# Amplifier brands (Isn't a watt a watt?)



## agentk98 (Oct 31, 2006)

I'm looking for an amp that pushes [email protected] (L18andNeo). Checking the amps, I see some that the same specs sell from $300-$800 and above. I know that they have their differences... but to those like me with a very much inferior hearing than _npdang_, would i notice the difference? 
I was looking at these brands by the way: Autotek, Orion, PPi as opposed to Arc, Focal, DLS, AudioTwister, Genesis.


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## legend94 (Mar 15, 2006)

"(Isn't a watt a watt?)" wheres that dead horse link? 

how much do you have to spend on amps?


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## chad (Jun 30, 2005)

Where's that little animation of the guy eating popocorn when you need it?

I'll hang for a bit and give my side of the fence... Then I may be banned.......

Chad


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## agentk98 (Oct 31, 2006)

*legend94* Certainly not in your McIntosh range.  Maybe $200-$400.

_Where's that little animation of the guy eating popocorn when you need it?
I'll hang for a bit and give my side of the fence... Then I may be banned.......
Chad_

Sorry i don't get it. I'm guessing I had a wrong take on the phrase? 

p.s.


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## FoxPro5 (Feb 14, 2006)

I got my tickets early!


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## zfactor (Oct 19, 2005)

lol .. i dont totally believe that a watt is a watt... i know to my ears i have heard differences in amps.. some dont believe me on the boards but a lot of others agree... and if a watt was really a watt that would mean you could take 10 watts of pyramid power against 10 watts of arc se power and it would sound exactly the same?? i think not... again this is just mo though...

okay hold on..... alright im now waiting for the bashing to begin... lol


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## zfactor (Oct 19, 2005)

btw i am really liking the pdx 4.150 now.. and now they are getting much cheaper on ebay i looked the other day and saw them for like 380 or so now... great sound and super tiny


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## minitruck_freq (Mar 27, 2005)

a watt is a watt, and all amps sound the same.


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## JasonH (Oct 27, 2005)

I don't notice any difference between my Next 4.400 and my 10 year old Alpine V12.


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## dbphelps (Jun 30, 2006)

I believe the key here is that a watt is a watt, only if you know for certain what the "real" output power is...

In other words, any decently built amp (key here is proper design and manufacture) that puts out 100 watts "real" RMS would sound the same as any other amp that is decently built that puts out 100 watts "real" RMS...

The sound differences some 'claim' to hear can be attributed to a ton of things, such as built-in crossover characteristics, input stage design, improper vs proper design and build, etc...

The 'real-world' aspect of things comes down to choosing an amp that is built by a reputable manufacturer (only to help ensure proper design/build quality) that produces the power you want with the features you want, at the price you want.

Some of us are 'sold' on a given manufacturer/amp-line for a number of reasons, including consistency of product, known options and characteristics, asthetics and given output relative to thier ratings...

One perfect example (and my amp of choice) is the ESX Quantums... Great build quality, bullet-proof design, features to match no others (balanced/unbalanced inputs, configurable for any ohm load and speaker config, strappable, etc), and output well above rated power... Asthetically they are tanks, but perform like one as well... Thus these amps tend to hold thier value even though they haven't been manufactured in over 8 years... Same goes for older Hifonics, older Rockford Fosgate stuff, etc, etc...

As far as newer amps go, with the advent of mega-corps who have been gobbling up known name-brands and cookie-cuttering thier lineups, things have gotten much more precarious in selecting a 'decent' product... Then you have the esoteric uber-expensive stuff that I am sure only hard-core 'audiophiles' (or should I say lemmings with too much cash in thier pockets) 'blow' thier money on (not naming any amps here, as I don't want to start a pissing match, but when a 100x4 amp costs $1400-1500 there is something REALLY wrong there, and maybe some will pay for the asthetics, but unless it is underrated by 300% I can't see the justification of cost)...

One more thing is that most Class D sub amps are actually pretty close in design and output, outside of certain manufacturers who came up with unique designs to enhance damping factors (such as the Zed Audio Minilith), thus most of those come down to matching power requirements with cost and taking asthetics into consideration as a final decision factor (such as if you want it to match your component amp as well or not)...


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## Diru (May 23, 2006)

zfactor said:


> lol .. i dont totally believe that a watt is a watt... i know to my ears i have heard differences in amps.. some dont believe me on the boards but a lot of others agree... and if a watt was really a watt that would mean you could take 10 watts of pyramid power against 10 watts of arc se power and it would sound exactly the same?? i think not... again this is just mo though...
> 
> okay hold on..... alright im now waiting for the bashing to begin... lol



I'm with Z on this one.


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## zfactor (Oct 19, 2005)

"The sound differences some 'claim' to hear can be attributed to a ton of things, such as built-in crossover characteristics, input stage design, improper vs proper design and build, etc..."

now this i feel is true...now if you are comparing a 1 watt amp to the same 1 watt amp of the same class, design, input stage, x-over specs (12db 18db etc.. and type..), fet type (sanken, etc) and if they are exactly the same then i agree a watt is a watt... but even as you stated the above things DO make differences in the end output of an amp and effect the overall sound character. while i agree i would not spend 3,000$ on a 100x4 amp (i dont see that justification nor do i feel there would be that much sonic advantages over a 1000$ amp) i do feal though that there is a good difference between the 150$ amps and the 500$ amps out there. and what i stated on the first page about the 10 watt pyramid and 10 watt arc se.. was assuming THEY ARE outputting a real 10 watts. i dont feel anyone couldnt hear a difference between those.. but again imo here


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## sqkev (Mar 7, 2005)

Anybody who claim that all amps sound the same obviously never heard alot of amps. There, I said it.


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## FoxPro5 (Feb 14, 2006)

sqkev said:


> Anybody who claim that all amps are sound the same obviously never heard alot of amps. There, I said it.


How dare you!  I second that notion.

The best amp I ever heard was one that had the most power, was the right size, had the most amount of features and did what my HU told it to do all day, everyday. Oh and the sound always seems to improve the prettier the amp is too.


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## alphakenny1 (Dec 21, 2005)

yea we need all of those ca.com smilies. i love the woot guy and the guy popping popcorn, lol.


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## MiniVanMan (Jun 28, 2005)

Ask yourself this as well. How much does it really matter driving down the freeway at 70-80mph with the wind rushing past the car, the semi next to you and all the other road noise? For that, I'll take the $300.00 amp. 

For a home audio setup, it's much easier to justify the cost of a high quality amp.


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## Thoraudio (Aug 9, 2005)

do a search on www.carsound.com and www.elitecaraudio.com

this topic has been beaten to death a dozen times.... and rarely is anybody converted from one side to the other. 

IF you could hear a difference, IMNSHO, the question of amp choice between amps of similar real power, rates just above wires in level of importance. 

Speaker choice, speaker placement, vehicle treatments, eq, ta are all more important to overall SQ by several orders of magnitude.


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## Thoraudio (Aug 9, 2005)

sqkev said:


> Anybody who claim that all amps sound the same obviously never heard alot of amps. There, I said it.


I've heard alot of amps.

There.... said it.


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## cam2Xrunner (Apr 30, 2005)

agentk98 said:


> I'm looking for an amp that pushes [email protected] (L18andNeo). Checking the amps, I see some that the same specs sell from $300-$800 and above. I know that they have their differences... but to those like me with a very much inferior hearing than _npdang_, would i notice the difference?
> I was looking at these brands by the way: Autotek, Orion, PPi as opposed to Arc, Focal, DLS, AudioTwister, Genesis.



Bridge the A404 you have for the midbass then get an A300.2 or something for the tweeters.


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## jay (Sep 12, 2005)

Thoraudio said:


> Speaker choice, speaker placement, vehicle treatments, eq, ta are all more important to overall SQ by several orders of magnitude.


x2


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## sqkev (Mar 7, 2005)

Thoraudio said:


> I've heard alot of amps.
> 
> There.... said it.


Assuming you don't hear a difference between amps.
Build a small aleph and tell me how it performs vs. your favorite amp with the same power. The smallest aleph, I believe, makes anywhere from 7-15watts.


