Building the ultimate DIY power amp

[tcpip]

Originally posted by traderbam
How does a DIY'er beat Ferrari?

Thanks for your interesting reply.

The Ferrari comparison is particularly significant. I thought that in the general case, the Ferrari analogy would hold, i.e. it would apply to most engineering disciplines. But for audio, specially for audio circuits built using analog components (i.e. where special fabrication of digital IC/FPGAs etc are not needed), an individual sitting at home and with a reasonable test bench of instruments would be able to do, over a couple of decades, what a very good team in a company can do. This is not possible in areas like building aeroplanes or cars, because the resources needed to design and test out a car prototype are way beyond the means of an individual.

In fact, Randy Slone, in his book, says precisely this while defending the reasons why a music lover and electronics hobbyist can justify time and effort spent in analog audio electronics. He says that a good amateur can actually get results better than most high-end commercial establishments, if he puts in enough time and effort. Are you saying that there are things done by the Krells and Mark Levinsons which are just not doable by such an individual for experimentation and prototyping?

Even when it comes to speaker building, I feel resource availability may make a difference between an individual and a B&W. But for amps, I thought this difference was not so big...

[traderbam]

I agree that you son't need millions of $ to develop hifi. But you may need $10ks to buy the right test & measurement equipment.

He says that a good amateur can actually get results better than most high-end commercial establishments, if he puts in enough time and effort.

There was something Douglas Adams wrote regarding monkeys and Shakespeare that rings a bell . Time and effort are not enough on their own.

Are you saying that there are things done by the Krells and Mark Levinsons which are just not doable by such an individual for experimentation and prototyping?

I am not meaning to suggest the plight of the amateur is in vain. I think most of the commercial designers started off as amateurs, made a cunning discovery or two and then developed a business out of it. I think D'Agostino worked for a speaker maker before he grew Krell Industries out of his basement. I believe Julian Vereker was a racing car driver before he made the first Naim amp. And you too could start the next Mark Levinson empire.

What I'm saying is that making high-end hifi is extremely difficult. It is a very technical, complex problem. People don't get there by hit and miss experimentation. You have to have a very good understanding of what you are doing and a rigorousness of method to make the leading edge breakthroughs. In other words, you need to be really serious about it and sort of get out of the hobbist mindset. It is not so much the lack of a CNC machine that makes building a Ferrari engine so hard it is the knowledge of what shape the metal needs to be machined to and what metal is needed and details, details, details and testing, testing, testing.

Try this at home: Read Slone's or Self's websites and critically examine their design and evaluation process. Not their results or how pretty the symmetrical schematic looks but just their process. How rigorous is it? How good is the process at improving the sound quality of their designs? When you read the construction info about one of these designs just how specific is it about parts and how to select them - how far does the specification go beyond mfrs part numbers? Is every part and it's value and method of selection justified?

Of course the route to perfection requires a different approach to that which most amateurs wish to follow. Amateur audio is great fun regardless of how fanatical one is or how good the results are and I am in no way suggesting this should be any different. I'm just addressing the original question which is about how good DIY kits are and my opinion and experience is that I don't know of any that are in the Ferrari league (I'm talking solid state rather than valves of which I have minimal experience). And I would be delighted to hear of experience to the contrary.

[analog_sa]

How good is the process at improving the sound quality of their designs?

They probably see no justification in improving above their perceived listening threshold.

Can a truly great amp be developed entirely by smart reasoning and solid theory? I have no doubt that practically all the well regarded audio manufacturers spend serious time listening at each stage of development. How many PCB layout prototypes it takes before it all gells? How many permutations of passives before the 'house' sound is achieved?

[Upupa Epops]

It is only about money and time. Most of DIYers stop " research ", if do one machine, which work little bit correctly. Practicaly nobody do not build three different machines for comparision, which way is the best. Three machines = three times more money and time and when is all ready, two goes to the asham, 'cos third is the best. Yes, DIYer can to do " State of art ", but mostly is it coincidence. Top class product is many years of honest and hard work, not any " happy conjuring ".

