# Amp Guts Part II



## envisionelec (Dec 14, 2005)

I think it's important to address some things, particularly my intentions in these threads where I bring to light some interesting details about the automotive aftermarket amplifier industry. I suppose I should clarify that my knowledge comes from many years of intense research into car amplifier design. I am relatively young (31) but have spent the past 16 years buying car amplifiers, repairing them, reverse engineering the boards and extracting schematics. I worked at a couple car audio shops doing nothing but repairing amplifiers for five years (I'm a terrible installer). I have an excellent visual memory which gives me the ability identify and trace manufacturer lineage. 

I don't need to personally enter the car audio market, but I think it would be an exciting challenge to bring real technological advances and more well-known designers into car audio. I have some years experience as a contract manufacturer designing and improving audio products for companies across the country. I am not a degreed electrical engineer, but I work in engineering and I design electronic equipment. I'm not a big manufacturer or an industry insider no matter what one might think based on the information I am presenting.

What I noticed is that, in the past six years or so, it has become harder to identify amplifier PCB manufacturers based on their circuit topologies. I started to see such incredible similarities among (especially the upstart companies) amplifiers that I began to branch into the research of the actual origin of these designs. And found that almost all of them not only emigrate, but originate from Korea, China and Taiwan. 

When I talk about similar topologies, I am pointing out the similarities in the amplifier's actual structure of the components - how they're connected. I am increasingly seeing an overwhelming amount of low bias Class A/B amplifiers flooding the market. 

The basic premise of an amplifier is to reproduce an audio signal faithful to the input signal, without added distortion. We know that adding distortion is impossible to avoid, but a designer usually strives to keep it low. In these cheap import designs, you have three flawed circuits that keep the price low and produce marginally acceptable distortion figures. These characteristics are shared with both high and low priced amplifiers that are cut from the same cloth. Remember, price drives a perception of quality, which is why many companies have a minimum advertised price (MAP).

Without going into great technical detail, I will outline the most glaring errors:

Input Differential Amplifier with no current mirrors. Simple resistor voltage dividers do not maintain consistent current through the input stage changing gain and input bias characteristics with varying rail voltages and, in the worst cases, varying speaker loads.

Bias voltage. In many of these import designs, the bias voltage is so low that it might as well not exist. A great deal of these amplifiers use Emitter Follower outputs that do not need a heatsink-attached bias compensation transistor. Distortions increase as current requirement increase and there is no mechanism to prevent this.

Voltage Amplifiers that consist of undersized driver transistors. Small, unheatsinked driver transistors can't support the current demands of the output transistors that are driving low impedance loads. Adding more output transistors doesn't fix this problem. Under high current conditions, the transistor's gain actually decreases and the amplifier distorts severely compared with a similarly rated, properly designed amp.

There are very good reasons why these "old school" designs often set the standard for quality car audio amplifier designs - they were built to perform well and today's designs struggle to meet these basic goals. I realize this is a very introductory treatise, but I'm not planning to disappear from the boards. If anyone wants to discuss this further, you are welcome to ask questions in any thread to which I post.


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## GlasSman (Nov 14, 2006)

Well you obviously know your stuff. I'm not electrical engineer. And without knowing the basics it's difficult to grasp. I'm learning little by little. I do know a good design when I see one. 

And it smacks me in the face every time I see one of these cookie cutter designs you speak of. 

Ampguts.com is a big help .


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## Guest (Oct 13, 2007)

i don't know you dude, but i kinda like your style  please allow me to add to your rant (of sorts) ...

Let's face facts ... most power amplifiers in our god-forsaken hobby are rip-offs of previous designs ... you know it, i know it, and the american people know it  So much so, the word "design" has somehow become synonomous with "copy and tweek". Most amp "designers" or "manufacturers" wouldn't be able to even produce a schematic of their products ... or tell you what the measured specs are. Is it because they are protecting some intellectual property? That's laughable ...

There are, of course, exceptions. One (of many) reasons why i still respect McIntosh, after all these years. Anyone can purchase a service manual, with detailed schematics ... including recommended output stage bias setting  And the similarity (of the latest car amps, a significant improvement over their first generation car audio products) to their home amps is quite obvious. These amplifiers were, indeed, designed by engineers within McIntosh.

The audio power amp is not rocket science. But there are very significant differences between the good ones and the bad ones : How much margin to the safe operating area in the output stage devices? How well is heat managed? How well is the output stage protected from excessive current demands? How well does the AB bias current behave over temperature and age? How well does the input stage cancel common mode noise? yada yada ...

How many design engineers are working ... worldwide ... in the car audio amp business? I mean real engineers, designing _new_ products without copying other manufacturers? I strongly suspect you don't need more than one hand to count them all


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## MiniVanMan (Jun 28, 2005)

I sense a tutorial coming. This would be very good information to put in the tutorial section, building on it periodically with more and more information. 

I'm like you, as I'm not a degreed engineer. I work as an engineer (in a very high tech field, NMR), and I learned electronics in the military. I can troubleshoot, and fix just about anything man-made. So, I know where you're coming from.

The myths surrounding car audio amplifiers are innumerable, so a tutorial debunking many of the common ones (i.e. more expensive = better, etc). I for one would love to see it.

It's not easy, as my crossover tutorials, especially Part II, took quite a bit of time themselves. I just sounds like you have a really good foundation, and have a lot to offer.


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## bdubs767 (Apr 4, 2006)

werewolf and ezaudio

My question to you guys though is what can be introduced to the market that is not already there? Thats is what will make a special amp...


If we want a high end amp that you speak of we jsut have to buy used or fork over some cash.

There are still great companies out there like audison, sinfoni, brax, mcintosh, genesis, steg, zpaco, arc, and a few others that make one hell of a product. Or we can buy used like old PG, old PPI, old Orion, old SS....


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## ~thematt~ (Sep 14, 2007)

I think this thread has a more positive benefit then the previous one (part I), so Ill subscribe and keep abreast of some of the discussions. One thing though, can we please work to keep out the "American made" bollocks from this one? Im sure its all great when you're an American, but when your not, its very annoying. I tend to think of it more along the lines of 'Clever designers who currently live in America' as opposed to 'only US made is quality'. This way, we tend to increase our boundaries of thought by including any clever designer, irregardless of locality, as opposed to only a Yank. 

Sometimes some people forget that European brands are just as good (if not better) then a lot of 'US' brands, both of which utterly destroy the quality coming out of the Asian sweatshops. 

Oh, and dont forget the DEQX, Theile and Small were all Aussies. 


Back on topic, you gave a few examples of poor designs and selections for amplifier topology. What is the example of the reverse? ie. a cost-effective topology that produces the desired goals? By cost-effective I dont mean using Silver trace wire, with Gold leaf caps etc. Just the right things in the right places to do the job correctly.


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## thehatedguy (May 4, 2007)

Class A with balanced inputs...tubes would be nice too...if you are asking what would make an amp special.


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## MiloX (May 22, 2005)

~thematt~ said:


> I think this thread has a more positive benefit then the previous one (part I), so Ill subscribe and keep abreast of some of the discussions.










tm

This could get good. 

Bravo Captain Amplifier. Look forward to seeing where this goes.


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## bdubs767 (Apr 4, 2006)

thehatedguy said:


> Class A with balanced inputs...tubes would be nice too...if you are asking what would make an amp special.


Class A would be, but is it really realistic to have an entire class A run car. You'd need a trailer w/ alternators and batteries behind you.


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## Ge0 (Jul 23, 2007)

EZaudio, we need to talk. Almost identical backgrounds. I'm a degreed design engineer who has worked at contract manufactures and have designed OEM product offerings for 15 years.

I agree it is sad to see so much duplication. Electronics have become a chaep commodity. We used to make fun of the likes of Jensen and Boss Audio. Now, numerous manufatures, even ones we used to revere, have joined the ranks. It all comes down to economics. The shops striving for ultimate quality can't make a living when swamped it chains like Best Buy. They go belly up or sell out for name brand recognition.

However, there has been some innovation. Class D amp design has come a long way. Especially in its variations like ICE Power and Tripath.

In the long run what it comes down to is customer perception of quality vs. price point. If you spend a buttload of money on a product for perceived quality (like me) and are happy with your choice, who cares if this amp design is outdated. As long as you know the company did not make SERIOUS compromises to improve profit margin.

It is saddening to see innovation almost crawl to a standstill. Lifelike multichannel audio and further development was crushed by the ipod generation. Who wants to spend $1K on a player and $20 on music media when you can spend $100 on a portable player and download (a.k.a. steal) the music for free?

So many new products out there that many would consider cutting edge are "ALMOST" there. However, key features may have been removed to save on expense and get it to market sooner.

If you're a business owner, no matter how good your intensions, its all about the dollar. If you don't make enough you go under. To compete, you need to cut corners. Those of us demanding the utmost quality with no cost limitations are a VERY small percentage of the consumer pool. Who would you go after to ensure the success of your company and to put food on your families plate?

Ge0


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## DearS (May 14, 2005)

Great thread! Thank you! I really wanted to know how amps worked, how to tell a good one from a not so good one. This thread has really helped me get started/progress. 

I'd like to add something....People are responsible for their expectations. Its ridiculous to think the dollar amount set on an amp is directly relate to quality. Its not in any way directly related to quality. Price along with other facts can be used for an "educated guess"/"strategic risk" , thats it! nothing more! Its brainwashing that produces such ridiculous considerations! We are targets for being brainwashed by people who are themselves brainwashed and do not know it. Its still our responsibility to take control of ourselves and our regards. No matter how much BS is out their, we are still responsible for the risks we take. Still we cant do human perfect, so its really an opportunity for growth, a lesson.


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## chad (Jun 30, 2005)

werewolf said:


> The audio power amp is not rocket science. But there are very significant differences between the good ones and the bad ones :


I'm in......

But I have to bust my ass at the ranch this weekend and it's too late to... well... too altered to go into a "rant."

Keep it rolling!

Chad


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## envisionelec (Dec 14, 2005)

~thematt~ said:


> I think this thread has a more positive benefit then the previous one (part I), so Ill subscribe and keep abreast of some of the discussions. One thing though, can we please work to keep out the "American made" bollocks from this one? Im sure its all great when you're an American, but when your not, its very annoying. I tend to think of it more along the lines of 'Clever designers who currently live in America' as opposed to 'only US made is quality'. This way, we tend to increase our boundaries of thought by including any clever designer, irregardless of locality, as opposed to only a Yank.
> 
> Sometimes some people forget that European brands are just as good (if not better) then a lot of 'US' brands, both of which utterly destroy the quality coming out of the Asian sweatshops.
> 
> ...


Austrailians have a long history of excellent audio designers, including those in our present time. I'm sure you've heard of Hugh Dean the designer of the AKSA amplifier. Or Rod Elliot, the man to whom many owe their knowledge of excellent audio design (www.sound.westhost.com).


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## GlasSman (Nov 14, 2006)

~thematt~ said:


> Sometimes some people forget that European brands are just as good (if not better) then a lot of 'US' brands, both of which utterly destroy the quality coming out of the Asian sweatshops.


This is the point I was trying to make in the first part of this thread when I mentioned several quality brands US or European based. I didn't think I had to spell it out considering people around here are actually quite intelligent. 

The simple fact is you can point out more quality European brands than US based brands. I think I was *called out* to the fact that some on my list weren't US companies. I might not be an electrical engineer and sometimes I feel as though I can't really contribute anything to these type of discussions. 

But like I said a few posts up....I know quality when I see it.


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## envisionelec (Dec 14, 2005)

Ge0 said:


> EZaudio, we need to talk. Almost identical backgrounds. I'm a degreed design engineer who has worked at contract manufactures and have designed OEM product offerings for 15 years.
> 
> I agree it is sad to see so much duplication. Electronics have become a chaep commodity. We used to make fun of the likes of Jensen and Boss Audio. Now, numerous manufatures, even ones we used to revere, have joined the ranks. It all comes down to economics. The shops striving for ultimate quality can't make a living when swamped it chains like Best Buy. They go belly up or sell out for name brand recognition.
> 
> ...


I wasn't going to actually start comparing Jensen and Boss to these amplifiers - but you're entirely correct. Jensen, Boss, Pyramid, Legacy...all these amplifiers have been using the same design (and I mean the SAME) since the mid 1980s. It's disposable, simple to manufacture (no tweaking) and is simple to repair. But it's no good.  
I haven't been able to really put my finger on the definitive cause, or solution, to this trend. But, I'll share my thoughts on why I think this line of reasoning exists:

I got out of car audio for good in 2000 when folks were buying the TC Sounds/Eclipse woofers that ate 800W without making a sound (I'm exaggerating..but not by much). Sure, the old woofers didn't handle 500W, but they were much more efficient. The new breed of super power-hungry "SPL" woofers required a new type of amplifier, namely the noisy Class D. Car audio doesn't have FCC guidelines that restrict the amount of radiated noise emitting from its appliances, so manufacturers just built glorified power supplies that drove speakers with minimal filtering. 