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## agentk98 (Oct 31, 2006)

zfactor said:


> btw i am really liking the pdx 4.150 now.. and now they are getting much cheaper on ebay i looked the other day and saw them for like 380 or so now... great sound and super tiny





cam2Xrunner said:


> Bridge the A404 you have for the midbass then get an A300.2 or something for the tweeters.


Thanks for the tips!


dbphelps said:


> In other words, any decently built amp (key here is proper design and manufacture) that puts out 100 watts "real" RMS would sound the same as any other amp that is decently built that puts out 100 watts "real" RMS...


That's what i thought the phrase meant. I myself don't believe pyramid amps are comparable to arc audio (real output, thd, build quality, features) but among those brands that are not far off from each other..._(...I was looking at these brands by the way: Autotek, Orion, PPi as opposed to Arc, Focal, DLS, AudioTwister, Genesis...)_ can i justify getting a $500 watt amp over a $250? I don't have the same budget you guys have.


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## cam2Xrunner (Apr 30, 2005)

You should check out the DLS Reference series amps. Cheaper and some say, just as nice as the A series. 


I think it's worth it to buy the better amps due to reliability, build quality and resale value/ease of resaling.


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## nauc (Sep 12, 2006)

if you havent, read this http://www.davidnavone.com/a2000/Amp challenge 2001 Revision.pdf


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## tard (Jul 13, 2006)

poo poo.


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## T3mpest (Dec 25, 2005)

A watt is a watt, but amps do more than just put out watts, that's just how it is. Tube amps have even order distortion, so yes they do sound different, sure you could probably create a similar sound out of a SS amp, but it'd take a bit of tweaking and many people enjoy the authenticity. Then you have to take into account that many cheaper amps won't even put out the power they say they will. A watts a watt until one amp starts clipping... 

Even richard clark himself will tell you that unless you level match the amps and take away certain nasty features (crappy built in EQ's, click on noises, etc) you can tell the difference.


Regardless, with an amp from the likes of arc or tru, you at least know you have a very solid amp made with high quality standards, from a company that 
stands behind their products, and that' worth quite a bit over the likes of a pyle or pyramid. Buy what you feel you can afford. As with anything as price goes up you do get a lowered price/performance ratio, somewhere you have to make the decision where enough is enough, and that's personal.

To sum it all up 
A watt is a watt is true
All amps sound the same is false
therefore 

A watt is a watt does not mean all amps sound the same!


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## cvjoint (Mar 10, 2006)

I've tested amps that cost more and are rated for more power against my polks and I kept them because there was a noticeable difference in output characteristics, mainly the polks sounded warmer and much more detailed. I would venture to say there is something very important in the way amps are designed and that leads to different output characteristics aside from power variations. In my book amps. deff. don't sound the same.


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## tard (Jul 13, 2006)

high five to those who let their ears tell them what they hear. and who have the cojones to stand up about it.


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## squeak9798 (Apr 20, 2005)

http://forum.elitecaraudio.com/showthread.php?threadid=123226

Covered in detail.



Anyways......a good quality amplifier that appears to be in your budget range is the JBL Gto 75.4II on sounddomain;

http://www.cardomain.com/item/JBLGTO754II

And the Eclipse EA4000 on SD aswell;

http://www.cardomain.com/item/ECLEA4000


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## npdang (Jul 29, 2005)

Semantics. A watt is a unit of measurement. Much like an inch. So it would depend if you consider an inch of grass to be the same as an inch of concrete.

Amps do not all sound the same. However, Imho there are concrete reasons for why they don't, none of which justifies the difference in price between many amplifiers.


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## PlanetGranite (Apr 12, 2005)

All amps that measure the same will sound the same.


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## T3mpest (Dec 25, 2005)

PlanetGranite said:


> All amps that measure the same will sound the same.


bingo!


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## MarkZ (Dec 5, 2005)

sqkev said:


> Anybody who claim that all amps sound the same obviously never heard alot of amps. There, I said it.


I've heard a lot of amps. They don't all sound the same. But I can get them to all sound the same. Here's how: don't overdrive them and don't use any of their built-in signal processing.


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## MarkZ (Dec 5, 2005)

tard said:


> high five to those who let their ears tell them what they hear. and who have the cojones to stand up about it.


High five to those who perform the tests correctly to be able to identify exactly where the differences truly lie.


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## sqkev (Mar 7, 2005)

MarkZ said:


> I've heard a lot of amps. They don't all sound the same. But I can get them to all sound the same. Here's how: don't overdrive them and don't use any of their built-in signal processing.


and this applies to class A and tubes as well?


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## Fozz (Dec 16, 2005)

I've done my own A/B testing with amps. I used two older Blade amps (one of their tube amp and one solid state) and one of my Memphesis amps. There were no, eq settings, crossovers or any other adjustments made to the amps. They were all fed from the same none cliped signal and listened to at the same level.

The VHT (blade tube) sounded better the all the others. Not by much, but by enough that my wife could hear the difference! There was very little difference in the tonality of the amps. Though I found the Memphis to sound a little "harsher" in the upper frequencies. The big difference was in the staging of the amps. Both the Blades had higher, wider and deeper stages. They also seemed to give off a more realistic performance (not sure how else to descrebe it).

My test wasnt perfect, but it's good enough for me. I had a friend help, so we wouldnt know what amp was being used. 

So, I think a watt is a watt, but each amp inst the same.


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## tard (Jul 13, 2006)

if anyone is going to ces in jan, maybe they should stop by the tru tech booth and talk to john fairchild or jonh yi. ask them about how they hand tweek the sound of their amps with differen pieces. and i don't mean eq effect. mr fairchild is very passionate about his work, knowledge and experience. he will share what ever designing, building, etc, info with you that you ask.

there's a lot of brilliant engineers, but i can't think of one in the car audio industry with as much experience as mr. fairchild. try and tell them that different components in an amp won't make it sound different and that 20watts from their amp doesn't sound any different than 20w from a legacy.

the statement of if amps measure the same, they will sound the same, can be acceptable. as long as you are measuring every aspect, not just 1.


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## Rbsarve (Aug 26, 2005)

I have done blind AB-listening tests of several amps under controlled circumstances.

My findings:
Differencs between amps definitly exists.
More expensive is usually better.
Amplifier bias (voiceing) is usually of larger difference then detail rendition.
Differencies are usually not that big.

My conclusion:
By the speakers that sounds best to your ears without looking to budget. By the best amp you can get for whatever's left...


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## 3.5max6spd (Jun 29, 2005)

tard said:


> if anyone is going to ces in jan, maybe they should stop by the tru tech booth and talk to john fairchild or jonh yi. ask them about how they hand tweek the sound of their amps with differen pieces. and i don't mean eq effect. mr fairchild is very passionate about his work, knowledge and experience. he will share what ever designing, building, etc, info with you that you ask.


Newsflash. John Fairchild has passed away.... for some time now.

What is a nice feature in the new Tru Billet amps is how you can bypass altogether the preamps. Many amps dont do this, even if you are not using it.


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## tard (Jul 13, 2006)

wow, that sucks. didn't read or hear about his passing. i knew he was an old timer, but he was kicking strong 10 months ago. i guess DD alice was an unexpected shock also though.


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## MarkZ (Dec 5, 2005)

sqkev said:


> and this applies to class A and tubes as well?


Some, but not all. I have to admit that I engaged in a little hyperbole in my post, but so did you.  

Most class B amps are pretty much as "clean" as their class A counterparts. In usage, class B is cleaner, because class A amps tend to be very low in power output, usually only suitable to drive tweeters or to drive mids with high sensitivity or low desired output levels. Anything beyond that and you're clipping, which ruins all of the supposed benefits of class A.

Technology has progressed. Class B is here, and it's designed to be high output and low distortion in a variety of different pricepoints. Soon, class G and switching amplifiers will be able to say the same.


