioneer "autotune" EQ switched on. It drove a 10db plateau from 600 Hz all the way past 3Khz. It was primarily those settings that drove my opinions on how the class D and class AB amplifiers sounded.


----------



## Ampman

avanti1960 said:


> The attached pic shows an RTA of my car with zero EQ. Notice the 10db plateau @ 1.3Khz. This creates an overbearing midrange sound. Prior to this I had the Pioneer "autotune" EQ switched on. It drove a 10db plateau from 600 Hz all the way past 3Khz. It was primarily those settings that drove my opinions on how the class D and class AB amplifiers sounded.


It's one thing to make statements and another when one can back up their findings very cool


----------



## TOOSTUBBORN2FAIL

Thats a function of the speakers, install, and car environment, not the amp. The amp plays pretty damn flat from 5hz past 20,000hz.


----------



## minbari

TOOSTUBBORN2FAIL said:


> Thats a function of the speakers, install, and car environment, not the amp. The amp plays pretty damn flat from 5hz past 20,000hz.


Exactly. How you have it eqd has nothing to do with the amplifier

Sent from my phone using digital farts


----------



## t3sn4f2

avanti1960 said:


> The attached pic shows an RTA of my car with zero EQ. Notice the 10db plateau @ 1.3Khz. This creates an overbearing midrange sound. Prior to this I had the Pioneer "autotune" EQ switched on. It drove a 10db plateau from 600 Hz all the way past 3Khz. It was primarily those settings that drove my opinions on how the class D and class AB amplifiers sounded.





Ampman said:


> It's one thing to make statements and another when one can back up their findings very cool












"Tuned flat" knuckleheads!


----------



## Ampman

t3sn4f2 said:


> "Tuned flat" knuckleheads!


I've always heard it said it takes one to know one haha


----------



## chad

wow.


----------



## cvjoint

avanti1960 said:


> The attached pic shows an RTA of my car with zero EQ. Notice the 10db plateau @ 1.3Khz. This creates an overbearing midrange sound. Prior to this I had the Pioneer "autotune" EQ switched on. It drove a 10db plateau from 600 Hz all the way past 3Khz. It was primarily those settings that drove my opinions on how the class D and class AB amplifiers sounded.


Try these two experiments:
I.
RTA left speaker and right speakers separately. If your theory is right and amplitude deviations from flat are amplifier driven than they should look exactly the same. That's because left and right use the same speakers and amplifier. 


II. RTA the same speaker from one mic position. Secondly, RTA the same speaker from a different mic position in the car. If your theory is right and amplitude deviations from flat are amplifier driven than they should look exactly the same. That's because in both cases you used the same speaker on the same amplifier. By the same token move the mic around the car since it is real time. If the FR varies widely than guess what, there's more to this than the amp. 

In fact the amp has a negligible impact. Most modern amps are under 1 db variation throughout the audible range. I only know RF as a manufacturer that builds in odd target curves on purpose


----------



## bamelanc

cvjoint said:


> I only know RF as a manufacturer that builds in odd target curves on purpose


I told this to a dealer recently and they looked at me crazy. :cwm13:


----------



## subwoofery

bamelanc said:


> I told this to a dealer recently and they looked at me crazy. :cwm13:


Show them this next time you go to their shop: 









Kelvin


----------



## chad

Top & Flop

Sounds like an event at Freaknik.


----------



## cleansoundz

cvjoint said:


> Try these two experiments:
> I.
> RTA left speaker and right speakers separately. If your theory is right and amplitude deviations from flat are amplifier driven than they should look exactly the same. That's because left and right use the same speakers and amplifier.
> 
> 
> II. RTA the same speaker from one mic position. Secondly, RTA the same speaker from a different mic position in the car. If your theory is right and amplitude deviations from flat are amplifier driven than they should look exactly the same. That's because in both cases you used the same speaker on the same amplifier. By the same token move the mic around the car since it is real time. If the FR varies widely than guess what, there's more to this than the amp.
> 
> In fact the amp has a negligible impact. Most modern amps are under 1 db variation throughout the audible range. I only know RF as a manufacturer that builds in odd target curves on purpose


This is true as i have used the rf t400-4 and t600-4 for several years. I bet that all of the future rf amps will not have any more treble boost built up in them.


----------



## D-Bass

uh oh! I'm about to use a T600-2 for my mids, and half a T600-4 for my tweets! I can't wait to battle this ****


----------



## minbari

subwoofery said:


> Show them this next time you go to their shop:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Kelvin


although it looks like it is taking a serious dive. if you look at the 20khz line, it is only about -2db. not really that bad all things considered.


----------



## cleansoundz

ChrisB said:


> Let me answer your question with a question: Why does .01% THD+N matter when the amplifier is installed in a motorized vehicle that can have anywhere between 60 dB to 100+ dB of road noise while actually driving the thing?
> 
> EDIT: To keep things relevant... it's down to the Zuki SPL 5, Kenwood XR-5s x 2, JL Audio HD900/5, or Alpine PDX-V9 for my up and coming install.


I have heard the hd series and the pdx series and you can't do wrong with either.


----------



## envisionelec

tnbubba said:


> hmm funny yea i've only designed a few hundred million dollars worth of assembly and test equipment over the last 30 yrs.. some for the audio industry most for automotive and medical. and throw 10+yrs in designing race engine components too.
> 
> did I mention I was a speaker designer for panasoninc here in the US for 4 yrs
> 
> yea don't know **** i guess


You're not a EE.

Maybe an EET. _Maybe._


----------



## tnbubba

htf do u know asswipe..
not wasing my time coming back from vacation dealing with retards
you havent answered the 50 db question either mr rocket scientist..


----------



## chad

LOL Classic.


----------



## ChrisB

I'm still sticking to my guns on the amplifier topology doesn't mean a thing in a damn car, provided we are talking one competently designed topology versus another.

Disclaimer: I'm not an engineer, nor do I play one on the internet but I do have a DIY RTA setup!


----------



## TOOSTUBBORN2FAIL

tnbubba said:


> htf do u know asswipe..
> not wasing my time coming back from vacation dealing with retards
> you havent answered the 50 db question either mr rocket scientist..


And you haven't answered if you can hear a whisper across a large room while music is blasting at 100db. Because you seem to think you can.


----------



## lizardking

I installed the Arc Audio SE2300 today in place of the Zed Audio Leviathan III and I could tell a huge difference in dynamics with the Arc amp. It blew me away how much greater the system sounded. Midbass was tight and accurate and highs seemed more detailed. However, the noise floor on the Arc amp is much greater than the Zed amp. Zed amp had zero noise floor or at least what I was able to hear. The amp was the only change I made.


----------



## MarkZ

lizardking said:


> I installed the Arc Audio SE2300 today in place of the Zed Audio Leviathan III and I could tell a huge difference in dynamics with the Arc amp. It blew me away how much greater the system sounded. Midbass was tight and accurate and highs seemed more detailed. However, the noise floor on the Arc amp is much greater than the Zed amp. Zed amp had zero noise floor or at least what I was able to hear. The amp was the only change I made.


This sounds like a prototypical example of changing gain structure. The noise issue and the difference in dynamics are consistent with that.


----------



## lizardking

The Zed amp gain was about 1/2 way and the Arc is about 1/4 or a hair less. Just can't believe it made that much difference. I've never been one that could "hear" differences in amps. Gain makes sense though. Both being feed by the Audison Bit One.


----------



## minbari

lizardking said:


> The Zed amp gain was about 1/2 way and the Arc is about 1/4 or a hair less. Just can't believe it made that much difference. I've never been one that could "hear" differences in amps. Gain makes sense though. Both being feed by the Audison Bit One.


1/2 of what and 1/4 of what? That tells me nothing. Of one goes to 10v and the other goes to 5v, then 1/4 10v and 1/2 5v would be exactly the same. However, 1/4 5v and 1/2 10v would not be the same at all

Sent from my phone using digital farts


----------



## lizardking

1/4 of 4 volt ( Arc ) and 1/2 of 8 volt ( ZED ). I believe the Zed was at the 1.4v setting. The Arc was actually under 1/4 by a hair.


----------



## minbari

So you had the arc set to 3v and the zed set to 4v. About the same

Sent from my phone using digital farts


----------



## lizardking

Its like I said earlier. I've never been one that notice differences in how an amp sounds, but the Zed amp was my first Class D amp. I've mainly ran all Arc and Zapco.


----------



## 14642

lizardking said:


> 1/4 of 4 volt ( Arc ) and 1/2 of 8 volt ( ZED ). I believe the Zed was at the 1.4v setting. The Arc was actually under 1/4 by a hair.