[AKSA]

Interesting thread. The answer is detail, detail, detail, just as Traderbam suggests.

On reflection, eight factors stand out:

1. Deep knowledge of the history of audio amplifier development.
2. The patience to undertake sonic 'sleuthing'.
3. Awareness that psychoacoustic perception does not always correlate with distortion, slew rate, FR measurements, et al.
4. Awareness that layout has an effect on sonics.
5. Awareness of the sonic signature of components.
6. An understanding an tolerance of the power of iteration, and repeated AB testing under realistic listening situations.
7. Lots of money, and
8. Truckloads of passion.

I won't add topology, as this is obvious.

These six factors prescribe a huge investment in time, effort, money and passion. That's really all it takes.

Cheers,

Hugh

[andy_c]

Originally posted by tcpip
(...)what's the difference between something carefully designed by a Doug Self or a Randy Slone with decades of experience, and the really famous commercial brands like the Mark Levinsons or Krells or whatever?(...)

Umm, marketing maybe? If you want to make your own clothes that are as good as the emperor's new clothes, you'll need lots of gold thread. By the way, I'm selling gold thread at my web site here: http://www.deoxy.org/emperors.htm

[tcpip]

Originally posted by traderbam
I agree that you son't need millions of $ to develop hifi. But you may need $10ks to buy the right test & measurement equipment.

This a smaller sum that what many Americans spend on their cars, even if they don't have much emotional involvement with them. Therefore this can't be "big money" in many countries.

There was something Douglas Adams wrote regarding monkeys and Shakespeare that rings a bell . Time and effort are not enough on their own.

Please don't trivialise the discussion.

I am not meaning to suggest the plight of the amateur is in vain. I think most of the commercial designers started off as amateurs...

Maybe I have been careless in my choice of words. I didn't mean "amateurs", strictly speaking. I meant individuals who were working outside the support structure of large companies, on their own, maybe in their homes. Whether they profit financially from their work (amateur versus professional) is not important.

What I'm saying is that making high-end hifi is extremely difficult. It is a very technical, complex problem. People don't get there by hit and miss experimentation.

I am an engineer, FWIW. I have two engineering degrees from one of the best engineering institutes in the world. Again, FWIW.

When I read the writings of Randy Slone or Doug Self, I don't get the impression that they are doing hit and miss experimentation. I may not know much about audio amp design, but I have a lot of confidence in my ability to recognize systematic, scientific investigation and experimentation when I see it. What I've seen these people do may be very different from the "opamp-rolling" casual approach of many diyers on this forum, but then I was not referring to designs created by such diyers. I was referring to people like Randy Slone or Doug Self.

Today, Nelson Pass and Hugh Dean are acclaimed amp designers. Some years ago, they were individual enthusiasts. Changing the label we attach to them does not change their basic approach or ability or passion. In that case, maybe we can take this discussion forward by dropping all references to "amateur" and moving to amps designed by these individuals. Do you feel that the best amps designed by these individuals will necessarily be inferior to the Mark Levinsons and Krells?

Let's avoid confusion a priori, by clarifying that AKSA amps are sold as kits, and therefore Hugh may have an interest in choosing simplicity of construction over no-holds-barred sound quality. But my question is not about any amp he has designed, but rather about what he --- or someone like him --- can design. With a garage full of $10K of equipment, and all his knowledge and experience and passion and patience, can someone in his position beat the big brand amps if he didn't have kit builder constraints?

Hope I've made my question clear.

Try this at home: Read Slone's or Self's websites and critically examine their design and evaluation process. Not their results or how pretty the symmetrical schematic looks but just their process. How rigorous is it?

You can do better by reading their books, instead of their Websites. Slone's Website contains very little. Try reading their books at home. What do you feel about their reasoning ability? To accuse these two sincere engineers and researchers of hit and miss experimentation is gross injustice to them, and probably more a comment of those who assess them than a comment on them.