The new era of extreme power in a tiny chassis was born. And manufacturing went to China in droves because - again - no restrictions on car audio equipment according to the FCC. It could flame out and no regulatory agency controls what products are licensed to go in a car. What the industry doesn't understand is that they shot themselves in the foot. The consumer buy the cheapest products first - if those products appear to do the job, those consumers buy LOTS of the cheap goods. Remember the biggest deals in Class D amplifiers? Lanzar Vibe 1200D, Boss REV300D, the Tsunami GXA1000D...

Manufacturers scrambled to produce their sub-kilowatt designs for even less than the $300 that the Class Ds were going for. How is this possible? It's impossible to maintain a cutting edge design to sell for that kind of undercut price. So, the industry took a flying leap _backwards_. Profit margins plummeted and the once highly respected companies either disappeared completely or were merged into others to form highly integrated powerhouses. 

And here we are today.

Ge0, I have some ideas for the industry and I'm not opposed to sharing some of these thoughts in public. Granted, I won't be giving all my ideas away, but I'm happy to talk (or speculate) about what the next moves should be. I am currently working with some designers that are extremely well known in the professional and home audio arenas. My contact list is relatively short, but only the best and brightest comprise that list. One idea, which I've broached in another thread http://www.diymobileaudio.com/forum/showpost.php?p=209685&postcount=62 is producing an amplifier that requires a tiny space in which to work. 

New advances in digital (not Class D) amplifier technologies from Texas Instruments have been all but overlooked by the car audio markets. With these types of amplifiers, you could actually have 50W x 4 in a headunit rather than the super ILS (if lightning strikes) power that they claim. The power supply in these amplifiers would actually be _less efficient_ than the audio output section itself. However, with advances in planar magnetics this efficiency can go up serveral percent. A goal of mine is to produce a very small amplifier with *total* efficiencies exceeding 95%. A 100W amplifier would produce ~5W of heat, something that is completely unheard of in today's market. Marketing proclivities aside - there are no 95% efficient car amplifiers at the present time.


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## envisionelec (Dec 14, 2005)

GlasSman said:


> This is the point I was trying to make in the first part of this thread when I mentioned several quality brands US or European based. I didn't think I had to spell it out considering people around here are actually quite intelligent.
> 
> The simple fact is you can point out more quality European brands than US based brands. I think I was *called out* to the fact that some on my list weren't US companies. I might not be an electrical engineer and sometimes I feel as though I can't really contribute anything to these type of discussions.
> 
> But like I said a few posts up....I know quality when I see it.



Aww, gee, GlasSman, I wasn't trying to call you out on anything.  It seems as though you guys have been traumatized by other car audio forums or something.  Please, continue to contribute. I have no traffic on my forum, so I enjoy this tremendously.


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## GlasSman (Nov 14, 2006)

ezaudio said:


> Aww, gee, GlasSman, I wasn't trying to call you out on anything.  It seems as though you guys have been traumatized by other car audio forums or something.  Please, continue to contribute. I have no traffic on my forum, so I enjoy this tremendously.



No offense taken.


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## skylar112 (Dec 8, 2005)

ezaudio said:


> A goal of mine is to produce a very small amplifier with *total* efficiencies exceeding 95%. A 100W amplifier would produce ~5W of heat, something that is completely unheard of in today's market. Marketing proclivities aside - there are no 95% efficient car amplifiers at the present time.


I'm in love!:blush:


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## Diru (May 23, 2006)

Yeah Ez your in love with the chip amp. But, 95% efficent not a big deal really.

I would rather see a real PWMs that are EMI/RFI sheilded on the input and outputs. Seperate B+/- rails for the output trannies and driver stages[including input], all regulated. 

Step up the bias to give the first 5 to 10 watts in Class A mode. Then switching out at higher power levels.

As far as the input is concerned. NO phuken filters of any kind. Just a real attenuator, no phuken gain , no phuken boost. Just 1 volt of drive needed for full power out. And if you got one of those phuken HI volt decks you can atten the input to fit your output.

I think you get the idea, less is more in the audio path. As it is everyone has their pet processor that they will use in front of the amp.

Oh yeah while I'm thinking it, none of the amps should be used in bridged mode. Everything should be 2 CH or Mono. 

The amps should be rated @ 4 ohms stereo under full power bandwidth[20hz to 20khz]. Should not have a 2 ohm rating, but will be able to drive loads down to 1 ohms for the passive crossover crowd.

And if you want massive power over say make the upper limit 300 Watts for these puppies, then get a class d for subs and crap like that, hell its just car audio...................

so like what

50 x 50 @ 4/2ch
100x100 @ 4/2ch
300x300 @ 4/2ch
600 @ 4/1ch mono

bigger get a D

thats what I would like

ok im done blow'n smoke


Oh yeah, bad thought, no phuken fuses on the amps, all exteral. Except for the secret ones inside the amps , that way you would know if the installer phuked up.


oh yeah didn't ADS make something like that years ago


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## envisionelec (Dec 14, 2005)

Diru said:


> Yeah Ez your in love with the chip amp. But, 95% efficent not a big deal really.
> 
> I would rather see a real PWMs that are EMI/RFI sheilded on the input and outputs. Seperate B+/- rails for the output trannies and driver stages[including input], all regulated.
> 
> ...


Assuming you're talking about the PointZero, I don't believe I'm in love with any "chip amp". I happen to make a LM3886 based chip amp kit, but it doesn't sound any better than any other LM3886 based kit. It's just the easiest kit to build with (so far) zero failures. I tend to think that's a good thing. But this is sliding off topic.

Thanks for your input. In my opinion, stiff regulation is rarely necessary as the car has its own voltage regulator in combination with the battery. If your electrical system can't handle the peak current demands, you need a better electrical system. Secondly, regulated power supplies are much noisier than unregulated designs and require more attention to secondary-side filtering. The idea that a regulated audio amplifier is better is a pretty huge misunderstanding of how power amplifiers work. 

95% efficient _anything_ is difficult to acheive. A Pure Digital amplifier is 100% digital from input (S/PDIF) to output, just before the final analog filters. THD and noise is astonishingly low for a switching amplifier. I have one on my desk, presently. 

I believe in "secret" fuses. Fuses protect the amplifier from starting fires. I see increasing fuse rating on amplifiers where the input terminal blocks are rated for 50A max and 120A of fusing. And those fuses blow after 5 seconds of 240A of current. This is not a safe design. Fuses tell very little about an amplifier's power and should not be easily accessible to the uninformed.

While you candor is definitely colorful, I think I see what you're after: take out all the junk that makes an amplifier perform poorly and just leave the goods. I couldn't agree more with your assessment.

EDIT: Let me clarify the "regulation" portion of this post. I agree that the VA stage should be regulated or powered with a separate winding/transformer but regulating the main rails is a no-no when it comes to developing a quiet design.

RE-EDIT: Ok, forget the regulation debate. I hold certain opinions about this subject and I've changed the wording to reflect an opinion. Thanks.


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## Guest (Oct 13, 2007)

hey dude ... let's explore your anti-regulation claims in the power output stage a bit more 

Is it your position that regulated amps have worse SNR performance? Worse Dynamic Range? If so, show us the data!  It should be obvious from any honest spec sheet for an amp, no?

I hope you're not suggesting a noise component that somehow mysteriously escapes SNR or Dynamic Range measurements over 20kHz?

Not trying to be a dick ... but in my experience, blanket statements like this are usually so full of counter-examples in audio, that they tend to be rather meaningless ...


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## Diru (May 23, 2006)

Yeah yeah regulation on the output tranny rails is a bit over board , but I would still have it if I could.

As far as noise added because of regulation, ain't going to do it. Wouldn't be prudent to say. 

I would only agree that regulation could possibly add noise only if designed poorly. 

And this is not about poor design. 

That is if I follow this correctly in this thread about amps in general.

So its a bit of a pipe dream to think up chit like this, yes yes. 

Can it be done ? phuck yes. but who is going to buy it. 

I think I ramble. 

As for myself , I have 30 years under my belt in electronics. So phuket, lets get some beer and make monsters.

A true techie worries not about spelling and grammer. I mean come on , ever see a doctor write a scirp. 

anywas yeah and stuff


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## Diru (May 23, 2006)

Just had a thought, just like I posted about but, heres the deal.

MONOBLOCKS

ehh ehhh ehhhhh ehhhhhh

same idea on the power

50
100
200
300
600

bigger make a D




Ok it might take up a bit more room, but depending on the layout of the chassis might not be bad at all.........[modular]


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## Guest (Oct 13, 2007)

i'll play some more ...

"Regulation" is, in itself, not a rigid or precisely defined concept ... in that it has to be considered relative to the application. What i mean is this : how "well regulated" is the native power supply system in an automobile? It varies from, say 11 Volts to well over 14 Volts at subsonic frequencies (meaning, over time periods measured in hours or days), and contains how many tens or hundreds of millivots of "hash" well within the audible range (from alternator charging upstream to switching electronics dowstream)? The simple point being, the car's system may certainly be well-regulated enough to keep your headlights bright, and your ignition system functional ... but does this mean it's also well regulated enough for a high-fidelity audio system?

Now ... one may tend to answer in the affirmative, suggesting that the amp just needs enough PSRR (power supply rejection ratio) to accomodate the poorly-regulated (by audio standards) electrical system in the car. To which i will answer the following : a regulated supply inisde the amplifier is nothing more than one (of several) means for improving the amplifier's PSRR


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## DearS (May 14, 2005)

Can I assume Zapco, Arc, and Audison are doing exactly what you guys are saying is appropriate amp building?


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## Diru (May 23, 2006)

Well all most all car amps have some level of regulation going on, hence PWM.

It changes pulse width to increase or decrease voltage output of said supply'

The matter is how well[or hard] the regulation is.



In said unregulated supplies, the more input voltage, the more output voltage[more output power]. And the same can be said for voltage sag. just the opposite[less output].

So this is my thinking on the matter, no matter how well the car system holds the potential voltage at the amp power terminals under heavy current demands there will be a voltage sag. In turn the sag or drop on a unregulated amp will have an effect in its power supply output.


Mkkkkkk


check me,

say you have 14.4 volts on your system, and the amp rails are at say 43.2 V+/- [ give us a ratio of 3:1 ]. now this amp is a unregulated kind. 

now we jam on it, play it loud, piss off the hood at 1 am. we look and see the system voltage dived to 12.8 volts, now what do we have at the rails?====38.4 V+/-

we get 4.8 V+/- loss at the rails or 9.6v of swing lost at the output trannies.



hard regulation, ready set go, 14.4volts system , 43.2 V+/- rails, system dive 12.8 volts, rails 43.2 V+/-. no loss on the output.


I would even get stupid at this point , make a PWM that gave good[nevermind] rails of 60V+/- , then linear regulation at this point with some nice big assed TO-3P trannies. but, this is truely over the top. oh, reg it down to 45-50V+/- what ever. 


harder to do yes, worth it? i think so.



{thinks more about monoblock moduals}







You know I look over at my Aragon 8003, and it screams to me[3 / [email protected] mono blocks right here], give me 90V +/- and lets party.

But I don't have an extra 8003, so no bad thoughts.


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## Guest (Oct 13, 2007)

Diru ... extend your question further  or more accurately, a bit higher in frequency ...

Unregulated amp ... you did an analysis at DC, or at what i've called "subsonic frequencies"  Now what happens if the power supply voltage to the amp varies, not slowly, but at say 200Hz? Will the rail voltages of the unregulated amp's output stage "follow" this variation, as easily as they do much closer to DC? Is _that_ a desirable feature?

It's _all_ PSRR, ladies and gents  How much you got? How much you need? How much noise MIGHT you incur through internal regulation, versus allowing more noise through from the source?


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## Diru (May 23, 2006)

I can't beleive 200hz riding on the DC system voltage would show on the outputs of a unregulated amp. Unless it had bad filter caps or it was a crap amp.

But, I would think 1hz to 20hz[pulling out my arse] would be fairly easy to read on the outputs. 

But, here again if the rail voltages swing the exact same amount with the freq you toss up here[or even the ones pulled out my arse], there would be 0 difference, maken no output at the spk outs.

0 difference doesn't mean its not there. ahhh haaaa you thought you had me. 

Not too sure of this one without putting it to the stone to see first hand.



gave it a bit more thought, the switching xformer is kind of like a hi pass filter[running @ 30 to 70 khz]. making it kind of hard for 200hz to pass, but 1 to 20 hz a bit easier to pass as it is slow enough for an unreged PWM supply to follow. 

now my head hurtz


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## Guest (Oct 13, 2007)

Diru said:


> I can't beleive 200hz riding on the DC system voltage would show on the outputs of a unregulated amp. Unless it had bad filter caps or it was a crap amp.
> 
> But, I would think 1hz to 20hz[pulling out my arse] would be fairly easy to read on the outputs.
> 
> ...