 
The difference between 1 volt (1/4 of 4) and 4 volts (1/2 of 8) is 12dB.


----------



## minbari

Andy Wehmeyer said:


> The difference between 1 volt (1/4 of 4) and 4 volts (1/2 of 8) is 12dB.


Yes but all the way down is 4v. 1/4 up would be 3v.

For the zed 1/2 way is 4v. 

Difference is negligible

Sent from my phone using digital farts


----------



## lizardking

1/2 way on the Zed amp said 1.4 volts.


----------



## lizardking

The one thing I can say about that Leviathan, it was dead silent with 1/2 gain. Unbelievable compared to the Arc Audio SE.


----------



## Waterfowl

lizardking said:


> The one thing I can say about that Leviathan, it was dead silent with 1/2 gain. Unbelievable compared to the Arc Audio SE.


The 2300 is a 2 channel amp. Right? The zed is a 6 channel. How is the se and how was the Zed wired? Did you bridge the zed?


----------



## lizardking

I ran the Zed amp as a four channel amp non bridged and as a 6 channel with 5/6 channels on subs. However, I never ran the rear speakers.
The arc amp is wired to the my fronts only, and rears off my deck for rear fill only.


----------



## Waterfowl

lizardking said:


> I ran the Zed amp as a four channel amp non bridged and as a 6 channel with 5/6 channels on subs. However, I never ran the rear speakers.
> The arc amp is wired to the my fronts only, and rears off my deck for rear fill only.


The Arc is rated at 330w at 4 ohm per channel. The Zed is rated at 190 per channel at 4 ohm. It would be interesting to hear the Zed bridged to your fronts and find out your opinion then. Is it just the higher volume with less gain that is the difference that your hearing or is it the a/b vs d?


----------



## lizardking

Good point


----------



## ChrisB

Waterfowl said:


> The Arc is rated at 330w at 4 ohm per channel. The Zed is rated at 190 per channel at 4 ohm. It would be interesting to hear the Zed bridged to your fronts and find out your opinion then. Is it just the higher volume with less gain that is the difference that your hearing or is it the a/b vs d?


As I have stated before, and I will state again, differences in amplitude are easier to pick out than differences in properly level matched amplifiers that measure the same. It's not rocket science although those who claim that they can hear grass growing seem to think there is something mythical to audio reproduction in the absolute worst environment to reproduce audio in.


----------



## xtremevette

I think the Class A/B and the Class D both have their places in the audio world. Really depends on what your looking for. If one was not better then then other in a particular way then that topology would go away for being obsolete. Just common sense there.


----------



## avanti1960

are most of the highly regarded and sought after amplifiers class ab or class d?


----------



## W8 a minute

avanti1960 said:


> are most of the highly regarded and sought after amplifiers class ab or class d?


Lately the most sought after amplifiers are free amplifiers. :laugh:


----------



## subwoofery

W8 a minute said:


> Lately the most sought after amplifiers for me are free amplifiers. :laugh:


Edited  

Kelvin


----------



## ChrisB

Just because they are sought after doesn't always mean they are great. Ask me how I know that.


----------



## SaturnSL1

Maybe. I think there is more to it than the amplifiers class to consider. Personally, I've never heard an amp (in my car, on my speakers) sound as good as my USA-400. Never heard one as clean or as warm sounding. 

Is it because it's class A/B? Or is it the quality of the parts used, the age of the parts, the abuse they've seen over the years?

When ever I acquire a new amp I sit in my car and listen to it for a few hours after installation, so I have a lot of time to sit and wonder about stupid crap like this.


----------



## huggy54

I prefer class AB, to my ears they just sound sweeter than any class Ds I previously ran.


----------



## jsun_g

I've run class D before and at low volume levels they were fine. At high volume, they seemed to lose fine detail and dynamics. Not generalizing about all class D amps, just something I noticed with the amps I used.


----------



## narvarr

I think synergy between the amp and speaker play a large roll in the sound. I have heard JL HD's in both Mark's and Todd's car and they both sound Phenomenal on JL speakers. But on more neutral drivers, it may be a different story.

Sent from my SAMSUNG GALAXY NOTE using Tapatalk 2


----------



## BuickGN

I can say the HD/Dynaudio combo is great. I'll never buy into the BS that a good class D sounds even a little worse than an A/B. as I've said before I have a McIntosh collecting dust because there was no difference in SQ between the HDs and the HDs have several big advantages. Everyone who has heard my car has brought up on their own that class D sounding worse must be a myth.


----------



## ceri23

The big advantage in my case, and the reason I went with a Zed Leviathan III was that the class D doesn't warm up at all. That's almost fully enclosed inside an amp cabinet with no fans, mounted on the opposite side of an MDF board with another class D sub amp. Show me a class AB that can do that. Throw on the efficiency (basically the same thing stated another way) and I don't even need to upgrade the big 3 for my SQ/SQL system. Class D is still a growing segment of car audio amplifiers. The PWM power supply was a noise hurdle for full 20-20k operation, but technology has arrived that allows them to be realized. There's no doubt in my mind that AB will be gone with tube amps in 10 years. Class D have overcome their shortcomings. Now we just have to wait for the prices to start dropping for them to become more mainstream in the full range segment. Where size and efficiency don't matter (home audio) A and AB might cling on like tube amps as a novelty for the wealthy, but class D are the i7 of modern audio. It's transitioning from "have your cake and eat most of it" to "eat it".


----------



## jguthrie

Yuck. said:


> This could come down to how much some people's ears can really discern over others, but time spent with one or the other could reveal differences. I am open to being proven wrong, not sure how subjective it could all be however.


I was always told to use Class D for Subs.


----------



## subwoofery

ceri23 said:


> The big advantage in my case, and the reason I went with a Zed Leviathan III was that the class D doesn't warm up at all. That's almost fully enclosed inside an amp cabinet with no fans, mounted on the opposite side of an MDF board with another class D sub amp. Show me a class AB that can do that. Throw on the efficiency (basically the same thing stated another way) and I don't even need to upgrade the big 3 for my SQ/SQL system. Class D is still a growing segment of car audio amplifiers. The PWM power supply was a noise hurdle for full 20-20k operation, but technology has arrived that allows them to be realized. *There's no doubt in my mind that AB will be gone with tube amps in 10 years. *Class D have overcome their shortcomings. Now we just have to wait for the prices to start dropping for them to become more mainstream in the full range segment. Where size and efficiency don't matter (home audio) A and AB might cling on like tube amps as a novelty for the wealthy, but class D are the i7 of modern audio. It's transitioning from "have your cake and eat most of it" to "eat it".


^ Are you so sure that you're willing to bet big money on your statement?  I know I wouldn't...

Kelvin


----------



## avanti1960

ceri23 said:


> ...There's no doubt in my mind that AB will be gone with tube amps in 10 years. Class D have overcome their shortcomings. ......."


Can you please describe the shortcommings you experienced with the class D amps?


----------



## avanti1960

avanti1960 said:


> are most of the highly regarded and sought after amplifiers class ab or class d?


so no takers for serious answers to this question? 

I'll be the first-

based on an understanding of the top sounding, most highly regarded and sought after audiophile mobile amplifiers on the market class D is in an extreme minority if on the list at all.


----------



## Guest

A well designed Class D can sound just like a well designed Class AB or Class A.

Absolutely no reason they can not... Just a different way to get to the same goal.


----------



## ChrisB

avanti1960 said:


> are most of the highly regarded and sought after amplifiers class ab or class d?





avanti1960 said:


> so no takers for serious answers to this question?
> 
> I'll be the first-
> 
> based on an understanding of the top sounding, most highly regarded and sought after audiophile mobile amplifiers on the market class D is in an extreme minority if on the list at all.


I answered it a few posts back, and yes I was serious when I answered it:


ChrisB said:


> Just because they are sought after doesn't always mean they are great. Ask me how I know that.


Since Class D amplifiers are relatively new, and don't have a lot of hype and mythology associated with them, it is unfair to compare them to something sought after from the 1980s and 1990s. You have people hitting their 40s, or older, who remember how awesome some of those sought after amplifiers were in the 80s and 90s, but couldn't afford them at the time due to a number of factors. Now they see them on eBay, or the various forums, and pay top dollar for them. I know because I once did the same thing myself seeking out Linear Power, Orion, Rockford Fosgate, and Zapco amplifiers.