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## Thoraudio (Aug 9, 2005)

MarkZ said:


> Some, but not all. I have to admit that I engaged in a little hyperbole in my post, but so did you.
> 
> Most class B amps are pretty much as "clean" as their class A counterparts. In usage, class B is cleaner, because class A amps tend to be very low in power output, usually only suitable to drive tweeters or to drive mids with high sensitivity or low desired output levels. Anything beyond that and you're clipping, which ruins all of the supposed benefits of class A.
> 
> Technology has progressed. Class B is here, and it's designed to be high output and low distortion in a variety of different pricepoints. Soon, class G and switching amplifiers will be able to say the same.


I'm assuming that you mean A/B... what with all that xover distortion shenanigans and goings on.


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## MarkZ (Dec 5, 2005)

B, A/B...in audio, it's pretty much the same thing.

Most of the time, what we (and manufacturers!) usually refer to as A/B is actually B. It depends on which definition you use. If you use the definition that the output devices are operating at 50% duty, then most "A/B" amps are really B. People just assume that because there's a bias stage involved then it must be A/B, but in fact the bias stage is just getting you back to zero. This is all described in Self's books, and you'll usually see it called correctly in the old amplifier papers and such.

PS - crossover distortion is present in both B and A/B designs. A/B is theoretically supposed to eliminate it, but you still have asymmetries and the like which could be classified as crossover distortion.


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## agentk98 (Oct 31, 2006)

Now I know what the *"Popcorn Guy"* was for.


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## cvjoint (Mar 10, 2006)

I simply don't believe any of these arguments claiming all amps sound the same given there is no on-board processing done. 

1. most folks on this forum use headunit xovers
2. big bonner for arc and dls amps and these aren't cheap by any standards
3. the availability of really cheap amps, most of the times you can buy like 4 for the price of a top shelf DLS amp
4. people still prefer the expensive amp vs. the 4 cheaper ones

The way I see it, you would all buy Legacy and Pyramid amps in bulk or bridge quadrupling power per dollar and get better or equal sound quality.


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## MarkZ (Dec 5, 2005)

cvjoint said:


> I simply don't believe any of these arguments claiming all amps sound the same given there is no on-board processing done.
> 
> 1. most folks on this forum use headunit xovers
> 2. big bonner for arc and dls amps and these aren't cheap by any standards
> ...


There are several reasons to buy higher priced amps. Just like there are several reasons to buy higher priced DVD recorders. In the end, your recorded DVD isn't going to look and sound better with the more expensive unit -- but that doesn't mean that the cheap unit is as reliable, as fast, as compatible, as quiet, looks as nice, etc as the more expensive unit.

Basically, you can't base your argument on buying trends. The argument boils down to this: 

1) what could make an amplifier sound different from another one.
2) what are amplifier manufacturers currently doing different from each other, to potentially give rise to a difference in sound.
3) are the tests that are devised to determine whether or not there's a difference conclusive? In other words, have all possibilities been exhausted?

The problem with the debate is that #1 is completely ignored by most participants, #2 is unknown to most participants, and #3 is glossed over by most participants. So until people are willing to roll up their sleeves and really decide to systematically test the question by implementing all the proper controls, the answer will remain elusive to most.


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## tyroneshoes (Mar 21, 2006)

I was a big believer in oldschool classic amps are as good as it gets. I had my zapco studios in 4 different systems. Recently, I had some debt I had to take care of so I sold them and picked up these blaupunkt velocity amps that were going for an unbelievable price. I notice no difference in sound what so ever. Only thing I noticed is the bass is just a little sloppier (barely noticable) than with the high dampening factor of zapco.

But keep in mind, the zapcos are costly but lased me 7 years with no problems. Build quality is always important.


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## cvjoint (Mar 10, 2006)

reliability issues you can avoid most of the times by getting a high wattage amp./ lower gains and using higher impend. speakers, like 8 ohmers, that people use anyways.

I see brand preference in use as proof, and to me it is essential that you buy what you believe in. You can put me to sleep arguing how you can't hear differences. But if you make your purchase as if it makes all the difference in the world I won't believe you.

I doubt most people here care much about ergonomics and bling factor. A lot of people don't mind if their window can't roll down all the way due to depth issues, or if their tweeters are just hanging or velcroed.


Then you have a whole lot of issues that you won't address if a watt is just a watt, such as damping factors, s/n ratios, and slew rates. From what I know THD is the only exception because it changes with the power level.


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## MarkZ (Dec 5, 2005)

cvjoint said:


> reliability issues you can avoid most of the times by getting a high wattage amp./ lower gains and using higher impend. speakers, like 8 ohmers, that people use anyways.
> 
> I see brand preference in use as proof, and to me it is essential that you buy what you believe in. You can put me to sleep arguing how you can't hear differences. But if you make your purchase as if it makes all the difference in the world I won't believe you.


I make my purchase based on what qualities I'm looking for in an amp. Paramount to these, IMO, is reliability -- both in terms of longevity and not shutting down when it gets hot. Alleged sound quality differences never factor into my decision. To say that anyone who chooses anything better than a Pyramid shouldn't be believed is a bit silly.




> Then you have a whole lot of issues that you won't address if a watt is just a watt, such as damping factors, s/n ratios, and slew rates. From what I know THD is the only exception because it changes with the power level.


I'm willing to address any of those. Damping factors have been proven to be of little consequence in today's amplifiers. Here's a good link to demonstrate:

http://www.diyspeakers.net/Articles/Richard Pierce DAMPING FACTOR.pdf

S/N is important, but difficult to quantify on a per-amp basis because it's dominated by noise issues arising from the specifics of the installation, including the particular car. The on-paper s/n specs are quite frankly useless, because I've never ever measured an amplifier IN A CAR that came even within 10dB of their rated specs. Higher s/n than 90dB? Puh-leeze. But I will agree that better amps will often reject noise more easily than crappier amps. That doesn't mean you can't get rid of the noise with the cheap amps. It just means that it can often be more difficult.

Slew rates don't generally become an issue in today's amplifiers. The fact of the matter is that slew rate is dominated by the input stage circuitry, much of which is overly simplistic in even the most expensive amps. There are, of course, benefits to the simplicity approach (eg. reliability due to decreased parts count, space/complexity saving, literally a few pennies worth of savings in parts, etc). But for the most part, an amplifier's ability to slew is perfectly fine for the relatively low frequency application of audio.

And yes, THD is very involved. Single THD specs are ridiculous. THD usually varies dramatically with power level, load impedance, frequency, and age. But what you find these days, which wasn't necessarily the case twenty years ago, is that THD values tend to be pretty low if the amp isn't clipping. They're usually at least one order of magnitude less than that produced by the speakers they're driving. So if the difference between amp A and amp B is .05% THD and your speaker produces 1% THD (which may increase to 3% when it's really singing), the amplifier THD difference really becomes too low to have an audible effect. Clipping, on the other hand...that's a whole new ballgame.


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## cvjoint (Mar 10, 2006)

All the amps I've tested had no problem driving a 4 ohm load in the desert and not shutting down. If that's the case it's a really bad design and imo quite rare, most amps will not have this problem. If you lower to 2 ohm on an AB amp than it's a different story, but then again you can buy two cheap amps to go around it.

As far as damping goes there are a lot of articles out there that claim opposite theories. Some say 10 is enough, some 20, some 50. Keep in mind that df is diminished by lowering imp., with small g. wire and long runs. I will be honest and tell you that I can't follow the math. approach.

I agree with you that s/n ratio tests are done by isolating variables, but it is meaningful and you gotta start somewhere. If you start with a 60 in ideal environment imagine how bad it can get following your reasoning. It is difficult, it is relative, but it's meaningfull. I've tried a couple of amps with awful background noise and will never use them again in instals. The pattern that I've noticed is that 60-70 ratios are noticeable, around 100 not so much.

What do you mean by "But for the most part, an amplifier's ability to slew is perfectly fine for *the relatively low frequency application of audio*." What's high frequency, 20k up?


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## MarkZ (Dec 5, 2005)

cvjoint said:


> All the amps I've tested had no problem driving a 4 ohm load in the desert and not shutting down. If that's the case it's a really bad design and imo quite rare, most amps will not have this problem. If you lower to 2 ohm on an AB amp than it's a different story, but then again you can buy two cheap amps to go around it.