The amp has to accept DC from the input power, no doubt about it. In the absence of active regulation, therefore, the most the amp can hope to do (for improved PSRR) is provide some passive _low-pass filtering_ of the input noise. In which case, it's much _easier_ to filter 1kHz than it is to filter 200Hz  Now the output stage itself will tend to allow higher frequencies that _are_ on the rails to reach the output, moreso than lower frequencies ... because capacitive coupling gets worse, and the effectiveness of the amp's own feedback degrades at higher frequencies. So it seems to me that which one dominates in an unregulated amp is a bit hard to call ...

My educated opinion is this : an excellent amp can be designed with _either_ type of supply ... regulated or unregulated. It's a mistake to categorically dismiss either. I know ... we would all like to live by simple "mantras" in audio ... like "regulated supplies are noiser". But the truth is, there's too many variables at play for such simple statements to apply, all the time, in all cases.


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## Diru (May 23, 2006)

cajunner said:


> Is it possible that car audio amp designers aren't really necessary anymore, because the chinese have enough clues already how to mass produce a working example of "good enough"?



Ain't that the truth......... kind of like that $ehringer guy. Yep and I do use there stuff, alot.


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## Guest (Oct 13, 2007)

Diru said:


> I can't beleive 200hz riding on the DC system voltage would show on the outputs of a unregulated amp. Unless it had bad filter caps or it was a crap amp.
> 
> But, I would think 1hz to 20hz[pulling out my arse] would be fairly easy to read on the outputs.
> 
> ...


If the switching power supply were really a high-pass filter ... how would the DC input be able to supply power to the amp?   

No, a high-pass filter is not a good model for the switching power supply. The switching power supply is a _modulator_ ... it modulates the low-frequency input (DC) of the car's power supply up to a higher frequency, through switching (which can be mathematically modeled as multiplication by a square wave), so that it can be "transformed" to a high voltage through a transformer. Transformers don't work at DC  so we need to _modulate_ to a higher frequency, pass through the transformer for voltage gain (no power gain, of course!), then _demodulate_ with a diode-capacitor rectifier (in principle, much like a simple textbook AM demodulator).

And there's nothing inherent about the switcher itself, operating at 40kHz or higher, to distinguish between DC and 200Hz on the power input. Hence, if you want (or need!) more PSRR, you've got a couple choices : passive low-pass filtering (not trivial to low-pass at frequencies _below_ audio band, while still allowing mongo DC power to pass), or actively regulate the internal supply of the amp to _reject_ the noise on the input supply.

Just remember : no regulation at DC also tends to mean no regulation at very audible frequencies


----------



## envisionelec (Dec 14, 2005)

werewolf said:


> hey dude ... let's explore your anti-regulation claims in the power output stage a bit more
> 
> Is it your position that regulated amps have worse SNR performance? Worse Dynamic Range? If so, show us the data!  It should be obvious from any honest spec sheet for an amp, no?
> 
> ...



Actually I gave you a factual statement based on common power supply engineering knowledge. Instead, I'd like you to prove otherwise based on hearsay or a belief based on spec sheets. In other words, it would make no difference if I gave you a book of numbers and proof if all you wanted to do was question the validity of physical fact.


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## Diru (May 23, 2006)

werewolf said:


> If the switching power supply were really a high-pass filter ... how would the DC input be able to supply power to the amp?
> 
> No, a high-pass filter is not a good model for the switching power supply. The switching power supply is a _modulator_ ... it modulates the low-frequency input (DC) of the car's power supply up to a higher frequency, through switching (which can be mathematically modeled as multiplication by a square wave), so that it can be "transformed" to a high voltage through a transformer. Transformers don't work at DC  so we need to _modulate_ to a higher frequency, pass through the transformer for voltage gain (no power gain, of course!), then _demodulate_ with a diode-capacitor rectifier (in principle, much like a simple textbook AM demodulator).
> 
> ...



Thats what I said I think in so many words or something. Yeah yeah its not hi pass filter [my bad spank monkey], but it is made to pass the switching pulses @ said hi freq. 

I still don't see it passing 200 to 1000 hz through a toriod made to switch @ speced freqs. even if it did I would think it to small.

but , back to 1 to 20 hz, now that can influence the DC system supply voltage, directly effecting the output of the PWM[unreged].

So yeah there and stuff I agree to apoint of , ohhhh group hugg. Get off you fruit!


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## Guest (Oct 13, 2007)

ezaudio said:


> Actually I gave you a factual statement based on common power supply engineering knowledge. Instead, I'd like you to prove otherwise based on hearsay or a belief based on spec sheets. In other words, it would make no difference if I gave you a book of numbers and proof if all you wanted to do was question the validity of physical fact.


clever, but not satisfying ...

If your statement is correct, that regulated power supplies = noisier amps, then a quick survey of many car audio power amps would clearly demonstrate this "fact" ... true? You don't have to present the data yourself, since you're convinced of it's validity. I'm just verifying your confidence that the specs of many car audio amps will clearly demonstrate that the regulated ones are noisier.

True?


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## Guest (Oct 13, 2007)

Diru said:


> Thats what I said I think in so many words or something. Yeah yeah its not hi pass filter [my bad spank monkey], but it is made to pass the switching pulses @ said hi freq.
> 
> I still don't see it passing 200 to 1000 hz through a toriod made to switch @ speced freqs. even if it did I would think it to small.
> 
> ...


200Hz won't pass through the toroid ... any more effectively, really, than DC will pass through the toroid. But that's irrelevant 

Here's how the modulation will work :

DC gets modulated to 30kHz by the switching action, to pass through a small toroid.

200Hz gets modulated to 30.2kHz by the switching action, to pass through the same small toroid.

The switcher itself has no mechanism to filter, or distinguish, bewteen 30kHz and 30.2kHz. Hence, an unregulated amp (without substantial low-pass filtering in place of active regulation) provides ZERO attenuation of low-freq noise to the power amp's rails. How much shows up on the _output_ depends on the PSRR of the amp's signal path


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## envisionelec (Dec 14, 2005)

werewolf said:


> i'll play some more ...
> 
> "Regulation" is, in itself, not a rigid or precisely defined concept ... in that it has to be considered relative to the application. What i mean is this : how "well regulated" is the native power supply system in an automobile? It varies from, say 11 Volts to well over 14 Volts at subsonic frequencies (meaning, over time periods measured in hours or days), and contains how many tens or hundreds of millivots of "hash" well within the audible range (from alternator charging upstream to switching electronics dowstream)? The simple point being, the car's system may certainly be well-regulated enough to keep your headlights bright, and your ignition system functional ... but does this mean it's also well regulated enough for a high-fidelity audio system?
> 
> Now ... one may tend to answer in the affirmative, suggesting that the amp just needs enough PSRR (power supply rejection ratio) to accomodate the poorly-regulated (by audio standards) electrical system in the car. To which i will answer the following : a regulated supply inisde the amplifier is nothing more than one (of several) means for improving the amplifier's PSRR


But if fixing the power supply was the case for improving PSRR in an amplifier, why aren't some of the most expensive home audio amplifiers in the world regulated? They're running at 60Hz and their filter caps recharge at a rate 1/500th of the typical car audio design. PSRR isn't designed to be fixed at the power supply, and you certainly can't do it with a regulated design.

My point is that regulated designs draw more current in slices than an unregulated design. You are seriously stressing the MosFets out during periods of high current draw when the battery voltage is lowest. Think about it: when the amplifier is in most demand of current, the battery voltage is lowest and the amplifier tries to compensate by widening the switching pulse - pulling more current and lowering available voltage again. I'm not getting into magnetic saturation, leakage inductance, radiated RFI and all the gremlins that lurk in regulated designs that elude even good designers and you've got a recipe for disaster.

Regulated designs are unreliable for car audio - and that is a fact.


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## envisionelec (Dec 14, 2005)

werewolf said:


> clever, but not satisfying ...
> 
> If your statement is correct, that regulated power supplies = noisier amps, then a quick survey of many car audio power amps would clearly demonstrate this "fact" ... true? You don't have to present the data yourself, since you're convinced of it's validity. I'm just verifying your confidence that the specs of many car audio amps will clearly demonstrate that the regulated ones are noisier.
> 
> True?


False. Spec sheets will never deliver this information. Noisier can be noisy at 500KHz - nowhere near audio frequencies. But RF oscillations and subsequent ingress certainly affect an amplifier's stability. You would need _two identical amplifiers _- one with and one without a regulated supply to measure the difference. Otherwise, it's just apples and oranges.

I designed the power supply pictured below. It is an unregulated design with linear regulators on the secondary side for low voltage needs of the Behringer DCX2496. I explored and tested a regulated design of this power supply. It was optically isolated, switching at 67kHz. I measured an approximate 7dB increase in conducted noise at 2MHz. Radiated noise - that which will jump right over your filters - jumped tenfold. This was measured with an FCC certified noise detector on a spectrum analyzer. I consequently left the design unregulated. It would have required significant amount of physical filtering (copper shield cans or screening) and that wasn't in the budget.


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## Guest (Oct 13, 2007)

ezaudio said:


> But if fixing the power supply was the case for improving PSRR in an amplifier, why aren't some of the most expensive home audio amplifiers in the world regulated? They're running at 60Hz and their filter caps recharge at a rate 1/500th of the typical car audio design. PSRR isn't designed to be fixed at the power supply, and you certainly can't do it with a regulated design.
> 
> My point is that regulated designs draw more current in slices than an unregulated design. You are seriously stressing the MosFets out during periods of high current draw when the battery voltage is lowest. Think about it: when the amplifier is in most demand of current, the battery voltage is lowest and the amplifier tries to compensate by widening the switching pulse - pulling more current and lowering available voltage again. I'm not getting into magnetic saturation, leakage inductance, radiated RFI and all the gremlins that lurk in regulated designs that elude even good designers and you've got a recipe for disaster.
> 
> Regulated designs are unreliable for car audio - and that is a fact.


It is far, FAR from a "fact" that regulated designs are unreliable for car audio!!  

I ... as well as others, i'm sure ... have used amplifiers with regulated supplies, and found them to be very reliable indeed! Hence, the "fact" is disproven.

It is very true that most home audio amps do not use regulated supplies. A combination of HUGE filtering caps for supply filtering, coupled with good PSRR of the amplifier's signal path, tend to prevent 60Hz from showing up at the output. But car audio is a different story ... the "noise" on the car's supply voltage may be significantly higher than 60Hz, and may more easily couple into the amp's ouput (as i stated, high capacitive coupling, less feedback to fight it). Hence, a good designer will want to filter the noise ... either with passive filtering, or active regulation.

Of course, the duty cycle cycle of the switching FET's must _increase_ to supply the regulated supply as the input voltage _decreases_. But to conclude from this observation that regulated supplies are unreliable is just plain silly ... if the number and type of FET's are designed (and heatsunk) adequately for the duty cycles to be encountered, they will prove to be no more unreliable than different FET's, operating at different duty cycles, in unregulated amps.

The bottom line remains the same : Although I'm sure that poor examples of regulated as well as unregualted amps can be found, EITHER type of amp can be designed to outstanding specs, and great reliability.


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## Guest (Oct 13, 2007)

ezaudio said:


> False. Spec sheets will never deliver this information. Noisier can be noisy at 500KHz - nowhere near audio frequencies. But RF oscillations and subsequent ingress certainly affect an amplifier's stability. You would need _two identical amplifiers _- one with and one without a regulated supply to measure the difference. Otherwise, it's just apples and oranges.
> 
> I designed the power supply pictured below. It is an unregulated design with linear regulators on the secondary side for low voltage needs of the Behringer DCX2496. I explored and tested a regulated design of this power supply. It was optically isolated, switching at 67kHz. I measured an approximate 7dB increase in conducted noise at 2MHz. Radiated noise - that which will jump right over your filters - jumped tenfold. This was measured with an FCC certified noise detector on a spectrum analyzer. I consequently left the design unregulated. It would have required significant amount of physical filtering (copper shield cans or screening) and that wasn't in the budget.


So ... you're worried about noise at 500kHz ... that will never find it's way into a power amp spec. Either increased noise floor, intermodulation distortion, stability at lower impedance loads ... nothing. No place.   

And you haven't even mathematically proven why, or by how much, noisier a regulated amp will be than an unregulated amp?

And you're using this as "evidence" that regulated amps are noisy ??? To be avoided for high quality audio at all costs, categorically, in all cases?

Right ... i think my time is done with this thread. As i've already suggested ... if only good engineering were as simple as memorizing a few "mantras"   

Best of luck!


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## Diru (May 23, 2006)

Ummm I need a drink, leave the bottle.


Um sure LM[linear pack type] linear regulators are noise as hell untreated, all the way up into the radio broadcast band{am radio}, you got to filter them up nicely.

I think I follow you Wolf, you are saying 200 hz on the DC superimposed into switching freq out of the fets. Still not sure if it would pass the toriod. You would have to have bad or next to no caps in the input or output filters banks to really see that 200hz get to the output.


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## Diru (May 23, 2006)

werewolf said:


> 200Hz won't pass through the toroid ... any more effectively, really, than DC will pass through the toroid. But that's irrelevant
> 
> Here's how the modulation will work :
> 
> ...




OH!!!!!!!!!!! 

