A good Elliot Sound article on power amplifier design guidelines

P

PENG

Audioholic Slumlord
I read this article a long time ago, have had trouble finding it, until now.

It is a long one, but I find section 5 on Measurements Versus Subjectivity most interesting.
If you have time and read the whole article, you may find that a lot of your questions answered.
 
lovinthehd

lovinthehd

Seriously, I have no life.
I like his use of "x-spurts"....reminds me of Arny K and eggspurts.
 
P

PENG

Audioholic Slumlord
I like his use of "x-spurts"....reminds me of Arny K and eggspurts.
It feels good to see a designer/engineer wrote articles on design guidelines while brave enough to debunk some myths at the same time; and I am happy to know I wasn't the only one saying things like:

"Measurements are not meaningless, and real world signals are sinewaves! The only difference is that with music, there is usually a large number of sinewaves, all added together. There is not a myriad of simultaneous signals passing through an amp, just one (for a single channel, naturally)."

"We need measurements, because they tell us about the things that we often either can't hear, or that may be audible in a way that confuses our senses. Listening tests are also necessary, but they must be properly conducted as a true blind A-B test or the results are meaningless. Sighted tests (where you know exactly which piece of gear you are listening to) are fatally flawed and will almost always provide the expected outcome."

His linked article on power supplies is also a good read, it should answer some of the questions @RickyT raised recently on transformer size. Highly recommended for "DIYists".. It explains in easy to understand language, why manufacturers are able to go with PS transformers much smaller than what appears to be another apparently popular that it has to be sized to account for the class AB efficiency of between 50-75% (approx.).

 
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Irvrobinson

Irvrobinson

Audioholic Spartan
It feels good to see a designer/engineer wrote articles on design guidelines while brave enough to debunk some myths at the same time; and I am happy to know I wasn't the only one saying things like:

"Measurements are not meaningless, and real world signals are sinewaves! The only difference is that with music, there is usually a large number of sinewaves, all added together. There is not a myriad of simultaneous signals passing through an amp, just one (for a single channel, naturally)."

"We need measurements, because they tell us about the things that we often either can't hear, or that may be audible in a way that confuses our senses. Listening tests are also necessary, but they must be properly conducted as a true blind A-B test or the results are meaningless. Sighted tests (where you know exactly which piece of gear you are listening to) are fatally flawed and will almost always provide the expected outcome."

His linked article on power supplies is also a good read, it should answer some of the questions @RickyT raised recently on transformer size. Highly recommended for "DIYists".. It explains in easy to understand language, why manufacturers are able to go with PS transformers much smaller than what appears to be another apparently popular that it has to be sized to account for the class AB efficiency of between 50-75% (approx.).

I remember reading this article about the time it was published, which is almost two decades ago. It is still bookmarked in my browser, I just noticed. To the old pain-in-my-butt poster GrimSurfer, note section 5.3 of the article, about how smoothing capacitors in a linear power supply work, supported by measurements. These capacitors do not and cannot increase power output of the power supply beyond what the transformer is capable of. Dolt.
 
slipperybidness

slipperybidness

Audioholic Spartan
It feels good to see a designer/engineer wrote articles on design guidelines while brave enough to debunk some myths at the same time; and I am happy to know I wasn't the only one saying things like:

"Measurements are not meaningless, and real world signals are sinewaves! The only difference is that with music, there is usually a large number of sinewaves, all added together. There is not a myriad of simultaneous signals passing through an amp, just one (for a single channel, naturally)."

"We need measurements, because they tell us about the things that we often either can't hear, or that may be audible in a way that confuses our senses. Listening tests are also necessary, but they must be properly conducted as a true blind A-B test or the results are meaningless. Sighted tests (where you know exactly which piece of gear you are listening to) are fatally flawed and will almost always provide the expected outcome."

His linked article on power supplies is also a good read, it should answer some of the questions @RickyT raised recently on transformer size. Highly recommended for "DIYists".. It explains in easy to understand language, why manufacturers are able to go with PS transformers much smaller than what appears to be another apparently popular that it has to be sized to account for the class AB efficiency of between 50-75% (approx.).