[Terry Demol]

Originally posted by tcpip
This a smaller sum that what many Americans spend on their cars, even if they don't have much emotional involvement with them. Therefore this can't be "big money" in many countries.

Please don't trivialise the discussion.

Maybe I have been careless in my choice of words. I didn't mean "amateurs", strictly speaking. I meant individuals who were working outside the support structure of large companies, on their own, maybe in their homes. Whether they profit financially from their work (amateur versus professional) is not important.

I am an engineer, FWIW. I have two engineering degrees from one of the best engineering institutes in the world. Again, FWIW.

When I read the writings of Randy Slone or Doug Self, I don't get the impression that they are doing hit and miss experimentation. I may not know much about audio amp design, but I have a lot of confidence in my ability to recognize systematic, scientific investigation and experimentation when I see it. What I've seen these people do may be very different from the "opamp-rolling" casual approach of many diyers on this forum, but then I was not referring to designs created by such diyers. I was referring to people like Randy Slone or Doug Self.

Today, Nelson Pass and Hugh Dean are acclaimed amp designers. Some years ago, they were individual enthusiasts. Changing the label we attach to them does not change their basic approach or ability or passion. In that case, maybe we can take this discussion forward by dropping all references to "amateur" and moving to amps designed by these individuals. Do you feel that the best amps designed by these individuals will necessarily be inferior to the Mark Levinsons and Krells?

I think you missed a simple most important
factor that differentiates Self from Pass & Dean.
Self doesn't do careful listening tests as part of his
development methodology, they do.

Cheers,

Terry

[Damon Hill]

Originally posted by LRRockBox
I'm not exactly a first timer. To building an amp, yes, However, I do have a masters in electronics, and a VERY good soldering iron
Power : yes please. I mesioned a threesome by the big US boys. I DO like the sound of 'em. Given the money, I'd seriously look into the X600 or the FPB's.
[/B]

Excellent.

I'd been giving thought to a high power amplifier myself. The popular approach to this has been with lots of MOSFETs or bipolar transistors in parallel, and in the past with 'totem pole' series-parallel configurations.

You'll find kits for Optimos amplifiers up to 400 watts at http://www.sealelectronics/com; that's Randy Sloan's
site. I recommend his books, too; you may not want
to use his exact designs, but the general reading and construction tips are valuable. And I equally recommend
Doug Self's book; more details here:

http://www.dself.dsl.pipex.com/ampins/ampins.htm

I was thinking of using Marshall Leach's basic design
with four or five pairs of MJ21193/94s on a forced convection
heatsink that is conveniently prewired for that many
emitter followers including the emitter resistors. I'd
have to make some other parts changes, but I like his
design philosophy. You'll find his Low-TIM amp here:

http://users.ece.gatech.edu/~mleach/lowtim/

He also has a higher-power amplifier using the 'totem-
pole' concept here:

http://users.ece.gatech.edu/~mleach/superamp/

If you want even more power, be prepared to spend
more time researching. You could start here:

http://www.aussieamplifiers.com/

At this point, I recommend reading these sources and
listening to the considerable range of opinions here
before rushing into construction. There are certainly
other sources for project designs, but I've named
several that I feel comfortable recommending.

My projects usually stall for lack of money and the
skills and tools needed to physically construct reasonably
attractive, finished chassis. I scrounge parts as I can,
and build on existing chassis for upgrades.

Whether or not you'll end up with an amplifier that's
the equal of a Krell or other big-name lable is another
thing altogether. I don't know if anyone's seriously
compared Sloan's or Leach's designs to the best
commercial products available, but I think you will get
very good results. Hopefully our combined efforts in
DIY-land could lead to improvements in these projects
that would place them a notch closer to the best
available at any price.

[mikeks]

After a great deal of research, i have no choice but to accept that the simple generic gain-stage topology as used by Self, AKSA....Rod Elliot...etc...simply cannot be improved upon by so-called 'symmetric'...quasi-symmetric designs, 'current' feedback...etc....period.....

rather disappointing....as i had hoped that the visually appealing 'new-age' designs would come up trumps.....