Agreed. Most amps will do fine handling the 4 ohm load, unless playing at insane volume levels or for very long periods of time (eg. heavy clipping, low crest factor). I've sent my a/d/s/ amp into protection once driving 4 ohm mids and highs, and it was after listening to an album with a low crest factor at full blast for nearly an hour with no pause (something I don't do very often, by the way). Other than that, I don't think I've ever personally gotten non-bridged amps to do that -- even cheap ones like Alphasonik/USAcoustics, Jensen, Kenwood, Sony, etc. I did have a Profile about 10 years ago that flipped out sometimes, but it was running a low frequency driver. 

But bridged is where you really separate the men from the boys. I like having amps that I never ever have to worry about shutting down. Or, as you say, at least create a situation where it will never happen like running additional to amplifiers to gain the added power that bridging would get you.



> As far as damping goes there are a lot of articles out there that claim opposite theories. Some say 10 is enough, some 20, some 50. Keep in mind that df is diminished by lowering imp., with small g. wire and long runs. I will be honest and tell you that I can't follow the math. approach.


Well, the math approach is really the only way to understand exactly what it is, and why its importance quickly falls off. Pierce's article is one of the few that doesn't arbitrarily choose a number -- he deduces it based on signal levels. If you have a contrary article to provide, I'd be glad to read it.



> I agree with you that s/n ratio tests are done by isolating variables, but it is meaningful and you gotta start somewhere. If you start with a 60 in ideal environment imagine how bad it can get following your reasoning. It is difficult, it is relative, but it's meaningfull. I've tried a couple of amps with awful background noise and will never use them again in instals. The pattern that I've noticed is that 60-70 ratios are noticeable, around 100 not so much.


They still make amps with -60dB s/n?



> What do you mean by "But for the most part, an amplifier's ability to slew is perfectly fine for *the relatively low frequency application of audio*." What's high frequency, 20k up?


Sure. 20kHz isn't very high for an amplifier of any sort. Try designing a power amplifier that has to reach to 100kHz (which also isn't that high, but it's high enough to be difficult). The slew rate has to go up nearly an order of magnitude (which may call for a completely different design!). Overall, slew rate is one of those things that audio amplifiers over the years have completely addressed and no longer becomes an issue. At higher frequencies, however, there are other concerns that can rear their ugly heads in some cheap amps. There's a THD/stability tradeoff that always exists, and as you raise the frequency beyond 20kHz it becomes a far greater issue. So yeah, 20kHz is low because those issues can be designed out with ease.


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## chad (Jun 30, 2005)

I build amps that operate at 440 MHZ As in MEGA-Hurts 

That **** will cook your boys if you are not careful.

Chad


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## cvjoint (Mar 10, 2006)

MarkZ said:


> Well, the math approach is really the only way to understand exactly what it is, and why its importance quickly falls off. Pierce's article is one of the few that doesn't arbitrarily choose a number -- he deduces it based on signal levels. If you have a contrary article to provide, I'd be glad to read it.


http://www.classic-audio.com/marantz/mdampingfactor.html

Here, it took me 2 min to find one that claims anything bellow df of 20 is bad and he claims it's noticeable. I know there was a link on this site to a page that lets you plug in wire length and thickness to find df at speaker, impressive how low it can get. U also gotta keep in mind companies might overrate df cuz no one will actually test for it, it's hard enough and costly enough to bench test an amp for power specs. For example my Orion had df of 50, claimed anyways. At 1 ohm that I was running it, it would amount to 12.5=bad control.

The Kicker Sx amps and Infinity amps have an s/n around that range. These are not entry level or rare amps.

all I was really saying is that by the very creation of these terms such as df, s/n, and slew rates there is more to an amplifier than power, and maybe much more than we have terms or standards to measure. I stand by my claim that there is more to an amp than cooling properties and power ratings. It may be based more on my experience and other folks who installed stuff with me but for me it was reason enough to dump some amps over others purely on sonic timber.


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## MarkZ (Dec 5, 2005)

cvjoint said:


> Here, it took me 2 min to find one that claims anything bellow df of 20 is bad and he claims it's noticeable. I know there was a link on this site to a page that lets you plug in wire length and thickness to find df at speaker, impressive how low it can get.


There's a difference between a claim and a rigorous analysis though. What is the source of his claim? Where's his data?



> U also gotta keep in mind companies might overrate df cuz no one will actually test for it, it's hard enough and costly enough to bench test an amp for power specs. For example my Orion had df of 50, claimed anyways. At 1 ohm that I was running it, it would amount to 12.5=bad control.


How did you measure it? 12.5 is really low for a solid state amp built...um...this century. Most of them test somewhere in the tens to hundreds. Even cheap amps like this one exhibit damping factors over 100: http://www.carsound.com/review_archive/amps/ats50rx.html

Most fairly well known manufacturers with a reputation to uphold will try to make their specs reproducable to cover their asses. And, to a lesser degree, to look good when they are tested (like by carsound, for instance).



> The Kicker Sx amps and Infinity amps have an s/n around that range. These are not entry level or rare amps.


Are you sure about that? Carsound tested a kicker amp's s/n at -103dB. Granted, it's not the same amp, but I can't imagine they changed their design so dramatically to go from 103 down to 60.



> all I was really saying is that by the very creation of these terms such as df, s/n, and slew rates there is more to an amplifier than power, and maybe much more than we have terms or standards to measure. I stand by my claim that there is more to an amp than cooling properties and power ratings. It may be based more on my experience and other folks who installed stuff with me but for me it was reason enough to dump some amps over others purely on sonic timber.


The terms weren't created to characterize audio amplifiers. They're measures of signals in general that often have nothing to do with audio. You can use them to describe microwaves, photographs, or any measurable quantity. And indeed they do have applications in electronics in general, and even in image processing and whatnot. So the fact that some manufacturers have adopted them to describe the electrical characteristics of their amplifiers is not proof that they're meaningful quantities. They're just a method of describing the transfer function of the amp.

You can FULLY characterize a signal with a simple method -- by parsing out the linear and nonlinear aspects of the output signal with respect to the input signal. As an example, you can perform the old Hafler experiment and take the original signal and subtract it from the amplified signal and see if there's anything left. If there is, it ain't supposed to be there. So you can quantify two things: 1) how much of that extra stuff is present; and 2) under what conditions you can get it to be present. And that's precisely what these specs are supposed to indicate to us. Some specs go into greater detail in an attempt to reveal what the source of the extra stuff is. But in the end, you've got the input signal and the output signal and the question becomes how different are they. So there's never a situation where you can say that it's not a measurable quantity, or that it can't be fully described.


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## cvjoint (Mar 10, 2006)

Orion gives the 50 figure and that's at 4 ohms. this is the 2500d model by the way. It would be 25 at 2ohms and 12.5 at 1 ohm.

As for the Kicker I saw it in their brochure for 05 or 06 I don't remember. They had their claimed 100 s/n or someting and in small print CEA 60 s/n right underneath it.

I think amp. sonic fingerprint is very similar to speaker timber, somewhat similar to differences in paper cones and metal cones. I couldn't tell you it's a paper cone by looking at the graphs but most of the time it's easier to tell by listening to it. Maybe that extra stuff you mentioned is what makes amps sound different.

Hard to believe you would buy an amp. based on how it might handle bridging in the future. I can tell you that for me it has been more of the trial and error type. I was surprised how different they were. For example the Jl 450/4 deffinetly had more power and cooled at least as good as my polk amps, and had the ability to do bandpass which was a nice bonus. I bought it knowing for sure it is better, but ended up selling it in about a week. I prefered the sound of the polk, but missed the power so I bridged, then bought more amps etc. I used to go by numbers but in the end it was always trial and error when picking and choosing amps.


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## chad (Jun 30, 2005)

But what is the dampling factor AT THE VOICE COIL (where the buisness gets done)? The speaker wire, tinsel leads and every connection makes a difference. It all boils down to the fact that you could have a kazillon dampling factor but at the coil the playing feild gets evened out right quick. The amplifier is transformerless, the amp's output impedance is incredibly low. DF is a ******** spec that should be ignored because it is affected by an incredible amount of variables. Hell, one loop in the wire at the right frequency and the DF figure goes to hell in a handbag at the frequency at where it will resonate.