But I'll digress as some will call me a hypocrite for running class ab on my mids and highs and class d on my subwoofer. My amplifiers were even hand assembled in Louisiana using foreign and domestic components. They may not measure the best on an audio precision, but they are more than adequate for reproducing audio in a mobile environment and built tough as nails.


----------



## ceri23

subwoofery said:


> ^ Are you so sure that you're willing to bet big money on your statement?  I know I wouldn't...
> 
> Kelvin


I may be exaggerating a bit, but I would bet money that class D would account for more than 75% of sales in the mobile market in 10 years, basically relegating AB to the scrap heap of history. Considering sub amps are more commonly purchased than full range these days, I'd throw out a complete guess that they are already approaching 25-30% of sales. I've got nothing to back that up, but a company like sonicelectronix/woofersetc might have some data that could be mined to find this out.


----------



## subwoofery

I guess we'll see in 10 years from now  

Kelvin


----------



## avanti1960

ChrisB said:


> I answered it a few posts back, and yes I was serious when I answered it:
> 
> 
> Since Class D amplifiers are relatively new, and don't have a lot of hype and mythology associated with them, it is unfair to compare them to something sought after from the 1980s and 1990s. You have people hitting their 40s, or older, who remember how awesome some of those sought after amplifiers were in the 80s and 90s, but couldn't afford them at the time due to a number of factors. Now they see them on eBay, or the various forums, and pay top dollar for them. I know because I once did the same thing myself seeking out Linear Power, Orion, Rockford Fosgate, and Zapco amplifiers.
> 
> But I'll digress as some will call me a hypocrite for running class ab on my mids and highs and class d on my subwoofer. My amplifiers were even hand assembled in Louisiana using foreign and domestic components. They may not measure the best on an audio precision, but they are more than adequate for reproducing audio in a mobile environment and built tough as nails.


this is a very fair and reasonable answer. i would just like to update the assumptions to include sought after amps as of TODAY. Mosconi is one of the hottest brands in amplifiers if the buzz on these boards is any indicaton as well as my own personal experiences. 
a recent long running SQ amp thread mentioned many european, non class-d amps as exhibiting the best possible SQ they have ever heard. 
i personally run a highly regarded class-d on my mids and tweeters and often wonder about the source of certain mid volume distorted sounds and harshness that is very audible, and if the best of the best in AB amp technology would sound better to my critical ear, where i am constantly noticing a lack of absoulte clarity in reproduction despite the mobile environment.


----------



## tnbubba

I'll say it... slap one your your class D amps in a good quality home system..
with a good known set of speakers like the wilsons grand utopa.. celestions.. b&W..etc
you will run out of the room screaming..
I have yet to hear ANY class D amp..home or car.. that sound worth a **** on my home system.. when it come to subs.. no I cant hear a difference.. anything above that yes.. if is sounds like **** in the house it don't go in car.. and yes my home sub amp is a CROWN K series.. slightly tweaked the rest is CODA, bryston , parasound or carver tube amp(modded)

BTW my home system is a full 4 way active, 15" subs 10" Midbass 5" mids and 1" tweets 
from all various manuf.. and all completely modular so I can easily swap out speaker modules to evaluate drives.. wish my amp setup was that easy..


----------



## TOOSTUBBORN2FAIL

Interesting. Considering the jl hd's switch at over 400,000hz, your saying you can hear differences as small as 0.0025 milliseconds. On top of the fact that unless your clipping an HD, your speaker is putting out 10-30 times as much distortion at mild listening levels. Wait, i forgot, it was you who argued that you could hear a whisper while 110db music was playing.


----------



## tnbubba

well I don't see you hooking up your JL to your system now do you??

and a lot of bipolars or mopsfets switch in the MZ used in regular a/b amps switch that fast 
point is..???

I'm not the only one who can here the diff..


----------



## subwoofery

avanti1960 said:


> this is a very fair and reasonable answer. i would just like to update the assumptions to include sought after amps as of TODAY. Mosconi is one of the hottest brands in amplifiers if the buzz on these boards is any indicaton as well as my own personal experiences.
> a recent long running SQ amp thread mentioned many european, non class-d amps as exhibiting the best possible SQ they have ever heard.
> i personally run a highly regarded class-d on my mids and tweeters and often wonder about the source of certain mid volume distorted sounds and harshness that is very audible, and if the best of the best in AB amp technology would sound better to my critical ear, where i am constantly noticing a lack of absoulte clarity in reproduction despite the mobile environment.


Mosconi makes great and solid products but it's just a forum boner right now. 
As soon as a new "breed" of amp comes out, you'll see a lot of Mosconi amps for sale - there's already quite a few for sale every now and then... 

Try a search on which brand doesn't get sold very often on this forum <-- those brands are either very expensive and therefore not many people have it (Brax, Phass) or ... they are just too great that not many sell them after acquiring them (Sinfoni, Genesis) unless the amp doesn't fit their install 

Having heard both the Arc Audio SE line and the Mosconi AS line, I'll always recommend the Arc Audio SE over the Mosconi AS - sounds more transparent and as dynamic (without the bump in bass region - below 100Hz) as the Mosconi...

My opinion, 
Kelvin


----------



## TOOSTUBBORN2FAIL

tnbubba said:


> well I don't see you hooking up your JL to your system now do you??
> 
> and a lot of bipolars or mopsfets switch in the MZ used in regular a/b amps switch that fast
> point is..???
> 
> I'm not the only one who can here the diff..


If your not hearing power supply switching, then what is it you think your hearing? The HD's are as low or lower distortion than many of the "highly reguarded" class a/b car audio amps, like the sinfonis. 

And yes, ill be using HD's in my new install. After listening to many cars with class d vs class ab, and listening to a sound producer with 4 oscars for best sound say that he cant here a difference (and his home setup is B&W i believe). In fact, he won the 2010 Modex national championships with a true 5.1 car, with all class d alpines.


----------



## tnbubba

so? I've met many a deaf ass know it all sound producers in Nashville and CA in my lifetime too..
oh is that the same producer that got a grammy for that HORRIBLY clipped distorted Nora Jones CD a few years back?

and I don't put much stock in any SQ car.. yea I heard plenty and quite a few show winners.. sorry but they don't even come close to comparing to SL orions in his house..
or a few other systems I been privileged to listen too.
oh BTW those were the 1st gen Orions I heard too..


----------



## TOOSTUBBORN2FAIL

Aside from FR, you cant tell a difference. But ill let you continue to believe you hear a difference. I guess some people believe in the ability to hear grass grow, some people believe in unicorns.

And no, not the same producer at all.


----------



## tnbubba

wont go there lets just say RC owes me 10K


----------



## t3sn4f2

tnbubba said:


> wont go there lets just say RC owes me 10K


:icon_bs:

Prove it.

Join your friends......

Matrix HiFi --> Blind testing high end full equipments









http://www.matrixhifi.com/imagenes/ppec_escuchantes.jpg

Oh wait I know, the price of admission for the audio gear is not up to your standards maybe? If it's not a $100,000 piece of furniture, uhhmmm loudspeaker, it doesn't qualify.


----------



## TOOSTUBBORN2FAIL

^this.


----------



## quality_sound

^^^That


----------



## chad

Gettin' fuken deep in here.


----------



## tnbubba

already did he refused the trip to nashville 14 yrs ago..
and i wasn't hauling my studio gear from nashville to his place
not going into details it was posted on some other audio forums years ago

still have the video tape i think..
want the witness names

an naw my place looks like hell.. true man cave!!!!!!


----------



## tnbubba

I'm not going into why ABX system is totally wrong for human testing..
been there too many time in 30 yrs and there are multiple PHd papers explaining this( not just auditory).. but basically the HUMAN machine is a great comparative measurement tool/device not a absolute measurement tool..if you don't understand or grasp this you will not understand abx testing or why its an improper tool for subjective audio analysis.

oh yea any statistician will tell ya that Matrix test statistically doesn't prove anything!


----------



## ChrisB

Is this where I propose the Integra Type R challenge again? 

First, we find an otherwise stock Integra Type R. For the example to hold true, no deadening of any kind will be allowed except for the doors. You can seal the access holes and mass load the outer door skin, that's it! 

Next we install an A/B/X switcher in it, pick out all the high end, bonerriffic loudspeakers and subwoofers with properly level matched amplifiers designed to play the same at 1/2 volume. 

Finally, the car gets driven on the interstate at 70 MPH with the windows down, the listener A/B/Xs the amplifiers. Let's see if they can pick out with any statistical significance which amplifier is playing. Ok, the windows down was unfair, I'll let you leave them up and still see if you can pick out which amplifier is playing with any statistical significance.