You got 30khz of switch freq[square wave] + 200hz superimposed ontop[on the high of the square wave only] of the DC supply voltage from the system.. Nope, still don't see it get through...

Need to test this.....ohh and the 30khz and the 200hz don't add together to make a new frequency.


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## Guest (Oct 14, 2007)

Diru said:


> OH!!!!!!!!!!!
> 
> You got 30khz of switch freq[square wave] + 200hz superimposed ontop[on the high of the square wave only] of the DC supply voltage from the system.. Nope, still don't see it get through...
> 
> Need to test this.....ohh and the 30khz and the 200hz don't add together to make a new frequency.


yes, they do ... under the nonlinear operation known as _modulation_ (aka switching).

The input "signal" is "translated" up to the switching frequency (30kHz). DC is translated to 30kHz, to get through the toroid. Anything at 200Hz on the input power will get translated to 30kHz +/- 200Hz ... this is like very simple AM modulation. The toroid does not have the selectivity to distinguish between 30kHz and 30.2kHz ... therefore unregulation of DC, also means unregulation of 200Hz. There's simply no selectivity in the switcher to distinguish between the two.

However, as i've stated, it is possible to distinguish between the two with heavy low-pass filtering (pre or post modulation), to help reject any "noise" before it reaches the output stage supplies. Or, the noise can be actively rejected with active regulation.

It might be interesting to form a list of known car audio amps with regulated supplies ... so we all know which ones are absolutely, factually, without qualification, both noisy and unreliable


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## envisionelec (Dec 14, 2005)

werewolf said:


> So ... you're worried about noise at 500kHz ... that will never find it's way into a power amp spec. Either increased noise floor, intermodulation distortion, stability at lower impedance loads ... nothing. No place.
> 
> And you haven't even mathematically proven why, or by how much, noisier a regulated amp will be than an unregulated amp?
> 
> ...


Sorry, but because you've used an amp...or your friends use an amp with a regulated supply and it "works fine" doesn't prove that it's not a reliable method of designing a car audio amplifier. I personally use a regulated design amp (Xtant 3300c) in my vehicle. It's electrically very noisy, is poorly designed, but it sounds good and was cheap. So I use it for the time being.

I have two words to your first paragraph: Prove it. You still think I should be proving my point when it is common knowledge that, in a debate, you must first disprove a factually questionable statement.

You can read all about the design of audio amplifiers and the negative effects of RFI on an amplifier's ability to accurately reproduce audio. Maybe you should read papers from R.R. Cordell (a personal friend of mine). Or any book on audio amplifier design. Or build some car amplifiers from scratch. 

If only knowledge was as simple as gaining a few thousand posts in an internet chat forum and pretending that reality doesn't exist.


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## envisionelec (Dec 14, 2005)

Diru said:


> Um sure LM[linear pack type] linear regulators are noise as hell untreated, all the way up into the radio broadcast band{am radio}, you got to filter them up nicely.


Really? Let's see the datsheet on that. And...how would that translate on a $70K RFI noise "sniffer". It wouldn't. Stop grasping at straws.


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## envisionelec (Dec 14, 2005)

werewolf said:


> It might be interesting to form a list of known car audio amps with regulated supplies ... so we all know which ones are absolutely, factually, without qualification, both noisy and unreliable


To be nice - you're being absurd. What is your background? You seem to be the book knowledge type with no lab experience whatsoever - otherwise this conversation would have been understood as two points of view rather than a broad brushed "you're wrong" from someone that hasn't even attempted to point out exactly what incorrect thing I've said. I'm not about to get sucked into a debate with someone that has no more than an inkling of an idea of how amplifier power supplies are designed. Compare my statements with bonafide design facts. I still have yet to hear your response to this.


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## ca90ss (Jul 2, 2005)

ezaudio said:


> I'm not about to get sucked into a debate with someone that has no more than an inkling of an idea of how amplifier power supplies are designed.


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## envisionelec (Dec 14, 2005)

ca90ss said:


>



Yes, thank you.


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## ca90ss (Jul 2, 2005)

ezaudio said:


> Yes, thank you.


So you realize you're digging yourself a mighty big hole by calling out one of the most knowledgeable members on this forum.


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## rhinodog00 (Jul 1, 2007)

I was watching the red sox indians game ,but I think that this is going to be much more interesting.


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## envisionelec (Dec 14, 2005)

ca90ss said:


> So you realize you're digging yourself a mighty big hole by calling out one of the most knowledgeable members on this forum.


I thought we were burying the issue. I guess I misread the "plot". Heh.

I've already made my case. I don't personally know these "members of the forum" nor do I know what they do. I can only go by what they say, and I'm not convinced this person isn't overreaching his limits. I'm trying to play fair and state factual information. This individual only has "NO" to say...and I'm not going to be swayed by that. It's nothing personal. I know there are two schools of thought and I was trying to get some semblance of dialogue going about it, but this person doesn't seem interested in fact finding.


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## Guest (Oct 14, 2007)

stop now dude, save yourself.

Unlike yourself (correct me if i'm wrong), i _am_ a degreed electrical engineer. BSEE from Lehigh University 1983, MSEE from MIT 1985. I've designed more electronic circuits than you have even dreamed about. I was a design engineer at AT&T Bell Labs and Crystal Semiconductor, working in digital audio two decades ago, followed by Design Manager, followed by Vice President of Engineering. This, before I left to start my own company called Silicon Laboratories ... you can find all you want through a search. If you want to compare resumes or backgrounds, you will lose. Enough of that.

In this thread you have stated, without qualification, that regulated power amps are noisy (in ways that don't manifest in any known power amp specs over the audio band, by the way) and unreliable. And you think the burden of proof lies with those who question these blanket, categorical, simple-minded statements?

goodbye now


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## Thoraudio (Aug 9, 2005)

I don't post much here anymore.... but, EZ, to quote Cartman.... "Somebody's about to get pwn3d".... 

I think you'll find everybody here has got wolfie's back. He's got the skin's on the wall, the patents in the filing cabinet, and the multi-billion dollar company to prove it.

If you wanna see some good discussions on regulated vs. unregulated, try carsound and Elite for some great discussions including industry notables like Manville Smith, Werewolf, and Richard Clark.

I'm curious as to how your Xtant is noisy, but sounds good? 

BTW, Bruce McMillan would probably disagree with you on that.... as he designed the old PPI's, the Xtants, and the JL / amps.... all of which are tightly regulated amps with a great reputation.


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## CMR22 (Feb 10, 2007)

ezaudio said:


> What is your background? You seem to be the book knowledge type with no lab experience whatsoever...


Knowing who are conversing with is always a good idea, in my humble opinion.


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## envisionelec (Dec 14, 2005)

werewolf said:


> stop now dude, save yourself.
> 
> Unlike yourself (correct me if i'm wrong), i _am_ a degreed electrical engineer. BSEE from Lehigh University 1983, MSEE from MIT 1985. I've designed more electronic circuits than you have even dreamed about. I was a design engineer at AT&T Bell Labs and Crystal Semiconductor, working in digital audio two decades ago, followed by Design Manager, followed by Vice President of Engineering. This, before I left to start my own company called Silicon Laboratories ... you can find all you want through a search. If you want to compare resumes or backgrounds, you will lose. Enough of that.
> 
> ...



My sincerest apologies with respect to questioning your intelligence. However, I must note that you're misintepreting what I've said. I said that regulated power supplies are noisier than unregulated. This is still true. You have to implement more post-secondary filtering to counteract the effects of leakage inductance. 
You have to understand that my persistence has its place and a categorical rebuttal would have been welcomed. Instead, you mocked me and offered no antithesis. You certainly can't expect me to glean from that kind of conversation your extensive background and qualifications. 

It's a cheap shot and you know it. I'm not amused. I am, infact, quite disheartened to learn that, with all those qualifications, you choose egotism over genuine debate. This site is a place for people to learn, not be quashed by an industry veteran. It seems out of place...


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## Thoraudio (Aug 9, 2005)

You're the one who was talking out of his butt. 

The question is, can you _hear_ the difference?


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## envisionelec (Dec 14, 2005)

Thoraudio said:


> You're the one who was talking out of his butt.
> 
> The question is, can you _hear_ the difference?


Thank you for your opinion. 

I don't know. Can you? Do you have two identical amplifiers, one with a regulated supply and one with a non-regulated supply side-by-side in an ABX test? I don't. I stated two things about regulated power supplies and I have yet to hear an opposing viewpoint. I see a lot of "well, it ISN'T like that" but no attempts to reconcile the rebuttal. Sorry, but that's not helpful for anyone. 

I don't like the Xtant amp that much, but sure - it sounds nice. It wreaks havoc with AM reception, though and the toroidal transformer squeals loudly under load. Regulated is great, right?
It is a unique design, but poor implementation. The matched FETs are a nice touch. I don't need to hear what the designer thinks as his opinion might differ from mine. Thanks!


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## Diru (May 23, 2006)

because I can.


we all know thats a 120 outlet.


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## rhinodog00 (Jul 1, 2007)

This would be better if it were just werewolf and ezaudio.


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## Thoraudio (Aug 9, 2005)

ezaudio said:


> Thank you for your opinion.
> 
> I don't know. Can you? Do you have two identical amplifiers, one with a regulated supply and one with a non-regulated supply side-by-side in an ABX test? I don't. I stated two things about regulated power supplies and I have yet to hear an opposing viewpoint. I see a lot of "well, it ISN'T like that" but no attempts to reconcile the rebuttal. Sorry, but that's not helpful for anyone.
> 
> ...



I had an unregulated Rockford that you could hear music out of the toroid. Doesn't prove nothing for nobody. 

90+% of car amps produced today are of the unregulated variety.


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## chad (Jun 30, 2005)

ezaudio said:


> Thank you for your opinion.
> 
> I don't know. Can you? Do you have two identical amplifiers, one with a regulated supply and one with a non-regulated supply side-by-side in an ABX test? I don't. I stated two things about regulated power supplies and I have yet to hear an opposing viewpoint. I see a lot of "well, it ISN'T like that" but no attempts to reconcile the rebuttal. Sorry, but that's not helpful for anyone.
> 
> ...



Regulation has nothing to do with AM reception, it's just a noisy PWM power supply. Un-regulated ones do the same thing when they are noisy.... I have one.

Chad


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## Guest (Oct 14, 2007)

dude, you continue to think ass-bakwards.

YOU questioned my credentials, i offered them ... then you accuse me of dragging ego into this.

YOU made the blanket, categorical statements ... regulated amps are noisy and unreliable ... then suggest that the burden of proof lies with those who question these statements (and, apparently, offering several real examples that counter your facts hold no weight with your type of logic).

But i do agree ... background has nothing to do with logical, rational arguments that are consistent with known principles of electrical engineering. I'll offer some in my next couple posts ... i'll be generous, since this thread seems to have pulled our old friend Thoraudio out of retirement! 

But please keep in mind, the electrical arguments i will make are equally sound, whether they are offered by a degreed engineer or an internet dweeb with no background other than reading a thousand posts. That's the nature of science and engineering, in which there is precious little room for gurus. Listen to the arguments, not the background of those making them ... deal?


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## chad (Jun 30, 2005)

Diru said:


> because I can.
> 
> 
> we all know thats a 120 outlet.


It may be a european cartoon


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## envisionelec (Dec 14, 2005)

rhinodog00 said:


> This would be better if it were just werewolf and ezaudio.


Yeah, this thread went to sh*t in a hurry. I'm no longer answering posts in this thread. I regret ever bringing this up, not because I feel any pressure to stop discussing it, but because its goals are no longer in line with the overall focus of a Do It Yourself Mobile Audio forum.

EDIT: I broke my promise, but only to answer a direct question.


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## Diru (May 23, 2006)

chad said:


> It may be a european cartoon


Shhhhh[im not sure but it looked funny at the time]


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## envisionelec (Dec 14, 2005)

werewolf said:


> Listen to the arguments, not the background of those making them ... deal?


That's all I ask in return. Deal. 

Internet dweeb, eh? That's funny.


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## Diru (May 23, 2006)

werewolf said:


> But please keep in mind, the electrical arguments i will make are equally sound, whether they are offered by a degreed engineer or an internet dweeb with no background other than reading a thousand posts. That's the nature of science and engineering, in which there is precious little room for gurus. Listen to the arguments, not the background of those making them ... deal?





ezaudio said:


> Internet dweeb, eh? That's funny.



Here I thought I was better then that[that is if it was, probably not, nor do i care]

I make a sandwitch now.


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## Guest (Oct 14, 2007)

regarding "noise" ...

Even though the exact reason or analysis behind the statement "regulated amps are noisier" has not been offered by the opposite side of the debate, i will offer what i believe to be argument ... then, i'll respond 

A regulated power supply will necessarily vary duty cycle of the switching supply in order to maintain regulation. It will vary duty cycle to maintain supply as the input voltage varies, and it will vary duty cycle to maintain supply as the current demand on the output changes. The varying duty cycle will manifest as varying "ripple" ... let's call it switching ripple ... on the output supply. The voltage on the output supply cap will "droop" more, if duty cycle is significantly reduced. It is reasonable to conclude that, given this duty cycle variation and the resultant variation in switching ripple, that the magnitude of the ripple will typically _exceed_ that of an unregulated design.

