9 ms·

The Emperor's New Amplifier (2003)

57 points by nkoren 12y ago

bjornsteffanson 12y ago
This is absolutely fantastic, and thoroughly technical -- particularly the SPICE simulations. After becoming equally engrossed in designing a "perfect" microphone capsule, I'm tempted to build one myself. This was written 12 years ago -- I wonder how the author feels now. Specifically I'm curious if the author is still contented with the equipment. Also, apropos of nothing save for sheer curiosity, I'm interested to know what input media (i.e., specific recordings and formats) and output equipment the author used (or uses) for both testing and pleasure.
- ableal 12y ago
  Looking at the submitter's id, I'd guess he's still happy.
  - nkoren 12y ago
    I'm actually the author's son, but I can confirm that yes, he's still happy with it. Remarkably, it seems to have resulted in a permanent remission of what had previously seemed like terminal audiophilia (remodelling the house to properly dampen its resonance, that kind of thing). He has since channelled his obsessive tendencies into digital imaging, which is an altogether more profitable endeavour.
    - eitally 12y ago
      Are you Henry, or is Henry Koren your brother? I knew an hkoren way back in the olden days on the vwvortex forums....
      - nkoren 12y ago
        I'm Nathan. Henry is my brother.
nakedrobot2 12y ago
Here is another "make your own incredible tube amplifier" from a Dutch gentleman. I'd be interested to hear from someone who understands this stuff, how it compares. http://www.mennovanderveen.nl/eng/index.html http://www.mennovanderveen.nl/eng/index.html Also, I'd like to hear for myself how they both compare to the $20 solid state amps. http://www.amazon.com/exec/obidos/ASIN/B0049P6OTI/downandoutint-20 http://www.amazon.com/exec/obidos/ASIN/B0049P6OTI/downandout...
- VLM 12y ago
  As a piece of performance art, they are polar opposites. One is a craftsmanship project hand built according to some peculiar rules (pre 1970s tech when possible, etc) and methodically designed to optimize performance and then tested to verify that performance. The $30 amazon mass produced amp ships with a 1.5 amp power supply that was restickered to 2 amps (hope your fire insurance is paid up) and can't provide marketed power with the supply as provided anyway depending on speaker impedance connected and no one has any detailed performance stats so who knows how well it compares in all the parameters that matter. Also it runs about 1/10th the power of the tube amp. Finally it is a class D amp but the chip mfgr went all closed source on making a "special" D that got patented as "T", the "T" designator is merely marketing. Its a relatively early class D amp, I would assume modern class D amps would outperform it. Note that both amps are antique in their own way, one is a "70s amp" and the other is a "turn of the century amp". As a piece of art, one is roughly a highly talented semi-pro artist classic inspired painting, and the other is a walmart poster copy of a "Dale Earnhardt on black velvet" memorial mass produced kitsch, should be pretty obvious which is which.
JonnieCache 12y ago
The problem with having an amazingly transparent signal chain (although I doubt that valves are the way to achieve this but he seems to know what he's talking about,) is that it pushes all the responsibility onto you the listener, to choose program material that is well engineered and artistically resonant enough to justify all that outlay. It's like having special eye surgery to visit galleries. It doesn't quite add up. Consider that the gear Miles Davis made all his music through sounded completely fucked by this guy's standards. For some reason, harmonic distortion produced before the 80s is art, and harmonic distortion produced after the 80s is an affront. Its like some kind of analog/digital existential nostalgia. I blame postmodernism. The more transparent the amplifier, the better the music has to be, or you really are wasting your time. If you just want to build high performance electronic equipment, there are much more interesting areas to work in than simply applying gain to a pair of AC signals while preserving their phase relationship. But yeah, each to his own I guess. I expect these questions are half the fun if you're into designing your own amplifiers.
- melevittfl 12y ago
  I think there is a difference between transparent amplifiers, etc in the recording stage vs transparent amplifiers in the playback stage. In other words, harmonic distortion is art if it was put there during the recording process and not art if it is put there during the playback process.
  - JonnieCache 12y ago
    But presumably the average home listening gear in 1969 was truly awful too. Does that mean nobody had really appreciated In A Silent Way until decades later, when they were finally able to discern every detail of its noise floor in high resolution? When you abandon the traditional audiophile silliness of subjective judgements in favor of scientific measurement, you just enter an even deeper mire, and it becomes completely impossible to determine why you're doing what you're doing, or what you're looking for. The best thing about art, and especially music is that your soul/subconcious/whatever can tell you if its good or not, immediately, for free. Your brain does not need six sigma of certainty to decide if you should currently be weeping with joy.
justinsb 12y ago
> I thought about commercializing it, especially when the lab where I worked announced it was shutting down, but I soon realized that marketing high-end tube amplifiers is not a reliable way to make a living. (I'm paycheck-addicted.) It is wonderful that Kickstarter has removed much of the risk for people like this, that are obviously incredibly talented and have produced something great, but don't necessarily have the desire/risk-appetite to make it commercially without a proven market.
pjc50 12y ago