Chad


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## MarkZ (Dec 5, 2005)

chad said:


> But what is the dampling factor AT THE VOICE COIL (where the buisness gets done)? The speaker wire, tinsel leads and every connection makes a difference. It all boils down to the fact that you could have a kazillon dampling factor but at the coil the playing feild gets evened out right quick. The amplifier is transformerless, the amp's output impedance is incredibly low. DF is a ******** spec that should be ignored because it is affected by an incredible amount of variables. Hell, one loop in the wire at the right frequency and the DF figure goes to hell in a handbag at the frequency at where it will resonate.
> 
> Chad


Not only that, but improving your damping factor number often comes at the expense of other variables. For instance, removing your output zobel network and decreasing (?) emitter resistor values will have an effect on damping factor, but I personally would prefer to keep those things unchanged. Increasing NFB should end up doing the same thing too I think (all things equal), but could lead to stability issues -- especially if you try to stretch that increase to higher frequencies. 

Altogether, amplifier design often consists of a series of tradeoffs -- many of which just aren't worth it in order to improve a spec that you're not going to hear anyway.

But 12.5? That's f'd up. That's like tube amp low.


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## SQ_Bronco (Jul 31, 2005)

FWIW the orion spec is ">50 @ 4, 2, 1 ohm". As in, "greater than 50, but not necessarily equal to 50". So if it is >50 at 1 ohm, it is >200 at 4. 

For another bit of useless trivia, the old orion HCCA250's were ">400 bridged". I can't remember if that was at 1 or 4 ohms.


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## chad (Jun 30, 2005)

So I’ll chime in and pretty much piss every one off at me…… I agree with Mark. A modern amplifier in good working order will do it’s job and do it right. It will sound the same as another amplifier REGARDLESS OF POWER as long as both amplifiers are run within their intended operating conditions. 

That being said…. Different makes of amplifiers will have different clipping characteristics giving different amplifiers a noticeably different sound when being run on the ragged edge. If this is how you judge how an amp “sounds” then it’s time to GTFO this is an SQ group  J/K

THD figures are ******** unless the amp is broke, speakers mask the difference in THD by hundreds fold.

Tube amps. I am looking at 3 now. 2 are KT88 Mono Blocks that I built, they sound… Well… Like an amplifier, they do their job, and look damn cool doing it, and when pushed to the ragged edge are insanely loud and squish up rather nicely. Within their intended operating range they sound like any other amp. The other tuber I’m looking at is an old Scott 299C, it sounds well.. “like a tube amp” from the get go. Why? Because it’s worn the hell out! It has had a partial re-build but I left a partially worn out rectifier tube in there, some lytics still need replaced and are probably quite dry, the PS sags like Anna Nicole’s tits will in 30 years. I left it as it stands because it’s got character and is fun to listen to on a winter day. It’s BROKE! That’s why it sounds the way it does! I replaced all the bypass caps, PS filter caps and anything else that could possibly turn it into a pipe bomb in my loft.

My amps all sound the same when using them within their reason. They look different, weigh a different amount, cost vastly different amounts, and have different sentimental values. But they are all amplifiers and with the exception of the Scott they all work fine. And sound good. Some are placed in certain applications because of their sound… When run balls out, and trust me I run the hell out of things. But “watt for watt” they all sound the same as long as the smallest amp is the control specimen for the power output.

I have had my hands in and all over THOUSANDS of amplifiers, and that’s not an exaggeration. I have had them all on the best of the best in test equipment and yes, some fare differently in specs. But if you think you can tell me the difference in a double blindfold with the processing bypassed then I have some land to sell you.

When I purchase amplifiers I look for many things. 

1 How long does it take to heat up and how fast can it cool itself off?

2 Is it efficient (especially in some apps)

3 How finicky is it on the input side (grounding schemes, CMRR, sensitivity)

4 How ****ty does the operational protection sound (some amps let “the show go on” but protect themselves, this can sound like utter ass in some instances (ie, Crown ODEP))

5 Can I get it serviced easily; some Chinese wham-bam amps ARE disposable at best.

6 Reliability, not only track record but design criteria. For example, I know certain transistors can make X watts safely, but to rate the amp at that is a red flag in my book, put two per side in there and give me some lee-way for when I decide to get goofy.

7 and last, there IS more…. VALUE! How is it’s resale? In my application, How long will it take me to make it pay itself off? For whiz bang… Will the technology make my show $xxxx.00 better? When will it be no longer rider acceptable? Is it rider acceptable now? Does it make a difference?

And… well one more… 8. Does your purchase make YOU feel good, an item is only worth what YOU are willing to pay for it. If you think it “sounds different” then fine. But in my sandbox the rules are a bit different.

Chad


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## chad (Jun 30, 2005)

MarkZ said:


> But 12.5? That's f'd up. That's like tube amp low.


Again a useless spec. Damn right a tube amp has a low DF, in fact it approcahes ZERO when the impedance match is lost, and speakers have impedance curves, and capacatance curves, and indunctance curves. They also get a bit pissy about back EMF. 

This is corrected for the most part in the feedback loop, usually taken from a tap on the secondary of the OPT, and usually NOT the one the speaker is attached to.. Go figure 

Remember, tube output sections (not a butler amp (fake tube amp)) need an impedance match to deliver the energy.

Don't even get me started on tubes in a car 

Chad


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## chad (Jun 30, 2005)

SQ_Bronco said:


> FWIW the orion spec is ">50 @ 4, 2, 1 ohm". As in, "greater than 50, but not necessarily equal to 50". So if it is >50 at 1 ohm, it is >200 at 4.
> 
> For another bit of useless trivia, the old orion HCCA250's were ">400 bridged". I can't remember if that was at 1 or 4 ohms.



At WHAT though?

I have 60 pounds of well pressure 600' away from my house. All that pipe makes a bit of a difference in the end..... Ever try breathing thru a garden hose? Think about it that way.

DF is GREATLY affected by "internal resistance" Internal to the "system that is"

Mark, what is the DF of your switcher after it goes thru that big ass filter network to keep the hash out of the speaker line? That's something I never looked into!

Chad


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## FoxPro5 (Feb 14, 2006)

If only all amp manufacturers listed their specs like this, the world would be a better place: http://www.diymobileaudio.com/forum/showthread.php?t=6403&page=1&pp=10

Now that's my kind of marketing! 

IMHO, we should be buying amps based on relative value, not on specs. If I can afford to spend $1000 on amps and I found a killer deal on a pair of Brax Graphics for that price, I'd be all over it. I'd be interested in the power it put out based on my needs, but I know full well that I'm buying an AMPlifier, not a WATTifier.


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## FoxPro5 (Feb 14, 2006)

chad said:


> At WHAT though?
> 
> I have 60 pounds of well pressure 600' away from my house. All that pipe makes a bit of a difference in the end..... Ever try breathing thru a garden hose? Think about it that way.
> 
> ...


Agreed! And just to piggy back of that...

Go to www.bcae1.com and play with the damping factor input thingy (#99 on the page). It's pretty interesting to see what really happens to that precious, or should I say bogus, spec.


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## cvjoint (Mar 10, 2006)

I couldn't find at what impendance Orion rates the 2500d (site or manual). I assumed it was 4 ohm because that's the general rule of thumb. I still don't know where you got the spec.

Don't you guys generally agree that it is better to start with a df of 2000 rather than 200? smaller chance of reaching that critical value, whatever that is 20, 25, 30. 

by the way that was the table I looked at before. I plugged it the orion with a df of 50 at 1 ohm instead of 12.5 like I did before and it still gives me a sub 25 final value.


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## ArcL100 (Jun 17, 2005)

Well, I missed most of this thread but I'll just say what I always say - that outside of like competition cars with everything just perfect and listening in your driveway, I find it hard to believe you'll ever notice the subtle differences between a GOOD amp (and there are TONS) and the crazy elite amps when you're driving around. There's just so many other noises to compete with in traffic and a car is far from a listening room. Speakers and tuning will make an exponentially more significant difference then the sonic signature, so better to invest there.