HOWEVER, there are several problems with concluding that this means a noisier amp :

1. The magnitude of the ripple can be reduced by increasing the capacitance on the output rails, or by increasing the switching frequency of the switching power supply. With this recognition, it is entirely possible that a _regulated_ amp with more capacitance or with a higher switching frequency, might actually have _less_ ripple than an unregulated design. In other words ... regulated vs. unregulated is simply not enough info to tell you which has less switching ripple.

2. How much of the switching ripple on the supply rails actually ends up in the audio band at the amp _output_ depends on several factors in the amp's signal path ... including the native PSRR of the signal path, as well the linearity ... since it requires a nonlinear mechanism to modulate ultrasonic switching noise into the audio band. So it's entirely possible to find a amplifer with _more_ switching ripple on the supply rails that actually has _less_ audible noise on the amp output.

So the conclusion is : there are many factors involved! One cannot categorically state that "regulated sux". In addition to the above discussion, which was indeed offered by a degreed engineer but would be equally valid if it were offered by an internet dweeb, further proof is offered by a rather significant number of regulated amps on the market ... with a low enough noise floor to sound just fine


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## DearS (May 14, 2005)

I'd like to understand circuits and amps without getting a degree. Also if learning these things is not useful for me and others, then not worth my while. I hope to have a simple explanation in my possession at one point, but again when and if it I truly believe its worthwhile. 

This post may prove great reference. Thank you!

Wow, so amp design is an art, cool. It seems to follow the same principles as most, maybe all other things. Trial and (wonderful (a lesson), phucking (difficult)) error.

ps...you make this stuff out to be too simple.


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## Thoraudio (Aug 9, 2005)

DearS said:


> Maybe someone will answer this question.....Are amp designs an art? Are there many things that complicated and difficult to achieve in amp design?


Yes, there are many ways to get to the end, different topologies, component types, and even brand names and tolerances.

*BUT* the basics for car amps have been solved for about 15-20 years. Assuming it's in working order, and all the parts are up to spec, a quality amp from 1995 will make good power with no audible noise. Which is why we're at where we are now... they've become a mass produced commodity. That amp in 1995 cost $1/watt.... now you can get the same basic thing for less than $0.25/watt.


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## Guest (Oct 14, 2007)

regarding "reliability" ...

It's a fair point, that a regulated amp may indeed require larger duty cycles from it's switching transistors. This, in order to keep regualtion as input supply drops. So again, one may be tempted to conclude that regulated designs will be less reliable, since the switching devices are more heavily stressed.

HOWEVER, we must once agian realize the such absolutes are too simplistic. What if the regulated amp actually uses _more_ switching devices, acting (essentially) in parallel, to share the extra current (heat)? Or what if the regulated amp employs extra heatsinking to adequately dissipate the extra heat? Clearly, not ALL regulated switching supplies on the planet are unreliable, by virtue of "extra stress". It may very well be that a well-designed _regulated_ supply, with an adequate ... or overkill ... number of switching FET's, extremely well heatsunk, proves to be more reliable than an _unregulated_ design.

I think it's a fair conclusion (even Zeff would agree) that a well-designed _regulated_ amp is _more expensive_ than a well-designed _unregulated_ amp. For the very reasons i've stated ... more supply capacitance (and possibly lower ESR, as well) required, and more (or better) switching devices to accomodate the varying duty cycle. This is a much more reasonable engineering perspective, in my view, than simply stating that unregulated amps are noisy and unreliable.

As further proof, i'll again point to regulated amps on the market ... JL Audio is a great example ... that have a pretty damn good track record as far as reliability is concerned 

My advice, honestly no offense intended : avoid categorical, blanket statements. They tend to trivialize all of us ... not just the one making the statement, but also those engineers working in the field, who work hard to understand all of the relationships between the complex variables ... including cost ... that influence the search for optimal solutions.


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## thehatedguy (May 4, 2007)

Man, it must hurt to get pwnd like that.


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## envisionelec (Dec 14, 2005)

werewolf said:


> regarding "noise" ...
> 
> Even though the exact reason or analysis behind the statement "regulated amps are noisier" has not been offered by the opposite side of the debate, i will offer what i believe to be argument ... then, i'll respond
> 
> ...


Cool, thanks for the simplified version of this. But I wasn't talking about switching ripple. I am talking about large dv/dt reflected to the primary during small percentage duty cycles. If this was a non-issue then we wouldn't need shaped feedback compensation to handle lightly loaded supplies. 
Further, I think you're missing what I'm saying about "noisy amplifiers". So I'm putting it in a separate paragraph:

I'm not saying that the amplifier will exhibit a noticeably lowered signal-to-noise ratio in the spec sheet. You probably won't even hear it. I'm concerned with an amplifier being technically correct, whether or not you actually hear this anamoly (unlikely) - I CAN measure it.

We in the audio business are used to hearing people talk about things we can't (or haven't yet figured out how to) measure - "but I can hear the difference!". I don't think regulated "sux", my opinions (based on my own research and findings) were simply to further a point (of which I can't even remember now), not start a four page debate.

Let's let cooler heads prevail. Shall we?


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## DearS (May 14, 2005)

Thoraudio said:


> Yes, there are many ways to get to the end, different topologies, component types, and even brand names and tolerances.
> 
> *BUT* the basics for car amps have been solved for about 15-20 years. Assuming it's in working order, and all the parts are up to spec, a quality amp from 1995 will make good power with no audible noise. Which is why we're at where we are now... they've become a mass produced commodity. That amp in 1995 cost $1/watt.... now you can get the same basic thing for less than $0.25/watt.



Thank you! I changed the post a little now though.....Topologies, that word stands out. I wanna know about topologies.


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## thehatedguy (May 4, 2007)

Amplifier topologies (basically power supply design and operation differences) from the Rane site:

amplifier classes Audio power amplifiers were originally classified according to the relationship between the output voltage swing and the input voltage swing; thus it was primarily the design of the output stage that defined each class. Classification was based on the amount of time the output devices operate during one complete cycle of signal swing. Classes were also defined in terms of output bias current [the amount of current flowing in the output devices with no applied signal]. For discussion purposes (with the exception of class A), assume a simple output stage consisting of two complementary devices (one positive polarity and one negative polarity) using tubes (valves) or any type of transistor (bipolar, MOSFET, JFET, IGFET, IGBT, etc.).

[Historical Notes marked "GRS" provided by Gerald R. Stanley, Senior V.P. of Research, Crown International, Inc., designer of the famous Crown DC-300, inventor of the Crown K Series switchmode amplifier line and holder of over 30 U.S. Patents.]

[GRS on amplifiers: "At first there were no amplifiers as the very thought of amplification had yet to enter the vocabulary of electronics (another word which had yet to be birthed!). The invention of a three-terminaled device (DeForest Audion U.S. patent 841,386 or later triode) was the invention in 1906 of a more sensitive radio detector and not an element for an amplifier.

By 1912 the triode had become both a vacuum tube and an amplifier (multiple names can be attached to this collective achievement). The oscillator also dates to 1912 giving proof to the saying "When you set out to make an amplifier you get an oscillator and when you attempt to make an oscillator you get an amplifier."]

[GRS on amplifier classes: "Originally it was adequate to distinguish amplifier classes only by the conduction angles of the control elements (tubes or valves). More recently it has been necessary to add distinctions that relate to topology, degrees of conduction and control methods to be able to determine class."] 

Class A operation is where both devices conduct continuously for the entire cycle of signal swing, or the bias current flows in the output devices at all times. The key ingredient of class A operation is that both devices are always on. There is no condition where one or the other is turned off. Because of this, class A amplifiers in reality are not complementary designs. They are single-ended designs with only one type polarity output devices. They may have "bottom side" transistors but these are operated as fixed current sources, not amplifying devices. Consequently class A is the most inefficient of all power amplifier designs, averaging only around 20% (meaning you draw about 5 times as much power from the source as you deliver to the load.) Thus class A amplifiers are large, heavy and run very hot. All this is due to the amplifier constantly operating at full power. The positive effect of all this is that class A designs are inherently the most linear, with the least amount of distortion. [Much mystique and confusion surrounds the term class A. Many mistakenly think it means circuitry comprised of discrete components (as opposed to integrated circuits). Such is not the case. A great many integrated circuits incorporate class A designs, while just as many discrete component circuits do not use class A designs.]

[GRS Historical Note: "Class A - The most basic of operating modes saw both single-ended and push-pull embodiments by 1913. The first known use of push-pull appears in a patent of E.F.W. Alexanderson of GE U.S. 1,173,079 filed in 1913. While Alexanderson would have been aware of other levels of biasing his push-pull stage, such as classes B and C, he would have only been able to produce a useful result with a tuned stage such as a transmitter where resonant filtering would have managed the distortion problem. Negative feedback is not understood in 1913 to be able to cope with distortion problems."]

Class B operation is the opposite of class A. Both output devices are never allowed to be on at the same time, or the bias is set so that current flow in a specific output device is zero when not stimulated with an input signal, i.e., the current in a specific output flows for one half cycle. Thus each output device is on for exactly one half of a complete sinusoidal signal cycle. Due to this operation, class B designs show high efficiency but poor linearity around the crossover region. This is due to the time it takes to turn one device off and the other device on, which translates into extreme crossover distortion. Thus restricting class B designs to power consumption critical applications, e.g., battery operated equipment, such as 2-way radio and other communications audio.

[GRS Historical Note: "Class B - This class has no obvious inventor, but it does have its master and perfector. Loy Barton working for RCA developed tube designs and biasing methods to manage the open loop distortion of class B push-pull power stages. His IRE paper in 1931 titled "High Output Power from Relatively Small Tubes" is a landmark in the history of class B. Technically he only used class AB but the distinction was not in the language. Class AB is a later and probably unnecessary class fabrication."]

Class AB operation is the intermediate case. Here both devices are allowed to be on at the same time (like in class A), but just barely. The output bias is set so that current flows in a specific output device appreciably more than a half cycle but less than the entire cycle. That is, only a small amount of current is allowed to flow through both devices, unlike the complete load current of class A designs, but enough to keep each device operating so they respond instantly to input voltage demand s. Thus the inherent non-linearity of class B designs is eliminated, without the gross inefficiencies of the class A design. It is this combination of good efficiency (around 50%) with excellent linearity that makes class AB the most popular audio amplifier design.

Class AB1 & AB2 Subdivisions of Class AB developed for vacuum tube design. These subsets primarily describe grid current behavior: Class AB1 has no current flowing into the grid of the tube, and Class AB2 has some current flowing into the grid. Class AB1 operates closer to Class A, while Class AB2 operates closer to Class B. Most bipolar solid-state amplifiers would be classified as Class AB2, while power JFET designs mimic Class AB1.

Class AB plus B design involves two pairs of output devices: one pair operates class AB while the other (slave) pair operates class B.

[GRS Historical Note: "Class AB+B is a term that I'd coined and is intended to be very descriptive but is not truly worthy of its own class. The Crown DC-300 was the first to use this mode of operation in 1968."]

Class BD Invented by Robert B. Herbert in 1971 U.S. patent 3,585,517 and improved on by Neil Edward Walker as disclosed in his 1971 U.S. patent 3,629,616. Both patents are concerned with improving original class D design efficiencies by using various bridge connections and cancellation techniques. And most recently more improvements are claimed by inventors James C. Strickland & Carlos A. Castrejon in their U.S. patent 6,097,249 assigned to Rockford Corporation in 2000 for their Fosgate-brand automotive amplifier.

[GRS comments: "This is a class designation that would best be forgotten. It has been applied to multiple modulation schemes on a class D derived full-bridge. This is perhaps the most reinvented class design in recent history with "filter-less amplifiers" and other such things. An interleave of two class D full-bridge is what we actually have here, and it is a good improvement to an interleave of one class D full-bridge. However an interleave of four is actually possible on a full-bridge if one uses Class I design."]

Class C use is restricted to the broadcast industry for radio frequency (RF) transmission. Its operation is characterized by turning on one device at a time for less than one half cycle. In essence, each output device is pulsed-on for some percentage of the half cycle, instead of operating continuously for the entire half cycle. This makes for an extremely efficient design capable of enormous output power. It is the magic of RF tuned circuits (flywheel effect) that overcomes the distortion create d by class C pulsed operation.

Class D operation is switching, hence the term switching power amplifier. Here the output devices are rapidly switched on and off at least twice for each cycle (Sampling Theorem). Theoretically since the output devices are either completely on or completely off they do not dissipate any power. If a device is on there is a large amount of current flowing through it, but all the voltage is across the load, so the power dissipated by the device is zero (found by multiplying the voltage across the device [zero] times the current flowing through the device [big], so 0 x big = 0); and when the device is off, the voltage is large, but the current is zero so you get the same answer. Consequently class D operation is theoretically 100% efficient, but this requires zero on-impedance switches with infinitely fast switching times -- a product we're still waiting for; meanwhile designs do exist with true efficiencies approaching 90%.