This is basically the pinnacle of 1960s audio design. You can tell the author was trained in this era and knows his stuff by his reference to Bob Pease. On the other hand, he seems to regard MOSFET power supply regulation with suspicion. People in other comments have asked how modern class D amps perform. There are people doing a similar kind of thing with aggressively purist design craftsmanship, e.g. http://www.hypex.nl/technology/ucd.html http://www.hypex.nl/technology/ucd.html - producing a similar nice flat Bode plot. The really cheap ones may be suspect and spew EMI everywhere, but if you're not quite so concerned with shaving pennies off the price they're perfectly acceptable.
- VLM 12y ago
  Maybe I can help translate the author's EE work into "HN speak" in that what the author did with this amp design is similar to how programmers do "turing tarpit" language challenges. The game rules are usually picked based on how much the player wants to put up with. His spec for low freq 3dB down is weirdly low to me because I don't own drivers that run that low (LOL) although the spec for 1dB down is probably more "audiophile relevant". I suppose as a design goal if a recording has a 5 hz signal I'd want it to be properly amplified for the speakers to turn into heat instead of sound, rather than clipping and making noisy harmonics every 5 or 10 hz up the band, so there is that justification, but, why not input filter instead of just making heat in the speaker crossover? In this story, the game rules were use as little post-1970 components as possible while maxing out various specs to beyond human hearing. A good analogy for programmers would be writing a quicksort in BF or intercal. You don't do that because you need production code, you do that on a dare or to see if its possible or for the sheer heck of it. Personally if I needed 50 or so watts I'd use a TI TPA3116 and call it good. There's kits available on ebay and elsewhere, its a stereotypical more than a couple watts less than a hundred watts modern class D amp. Simple design one chip no need for heatsink at lower power out. Does need 24V power and a heatsink for full power out. The chip costs about a buck. But that breaks the rules of the game because those didn't ship till maybe two or three years ago, not 1965.
  - mark-r 12y ago
    I think you don't understand the project at all. The point wasn't to play some game by doing something retro, the point was to create an amp that sounds as good as reasonably possible. There are many people who believe that tubes are the best way to do this. I can't say they're wrong; the most realistic sound I've ever heard came from a tube amp in a shop.
alricb 12y ago
Speakers still add orders of magnitude more distortion than your amps, much like they did in the 1960s, unless you're using something insane like a servo-controlled Meyer X-10 (with an integrated amp, natch).
- gmarx 12y ago
  Also, more important than amp transparency (which is pretty easy these days) is how the amplifier reacts to the difficult loads many high end speakers present
  - alricb 12y ago
    For decent, modern amps, not really, as long as you're not getting something like the interaction between the output filter of a class D amp and the loudspeaker (as happened with some Crown class D amplifiers and some EAW speakers)
- mark-r 12y ago
  The distortions added by speakers and amps are orthogonal, they don't always mask each other.
ape4 12y ago
Norman, the copyright symbol is broken at the bottom on your photo pages pages http://www.normankoren.com/index.html http://www.normankoren.com/index.html Suggest you use ©
- mark-r 12y ago
  Lots of stuff broken on other pages as well. The problem is that the meta tag identifies charset=ISO-8859-1, when it really should be Windows-1252.
amelius 12y ago
I am wondering why high-end amplifiers are still so expensive. Amplification should be a solved problem by now. Also, what I miss most in the whole sound chain is that I can't change the volume of the tracks that existed before they were mixed into a single track. For example, making the volume of that trumpet in the background a little louder, etc.
- deleted 12y ago
  [deleted]
- ptaipale 12y ago
  > I am wondering why high-end amplifiers are still so expensive. I think it's a bit like why Gucci handbags are still so expensive. Because they are high end; there are people who are willing to spend that much, even if what I would call an engineer's assessment "do I get a reasonable bang for buck ratio" clearly answers NO. People by an experience, they buy a feeling. And it may be money well spent for them.
spiritplumber 12y ago
http://arstechnica.com/staff/2015/02/to-the-audiophile-this-10000-ethernet-cable-apparently-makes-sense/ http://arstechnica.com/staff/2015/02/to-the-audiophile-this-... Don't forget that these things exist because at least some people buy them.
akottas 12y ago
First time I visited Koren's website and read about his "perfect amp" was about 10 years ago (around 2006 - when I was designing and building my "perfect amp"). So this article definitely brings me back to simpler times. I always found this design waaaay too complex. Some sections seem unnecessary while others don't make sense (but that's just me - and it doesn't help that the schematic is drawn a little convoluted). But I suppose it totally depends on his amp's application (e.g. playing records, studio monitors, live guitar, bass amp, etc), so it really may be the perfect amp ...for his specific application. My thoughts... the power supply is a little too "verbose" for a tube amp -- just unnecessarily complex, and may actually remove some of the imperfections associated with that crispy "classic tube amp" sound. But I am a strong advocate of a well-designed power supply, so I can't say anything bad about it. But there's too much going on between phase-inverter and power amp stages (output drivers I presume). I would never do that, but to each their own. However, I do like that he used 6550s. Great tubes!