I think the Integra Type R challenge would be fun.


----------



## tnbubba

Next we install an A/B/X 

chris we had this discussion before 
read above post why ABX dont work!


----------



## tnbubba

and the thread was calls D can sound as good as A , a/b?? 
didn't say nutting about car or home amps..

anyway.. i got beer to drink and a drunk blond to entertain..


----------



## ChrisB

tnbubba said:


> Next we install an A/B/X
> 
> chris we had this discussion before
> read above post why ABX dont work!


Please tell me how you would be able tell the difference in the car with one of the highest known noise floors to man.:laugh: It was a loaded challenge.


----------



## chad

tnbubba said:


> read above post why ABX dont work!


.......because people wrote papers about it.


----------



## tnbubba

oh ChrisI know that, what u meant, but some people don't..
and the PHd's who did these studies and spent the whole life doing the research work, know this **** a lot better than us..that's why WE read THEIR papers, and they get paid for it!

If it was so damn obvious we'd all do it!


----------



## chad

Well apparently we all agree that Brawndo has electrolytes.


----------



## ChrisB

chad said:


> Well apparently we all agree that Brawndo has electrolytes.


Well, I've never seen _no plants grow_ out of _no toilet_.:laugh:


----------



## KSpan

As a bass player, this discussion is very interesting. There have been a number of Class D bass amps that have come out in the last 2-3 years that sound absolutely phenomenal, and if there is a main gripe about them from bassists it's usually that the low end doesn't have the same oomph as the lead sled A/B amps. This is funny to me because most everyone in the car audio world seems to accept Class D amps for subwoofer use, and the gripes have to do with the performance in the mids and highs.


----------



## chad

KSpan said:


> As a bass player, this discussion is very interesting. There have been a number of Class D bass amps that have come out in the last 2-3 years that sound absolutely phenomenal, and if there is a main gripe about them from bassists it's usually that the low end doesn't have the same oomph as the lead sled A/B amps. This is funny to me because most everyone in the car audio world seems to accept Class D amps for subwoofer use, and the gripes have to do with the performance in the mids and highs.


Lab gruppen, 
Crown K series, CE4000, Itech. 
Powersoft
Camco
QSC
Crest

Seems the guys on the other side of the mixing console don't mind class D


----------



## MarkZ

tnbubba said:


> oh ChrisI know that, what u meant, but some people don't..
> and the PHd's who did these studies and spent the whole life doing the research work, know this **** a lot better than us..that's why WE read THEIR papers, and they get paid for it!
> 
> If it was so damn obvious we'd all do it!


Actually, they don't get paid for writing papers.

But regardless, ABX testing is a valid procedure used in the scientific literature _all the time_. But yes, you have to be careful about how you interpret the results. But that's like anything else.

I'll tell you what you _don't_ find in the scientific literature. You won't find a single paper where someone says, "There's a difference between sample A and sample B. I have no measurements to support it, I have no reproducible procedure to describe, and I have no explanation for the mechanism underlying the difference. But there is a difference. I saw it with my own eyes!"


----------



## chad

MarkZ said:


> Actually, they don't get paid for writing papers.


They actually PAY TO write them.


----------



## avanti1960

ChrisB said:


> Is this where I propose the Integra Type R challenge again?
> 
> First, we find an otherwise stock Integra Type R. For the example to hold true, no deadening of any kind will be allowed except for the doors. You can seal the access holes and mass load the outer door skin, that's it!
> 
> Next we install an A/B/X switcher in it, pick out all the high end, bonerriffic loudspeakers and subwoofers with properly level matched amplifiers designed to play the same at 1/2 volume.
> 
> Finally, the car gets driven on the interstate at 70 MPH with the windows down, the listener A/B/Xs the amplifiers. Let's see if they can pick out with any statistical significance which amplifier is playing. Ok, the windows down was unfair, I'll let you leave them up and still see if you can pick out which amplifier is playing with any statistical significance.
> 
> I think the Integra Type R challenge would be fun.


With certain program material and a certain few class D amplifiers I would be able to discern if the class D was playing. 
It isn't about noise floor, it isn't about frequency response, it isn't about harmonic distortion- it is something beyond these boiler plate spcifications where the differences are. 
about a year ago i was ready to throw my system out the window but i decided to find the root cause of my sound reproduction dissatisfaction. 
it came down to my entry level class D amplifier, despite it being manufactured by a reputable brand and having reputable specifications. the sound quality at moderate volume was described as edgy, gritty, lacking smoothness. certain music brought it out and it was completely repeatable. i swapped out everything but the amp in an effort to fix this issue. i then visited my local dealer and was able to reprioduce the issue on at least (2) class D amps they had wired on their sound floor. the dealer rep agreed with me once i pointed out what to look for in the sound- we went over the track repeatedly- he then had an ear that could detect the issue. 
i tried the JL HD ONLY because they did not have any class AB amps in stock. The issue was not audible on the HD amp. I bought the amp and was a reasonably happy consumer. HOWEVER- now and then, this gritty, edgy, harsh tonal characteristic DOES SHOW UP ON THE HD AMP. IT DOES NOT SHOW UP ON THE JL SLASH AMP. 
If you let me spec the demo music in the Integra and run these (2) amps I will accept the challenge- as long as the music is at a volume high enough to hear above the wind noise.


----------



## MarkZ

avanti1960 said:


> With certain program material and a certain few class D amplifiers I would be able to discern if the class D was playing.
> It isn't about noise floor, it isn't about frequency response, it isn't about harmonic distortion- it is something beyond these boiler plate spcifications where the differences are.


I assure you that it is not. These are not boiler plate specifications. These are the three classes of differences between any two signals. There ain't no dark matter here.  We're not talking about mysteries of the universe. We're talking about the incredibly _simple_ and incredibly easy-to-measure differences between two electrical signals. Just because you didn't measure them in your testing doesn't mean they can't describe your observations.


----------



## KSpan

avanti1960 said:


> If you let me spec the demo music in the Integra and run these (2) amps I will accept the challenge- as long as the music is at a volume high enough to hear above the wind noise.


So you would want to use material that you've already decided sounds bad through a Class D amp, and the inaccuracy is so clear that you believe you can pinpoint exactly when it happens every time? Sounds legit.


----------



## ChrisB

Alrighty, now to find an Integra Type R because my wife won't let me buy one to call my own.


----------



## ceri23

KSpan said:


> So you would want to use material that you've already decided sounds bad through a Class D amp, and the inaccuracy is so clear that you believe you can pinpoint exactly when it happens every time? Sounds legit.


Well I believe that would satisfy the old Richard Clark challenge, which was envisioned before this Class D/Class A/B debate was even around in the mobile market.


----------



## narvarr

avanti1960 said:


> With certain program material and a certain few class D amplifiers I would be able to discern if the class D was playing.
> It isn't about noise floor, it isn't about frequency response, it isn't about harmonic distortion- it is something beyond these boiler plate spcifications where the differences are.
> about a year ago i was ready to throw my system out the window but i decided to find the root cause of my sound reproduction dissatisfaction.
> it came down to my entry level class D amplifier, despite it being manufactured by a reputable brand and having reputable specifications. the sound quality at moderate volume was described as edgy, gritty, lacking smoothness. certain music brought it out and it was completely repeatable. i swapped out everything but the amp in an effort to fix this issue. i then visited my local dealer and was able to reprioduce the issue on at least (2) class D amps they had wired on their sound floor. the dealer rep agreed with me once i pointed out what to look for in the sound- we went over the track repeatedly- he then had an ear that could detect the issue.
> i tried the JL HD ONLY because they did not have any class AB amps in stock. The issue was not audible on the HD amp. I bought the amp and was a reasonably happy consumer. HOWEVER- now and then, this gritty, edgy, harsh tonal characteristic DOES SHOW UP ON THE HD AMP. IT DOES NOT SHOW UP ON THE JL SLASH AMP.
> If you let me spec the demo music in the Integra and run these (2) amps I will accept the challenge- as long as the music is at a volume high enough to hear above the wind noise.


I think this is the best explanation I have heard on the sound difference between the two types of amps. Very well put sir. To add to this, I think headroom has a lot to do with being able to hear the difference as well. Keep class D amps away from the clipping threshold and you would have a harder time discerning the difference between the two. For example, first time I heard Todd's car, he was only running 2 of his 3 HD amps and the midrange did sound a little "edgy" as you described. Second time I heard it he had all 3 amps back in and the edgyness was gone. He played the same demo tracks the second time that he played the first time. I guess it is possible that it could have been how he had it tuned at the time, but I doubt it.