[Historical note: the original use of the term "Class D" referred to switching amplifiers that employed a resonant circuit at the output to remove the harmonics of the switching frequency. Today's use is much closer to the original "Class S" designs.]

[GRS Historical Note: "Class D is a subset of all possible switch-mode amplifier topologies that is typified by use of the half-bridge (totem-pole) output stage that has two interconnected switches operating in time alternation. The paradigm is that of Loy Barton's class B, but uses the statistics of conduction angle to produce amplification (PWM). There are many subclasses within class D that describe the origins of the modulation. Class D is at least as old as 1954 when Bright patented a solid-state full-bridge servo amplifier U.S. 2,821,639."] 

Class E operation involves amplifiers designed for rectangular input pulses, not sinusoidal audio waveforms. The output load is a tuned circuit, with the output voltage resembling a damped single pulse. Normally Class E employs a single transistor driven to act as a switch.

The following terms, while generally agreed upon, are not official classifications:

Class F Also known by such terms as "biharmonic," "polyharmonic," "Class DC," "single-ended Class D," "High-efficiency Class C," and "multiresonator." Another example of a tuned power amplifier, whereby the load is a tuned resonant circuit. One of the differences here is the circuit is tuned for one or more harmonic frequencies as well as the carrier frequency. See References Krauss, et al. for complete details.

[GRS Historical Note: "Classes E and F are distinguished by their resonant topology and not conduction angle else we would class them with C. A good reference to these is found in the many patents of Nathan Sokal. Also class S which is very old (1929-1930) has similar applications (resonant RF)."]

Class G operation involves changing the power supply voltage from a lower level to a higher level when larger output swings are required. There have been several ways to do this. The simplest involves a single class AB output stage that is connected to two power supply rails by a diode, or a transistor switch. The design is such that for most musical program material, the output stage is connected to the lower supply voltage, and automatically switches to the higher rails for large signal peaks [thus the nickname rail-switcher]. Another approach uses two class AB output stages, each connected to a different power supply voltage, with the magnitude of the input signal determining the signal path. Using two power supplies improves efficiency enough to allow significantly more power for a given size and weight. Class G is common for pro audio designs.

[Historical note: Hitachi is credited with popularizing class G designs with their 1977 Dynaharmony HMA 8300 power amplifier, however it is shown much older by GRS: "Class G - I have been searching for the proper inventor of this class, but have not been able to find a reference older than 1965 when I first encountered it in a college text "Handbook of Basic Transistor Circuits and Measurements" by Thornton et al., SEEC vol. 7. The method is introduced without references or fanfare. One is led to believe that it was common knowledge in 1965 and earlier. This is not the first known use of extended quasi-linear methods (beyond class B), as there is a dual found in Fisher U.S. 2,379,513 from 1942."]

Class H operation takes the class G design one step further and actually modulates the higher power supply voltage by the input signal. This allows the power supply to track the audio input and provide just enough voltage for optimum operation of the output devices [thus the nickname rail-tracker or tracking power amplifier]. The efficiency of class H is comparable to class G designs.

[Historical note: Soundcraftsmen is credited with popularizing class H designs with their 1977 Vari-proportional MA5002 power amplifier, however like class H above GRS finds precedence: "Class H - The apparent inventor of class-H in full-blown multi-level form was Manuel Kramer of NASA in 1964 U.S. patent 3,319,175. Class H optimally applied to a full-bridge was invented in 1987 (Stanley) U.S. 4,788,452. Classes G and H are all members of a class of amplifiers that has articulated rail voltages to improve the efficiency of class B power stages. Examples are available of tracking using binarily weighted segments, (Stanley) U.S. 5,045,990. Continuously variable tracking with switch-mode PWM appears to have been first done by Hamada in 1976 U.S. 4,054,843. The ultimate rail tracker using interleaved technology is found in (Stanley) U.S. 5,513,094. Only with interleave is the converter fast enough to meet the needs of full-bandwidth audio and yet have low switching losses."]

Class I operation invented and named by Gerald R. Stanley for amplifiers based on his patent U.S. 5,657,219 covering opposed current converters.

[GRS explains: The "I" of the class is short for "interleave" as this is the only four-quadrant converter known that uses two switches yet has an interleave number of 2 in the terminology of interleave. When used with fixed-frequency natural two-sided PWM it forms a theoretically optimum converter having the least unnecessary/undesirable PWM spectra. A good reference is found in the IEEE Transactions on Power Electronics Vol. 14, No. 2, March 1999, pages 372-380."]

Class J operation is the category/name suggested by Gerald R. Stanley for amplifiers that combine class B and class D where converters act in parallel to drive the load.

[GRS elaborates: "There are serious problems with the power efficiency of these products when processing fast signals into arbitrary loads. The class B stage is used to actively remove the ripple of the class D stage and other distortion problems that plague class D. No solution is offered for the MOSFET CSOA (current safe operating area) problem of class D. To solve that problem it would be necessary to parallel a class I and class B amplifier but this would be without merit as the class I amplifier generally does not need the class B amplifier to meet fidelity requirements."]

Class S First invented in 1932, this technique is used for both amplification and amplitude modulation. Similar to Class D except the rectangular PWM voltage waveform is applied to a low-pass filter that allows only the slowly varying dc or average voltage component to appear across the load. Essentially this is what is termed "Class D" today. See References Krauss for details.

[Final GRS Amplifier Historical Note: "All of our amplifier classes have thrived under a very important invention, without which most would have floundered. That invention is, of course, negative feedback. Harold Black in 1927 changed our world forever while riding to work on the Lackawanna Ferry. (See U.S. patent 2,102,671.) Harold Black did not stop there however, he also in 1953 wrote the text "Modulation Theory" which we today use to understand the fundamentals of PWM. In 1935, Terman, in his now famous "Fundamentals of Radio" handbook, wrote that it was good that class B was only used in places like radio stations as there needed to be an engineer on duty full time to keep the bias tweaked to where the distortion was acceptable. Thanks go to Harold Black for changing all that and leading us into the next century of amplification."]




DearS said:


> Thank you! I changed the post a little now though.....Topologies, that word stands out. I wanna know about topologies.


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## envisionelec (Dec 14, 2005)

werewolf said:


> My advice, honestly no offense intended : avoid categorical, blanket statements. They tend to trivialize all of us ... not just the one making the statement, but also those engineers working in the field, who work hard to understand all of the relationships between the complex variables ... including cost ... that influence the search for optimal solutions.



You're correct. My assessment was oversimplified. I apologize for getting everyone heated over this...  

Still trying to figure out what "getting Pwned" is. NM, I just Googled it. :blush: Yep, I was "pwned" in a way, but you have to understand that the innate anonimity of the internet certainly goes a long way towards creating embarrasing situations.


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## DearS (May 14, 2005)

Thank you! Hatedguy, I understand topologies a bit now. 

another question, Can someone tell what topology is in use from the sound?


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## Neil (Dec 9, 2005)

DearS said:


> another question, Can someone tell what topology is in use from the sound?


About as likely as being able to tell the difference between regulated and unregulated power supplies.



Sure, there are differences, but you can't categorically state that "Class A/b sounds like this" and "Class D sounds like that." There are so few constants in life.


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## DearS (May 14, 2005)

Thank You for the response, but the response is not quite instructive.

Maybe a creditable reference...JL makes regulated and unregulated amps, they say they are same besides that. I've heard them, then they really sounded different to me.

also I'm a pretty tactful person.


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## ArcL100 (Jun 17, 2005)

A watt is a watt.

-aaron


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## DearS (May 14, 2005)

ArcL100 said:


> A watt is a watt.
> 
> -aaron


Again not very instructive. I see Arc no? why not pyramid? no need to answer.


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## thehatedguy (May 4, 2007)

This is my opinion only...you are more apt to hear differences in topology with high sensitive speakers. Why? You will be listening to average levels with less than a watt of power...now I'm talking 100+ dB sensitive speakers here, not the typical home fi stuff at 87-88 dB.

Now, telling the difference between a solid state class A amp and a tube class A will start to get more difficult, especially when you are talking about JFET solid state amps vs your average SE tube amp.


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## DearS (May 14, 2005)

thehatedguy said:


> This is my opinion only...you are more apt to hear differences in topology with high sensitive speakers. Why? You will be listening to average levels with less than a watt of power...now I'm talking 100+ dB sensitive speakers here, not the typical home fi stuff at 87-88 dB.
> 
> Now, telling the difference between a solid state class A amp and a tube class A will start to get more difficult, especially when you are talking about JFET solid state amps vs your average SE tube amp.


So discernible difference between the sound output of topologies exist?


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## thehatedguy (May 4, 2007)

Again, my opinion, yes.

With such sensitivities, you can hear the smallest details. Crossover distortion in a/b amps could make such speakers sound harsh...but you'd never hear it on "typical" speakers.


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## ca90ss (Jul 2, 2005)

thehatedguy said:


> Again, my opinion, yes.
> 
> With such sensitivities, you can hear the smallest details. Crossover distortion in a/b amps could make such speakers sound harsh...but you'd never hear it on "typical" speakers.


What about the amps that claim to operate in class A up to x amount of watts and then switch to A/B?


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## DearS (May 14, 2005)

thehatedguy said:


> Again, my opinion, yes.
> 
> With such sensitivities, you can hear the smallest details. Crossover distortion in a/b amps could make such speakers sound harsh...but you'd never hear it on "typical" speakers.



I see what you mean. The speakers sensitivity works as a show case for the amps output distortion. Although I'm not sure things work like that. If so, then this points out a short coming in typical speakers in their ability to reveal details. If this is true, Its a new level of complexity for me.


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## thehatedguy (May 4, 2007)

You have one speaker that makes 100+ dB with one watt of input or another that make 88 dB with one watt of input. It is easy to see how much power you either need to make to get the same output...or the other way, how little power you need to get the same output.

Check out this post where werewolf and I get into this on ECA:

http://forum.elitecaraudio.com/showthread.php?threadid=117478

No comment on the class A for 10 watts and 150 after that...no first hand experience with them. But from what I hear, the Genesis and Tru amps like that were the real deal in class A operation.


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## DearS (May 14, 2005)

DearS said:


> I see what you mean. The speakers sensitivity works as a show case for the amps output distortion. Although I'm not sure things work like that. If so, then this points out a short coming in typical speakers in their ability to reveal details. If this is true, Its a new level of complexity for me.


Changed this statement a little...

Typical speakers have a trait that results in challenging the amp's output clarity's significance.

Thank you interesting thread. I see the humility of you guys in that post.LOL

I have a question...do ICE power amps have crossover distortion?


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## Abmolech (Nov 2, 2006)

Hi Ezaudio,

I hope you will keep posting, some of us learn more from starting conversations with some controversial statements.
(I have stood on a few toes myself :blush: )

At least it has spurred people into contributing to a worthwhile thread.


> Still trying to figure out what "getting Pwned" is. NM, I just Googled it. Yep, I was "pwned" in a way, but you have to understand that the innate anonimity of the internet certainly goes a long way towards creating embarrasing situations.


Your more of a scientist than most of these inane posters cognitive comprehension will allow. You can't be "pwned", "owned" or a host of other superlatives, offered a upon this alter of "winning" because your open minded and can admit your short comings.

Congratulations and I salute you.

Although implying that lycanthrope one is a lunatic, may not illicit the desired reaction.


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## DearS (May 14, 2005)

Abmolech said:


> Hi Ezaudio,
> 
> I hope you will keep posting, some of us learn more from starting conversations with some controversial statements.
> (I have stood on a few toes myself :blush: )
> ...


hahahaha. Thats a cool post to some degree. What kindness! 

Not sure if I'm minding my business but here goes....

Superlatives are often used as elicitations of inferiority to some degree. Although the person affirming it may not be honest with him/herself about it. Comparison of one with another is meaningless. By the same token, illicit affirmation is powerless and meaningless to others. We are not the source of each others means. Although that source is universal. My and/or their choices may result in an offering for elicitation to a self conclusion that is negative. It is not a coherent determination of our beings means. For that look in your heart. You'll find no one here is inane! If that seems like the default conclusion, its a lie. No one on earth is inane! We are works in progress, in process. Just like was said about Mr. Ezaudio......"because your open minded and can admit your short comings." We are all open minded, We simply have a hard time seeing that, and responding appropriately. Any truth about us, is a bit bigger than what a self elicitation of our self-identity critiqued can enlighten. Also I happen to think all elicitations are lies in disguise, I prefer evocations.


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## low (Jun 2, 2005)

some good stuff in this thread. now time to catch some zzzzz..


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## cheesehead (Mar 20, 2007)

DearS said:


> Superlatives are often used as elicitations of inferiority to some degree. Although the person affirming it may not be honest with him/herself about it. Comparison of one with another is meaningless. By the same token, illicit affirmation is powerless and meaningless to others. We are not the source of each others means. Although that source is universal. My and/or their choices may result in an offering for elicitation to a self conclusion that is negative. It is not a coherent determination of our beings means. For that look in your heart. You'll find no one here is inane! If that seems like the default conclusion, its a lie. No one on earth is inane! We are works in progress, in process. Just like was said about Mr. Ezaudio......"because your open minded and can admit your short comings." We are all open minded, We simply have a hard time seeing that, and responding appropriately. Any truth about us, is a bit bigger than what a self elicitation of our self-identity critiqued can enlighten. Also I happen to think all elicitations are lies in disguise, I prefer evocations.