At this point, I think it's undeniable that there are sonic differences. It was probably already mentioned or disputed (Im too lazy for 7 pages), but IIRC different components can alter the frequency curve. People never dispute HU sonic quality, so what's the difference? It's all electronics, lol, maybe I'm just super ignorant here. Also, I don't understand why people think you need to do a blind test with car amps - can't you just do this with home amps to prove the point?

In any case, I already stated my opinion above. For most of us, it just doesn't matter enough to worry about IMO.

-aaron


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## MarkZ (Dec 5, 2005)

ArcL100 said:


> At this point, I think it's undeniable that there are sonic differences.


I've denied it.



> People never dispute HU sonic quality, so what's the difference?


I do.  



> It's all electronics, lol, maybe I'm just super ignorant here. Also, I don't understand why people think you need to do a blind test with car amps - can't you just do this with home amps to prove the point?


Well, because the assertion is that all CAR amps sound the same (or, more accurately, can be made to sound the same with the elimination of built-in signal processing and an adherence to operating within the confines of clipping). However, I don't believe that *all* home amps sound the same, because there are some really B-A-D ones that masquerade as super-high-end equipment. I don't know of any like that in car audio.


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## 3.5max6spd (Jun 29, 2005)

chad said:


> But what is the dampling factor AT THE VOICE COIL (where the buisness gets done)? The speaker wire, tinsel leads and every connection makes a difference. It all boils down to the fact that you could have a kazillon dampling factor but at the coil the playing feild gets evened out right quick. The amplifier is transformerless, the amp's output impedance is incredibly low. DF is a ******** spec that should be ignored because it is affected by an incredible amount of variables. Hell, one loop in the wire at the right frequency and the DF figure goes to hell in a handbag at the frequency at where it will resonate.
> 
> Chad


Are those not reasons to want a healthy DF from the get go? Having more, in most cases, ends up being more when its all said and done.


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## Guest (Nov 7, 2006)

some unsolicited advice Mark, if I may ... 

Give it up. You're simply wasting your time. Critical, logical thinkers need no convincing, and the others ... well, can just never be convinced.

Science and Religion ... never the twain shall meet.


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## MarkZ (Dec 5, 2005)

I'm just excited and amazed that this topic can be discussed by people in a civil manner and with some willingness to listen to new ideas. Chad can tell you that I've been involved in zillion-post flamefests on this topic in rec.audio.car, and it usually deteriorates into strawmen and yo mama jokes by the third post...

Not that that's not fun or anything.


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## chad (Jun 30, 2005)

3.5max6spd said:


> Are those not reasons to want a healthy DF from the get go? Having more, in most cases, ends up being more when its all said and done.


The wire really makes THAT much of a difference, such that a high DF and a Low DF will appear damn near the same at the VC. 

Many call the DF "the ability of the amp to control the speaker." I see that phrase as the amps resistance to being "pushed around" by back EMF etc. Any quality transformerless, low impedance amp will exhibit this trait without the "my **** is larger" DF numbers. Notice that the DF has no unit of measure, Lets call it a "DF of (X) Whipsnades." 

Driver selection makes WAY more of a difference in the "control issue" than a DF figure EVER will. Some drivers play nice, some don't. I'll take a driver that plays nice with a low Le over a mondo excursion power-soak any day. Note that outside the car world where "bigger is badder" that the drivers that command the most respect have nice single layer voice coils that have a low Le.

The CV strokers, Older JBL GTi series, the old ID's made from EV parts. They sound good and are loved because they dont beat the piss out of an amp. They are efficient because the VC does not weigh 10 pounds. It's edgewound aluminum or copper in one layer, and amps like that DF or not.

Chad


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## ArcL100 (Jun 17, 2005)

MarkZ said:


> I've denied it.


Lol, well, I'm with ya there then. I've personally been through a handful of amps and never noticed any difference outside of noise floor.

That huge high-end HU showdown on ECA though, the panel was saying there were noticeable tonal differences between all the units and stuff, and many of the same respected members, and competitors, will tell you there's differences in amps sonic signatures. Sometimes real world and theory are two different worlds.

Haha werewolf's comment is funny and relevant in that some people have the amp faith and need the amp gospel in their lives, and the amp-athiest gets by with the workhorse.

-aaron


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## 3.5max6spd (Jun 29, 2005)

chad said:


> The wire really makes THAT much of a difference, such that a high DF and a Low DF will appear damn near the same at the VC.
> 
> Driver selection makes WAY more of a difference in the "control issue" than a DF figure EVER will.
> 
> Chad


Sure, there are ways of dancing around to variables that render amplifier spec useless. What if i dont want to use such (low Le) driver and prefer another driver tonally? Does that make my driver selection preference 'poor'? What if wiring remains optimal on both scenarios, or not?
While I see your point, I dont agree on the 'uselessness' of any spec.


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## tard (Jul 13, 2006)

this is an interesting statement to the topic i came across.......



"That challenge is a good test with some impressive results, but the important thing to understand it he is NOT trying to prove that all amps sound the same, unfortunately that's misunderstood by a lot of people. He's trying to prove that all amps that measure the same, sound the same. He will even physically modify the amps if necessary to get them to measure the same before performing the test - in fact that aspect of the test alone should tell you pretty definitely that not all amps sound the same (if they did, why would he need to mod them?). He's simply trying to prove that there's not some unmeasurable "X factor" in expensive amps that make them sound better than cheaper amps - that all audible differences between amps can be explained and quantified."


the old saying of "never bet with someone who is control of the outcome" comes to mind.


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## MarkZ (Dec 5, 2005)

tard said:


> this is an interesting statement to the topic i came across.......
> 
> "That challenge is a good test with some impressive results, but the important thing to understand it he is NOT trying to prove that all amps sound the same, unfortunately that's misunderstood by a lot of people. He's trying to prove that all amps that measure the same, sound the same. He will even physically modify the amps if necessary to get them to measure the same before performing the test - in fact that aspect of the test alone should tell you pretty definitely that not all amps sound the same (if they did, why would he need to mod them?). He's simply trying to prove that there's not some unmeasurable "X factor" in expensive amps that make them sound better than cheaper amps - that all audible differences between amps can be explained and quantified."


Where did that quote come from? I don't know a whole lot about Clark's test, but this is the first I've heard that he "physically modifies" the amplifiers. How exactly does one do that to achieve those results? It sounds like a bogus claim to me.


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## Thoraudio (Aug 9, 2005)

One of the things that I hate about the challenge is how rules are cherry picked out to show that there's some monkey business going on. 

Anytime you offer some money in a challenge like this, somebody is bound to come along to try to scam it away... so rules are put in place. 

The people who wish to do so, think that the audio signal is played *through* the AP1 where it's (alternatively) set to make the good amp sound bad, or through functions that only a $10,000 piece of equipment can do, makes the bad amp mimic the good one... They believe that the good sounding amps have the good sounding parts removed or (alternatively) that the bad amps have good parts added... they believe that bypassing a bass boost, or checking to see if an amp is in proper working condition is a modification of the amp... They believe it's not a 'real world' test even though it can be done in their cars with their amps...

I've had people tell me they've taken the test, and it was performed with specially prepared test tones (test tones are prohibited)... I've heard (third party) of an individual who claims he passed the test and wasn't paid, only to find out, he passed the preliminary test that allows you to take the challenge... 

If I were a manufacturer of high $, high quality amps, and I honestly believed that there was a significant difference, I'd beat a path to RC's door, and either pass the test, showing how great my amps are, or expose him as a charletan (sp?), documenting the changes and eqing that he does, or go back to selling my amps based on build quality, real power output, and features.


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## Diru (May 23, 2006)

MarkZ said:


> Where did that quote come from? I don't know a whole lot about Clark's test, but this is the first I've heard that he "physically modifies" the amplifiers. How exactly does one do that to achieve those results? It sounds like a bogus claim to me.



I mod mine, buy cheap , install a hand full of better parts where needed.