Sent from my SAMSUNG GALAXY NOTE using Tapatalk 2


----------



## avanti1960

narvarr said:


> I think this is the best explanation I have heard on the sound difference between the two types of amps. Very well put sir. To add to this, I think headroom has a lot to do with being able to hear the difference as well. Keep class D amps away from the clipping threshold and you would have a harder time discerning the difference between the two. For example, first time I heard Todd's car, he was only running 2 of his 3 HD amps and the midrange did sound a little "edgy" as you described. Second time I heard it he had all 3 amps back in and the edgyness was gone. He played the same demo tracks the second time that he played the first time. I guess it is possible that it could have been how he had it tuned at the time, but I doubt it.
> 
> Sent from my SAMSUNG GALAXY NOTE using Tapatalk 2


thank you. i thought about this a little more on the way home from work. i don't think it's a headroom issue because i witness the edginess at moderate volume. i wonder if it is an inability to reproduce busy dynamic music. 
i picture it as if it were a high-def TV- the earlier ones. when the picture is static, the screen is razor sharp, and would probably measure a high resolution for published specifications. but when the scene has lots of motion and the images are constantly changing, the early hi-def TVs would get all garbled, blocky, harsh edges, as if the design of the circuitry could not keep up with rapidly changing images. this is kind of what i am hearing- when the music is simple, a beat and a cymbal for example, it sounds sweet and pure. mix up a complex arranngement and the sound can occasionally get edgy and gritty.


----------



## avanti1960

MarkZ said:


> I assure you that it is not. These are not boiler plate specifications. These are the three classes of differences between any two signals. There ain't no dark matter here.  We're not talking about mysteries of the universe. We're talking about the incredibly _simple_ and incredibly easy-to-measure differences between two electrical signals. Just because you didn't measure them in your testing doesn't mean they can't describe your observations.


OK, what about the comparison to early hi-def TVs, where a static scene measured razor sharp resolution and could have been specified as such, yet when the scene was dynamic the sharpness went out the window because the set couldn't refresh the resolution fast enough. 
i am guessing that the output of an HD amp when measured against a static sweep signal can publish very clean and distortion free. but when asked to play a backdrop of complicated dynamic music it could be challenged to keep the sound so clean. this is what i am hearing. i am not talking abut dynamic range, loud to soft, just complicated music, lots of diverse instruments and vocals playing all at once. could it be that the class AB can keep up better when challenged, despite the similartitie in the published specifications?


----------



## ceri23

avanti1960 said:


> thank you. i thought about this a little more on the way home from work. i don't think it's a headroom issue because i witness the edginess at moderate volume. i wonder if it is an inability to reproduce busy dynamic music.
> i picture it as if it were a high-def TV- the earlier ones. when the picture is static, the screen is razor sharp, and would probably measure a high resolution for published specifications. but when the scene has lots of motion and the images are constantly changing, the early hi-def TVs would get all garbled, blocky, harsh edges, as if the design of the circuitry could not keep up with rapidly changing images. this is kind of what i am hearing- when the music is simple, a beat and a cymbal for example, it sounds sweet and pure. mix up a complex arranngement and the sound can occasionally get edgy and gritty.


I don't have any input either way here, but I think what you're talking about is slew rate. If that's the case, it's not a spec I see very often in amplifier spec sheets. The class D Zed Audio amps list it, but there's not much to compare it to. 

EDIT: I did some more digging and by and large the consensus seems to be that it's trivially large for audio signals and class D tend to have a much higher slew rate due to the need for high frequency switching of the power supply. I'm not an expert, but I think what I've read blows up your idea about the edginess, unless it's a psychoacoustic thing where our ears like a low slew rate and the class D is TOO good to be pleasurable.


----------



## squeak9798

narvarr said:


> I guess it is possible that it could have been how he had it tuned at the time, *but I doubt it.*


This statement right here exemplifies the problem with these types of discussion.


----------



## narvarr

ceri23 said:


> I don't have any input either way here, but I think what you're talking about is slew rate. If that's the case, it's not a spec I see very often in amplifier spec sheets. The class D Zed Audio amps list it, but there's not much to compare it to.
> 
> EDIT: I did some more digging and by and large the consensus seems to be that it's trivially large for audio signals and class D tend to have a much higher slew rate due to the need for high frequency switching of the power supply. I'm not an expert, but I think what I've read blows up your idea about the edginess, unless it's a psychoacoustic thing where our ears like a low slew rate and the class D is TOO good to be pleasurable.


He didn't say the slew rate was the issue, he was just using the refresh rate of an HD TV set as an example.

Sent from my SAMSUNG GALAXY NOTE using Tapatalk 2


----------



## narvarr

squeak9798 said:


> This statement right here exemplifies the problem with these types of discussion.


How do you figure that? 

Sent from my SAMSUNG GALAXY NOTE using Tapatalk 2


----------



## quality_sound

I had that exact same thought.


----------



## quality_sound

narvarr said:


> How do you figure that?
> 
> Sent from my SAMSUNG GALAXY NOTE using Tapatalk 2


You discounted the obvious because of your bias.


----------



## narvarr

quality_sound said:


> You discounted the obvious because of your bias.


What bias might that be?

Sent from my SAMSUNG GALAXY NOTE using Tapatalk 2


----------



## ceri23

narvarr said:


> He didn't say the slew rate was the issue, he was just using the refresh rate of an HD TV set as an example.
> 
> Sent from my SAMSUNG GALAXY NOTE using Tapatalk 2


I took a shot at characterizing what he was talking about in more precise terms. I think it was a decent assumption. If there's some better clarification I'm open to it. He was talking about the amp output's rate of change and it's inability to keep up when it needed to change very quickly during a combination of instruments. I believe that's the definition of slew rate. Complicated music would just be a "busier" fourier transform, which is where slew rate is important. Maybe I misunderstood it.


----------



## narvarr

Don't get me wrong here fellas. At no point did I say that either was better than the other. All I did was throw out some things that could contribute to either side of the argument. 

Sent from my SAMSUNG GALAXY NOTE using Tapatalk 2


----------



## squeak9798

narvarr said:


> What bias might that be?
> 
> Sent from my SAMSUNG GALAXY NOTE using Tapatalk 2


_You_ provided atleast one potential reason for there to be a difference between the sound of the system completely unrelated to the amplifiers (different tuning), but "doubt" that to be the case and instead suspect the amplifiers with absolutely no real supporting evidence or reasoning other than that's what you feel should be the problem.

You don't see any logical inconsistencies in this thought process?

The problem is one of fact verse opinion. A problem is identified, and immediately blame placed on _one specific variable_ out of *many* potential variables based on _nothing_ more than an opinion or feeling that that one specific variable must obviously be to blame.


----------



## quality_sound

narvarr said:


> What bias might that be?
> 
> Sent from my SAMSUNG GALAXY NOTE using Tapatalk 2


That you were hearing a difference in the amps and not the tune. It being the difference in the tune is FAR more likely.


----------



## narvarr

quality_sound said:


> That you were hearing a difference in the amps and not the tune. It being the difference in the tune is FAR more likely.


There are two variables to consider in that situation. I mentioned both. If I was showing bias, I would have only mentioned one. The fact that I threw in " I doubt it" at the end is due to the fact that I know Todd and his tuning skill.

Sent from my SAMSUNG GALAXY NOTE using Tapatalk 2


----------



## MarkZ

avanti1960 said:


> OK, what about the comparison to early hi-def TVs, where a static scene measured razor sharp resolution and could have been specified as such, yet when the scene was dynamic the sharpness went out the window because the set couldn't refresh the resolution fast enough.


"Resolution" is another word for the upper limits of frequency response. Your concern about whether or not an amplifier can reproduce fast dynamic passages can be wholly captured by the amplifier's frequency response and distortion profile. Someone else mentioned slew rate, which is a single number that describes the fast/dynamic thing. Slew rate is a measure of resolution, and it is related to frequency response and distortion in the same way that a speaker's frequency response is related to cone breakup.  

Frequency response (amplitude and phase), distortion (THD and other forms, like IMD), and noise tell us literally everything there is to know about an amp's performance. Frequency response describes the linear transform between input and output in Fourier space. Distortion describes the nonlinear components and how they are correlated to the input signal. And noise tells us about uncorrelated elements of the output signal. Those are the three sources of transformations that are possible. Other numbers, like slew rate, are just simplified representations of one (or more) of those three sources.