57 points by nkoren 12y ago

This is absolutely fantastic, and thoroughly technical -- particularly the SPICE simulations. After becoming equally engrossed in designing a "perfect" microphone capsule, I'm tempted to build one myself. This was written 12 years ago -- I wonder how the author feels now. Specifically I'm curious if the author is still contented with the equipment. Also, apropos of nothing save for sheer curiosity, I'm interested to know what input media (i.e., specific recordings and formats) and output equipment the author used (or uses) for both testing and pleasure.

ableal 12y ago
Looking at the submitter's id, I'd guess he's still happy.
- nkoren 12y ago
  I'm actually the author's son, but I can confirm that yes, he's still happy with it. Remarkably, it seems to have resulted in a permanent remission of what had previously seemed like terminal audiophilia (remodelling the house to properly dampen its resonance, that kind of thing). He has since channelled his obsessive tendencies into digital imaging, which is an altogether more profitable endeavour.
  - eitally 12y ago
    Are you Henry, or is Henry Koren your brother? I knew an hkoren way back in the olden days on the vwvortex forums....
    - nkoren 12y ago
      I'm Nathan. Henry is my brother.

nakedrobot2 12y ago

Here is another "make your own incredible tube amplifier" from a Dutch gentleman. I'd be interested to hear from someone who understands this stuff, how it compares. http://www.mennovanderveen.nl/eng/index.html http://www.mennovanderveen.nl/eng/index.html Also, I'd like to hear for myself how they both compare to the $20 solid state amps. http://www.amazon.com/exec/obidos/ASIN/B0049P6OTI/downandoutint-20 http://www.amazon.com/exec/obidos/ASIN/B0049P6OTI/downandout...