Commercial designs always have a series of compromises and trade-offs, while a DIY design does not have to play by the same artificial rules to make a $.

There are a few authors for amp design that have several books that should be read and understood by any audio electronics engineer or designer (commercial or DIY).

Douglas Self
G Randy Slone https://www.amazon.com/gp/product/0071341196/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Bob Cordell https://www.amazon.com/gp/product/007164024X/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

If you read and understand their work, and apply their principles taught, you WILL be a world class amplifier designer! Of course, no snake oil here, other than debunking their rubbish!

I started my amplifier design journey at the Power Supply. I have designed, sourced parts, and built a few Power Supplies for DIY amps and other audio gear. So, I have a thorough understanding of what is needed, and what is not needed or detrimental for an amplifier power supply.

Spoiler Alert: for a power amp, the ideal PS is a robust non-regulated linear power supply, while a SMPS is the worst choice. The caveat is that there have been advances in SMPS, but the parts count, and inherent problems that require workarounds for audio applications make SMPS remain a less ideal option (if pure performance measurements and reliability are the dominate design goals).
 
Verdinut

Verdinut

Audioholic Ninja
It feels good to see a designer/engineer wrote articles on design guidelines while brave enough to debunk some myths at the same time; and I am happy to know I wasn't the only one saying things like:

"Measurements are not meaningless, and real world signals are sinewaves! The only difference is that with music, there is usually a large number of sinewaves, all added together. There is not a myriad of simultaneous signals passing through an amp, just one (for a single channel, naturally)."

"We need measurements, because they tell us about the things that we often either can't hear, or that may be audible in a way that confuses our senses. Listening tests are also necessary, but they must be properly conducted as a true blind A-B test or the results are meaningless. Sighted tests (where you know exactly which piece of gear you are listening to) are fatally flawed and will almost always provide the expected outcome."

His linked article on power supplies is also a good read, it should answer some of the questions @RickyT raised recently on transformer size. Highly recommended for "DIYists".. It explains in easy to understand language, why manufacturers are able to go with PS transformers much smaller than what appears to be another apparently popular that it has to be sized to account for the class AB efficiency of between 50-75% (approx.).

It's good to know that Rod kept his useful detailed content available on the web. Originally, he had mentioned that the whole info would no longer be available when he retired.
 
P

PENG

Audioholic Slumlord
I remember reading this article about the time it was published, which is almost two decades ago. It is still bookmarked in my browser, I just noticed. To the old pain-in-my-butt poster GrimSurfer, note section 5.3 of the article, about how smoothing capacitors in a linear power supply work, supported by measurements. These capacitors do not and cannot increase power output of the power supply beyond what the transformer is capable of. Dolt.
I noticed that the old bookmarks for some of the Elliot Sound articles wouldn't work as they seem to have moved around sites often enough, I guess.:D
 
Irvrobinson

Irvrobinson

Audioholic Spartan
Spoiler Alert: for a power amp, the ideal PS is a robust non-regulated linear power supply, while a SMPS is the worst choice. The caveat is that there have been advances in SMPS, but the parts count, and inherent problems that require workarounds for audio applications make SMPS remain a less ideal option (if pure performance measurements and reliability are the dominate design goals).
The Benchmark ABH2 changed my mind about SMPS for power amps. If my ATI AT3000 boat anchor breaks again, and it's out of warranty, the Benchmark is probably my go-to choice.
 
slipperybidness

slipperybidness

Audioholic Spartan
The Benchmark ABH2 changed my mind about SMPS for power amps. If my ATI AT3000 boat anchor breaks again, and it's out of warranty, the Benchmark is probably my go-to choice.
At the end of the day, it just depends on your design goals and your budget.

Linear unregulated supply provides performance advantages (at least on paper), fewer part count, and is tried and true technology. It is also heavy, expensive and less efficient!

SMPS has higher part count (more opportunities for part to fail), has inherent problems that must be engineered around, it is more complex. On the other hand, it is cheaper, lighter, and more efficient.

No free lunch :)
 

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