Edit: the same is true for TVs, by the way. Except you have two more dimensions. [or one, depending on whether you consider the planar surface of a tv to be 1-D or 2-D, but that's another topic...] A tv has a spatial frequency response, a temporal frequency response, nonlinear components (distortion/ringing, etc), and noise.



> i am guessing that the output of an HD amp when measured against a static sweep signal can publish very clean and distortion free. but when asked to play a backdrop of complicated dynamic music it could be challenged to keep the sound so clean. this is what i am hearing. i am not talking abut dynamic range, loud to soft, just complicated music, lots of diverse instruments and vocals playing all at once. could it be that the class AB can keep up better when challenged, despite the similartitie in the published specifications?


Maybe. I will agree with you though that published specifications in audio are useless. You can't usually capture what there is to know with single numbers. You need plots that describe relationships when variables are changed. For example, there's a lot more to the frequency response of a speaker than "20Hz - 3kHz @ +/-3dB". That's what the spec sheet shows, but we all know that there are nuances to a speaker's frequency response that can help us predict what it might sound like.

That doesn't mean that frequency response can't describe a speaker's performance. It just means that the shorthand number the manufacturer provides in their sales brochure can't describe a speaker's performance.

Check out the data sheet for a typical op amp. Here's one. Scroll down to page 8 or so. Look at all the information they provide. _That's_ what amplifier manufacturers should give us. But they don't, because it would confuse the consumer. Engineers who are designing circuits need that information because they need to predict _exactly_ how that op amp will perform in their circuit before they start building prototypes.


----------



## Hanatsu

If the difference is not related to frequency response, distortion, noise or gain then what is it? There is no mystery parameter in the domain of magic that cannot be measured. 

The placebo effect is very real though, whether you're like it or not


----------



## tnbubba

anybody remember BOB CArver?
he proved all amps dDON NOT sound the same..

remember he took a single amp!!!! and change the sound simply by making some circuit changes.. wait the response was still ruler flat..the S/N didn't change.. the output devices were still the same.. there was no measurable difference int he amp before and after.. so.. now if any of you smart asses can dig that old test up and all the BS that went with it.. 

I'll throw my logic argument out later that no way even identical amps can sound the same.. no way no how.. but some of you super smart EE designers will already know that.

maybe hmm we should use dogs or bats or something that has better auditory skill than humans eh???


----------



## MarkZ

tnbubba said:


> anybody remember BOB CArver?
> he proved all amps dDON NOT sound the same..
> 
> remember he took a single amp!!!! and change the sound simply by making some circuit changes..


This is true...



> wait the response was still ruler flat..the S/N didn't change.. the output devices were still the same.. there was no measurable difference int he amp before and after..


...and this is not.


----------



## subwoofery

There you go: 
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CDIQFjAA&url=http%3A%2F%2Fcarvermk2.com%2FDocs%2FCarver%2520Stereophile%2520Challenge.pdf&ei=MUa2UMf8JdDliQLA5IFA&usg=AFQjCNHsg6VbZpZBzw1IU0GW4aE85ZYd4A&sig2=lLHtnUdootwIBnBn1pmSog 

So... What I wanted to say is that amps ... do not sound the same unless you open the cover and make them do <-- you can change your sig now Mark 

Kelvin


----------



## MarkZ

Haha I'll change mine when you change yours.

Thanks for the link. It talks about how he attempted to mimic the frequency response and distortion characteristics of the other amp. So obviously those parameters changed with his tweaking.


----------



## tnbubba

yes it was mark...
in some instances it wasn't not but in some instances the response was FLAT.. somewhere somebody has his unedited published article >>BEFORE the rag that did the interview published it.. and claimed all rights so he could not publish it.. I have a hard copy of the unedited version somewhere.. in a huge pile of papers paper..long before days of free internet and pdf files..

(Stereophile had first filed suit against Carver for reprinting the magazine's copyrighted material without authorization


----------



## MarkZ

tnbubba said:


> yes it was mark...
> in some instances it wasn't not but in some instances the response was FLAT.. somewhere somebody has his unedited published article >>BEFORE the rag that did the interview published it.. and claimed all rights so he could not publish it.. I have a hard copy of the unedited version somewhere.. in a huge pile of papers paper..long before days of free internet and pdf files..
> 
> (Stereophile had first filed suit against Carver for reprinting the magazine's copyrighted material without authorization


Wow, you have all kinds of secret documents to back up the several times people have called ******** on your claims, but you never seem to be able to produce them...

I'll be more than happy to look at these measurements if you can produce them. Until then, I think we can all feel reasonably confident that the difference in the amplifiers was indeed electrical, and not magic or some other yet-to-be-discovered physical force.


----------



## ceri23

That Bob Carver piece was somewhat impressive for what it was as a feet of engineering, but on a mass produced scale it would be of questionable morality (if not questionable legality). 

The short version for those that don't want to read the 8 pages is, he created a filter/mask to go over his cheaper amplifier to make it sound identical to a very high end amplifier. He did this with such dedication that he was tweaking the 6th order harmonics. He bridged 2 amps into a "macro-difference amplifier", which is like a blown up version of a regular op-amp so he could dial in an identical transfer function as the high end amp. It only amplifies what is different between the two amps. So by measuring it you can see the frequency response of the difference. Then you apply filters to zero out that response curve as much as possible, giving you essentially identical outputs from both amps. It's a clever application of basic amplifier theory on a large scale.


----------



## MarkZ

I thought it was David Hafler that came up with the idea, actually. Or Blumlein?


----------



## chad

What idea?


----------



## tnbubba

up urs mark.. they were published and available on the internet.. im not looking em up ..heck i moved 6 time in 10 yrs and been thru a divorce.. id ont hav eto prove anyting you look up the carver lawsuit..i think that's where i found it when i was following the lawsuit..


----------



## quality_sound

ceri23 said:


> That Bob Carver piece was somewhat impressive for what it was as *a feet of engineering*, but on a mass produced scale it would be of questionable morality (if not questionable legality).
> 
> The short version for those that don't want to read the 8 pages is, he created a filter/mask to go over his cheaper amplifier to make it sound identical to a very high end amplifier. He did this with such dedication that he was tweaking the 6th order harmonics. He bridged 2 amps into a "macro-difference amplifier", which is like a blown up version of a regular op-amp so he could dial in an identical transfer function as the high end amp. It only amplifies what is different between the two amps. So by measuring it you can see the frequency response of the difference. Then you apply filters to zero out that response curve as much as possible, giving you essentially identical outputs from both amps. It's a clever application of basic amplifier theory on a large scale.


A what?


----------



## tnbubba

quality.. you are correct from what i remember.. the freq resp was not touched.. but the filter poles effecting supposed inaudible harmonics.. i just remember back at tech a tube and SS amp were bandwidth limited and the freq responses in the band with were dead flat as far as could be measured with the HP analyzer we had back in the 80's i mean like 0.1 db.. and oh hell the sound diff was obvious and yes the speaker played was full rang with no passive components..so no issues with impedance freq response with the tube amp.
shortly after that carver came out with the m400 I think.. the big amp after the cube!

I had one.. didnt sound too bad and gobs of power.
not much on audio history as far as dates go.. 

point is.. I've been seeing this debate go on for 30+ yrs.. nothing has changed!


----------



## MarkZ

tnbubba said:


> quality.. you are correct from what i remember.. the freq resp was not touched.. but the filter poles effecting supposed inaudible harmonics.. i just remember back at tech a tube and SS amp were bandwidth limited and the freq responses in the band with were dead flat as far as could be measured with the HP analyzer we had back in the 80's i mean like 0.1 db.. and oh hell the sound diff was obvious and yes the speaker played was full rang with no passive components..so no issues with impedance freq response with the tube amp.
> shortly after that carver came out with the m400 I think.. the big amp after the cube!
> 
> I had one.. didnt sound too bad and gobs of power.
> not much on audio history as far as dates go..
> 
> point is.. I've been seeing this debate go on for 30+ yrs.. nothing has changed!



Then what the hell is your point in replying to me? I said there were three ways a signal could differ: FR, distortion, noise.

If he didn't change FR, then he changed one (or both) of the other two. You even said so above ("the filter poles effecting [sic] inaudible harmonics"). But two posts ago you said there were no measurable differences in the signals. So which is it? Differences in the harmonic content, or no differences? You can't have it both ways.

I think you just didn't understand my post and wanted to argue with it for the sake of arguing. Because now that you acknowledge that he did make changes, you're not saying anything I didn't already say.


----------



## DirectionsAndConnections

So who in the forum is rockin' a tape deck?