 Wow!


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## Rudeboy (Oct 16, 2005)

Is part of the regulated/unregulated debate going to depend on the capabilities of the vehicle's electrical system? This stuff is way over my head, but I have the felling that a bit of what separates the werewolf and ezaudio positions could be removed if each defined the operating context.


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## Oliver (Jun 25, 2007)

Rudeboy said:


> Is part of the regulated/unregulated debate going to depend on the capabilities of the vehicle's electrical system? This stuff is way over my head, but I have the felling that a bit of what separates the werewolf and ezaudio positions could be removed if each defined the operating context.


I think I "understand" your question, and no the electrical system is not in play, I believe they are discussing the merits of one design over the other design.

Werewolf has pointed out that "regulated" amps have distinguished their place in audio designs for cars: read that "they are just fine as a power supply", not noisier in the final analysis, just more expensive to manufacture.

EZ is contending he believes "unregulated designs have distinguished themselves as being less noisy".

If either design is getting the job done, then I'm sure they will both remain as viable options to power your drivers.

Unless of course I don't comprehend what I'm reading...if so, I apologize for wasting your time!


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## envisionelec (Dec 14, 2005)

DearS said:


> hahahaha. Thats a cool post to some degree. What kindness!
> 
> Not sure if I'm minding my business but here goes....
> 
> Superlatives are often used as elicitations of inferiority to some degree. Although the person affirming it may not be honest with him/herself about it. Comparison of one with another is meaningless. By the same token, illicit affirmation is powerless and meaningless to others. We are not the source of each others means. Although that source is universal. My and/or their choices may result in an offering for elicitation to a self conclusion that is negative. It is not a coherent determination of our beings means. For that look in your heart. You'll find no one here is inane! If that seems like the default conclusion, its a lie. No one on earth is inane! We are works in progress, in process. Just like was said about Mr. Ezaudio......"because your open minded and can admit your short comings." We are all open minded, We simply have a hard time seeing that, and responding appropriately. Any truth about us, is a bit bigger than what a self elicitation of our self-identity critiqued can enlighten. Also I happen to think all elicitations are lies in disguise, I prefer evocations.


However you describe it, the terms evocation and elicitation are considered synonymous in the English language; so forgive me for not having the slightest clue as to your intended meaning. Also, the lack of possessive and plural apostrophes in your sentences makes reading difficult.


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## DearS (May 14, 2005)

ezaudio said:


> However you describe it, the terms evocation and elicitation are considered synonymous in the English language; so forgive me for not having the slightest clue as to your intended meaning. Also, the lack of possessive and plural apostrophes in your sentences makes reading difficult.



I was saying Elicitations are about negative affirmations, Evocations are positive ones. I see them being used as such usually.


Example....Go F*** yourself is illicit. Its a negatively affirmation to us. Its saying we are not deserving of good. Hence its used in CD labels to describe this.

My intended meaning is a bit difficult to describe. I tried by best. Basically there is nothing wrong with us, is what I am saying. We were called inane. We are not. That was an illicit statement. I was defrauding that statement. I was also stating what the truth really was, and why it what makes sense.

When I say "means" in my last post, I mean our worthiness. I said "We are not the source of each others means". We are not the source of each others worth. In other words we, our behavior does not determine each others worth. Who here than can determine if someone is inane, they are not our source ie. god. They can offer an evocation to us, reminding us who we are. Or present an elicitation of the opposite. 

Illicit and Evoke are often used as the same. But I guess I'm using them to better discern between the lines.


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## envisionelec (Dec 14, 2005)

Abmolech said:


> Hi Ezaudio,
> 
> I hope you will keep posting, some of us learn more from starting conversations with some controversial statements.
> (I have stood on a few toes myself :blush: )
> ...


Yes, that's an interesting point you make. Thank you for your kind words. As DearS says (and I agree with him), it is better to evoke positive reactions by using non-inflammatory language. I believe that further enlightenment eludes those that would shun admission to error than accept it.


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## DearS (May 14, 2005)

Thank you, Thank you . The praise the feedback 

Its very interesting how Things in the Audio world evoke spirituality. Spirituality and Audio are parallel. Enlightenment results in distortion being more easily discernible by its weight on the systems clarity. Same thing in both audio and our spiritual journey. Its not coincidence we love car audio. We are love, car audio reminds us of this ie. resonates with us.

Another one. We are amplifiers/oscillators. Our resonant frequency is love. Love the frequency of no separation. When we accept ourselves we are oscillating. We are working as amplifiers of truth. 

Its difficult to be class A amps, dynamic to real life leves, and an insensitive speaker. Its difficult to be fulfilled. Hence we need to grow/change our system one way or the other to find whats best for us. We are on a journey. We are a work in progress, in process.

ps. Love is a choice.


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## Bluto Blutarsky (Apr 1, 2007)

DearS said:


> Thank you, Thank you . The praise the feedback
> 
> Its very interesting how Things in the Audio world evoke spirituality. Spirituality and Audio are parallel. Enlightenment results in distortion being more easily discernible by its weight on the systems clarity. Same thing in both audio and our spiritual journey. Its not coincidence we love car audio. We are love, car audio reminds us of this ie. resonates with us.
> 
> ...


 Normally, I need to be completely blasted to come up with this kind of stuff.


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## durwood (Mar 7, 2007)

I hope everyone can get past egos and this can develop into a good amp discussion.

I'd like to see where this is going still. I'd really like to maybe see a good head to head of amp examples that go with cheap resistor divider networks vs differential amp inputs, unregulated amp vs regulated amps, low ESR vs high ESR in power supplies, etc etc.

I own the XTANT3300C and can attest to it creating EMI and screwing up radio reception, but I also own some older soundstreams (original Ref series), A/d/s and I briefly owned some newer topolgy designs that didn't quite last more than a week (Tripath).  

Someone correct me if I'm wrong, but I also owned a couple kicker ZR amps 1st and 2nd gen. The 2nd gen stated that they went with an unregulated design (and admitted it was to save cost right in the manual). Now subjectively, from a noise standpoint, I couldn't tell the 2nd gen was any noiser than the 1st gen. I know this doesn't mean much, but just something to think about.


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## thehatedguy (May 4, 2007)

There is no reason to have a high ESR power supply...unless you want a bad design from the start.


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## DearS (May 14, 2005)

I'm going to need to look up the meaning of many technical terms....back to the topic

Perhaps we need to look at why bad designs continue being viable. I think the simple answer is people are brainwashed with dysfunctional logic. Why, because at some point being honest and having more integrity became too difficult, painful and/or scary. Like in my last posts, We are looking for things that resonate with us, so that we can feel happy. Money seems to be the easier way to that. Its funny that the closest thing to a technical advancement for me seems to be working harder and buying better equipment. I mean I'd be excited to own an Arc SE. On second thought Ill add damping/absorbers to my car.


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## Guest (Oct 14, 2007)

durwood said:


> I hope everyone can get past egos and this can develop into a good amp discussion.
> 
> I'd like to see where this is going still. I'd really like to maybe see a good head to head of amp examples that go with cheap resistor divider networks vs differential amp inputs, unregulated amp vs regulated amps, low ESR vs high ESR in power supplies, etc etc.
> 
> ...


not much more i can add to the regulated vs. unregulated debate. As Thor already mentioned, it's been discussed & beaten to death on all the car audio boards ... _for years_. The very presence of such a hotly debated topic means that the market has not eliminated either one as clearly inferior. For more info than you would ever care to know ... including very intelligent discussions by Manville Smith, Robert Zeff, etc ... just plug in the keywords "regulated unregulated" over on carsound. Set aside an afternoon, kickback and enjoy the ride 

I'll stand by my comments : EITHER topology is capable of absolutely fine performance ... concerning both noise and reliability. There are too many factors at play to summarily dismiss one versus the other, but I do believe a well-executed _regulated_ design will _cost_ more (for reasons already presented). And if memory serves, this perspective is shared by Robert Zeff (in an interview from Car Audio and Electronics, i think ... i'm sure a link can be found), as well as the manufacturer mentioned above. Perhaps one need look no further, to understand a major market trend in this god-forsaken business 

You will, no doubt, find noisy versions of both (as already presented by others in this thread), and you will find unreliable versions of both. Of course this observation, in itself, _proves_ nothing ... unless statistically meaningful correlations to power supply design are established (it's worth mentioning, though, that the unrelenting rules of logic dictate that it only takes one example to _disprove_ a broad claim  ).

it's all good  We're all passionate about this hobby. Nothing wrong with a good e-argument now and again ...


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## durwood (Mar 7, 2007)

thehatedguy said:


> There is no reason to have a high ESR power supply...unless you want a bad design from the start.


True, I guess what I meant was that in some amp power supply designs you will see a fairly large number of caps vs amps with a smaller quantity. I don't think any amp would want a high ESR as you have suggested either, I'm just wondering if it's really something to worry about or not, I'm not talking huge swing from one end to the other, just where does it start becoming a problem.



werewolf said:


> For more info than you would ever care to know ... including very intelligent discussions by Manville Smith, Robert Zeff, etc ... just plug in the keywords "regulated unregulated" over on carsound. Set aside an afternoon, kickback and enjoy the ride


I'll keep that in mind when I free time. It might make for some good "office" material. 



> I'll stand by my comments : EITHER topology is capable of absolutely fine performance ... concerning both noise and reliability. There are too many factors at play to summarily dismiss one versus the other, but I do believe a well-executed _regulated_ design will _cost_ more (for reasons already presented). And if memory serves, this perspective is shared by Robert Zeff (in an interview from Car Audio and Electronics, i think ... i'm sure a link can be found), as well as the manufacturer mentioned above. Perhaps one need look no further, to understand a major market trend in this god-forsaken business


Agreed


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## DearS (May 14, 2005)

Why design a better amp now?

Looking at the world, Who has good reason to stop making BS amps? BS amps make sound, thats still good, no matter how cheap the sound. I find one simple reason, because they do not resonate in a fulfilling way with human beings. Same reason I see others give up Crunch and Pyramid amps. Same reason people go looking for audio upgrades. I'm pretty practical, I try to do what works to live in luxury. A better amp can offer me more luxury. I have other options for luxury though. I want to see where the average person is. I need look at their budget, comprehension and resources. This may give me a clue as to where things are and where they are going. 

With forums like this one, its easy to see more people jumping on the high fidelity bandwagon. It will take time, but we are pioneers, we are advancing the cause.


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## Luke352 (Jul 24, 2006)

Well thought I'd throw out a challenge to "ezaudio" in a non serious friendly way  , I've attached two pics of amp internals from a manufacturer, and thought I'd see what you can tell us about it, power supply style, whether you consider it a solid design, is it a copy of someone else's design, can you pick the manufacturer, Of course others can chip in there opinions  

P.S. It's not American, or Asian built.


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## envisionelec (Dec 14, 2005)

Luke352 said:


> Well thought I'd throw out a challenge to "ezaudio" in a non serious friendly way  , I've attached two pics of amp internals from a manufacturer, and thought I'd see what you can tell us about it, power supply style, whether you consider it a solid design, is it a copy of someone else's design, can you pick the manufacturer, Of course others can chip in there opinions
> 
> P.S. It's not American, or Asian built.


Right, it's German. Audio System amplifiers - part of Steg Audio. I'm sure it's fine, the Germans don't skimp.

However, it's mostly SMD which I can't see from looking at some dark, fuzzy pictures...sorry.


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## Guest (Oct 16, 2007)

come on guys, now this is silly ... and not fair to ezaudio.

Do we really need to test his skills to visit the ampguts website, and match a photo to a manufacturer?  

First photo : Audio System F4-560
Second photo : Audio System F2-500


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## solacedagony (May 18, 2006)

I think it'd be interesting if we did one of those "Tech Clinic" type threads where we take an *extremely* basic amp design (schematic) and pick it apart to understand how and why it works (input, power supply, output). Maybe then add some things to make it work better, whatever. We seem to have quite a few capable engineers or electrical guys here so it could be quite an informational thread.

I might be proposing something not at all viable, so just tell me to shut up if so.  But I think that would be pretty cool.


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## Thoraudio (Aug 9, 2005)

cajunner said:


> The old smd vs. big ol' parts debate commences...
> 
> when Ranger came out with that, and touted greater reliability in the radios, it was hailed a major advance.
> 
> ...


Don't you know, RF's BBQ amps are the bestust thing evah!! I heart old school....

of course I'm old school enough to remember that when they came out, everybody liked the 'really old school' stuff better.


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## chad (Jun 30, 2005)

I think a lot of the lingering hate for SMD comes from old skool techs that find them a PITA to work on. I know I sure hated it at first, there IS a learning curve. But man, when I got good at it I SWEAR it's faster because you no longer have to flip tthe board over or put it on it's end and work from both sides!