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## Thoraudio (Aug 9, 2005)

MarkZ said:


> Where did that quote come from? I don't know a whole lot about Clark's test, but this is the first I've heard that he "physically modifies" the amplifiers. How exactly does one do that to achieve those results? It sounds like a bogus claim to me.


the only time an amp is physically modified, is when it has an audible feature that cannot be bypassed (i.e. a fixed bass boost, or channels wired out of phase). And the modification can be performed on either amp the listener wants it too...


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## MarkZ (Dec 5, 2005)

Diru said:


> I mod mine, buy cheap , install a hand full of better parts where needed.


And he's gonna do that on the fly? Car amps aren't very easy to modify, and simple replacement of parts more often than not isn't going to do jack unless the parts are faulty. Getting an already low distortion amplifier to exhibit even less distortion or less noise or flatter FR generally requires a complete re-design of the input stage and VAS. You could do some easier manipulations and get some minor results, but if we're talking about an amp that measures relatively poorly ("relatively" the key term there), you're not going to fix that by replacing filter caps, op amps, or output transistors.


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## Thoraudio (Aug 9, 2005)

but like Jeff has said... you can't convince a true believer. I've had one experienced competitor say that no amount of tests or demonstrations would convince him otherwise...


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## chad (Jun 30, 2005)

3.5max6spd Sed (IE's not playing well with others today)


Sure, there are ways of dancing around to variables that render amplifier spec useless. What if i dont want to use such (low Le) driver and prefer another driver tonally? Does that make my driver selection preference 'poor'? What if wiring remains optimal on both scenarios, or not?
While I see your point, I dont agree on the 'uselessness' of any spec.



----------------------
I guess what I was trying to convey is that regardless of DF at the amp terminals (if that's where it's measured, you never know, could be at the emitter resistors on the test jig) After the output gets to the speaker this figure is drastically changed and the playing field gets evened out. It's like saying i don't like amp X because it has a lower DF but in reality the amp IS BETTER because it has proper output filtering, etc.

I still don't see a use in this figure, it is NOT used outside the car world, like in the pro world where people use these things to convey their message to millions and make their money off of it. I have never seen or looked into a DF figure for a sub amp in pro use... I know that the 50' of 12/4 that I'm sending the signal down to subwoofers will change the figure drastically.

What is the unit of measure for damping factor? They haven't come up with one, That doesn't happen very often in scientific measure. I still vote for Whipsnades (or we could call it UD, for useless drivel)

But since we know it's the speaker's impedance divided by the amp's output impedance. What the ****? How the hell do you pull this off when the speaker's impedance is all over the place like a **** sandwich? The DF will never be even CLOSE to the published spec while driving a nice Dale non inductive resistor.

Now. We all know that most of the solid state amp world is an unmatched place. Low output to high input impedances. In a matched system like in tube amps or transformer coupled SS amps there needs to be a match, which would make your DF..... ONE! As stated before my monoblock KT88's sound just like my big Crowns, when run in linear mode.

So do a little math. Lets say the amp has an UBER low output impedance Like .001 ohm contributing to a very high damping factor of 4000UD. And we have another amp with a .05 Ohm output Impedance which gives us a blazing damping factor of 80UD. So that’s a BIG difference there eh? Sure, if you never plan to hook up a speaker! Let’s add a conservative figure of .1 Ohm for speaker cable, tinsel leads and connector resistance and calculate DF.

Amp A would have a total output impedance of .101 Ohm giving us a DF of 39.603UD

Amp B Would have a total output impedance of .15 Ohm giving us a DF of 26.667UD

So a difference of 3920 Useless Drivels turned into a difference of 1.485 useless drivels once the amps in question are put into their application. 

See my point?

Chad


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## chad (Jun 30, 2005)

Thoraudio said:


> the only time an amp is physically modified, is when it has an audible feature that cannot be bypassed (i.e. a fixed bass boost, or channels wired out of phase). And the modification can be performed on either amp the listener wants it too...


I agree with this. An EQ pot is never really defeated, it's detent is assuming that the center of the wiper is exactly half the pot's resistance value, this is never the case. There are pots that defeat at detent, but very few and prolly not used in car audio.

Nearly ALL car amps have one channel wired out of phase. This contributes to easy bridging by simply going to mono and not phase inverting the whole channel. This keeps the parts count down by having one channel out of phase from the get-go and wiring that speaker lead out of phase. Ever notice that real amps bridge between the two positives which makes sense? But car amps bridge between a positive and negative? That negative ain't ground!

Chad


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## SQ_Bronco (Jul 31, 2005)

chad said:


> What is the unit of measure for damping factor? They haven't come up with one, That doesn't happen very often in scientific measure.


It's pretty common in aero engineering/fluid dynamics. I'd go so far as to say the industry wouldn't exist if it wasn't for nondimensional numbers; Reynolds number, Nusselt number, prandtl #, grashof #, etc. Ratios of stresses, boundary layer thicknesses, heat transfer characteristics, etc that make it possible to accurately predict how the fluid and your airfoil/turbine blade/pipe are going to interact, and determine the most important variables in optimizing your component for the environment it is going to be used in.


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## chad (Jun 30, 2005)

I stand corrected. I purpose you give them a name  To avoid confusion, of course 

Chad


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## SQ_Bronco (Jul 31, 2005)

chad said:


> I stand corrected. I purpose you give them a name  To avoid confusion, of course
> 
> Chad


DF works just fine. "The ratio of the rated impedance of the loudspeaker to the source impedance" according to wikipedia. [Or we could call it the Chad number, if you insist ]

Anyway I'm not trying to claim that it is (or is not) useful or that I have any idea what a decent DF would be. I'm just pointing out that it is common practice to use numbers which don't have units attached to describe real world conditions.


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## zfactor (Oct 19, 2005)

i myself dont pay to much attention to amp specs other than real rms power... i do check them but the only way they would bother me or make me think twice is say one amp had a s/n of 40... hmmm id still give it a shot and listen to it.. it may sound just fine, always hard to tell until you listen to the amp.


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## cvjoint (Mar 10, 2006)

You can't even trust rms ratings, some underrate some overate, some cea, some not etc. I don't trust any of the spec. sheets. Like I said, with car amps. it is trial and error. I do think actual s/n, df, and rms figures are important, but there is no clear standard to base your decision on and every manufacturer has its on values.

With that said I pick my amps based on what I hear: pure clean sound ( no background noise) , good speaker control for woofers/subs, or warm detailed but not harsh sound on mids and highs. Power output is not that important to me because I can always get more amps and briddge.

Will this change after this thread? no. Not because I don't acknowledge that you guys have more technological prowess, but because of my personal tests. I've held variables fixed while going through a good number of amps and picked the one that fit my needs the best. I would not go back and pick one of the before tested amps because some spec sheet says it's better or because 99% of the people on this forum claim it won't make a difference. I know the minute I change the amp. I will hear a difference for the worst and that's what ultimately matters.

FWIW I've sold home audio for a while and to me Harman Kardon receivers sounded a lot different than say an Onkyo or Sony. I actually think my Polk Momo amps sound a lot like Harman Kardon ones, smooth and warm. It makes sense too, they are owned by the same company.

I'm not claiming that I always hear a differnce either. Most receivers in the same price range sounded the same to me, JVC and Sony for example, but not the older Sony, those where way better.


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## chad (Jun 30, 2005)

Polk is in the harman group now?????!!!!! Wow!


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## chad (Jun 30, 2005)

Wait... I can't find polk on here:
http://www.harman.com/

Chad


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## MarkZ (Dec 5, 2005)

chad said:


> Wait... I can't find polk on here:
> http://www.harman.com/
> 
> Chad


I know they were just sold to someone. I thought maybe it was to Directed.


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## cvjoint (Mar 10, 2006)

ohh..nevermind. Infinity was under Harman...yeah those didn't sound the same he he
but the momo's do sound like the harmans


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## zfactor (Oct 19, 2005)

directed owns polk now. when i said rms specs i always compare cea to cea and etc... but i know they are not always accurate but they prob imo more important than the other printed specs.