----------



## sqshoestring

I liked my tapes for the car. Metal tapes off a home Nak deck w/dolby C were pretty clean, fine for a car really. They were cheap and way easier to handle than a disk. I'd say I like SS storage better yet but just don't have time to compile all my Cds on it, or want to buy it all again lol. I made lots of tapes but had time to do it then.

I have to say my alpine sub amp does sound better than the kenwood I had in there (and had the alpine in there before it too). Not that much difference, but the alpine digs deeper and has near the same power even though its 500w and the kenwood 900w. Then again I did not really explore max power that much, other than to note there was not much difference. But I bet the alpine cost more new as well.

My class D kappa on highs seems to work fine, I can't hear any issues with it far as SQ.

Some amps do soft clip like tube amps or something similar, I am sure of it. They do sound smoother. I don't think it is an issue of topology, its the way the designer wanted it be it class D or AB. Today class D can play high frequency no problem, the only reason it might sound different is because it was built to sound that way. You would have to look at old or cheap class D amps to find an issue with it reproducing sound, just like with any cheap amp. They can clip more ugly, but how do you count clipping.


----------



## 9050lx

I remember the Stereophile Carver debate.Great publicity for Bob.The only Carver component I ever had (receiver) I soon traded away.


----------



## KSpan

PDX-V9 installed today, and after an our or two of listening to the tuning music I've been using for upwards of 10 years I'm quite happy. Still a lot of tuning to be done and I haven't deadened anything yet, but might be the sweetest-sounding system I've run.


----------



## avanti1960

subwoofery said:


> Mosconi makes great and solid products but it's just a forum boner right now.
> As soon as a new "breed" of amp comes out, you'll see a lot of Mosconi amps for sale - there's already quite a few for sale every now and then...
> 
> Try a search on which brand doesn't get sold very often on this forum <-- those brands are either very expensive and therefore not many people have it (Brax, Phass) or ... they are just too great that not many sell them after acquiring them (Sinfoni, Genesis) unless the amp doesn't fit their install
> 
> Having heard both the Arc Audio SE line and the Mosconi AS line, I'll always recommend the Arc Audio SE over the Mosconi AS - sounds more transparent and as dynamic (without the bump in bass region - below 100Hz) as the Mosconi...
> 
> My opinion,
> Kelvin


thanks for voicing your opinion. my local store just started offering audison amps and i have my eye on the voce av quatro- it fits and has the power i'm looking for. 
can you mention where this amp might fall among those mentioned above? also helix? 
the sinfoni, phass and genesis are too difficult to obtain- the brax is too expensive.


----------



## subwoofery

avanti1960 said:


> thanks for voicing your opinion. my local store just started offering audison amps and i have my eye on the voce av quatro- it fits and has the power i'm looking for.
> can you mention where this amp might fall among those mentioned above? also helix?
> the sinfoni, phass and genesis are too difficult to obtain- the brax is too expensive.


Best
Brax, Phass RE, 

Better
Sinfoni, Helix Competition and Precision, Genesis 3, Arc SE, Audison Thesis Due & Quattro, Mosconi Zero, Audio System HX

Good 
Audison AV, Mosconi AS, Audio System X, Focal FPS 

Kelvin


----------



## avanti1960

high end class A-B amplifiers are becomming more popular-

Crutchfield now carries Helix AND Brax! 
My local home boys (ABT Electronics) added Audison and Hertz this year to the Focal they already carried.


----------



## Yuck.

avanti1960 said:


> high end class A-B amplifiers are becomming more popular-
> 
> Crutchfield now carries Helix AND Brax!
> My local home boys (ABT Electronics) added Audison and Hertz this year to the Focal they already carried.


I think Helix/Brax was brought out by Rockford a few months back...


----------



## Catman

I realize that it is not exactly the question asked here ...but I recently bought a Class T Dayton from Parts Express. I'm VERY disappointed. I'd just as soon listen to an '80s 'boom box'. It is supposed to be 50wpc ....I'd bet it isn't 15-20wpc and the SQ is horrible. I was afraid the Class T amps were a joke ...and I was right.


>^..^<


----------



## MarkZ

Wow, a lot of people have had great luck with those, for _years_. What do you have it running?


----------



## CENTRAL

I have been living with a class D power amp in my living room since 2007. It’s a TacT (it became Lyngdorf later) SDA 2175.

This amp lies in between a Pass X2 and a pair of Spendor S8e speakers.

It outperformed every other amplifier design that I ever heard in my rig. Including valve amps.

6 years later and I still love what he does for my system. It’s a very natural amp, with lots of watts to deliver and great musicality. 

I never bother telling anyone it’ s “digital” and all I get is positive comments on my system’s sound quality…

I always thought that class D looks good for a car stereo and I just got the chance to order a JL XD700/5. 

I really hope I will be as impressed with it as I were when I left the A/B camp in home audio…


----------



## Catman

MarkZ said:


> Wow, a lot of people have had great luck with those, for _years_. What do you have it running?


I think there are A LOT of lemmings in the audio world that have never had a good reference as to what a system 'should' (or could) sound like. WAY too many people jump on the current popular 'bandwagon' ...and settle for (and defend) 'good enough'.

I've tried it on 4 different speakers. Advent Mini, Insignia coax 6.5" bookshelf (the ones everyone raved about), Old school Advent Heritage and Thiel 2.4. In all cases I have compared them against an old school Nakamichi STASIS receiver. The Class T honestly sounds like a 'boom box' ...thin and no 'balls'.

>^..^<


----------



## briansz

If it uses an external power supply, it sounds as if you need to upgrade it. In my experience, the quality/capacity of the power supply makes a huge difference in the performance of small class T amps.


----------



## MarkZ

What he said ^^^ . Those are notorious for needing power supply upgrades if you're going to use it on anything that requires even a little bit of power. I had one of the Sonic ones running a low power application (home theater bar), before I switched over to a class A chip amp (just because it was more modular). No problems that I remember. I just don't think that little amp suits what you're trying to do.


----------



## Catman

I really didn't buy this to be a 'project'. It already has a 'brick' that is bigger / heavier than the amp. This is not a small 'wall wart'. 

http://www.parts-express.com/pe/showdetl.cfm?partnumber=300-383

I had always suspected these were greatly over rated ...now I'm sure. I can play it at FULL VOLUME in a hotel room and never have a complaint. We carry a sound system when we travel because my wife has sleeping issues and we have found some CDs that help induce Delta Waves. When we drive I have been carrying a 'real' (Nak) receiver and the aforementioned Insignia speakers or sometimes JBL L20T or L40T. My intention was to get something that would have decent SQ / volume so that we could stop carrying a full sized receiver. We had been using a 2.1 Altec computer system (it was louder than the Class T). I thought about getting one of the cheaper 15-25wpc amps ...but since these are so over rated I'm glad I didn't.


>^..^<


----------



## Mic10is

Yuck. said:


> I think Helix/Brax was brought out by Rockford a few months back...


Rockford is the US distributor for Brax/Helix. They did not buy or own them


----------



## t3sn4f2

Inefficient amp classes are fo pussies.


----------



## squeak9798

Catman said:


> I realize that it is not exactly the question asked here ...but I recently bought a Class T Dayton from Parts Express. I'm VERY disappointed. I'd just as soon listen to an '80s 'boom box'. It is supposed to be 50wpc ....I'd bet it isn't 15-20wpc and the SQ is horrible. I was afraid the Class T amps were a joke ...and I was right.
> 
> 
> >^..^<


It's 50wpc @ <*5*% THD.


----------



## briansz

I'm running an 11 amp 24 volt medical grade SMPS with an external input line filter on two channels of the Sure Electronics '4x100' amp board. With acceptable THD, that's a 264 watt PSU for a ~ 30 watt x2 into 8 ohms amp.......

Driven by the variable output of a Sony 707ESD CD player and pushing a set of JBL L20T bookshelf monitors, it gets plenty loud. Velodyne ULD-15 fills in the low end.

Wall wart/brick isn't going to do it, imho.


----------



## Catman

squeak9798 said:


> It's 50wpc @ <*5*% THD.



This thing isn't putting out 50wpc @ 100% THD. :laugh: Too many people get hung up on that one spec. THD doesn't account for the thin sound and lack of balls ...and overall lack of output. 


>^..^<


----------



## quality_sound

No, but if the distortion prevents you from turning the volume up enough to come close to 50WPC it's going to sound exactly like you've experienced.


----------



## Catman

quality_sound said:


> No, but if the distortion prevents you from turning the volume up enough to come close to 50WPC it's going to sound exactly like you've experienced.