VLM 12y ago
As a piece of performance art, they are polar opposites. One is a craftsmanship project hand built according to some peculiar rules (pre 1970s tech when possible, etc) and methodically designed to optimize performance and then tested to verify that performance. The $30 amazon mass produced amp ships with a 1.5 amp power supply that was restickered to 2 amps (hope your fire insurance is paid up) and can't provide marketed power with the supply as provided anyway depending on speaker impedance connected and no one has any detailed performance stats so who knows how well it compares in all the parameters that matter. Also it runs about 1/10th the power of the tube amp. Finally it is a class D amp but the chip mfgr went all closed source on making a "special" D that got patented as "T", the "T" designator is merely marketing. Its a relatively early class D amp, I would assume modern class D amps would outperform it. Note that both amps are antique in their own way, one is a "70s amp" and the other is a "turn of the century amp". As a piece of art, one is roughly a highly talented semi-pro artist classic inspired painting, and the other is a walmart poster copy of a "Dale Earnhardt on black velvet" memorial mass produced kitsch, should be pretty obvious which is which.

JonnieCache 12y ago

The problem with having an amazingly transparent signal chain (although I doubt that valves are the way to achieve this but he seems to know what he's talking about,) is that it pushes all the responsibility onto you the listener, to choose program material that is well engineered and artistically resonant enough to justify all that outlay. It's like having special eye surgery to visit galleries. It doesn't quite add up. Consider that the gear Miles Davis made all his music through sounded completely fucked by this guy's standards. For some reason, harmonic distortion produced before the 80s is art, and harmonic distortion produced after the 80s is an affront. Its like some kind of analog/digital existential nostalgia. I blame postmodernism. The more transparent the amplifier, the better the music has to be, or you really are wasting your time. If you just want to build high performance electronic equipment, there are much more interesting areas to work in than simply applying gain to a pair of AC signals while preserving their phase relationship. But yeah, each to his own I guess. I expect these questions are half the fun if you're into designing your own amplifiers.

melevittfl 12y ago
I think there is a difference between transparent amplifiers, etc in the recording stage vs transparent amplifiers in the playback stage. In other words, harmonic distortion is art if it was put there during the recording process and not art if it is put there during the playback process.
- JonnieCache 12y ago
  But presumably the average home listening gear in 1969 was truly awful too. Does that mean nobody had really appreciated In A Silent Way until decades later, when they were finally able to discern every detail of its noise floor in high resolution? When you abandon the traditional audiophile silliness of subjective judgements in favor of scientific measurement, you just enter an even deeper mire, and it becomes completely impossible to determine why you're doing what you're doing, or what you're looking for. The best thing about art, and especially music is that your soul/subconcious/whatever can tell you if its good or not, immediately, for free. Your brain does not need six sigma of certainty to decide if you should currently be weeping with joy.

justinsb 12y ago

> I thought about commercializing it, especially when the lab where I worked announced it was shutting down, but I soon realized that marketing high-end tube amplifiers is not a reliable way to make a living. (I'm paycheck-addicted.) It is wonderful that Kickstarter has removed much of the risk for people like this, that are obviously incredibly talented and have produced something great, but don't necessarily have the desire/risk-appetite to make it commercially without a proven market.

pjc50 12y ago

This is basically the pinnacle of 1960s audio design. You can tell the author was trained in this era and knows his stuff by his reference to Bob Pease. On the other hand, he seems to regard MOSFET power supply regulation with suspicion. People in other comments have asked how modern class D amps perform. There are people doing a similar kind of thing with aggressively purist design craftsmanship, e.g. http://www.hypex.nl/technology/ucd.html http://www.hypex.nl/technology/ucd.html - producing a similar nice flat Bode plot. The really cheap ones may be suspect and spew EMI everywhere, but if you're not quite so concerned with shaving pennies off the price they're perfectly acceptable.