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## sqkev (Mar 7, 2005)

MarkZ said:


> Some, but not all. I have to admit that I engaged in a little hyperbole in my post, but so did you.
> 
> Most class B amps are pretty much as "clean" as their class A counterparts. In usage, class B is cleaner, because class A amps tend to be very low in power output, usually only suitable to drive tweeters or to drive mids with high sensitivity or low desired output levels. Anything beyond that and you're clipping, which ruins all of the supposed benefits of class A.
> 
> Technology has progressed. Class B is here, and it's designed to be high output and low distortion in a variety of different pricepoints. Soon, class G and switching amplifiers will be able to say the same.




Mark, I respect your opinion, but I also have mine.

The thing with amps is that the changes are very miniscule and hard to detect with a non-properly setup system. That includes room acoustics and gears used. 

In a proper treated room with good enough gears, a nicely built Aleph will sound entirely different from your typical receiver. 

Note that I never said anything about a car or car amps, imho, it's unnecessary to run such amps in the car. The speakers are rarely optimized and car acoustics simply sucks. In a car, as long as the amp works and puts out decent power, I'm happy. It's an entirely different ballgame when you step into home audio. 

I just want anyone to claim all amps sound the same to realize that: there are more than your typical poorly designed, and cheap components class A/B and D out there. Not all 20 watts sound the same.

Bring it on!


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## ArcL100 (Jun 17, 2005)

Lol, exactly how I feel sqkev.  

-aaron


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## MarkZ (Dec 5, 2005)

sqkev said:


> Mark, I respect your opinion, but I also have mine.
> 
> The thing with amps is that the changes are very miniscule and hard to detect with a non-properly setup system. That includes room acoustics and gears used.
> 
> ...


I agree with your last line. As I said earlier in the thread, I wouldn't extend my assertion to home audio, but probably for different reasons. There are a few amps out there designed purposely with a "sonic signature". They achieve this with the intentional addition of various distortions. Many of the highest priced amplifiers also have the highest levels of distortion, and it can be very pleasing to a lot of people. So, in that sense I agree with you. However, I don't know of any amps in the car audio market that are designed that way.


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## sqkev (Mar 7, 2005)

Mark, as far as I know. All amps, all speakers have their own sonic signatures. That's the beauty of audio. 

Different amps serve different purposes and I'll leave it as that.


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## cvjoint (Mar 10, 2006)

Allright then...I guess I'm not so outnumbered here. The opposition doesn't quite make up 99% of this forum at least. Can we do a poll or something?


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## brawas (Jun 30, 2008)

Fozz said:


> I've done my own A/B testing with amps. I used two older Blade amps (one of their tube amp and one solid state) and one of my Memphesis amps. There were no, eq settings, crossovers or any other adjustments made to the amps. They were all fed from the same none cliped signal and listened to at the same level.
> 
> The VHT (blade tube) sounded better the all the others. Not by much, but by enough that my wife could hear the difference! There was very little difference in the tonality of the amps. Though I found the Memphis to sound a little "harsher" in the upper frequencies. The big difference was in the staging of the amps. Both the Blades had higher, wider and deeper stages. They also seemed to give off a more realistic performance (not sure how else to descrebe it).
> 
> ...



Yeah, Blades are awesome. I have an SE6100 Series 3 and it sounds amazing, looks good too. Currently just sitting in my basement though, haven't had time to install in my new car, maybe I'll just sell it.


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## el_chupo_ (May 27, 2007)

brawas said:


> Yeah, Blades are awesome. I have an SE6100 Series 3 and it sounds amazing, looks good too. Currently just sitting in my basement though, haven't had time to install in my new car, maybe I'll just sell it.




An almost 2 year old thread, and a double post on a 1 year old thread, just to try to sell your amp...

Just post an ad in the FS section


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## brawas (Jun 30, 2008)

el_chupo_ said:


> An almost 2 year old thread, and a double post on a 1 year old thread, just to try to sell your amp...
> 
> Just post an ad in the FS section


LOL, I know, but I have to make 5 posts before I can start a thread in the FS section, and I was trying to get there fast.


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## ment (Jun 4, 2008)

dbphelps said:


> I believe the key here is that a watt is a watt, only if you know for certain what the "real" output power is...
> 
> In other words, any decently built amp (key here is proper design and manufacture) that puts out 100 watts "real" RMS would sound the same as any other amp that is decently built that puts out 100 watts "real" RMS...
> 
> ...



amen to this brother! 

sonic signature as result of amp design and components used. you'll hear the difference. You get what you pay for


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## t3sn4f2 (Jan 3, 2007)

ment said:


> amen to this brother!
> 
> sonic signature as result of amp design and components used. you'll hear the difference. You get what you pay for


Don't you mean no sonic signature? And after the midpoint you pay for what you don't get


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## MarkZ (Dec 5, 2005)

t3sn4f2 said:


> Don't you mean no sonic signature? And after the midpoint you pay for what you don't get


****-starter!


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## t3sn4f2 (Jan 3, 2007)

MarkZ said:


> ****-starter!


Gotta keep the revolution alive


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## dkh (Apr 2, 2008)

I agree with Markz on this one... all amps sound the same.

That's why I use Genesis amps with Class A pre-amps, not that they make a Blind-bit-of difference.

My personal experience and one which I haven't yet picked up in this thread is that a car is not the ideal installation location either, whether that's under the seat/s or in the trunk/boot.

What I mean to say is that interference or lack of should be seen as an integral part of an car amplifier's quality.

I initially had three RF amps (200a4 & two 50.2) and I had this horrible alternater whine... I changed the 200a4 to a PPI PC2200 and now the whine was only in the mids and tweeters!

I got a JBL 75.4 and used it for the fronts and the whine, although less apparant, was still there!

Next, I got an old DM200 (which I still use for the tweeters after modding the pre-amp) and no whining there...

I am now running all genesis amps for the front end and have no whining or other noises other than music which I play.


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## Oliver (Jun 25, 2007)

I think that some of the Boss amps [ 20,000 watts ], for $52.85 are the way to go


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## t3sn4f2 (Jan 3, 2007)

a$$hole said:


> I think that some of the Boss amps [ 20,000 watts ], for $52.85 are the way to go


Is that peak or rms?


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## sqshoestring (Jun 19, 2007)

The largest problem I see with new cheap amps is they break a lot. Most of the cheap pyramid type 1200 watt amps are just the same 2x75 or 2x100rms amp inside....and that is how they perform. Actually the pyramids are not that bad aside from the ratings (in that price range). Just like Clark says, all amps do sound the same long as they are EQ'd the same....because today and even back then making an amp that had the ability to produce sound beyond the quality the ear could detect is an easy feat, super easy today and very cheap at the cost of durability.


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## Antdaddy77 (Jan 6, 2022)

zfactor said:


> lol .. i dont totally believe that a watt is a watt... i know to my ears i have heard differences in amps.. some dont believe me on the boards but a lot of others agree... and if a watt was really a watt that would mean you could take 10 watts of pyramid power against 10 watts of arc se power and it would sound exactly the same?? i think not... again this is just mo though...
> 
> okay hold on..... alright im now waiting for the bashing to begin... lol


Well 10 watts is 10 watts regardless. But 10 watts out of a cheap 10 watt amp will more than likely be distorted where a good quality amp would be clean. Thats assuming the same hu set at a clean volume was the source for both amps. Back in the day I had a little 350 w Jensen ab amp 2 ch. I ran bridged and I thought that nothing would be better for more money. I hit hard but one day after work I was riding and hitting like any other time and smoke came out the little guy.
I had no other amp at the time and walmart stopped selling them. I went to the car audio store we had. And those amps where so much more money. But my unvle had a Rockford Fosgate amp that was150 w maybe it had a removeable circuit board that you could flip and put it backwards 3 different ways .that was the xover. sub ,mid, and high. Ive never seen another but anyways 150 watts now. It hit just as hard as the little jensen that could at 350 w bridged. And the quality was night and day. 
I noticed that amps that were heavier seem to be more powerful unless the manufacturer added weights to the case. Sorry but quality amp is better than cheap amps on the same exact setup. You may have a better system than a guy you know with best amp money can buy. But that will be becauseyou have a better enclosure and good heavy duty power wires or something to that nature


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## Bayboy (Dec 29, 2010)

????

Sent from my SM-G986U using Tapatalk


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