But ...if these were 'real' watts instead of imaginary / ClassT watts it would be too loud to play in a hotel room at full volume (regardless of SQ).


>^..^<


----------



## Catman

briansz said:


> I'm running an 11 amp 24 volt medical grade SMPS with an external input line filter on two channels of the Sure Electronics '4x100' amp board. With acceptable THD, that's a 264 watt PSU for a ~ 30 watt x2 into 8 ohms amp.......
> 
> Driven by the variable output of a Sony 707ESD CD player and pushing a set of JBL L20T bookshelf monitors, it gets plenty loud. Velodyne ULD-15 fills in the low end.
> 
> Wall wart/brick isn't going to do it, imho.



I'll be the first to admit that I'm no expert on the 'electronics' part of the equation ....but it is running a 24v 5A brick. IMHO that should be enough to at least be 'loud'.


>^..^<


----------



## quality_sound

Catman said:


> But ...if these were 'real' watts instead of imaginary / ClassT watts it would be too loud to play in a hotel room at full volume (regardless of SQ).
> 
> 
> >^..^<


The point is it probably ISN'T 50WPC.


----------



## 9050lx

It's surprising at how loud even 10 watts can be.I have a home-brewed set of push/pull tube amps , 2A-3's , 15 watts per channel, They get loud enough for most all listening in the living room.This admittedly paired with relatively efficient Klipsch Cornwall clones.These produce good bass and have a surprising amount of headroom.


----------



## Ampman

9050lx said:


> It's surprising at how loud even 10 watts can be.I have a home-brewed set of push/pull tube amps , 2A-3's , 15 watts per channel, They get loud enough for most all listening in the living room.This admittedly paired with relatively efficient Klipsch Cornwall clones.These produce good bass and have a surprising amount of headroom.


I've heard it said that for every 20 watts of tube output it equals 100 watts of solid state output an I believe it I've got an old fender deluxe reverb II guitar amp that's all tube that sucker is some kinda loud


----------



## MarkZ

guitar amps are different. Bandwidth limited, high efficiency speakers (usually), very high distortion (ie. more energy). The old fender deluxe amps especially, and even more if you put 6L6s in it.


----------



## Ampman

MarkZ said:


> guitar amps are different. Bandwidth limited, high efficiency speakers (usually), very high distortion (ie. more energy). The old fender deluxe amps especially, and even more if you put 6L6s in it.


I sure didnt know that I thought that was for all tube outputs thanks I learned something new ?


----------



## Randyman...

Yep - With a guitar amp - you WANT some distortion and crap to make your tone jive. Pushing those tubes past their "Clean" rating nets you more power - thus why a 20Watt Tube Amp pushed to its butter range (with a heaping helping of pleasant distortion) will sound as loud as a 100Watt Solid State amp kept within it's clean un-distorted range... 

Tube amps (class-A for the most part) have desirable OVERDRIVE characteristics (tube distortion and tasty transformer saturation) - so they sound good for guitar when you push them hard into clipping. They purposely _change_ the sound for the better in this case. You also get some designed "sag" (natural dynamic compression of the circuit at higher amplitudes) from them which most players love (this is extremely non-linear - so no good for accurate audio reproduction). They are used as an extension of the player and their instrument - a COMPLETELY different application than accurate sound reproduction.

Modern Solid State musical instrument amps (Guitar/Bass/Keys/etc) generally have circuits to mimic the way tubes gracefully morph into clipping - as solid state clipping on its own generally sounds like ass (with a few major exceptions - Neve 1272 Line Amps, for example - Class A Solid State Transformer coupled line driver that sounds pretty good when driven hard).

I've never had an itch to use Tubes in a reproduction system - only in the "front-end" for flavor and such when tracking and mixing. Of course, tubes can be clean - but why bother? Use them where they shine - in their non-linear range for fun and excitement  I'd even argue lots of what makes good Tube gear desirable in the Pro-Audio world (for "flavor") is their transformers IMO. You can get similar "smoothing effects" with good transformers on Solid State gear (must have 40 + tasty transformers in my tracking rig - most contained in Solid State gear!)...


----------



## chad

In hi-fi reproduction that "tube sound" when the circuit is being run linear is... the..... transformer.


----------



## Randyman...

chad said:


> In hi-fi reproduction that "tube sound" when the circuit is being run linear is... the..... transformer.


So put the Transformer in an appropriate maintenance-free SS circuit and be done with it


----------



## chad

Randyman... said:


> So put the Transformer in an appropriate maintenance-free SS circuit and be done with it


Mac does it. Or did it. 

Sent from my Sony Tablet S using Tapatalk 2


----------



## Ampman

Guess everyone has their pick my old fender bought it new in 83 and as for myself it has a better sound than solid state. Even the reverb effect has a better sound than dose transistor drivers. I bought a fender twin amp back in 2000 and its got some solid state in the preamp section an I think my old deluxe sounds better than it dose even the presences setting is more crisp than the twin amp ? my twin has way more output than the little deluxe however as far as the warm sound the deluxe puts out in my opinion is different between night and day


----------



## 9050lx

I also have a stereo '6550' 60w/channel tube amp U/L with Dynaco mk3 outputs because at the time I couldn't find a pair of Citation II outputs. Very ballsy and clean, not that much tube-like.580 plate volts, SS rectifier.An old associate named Henry Kuck designed it, I managed to not mess it up too bad by building it. Sounded better to my ears than my old Conrad Johnson MV75a.


----------



## chad

I base my hifi builds around the dynaco ultralinear transformers.

Have a stash


----------



## ecrimjr

I recently read an article written by Paul McGowan of PS audio fame on the subject of class D amps. Essentially, he likes the potential of class D amps for high quality audio but argued that the input (preamp) phase of these amplifier designes was the most critical element of the design and if not gotten right the amp would not sound very good. He also said in another post the following quote:
"Class D amplifiers are closely related to DSD. DSD uses PDM and Class D amplifiers use PWM but share something in common: their direct coded output is analog-like enough that you can play them directly into a speaker or preamplifier and get music." This is not true in a PCM based digital audio approach."
So it seems that their are differences and design choices that engineers have at both the input and output execution of the designs that do effect the sound quality of the amp and the class ab versus class d dichotomy is likely a gross over simplification of the difference. One problem effecting the car audio community is likely market factors, what people are willing to pay for high quality sound in the car versus the home market and the dilemma or designing something high quality at a point where it will sell. 
I'm in the middle of putting together a system right now and I need to decide if I am going to go with an older class AB design (Soundstream reference 405) or a newer JL audio HD amp which I have heard good things about but I have not heard myself. What I think I am going to do is buy the JL audio but hold on to the sound stream until I know for sure that I like the JL audio amp.


----------



## avanti1960

chad said:


> In hi-fi reproduction that "tube sound" when the circuit is being run linear is... the..... transformer.


and tube amps have a frequency response of 20 to 20Khz +/-???


----------



## chad

avanti1960 said:


> and tube amps have a frequency response of 20 to 20Khz +/-???


Depends on the transformer.

many of them have a flatter output than your CD player, especially up high. It's why they have NFB.

Tubes have no quams at running well into RF land. Most transmitters are still tube.


----------



## avanti1960

chad said:


> Depends on the transformer.
> 
> many of them have a flatter output than your CD player, especially up high. It's why they have NFB.
> 
> Tubes have no quams at running well into RF land. Most transmitters are still tube.


it was (in part) a way of asking if the warm sound of tube amps could be measured or if anything in their specs would red flag the fact that they would have that traditional tube amp sound.


----------



## chad

One that is built correctly should sound like any other amp (flame shield up) till you run it to the edge then she gets nice... Also there may be some power supply sag if there is a tube rectifier involved.


----------



## BuickGN

chad said:


> Depends on the transformer.
> 
> many of them have a flatter output than your CD player, especially up high. It's why they have NFB.
> 
> Tubes have no quams at running well into RF land. Most transmitters are still tube.


Way off topic but a ton of years ago back in another life when I used to put up cell sites and a couple broadcast stations I remember a really cool really old building up in the mountains with an old man living in there. From what I remember it was a 1 megawatt broadcast station and there were some really cool tubes in all of the equipment. These things were huge, maybe 2-3' tall, large diameter and they lit up, along with some smaller but still large tubes. Could that have been vacuum tubes or something similar? This old German engineer had been in this facility for 50 years and gave me an extremely detailed history and description of the equipment but unfortunately my memory isn't that good. I do remember him saying when one of them went out it knocked out all sorts of equipment in the area. Sorry for the off topic but this thread has been around for a while.


----------