VLM 12y ago
Maybe I can help translate the author's EE work into "HN speak" in that what the author did with this amp design is similar to how programmers do "turing tarpit" language challenges. The game rules are usually picked based on how much the player wants to put up with. His spec for low freq 3dB down is weirdly low to me because I don't own drivers that run that low (LOL) although the spec for 1dB down is probably more "audiophile relevant". I suppose as a design goal if a recording has a 5 hz signal I'd want it to be properly amplified for the speakers to turn into heat instead of sound, rather than clipping and making noisy harmonics every 5 or 10 hz up the band, so there is that justification, but, why not input filter instead of just making heat in the speaker crossover? In this story, the game rules were use as little post-1970 components as possible while maxing out various specs to beyond human hearing. A good analogy for programmers would be writing a quicksort in BF or intercal. You don't do that because you need production code, you do that on a dare or to see if its possible or for the sheer heck of it. Personally if I needed 50 or so watts I'd use a TI TPA3116 and call it good. There's kits available on ebay and elsewhere, its a stereotypical more than a couple watts less than a hundred watts modern class D amp. Simple design one chip no need for heatsink at lower power out. Does need 24V power and a heatsink for full power out. The chip costs about a buck. But that breaks the rules of the game because those didn't ship till maybe two or three years ago, not 1965.
- mark-r 12y ago
  I think you don't understand the project at all. The point wasn't to play some game by doing something retro, the point was to create an amp that sounds as good as reasonably possible. There are many people who believe that tubes are the best way to do this. I can't say they're wrong; the most realistic sound I've ever heard came from a tube amp in a shop.

alricb 12y ago

Speakers still add orders of magnitude more distortion than your amps, much like they did in the 1960s, unless you're using something insane like a servo-controlled Meyer X-10 (with an integrated amp, natch).

gmarx 12y ago
Also, more important than amp transparency (which is pretty easy these days) is how the amplifier reacts to the difficult loads many high end speakers present
- alricb 12y ago
  For decent, modern amps, not really, as long as you're not getting something like the interaction between the output filter of a class D amp and the loudspeaker (as happened with some Crown class D amplifiers and some EAW speakers)
mark-r 12y ago
The distortions added by speakers and amps are orthogonal, they don't always mask each other.

ape4 12y ago

Norman, the copyright symbol is broken at the bottom on your photo pages pages http://www.normankoren.com/index.html http://www.normankoren.com/index.html Suggest you use ©

mark-r 12y ago
Lots of stuff broken on other pages as well. The problem is that the meta tag identifies charset=ISO-8859-1, when it really should be Windows-1252.

amelius 12y ago

I am wondering why high-end amplifiers are still so expensive. Amplification should be a solved problem by now. Also, what I miss most in the whole sound chain is that I can't change the volume of the tracks that existed before they were mixed into a single track. For example, making the volume of that trumpet in the background a little louder, etc.

deleted 12y ago
[deleted]
ptaipale 12y ago
> I am wondering why high-end amplifiers are still so expensive. I think it's a bit like why Gucci handbags are still so expensive. Because they are high end; there are people who are willing to spend that much, even if what I would call an engineer's assessment "do I get a reasonable bang for buck ratio" clearly answers NO. People by an experience, they buy a feeling. And it may be money well spent for them.

spiritplumber 12y ago

http://arstechnica.com/staff/2015/02/to-the-audiophile-this-10000-ethernet-cable-apparently-makes-sense/ http://arstechnica.com/staff/2015/02/to-the-audiophile-this-... Don't forget that these things exist because at least some people buy them.

akottas 12y ago

First time I visited Koren's website and read about his "perfect amp" was about 10 years ago (around 2006 - when I was designing and building my "perfect amp"). So this article definitely brings me back to simpler times. I always found this design waaaay too complex. Some sections seem unnecessary while others don't make sense (but that's just me - and it doesn't help that the schematic is drawn a little convoluted). But I suppose it totally depends on his amp's application (e.g. playing records, studio monitors, live guitar, bass amp, etc), so it really may be the perfect amp ...for his specific application. My thoughts... the power supply is a little too "verbose" for a tube amp -- just unnecessarily complex, and may actually remove some of the imperfections associated with that crispy "classic tube amp" sound. But I am a strong advocate of a well-designed power supply, so I can't say anything bad about it. But there's too much going on between phase-inverter and power amp stages (output drivers I presume). I would never do that, but to each their own. However, I do like that he used 6550s. Great tubes!