I have seen less solder related failures with SMT stuff BUT, and a big BUT, there are some compopnents that just CANT be SMD...... Like things that go up in flames  For example Emitter Resistors in Crown's CE series  Sometimes you still need external surface area and mass to shag off heat and sometimes sudden heat, that's all there is to it.

Chad


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## envisionelec (Dec 14, 2005)

chad said:


> I think a lot of the lingering hate for SMD comes from old skool techs that find them a PITA to work on. I know I sure hated it at first, there IS a learning curve. But man, when I got good at it I SWEAR it's faster because you no longer have to flip tthe board over or put it on it's end and work from both sides!
> 
> I have seen less solder related failures with SMT stuff BUT, and a big BUT, there are some compopnents that just CANT be SMD...... Like things that go up in flames  For example Emitter Resistors in Crown's CE series  Sometimes you still need external surface area and mass to shag off heat and sometimes sudden heat, that's all there is to it.
> 
> Chad


Exactly. Rockford did have a little trouble with their VA drivers in the first BBQ amps, but later switched to TH MPSA56/06 which still got *HOT* but didn't melt into the surrounding FR-4. Heh.
The 500DSM...wonderful Grounded-Output Hafler design. Fantastic amp!


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## durwood (Mar 7, 2007)

SMT is fine as long as the board is mounted securely and not allowed to flex.


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## Luke352 (Jul 24, 2006)

Sorry "werewolf" I wasnt actually trying to pick on him or anything like that, I actually own 2 AudioSystem F2>500's and am interested in what the amp gurus like ez and yourself thought of the build layout etc... of the amps.

Yeah pics were the pist they had on ampguts ez.

Thanks 

Luke


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## Guest (Oct 16, 2007)

Luke352 said:


> Sorry "werewolf" I wasnt actually trying to pick on him or anything like that, I actually own 2 AudioSystem F2>500's and am interested in what the amp gurus like ez and yourself thought of the build layout etc... of the amps.
> 
> Yeah pics were the pist they had on ampguts ez.
> 
> ...


it's cool dude


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## dual700 (Mar 6, 2005)

Luke352 said:


> Well thought I'd throw out a challenge to "ezaudio" in a non serious friendly way  , I've attached two pics of amp internals from a manufacturer, and thought I'd see what you can tell us about it, power supply style, whether you consider it a solid design, is it a copy of someone else's design, can you pick the manufacturer, Of course others can chip in there opinions
> 
> P.S. It's not American, or Asian built.


Sorry to bring this back...
But isn't Steg and audio systems amps are made in korea?


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## invecs (Jul 30, 2005)

dual700 said:


> Sorry to bring this back...
> But isn't Steg and audio systems amps are made in korea?


That's what John Yi told me before. But according to the distributor in my country is that they are made in Italy.


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## Jack Watts (Sep 26, 2007)

invecs said:


> That's what John Yi told me before. But according to the distributor in my country is that they are made in Italy.


You should see the actual requirements for something to be designated 'made in Italy'.....


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## SQ_Bronco (Jul 31, 2005)

solacedagony said:


> I think it'd be interesting if we did one of those "Tech Clinic" type threads where we take an *extremely* basic amp design (schematic) and pick it apart to understand how and why it works (input, power supply, output). Maybe then add some things to make it work better, whatever. We seem to have quite a few capable engineers or electrical guys here so it could be quite an informational thread.
> 
> I might be proposing something not at all viable, so just tell me to shut up if so.  But I think that would be pretty cool.


FYI Perry Babin has done a great job of making a lot of this kind of information available on BCAE. Everything from "what is an electron" to a full-fledged tutorial on Amplifier repair basics. 

His non-free tutorial is also worth the money.


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## dual700 (Mar 6, 2005)

invecs said:


> That's what John Yi told me before. But according to the distributor in my country is that they are made in Italy.


John Yi is correct and unfortunately your distributor was mislead..
Just ask your DLS distro where are their products made, they will answer SWEDEN!  

http://www.gttrading.it/

gttrading is a korean amplifier manufacturing company.
You'd be surprised how many "high end, european/US amp manufacturers" have their amps made there and claim to be made in Europe/US


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## invecs (Jul 30, 2005)

dual700 said:


> John Yi is correct and unfortunately your distributor was mislead..
> Just ask your DLS distro where are their products made, they will answer SWEDEN!
> 
> http://www.gttrading.it/
> ...


Check this out at their webpage: http://english.gttrading.it/rivenditori/riv_esteri.htm

GT Trading claims that they make their amps in house in Italy.

I don't know if John is telling the truth. But he said that he saw the amps in a factory in Korea. But what the hell is he doing there? Hehehe! Something fishy about Tru...hehehe.


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## ca90ss (Jul 2, 2005)

dual700 said:


> http://www.gttrading.it/
> 
> gttrading is a korean amplifier manufacturing company.


Then why do they have an Italian address under their contact information and they're listed as the Italian distributor for Seas.


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## dual700 (Mar 6, 2005)

ca90ss said:


> Then why do they have an Italian address under their contact information and they're listed as the Italian distributor for Seas.


Back in the days, gttrading was all in korean website, korean languange. Korean address. 
Steg was available in Asia, early 2000, and I've tried to buy Masterstroke, but couldn't afford it and it's all 2 channels.. 
Don't get me wrong, they do distribute other things..
They do have "branches" in many countries, Italy for example, but I am 99.99% positive about that they manufacture steg and many others. Not that it is wrong, just want to clarify some things..
Looks like they completely revamped their site to Italian site..

Celestra has lower line made in Korea.. Helix's lowest line is made in China..And people thought they are all made in Germany/Italy (FYI)


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## dual700 (Mar 6, 2005)

invecs said:


> Check this out at their webpage: http://english.gttrading.it/rivenditori/riv_esteri.htm
> 
> GT Trading claims that they make their amps in house in Italy.
> 
> I don't know if John is telling the truth. But he said that he saw the amps in a factory in Korea. But what the hell is he doing there? Hehehe! Something fishy about Tru...hehehe.


Maybe now their Italian counterpart bought them and moved production to Italy?
Invecs, you are from Malaysia, right? Anyway to check the box of Steg, etc to see if there is a print of "Made in Italy"?  
I know it's not as strict as US regulation, but who knows... 
DLS stopped putting "Made in Sweden" on their products 2 yrs ago.


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## invecs (Jul 30, 2005)

I'm from the Philippines. According to our distributor that there is a label on the amps that states that it is made in Italy. But he admits that the Audiosystem speakers were outsourced from China and Germany.

There were also rumors that the Boston Acoustics amps were similar To Steg's...since some of BA amps were made in Italy. John Yi said that the Zapco Reference amps were outsourced from Italy. And I've heard some rumors that Zapco reference and some of the iforce amps are similar to the Audiosystem amps.

Quite confusing as to where those amps are being built. But for sure Steg's and Audiosystem's are built very well. I haven't heard of any single failure due to usage or abuse of the amps in my country. I'm friends with the distributor and with some shop owners who move alot of the amps...they don't have a single problem with them.


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## Luke352 (Jul 24, 2006)

Yeah I'm friends with the Australian inporter/distributor of Dynadio, Arc, Tru, Image Dynamics, and AudioSystem, (he isnt the sort to lie) and he has always stated the same that AudioSystem amp are made in Italy, but saying that the amps may have there PCB built in China with final assembly being done in Italy. I'm sure you would find that 99% of all audio companies source or have parts of there products built in asia.

But really who gives a **** where there made if it's good quality it's good quality, simple as that.


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## Luke352 (Jul 24, 2006)

dual700 said:


> Back in the days, gttrading was all in korean website, korean languange. Korean address.
> (FYI)


Have you done a google search and seen exactly how many companies called GT trading there are in world. There are ones in nearly every country dealing in nearly every product around the world.


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## exmaxima1 (May 31, 2007)

invecs said:


> John Yi said that the Zapco Reference amps were outsourced from Italy. And I've heard some rumors that Zapco reference and some of the iforce amps are similar to the Audiosystem amps.


Zapco used to import an Italian line of amps, but the name eludes me. Since Zapco is owned by an Italian company, it made sense at the time. They were not designed by Robert Zeff, and they didn't sound very good. I haven't seen those amps in years.

The current Reference and iForce lines are made in Asia, but with many US-sourced parts. Zapco sends many thousands of output transistors to Asia for use in their products, as the counterfeit transistors over there are too difficult to work with.

The Reference and iForce circuits are virtually identical except the Reference models have twice the number of output devices. They are not copies of someone else's design. Both lines sound awesome!

BTW, I talked with the head of DLS engineering a few years ago at CES, and he claimed that they have a dedicated factory in Taiwan for most of their products. Yet I have seen some of their amps being built in China.

Matthew


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## durwood (Mar 7, 2007)

invecs said:


> I don't know if John is telling the truth. But he said that he saw the amps in a factory in Korea. But what the hell is he doing there? Hehehe! Something fishy about Tru...hehehe.


I talked to the guys at TRU and he admited their entry level line is manufactured in Korea or China. It was still designed here by John Fairchild, they just had them not handmade in a factory. I don't think they have ever tried to hide that fact.



invecs said:


> Quite confusing as to where those amps are being built. But for sure Steg's and Audiosystem's are built very well. I haven't heard of any single failure due to usage or abuse of the amps in my country. I'm friends with the distributor and with some shop owners who move alot of the amps...they don't have a single problem with them.


Some info about Audiosystems from a person who lives in Belgium and his take on Audiosystems Twister amps (again this was just his observations)



> too was fond of steg and AS.... But have to say, I'm not so sure about AS anymore.... AS was hyped last year, and that turned against itsself. people constantly bought AS on advice of other people, and well...... retailers had complaints all over.... the 2 retailers in Belgium had to deal with overstock because they didn't sell anymore.... 1 of them even decided to stop with it completely.... AS is going down on it's own success....
> 
> They are beasts, yes.... they do have a nice output..... But SQ?.... maybe a small bit, but I'd go with steg QM's instead then.....





> I hope the twisters don't get hyped overthere as much as it is a hype overhere.... I't's getting so bad, some pro-twister guys are making up stroies to newbies like the twisters can measure up to much more expensive amps and al that ****..... people buy em for that and get dissapointed afterwards....





> As far as the Twisters go.... I'm sure you haven't talked to any Dutch people Who have used them..... In Holland it's a hype and it got to Belgium to for a while.... But people in Belgium have taken a step back from AS..... The only two retailers in Belgium don't seem to get rid of the amps anymore, and that is firsthand information from the the retailers themselves. the speakers on the other hand sell like candy.
> 
> Ow and yes, they have changed. 3th generation in 5 years actually.....


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## Luke352 (Jul 24, 2006)

I think amps are the exact opposite to speakers! Most amps perform roughly the same as there price dictates, a moderate priced amp like the AS twisters perform like a moderate level amp, but occaisionly amps come along that perform well UNDER what there price suggests. But with speakers (off the shelf retail comps) I think in most cases very few perform as there price suggests they should and in the exact opposite to amps occaisionly you will find a set of speakers that DO perform as there price suggests or outperform there price!!

Does that make sense??? lol


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## durwood (Mar 7, 2007)

ya I think I can agree to that.


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## sundownz (Apr 13, 2007)

The real secret guys... is more cowbell 

... the other industry guys might come after me for letting that out.


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## GlasSman (Nov 14, 2006)

sundownz said:


> The real secret guys... is more cowbell
> 
> ... the other industry guys might come after me for letting that out.


Can you say...COMPRESSION DRIVER?


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## dual700 (Mar 6, 2005)

Luke352 said:


> But really who gives a **** where there made if it's good quality it's good quality, simple as that.


I agreed with you, my post wasn't to point out that they are ****ty. Just trying to clarify things.


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## dual700 (Mar 6, 2005)

Luke352 said:


> Have you done a google search and seen exactly how many companies called GT trading there are in world. There are ones in nearly every country dealing in nearly every product around the world.


Yes I have. And how many of them has Steg? 1. I am not sure what you are trying to say here???
Again as what I said earlier, back in the early 2000s, the gttrading of Italy you see now was in all korean, with korean contact, korean address.


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## Luke352 (Jul 24, 2006)

dual700 said:


> Yes I have. And how many of them has Steg? 1. I am not sure what you are trying to say here???
> Again as what I said earlier, back in the early 2000s, the gttrading of Italy you see now was in all korean, with korean contact, korean address.


Cool was just wondering if it was the Steg site you were looking at, seems strange really, I could understand AudioSystem with it being there lower range, strange thing is they used to have a page up there that I can't found now that was a history of the companies founder who was some old Italian engeineer who had been building amps since like the 50's or something like that LOL!!


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## dual700 (Mar 6, 2005)

I could be wrong now, though...Perhaps they did move everything to Italy... 
Ah who cares, amp = amp


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## lust4sound (Apr 9, 2008)

Envision, I don't see you on anymore. If by any chance you get this message, would you be willing to repair a few PPI amps that I have?

PLMK..


Regards,
E Jan


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