- and Pavel, Jan, this is categorically the commercial paradigm. 
The designer, if he is to sell amps successfully, MUST sell to the market in preference to the technically correct solution, though it should be said that it may be these requirements are NOT mutually exclusive. I might add ruefully that he might get away with a purely specs-based product at the very high end, but at the mid-fi sector of the market it had better 'sound good', whatever that might mean.......
Pavel, you make the point about classical music. I agree that any distortion with this genre is clearly evident, particularly orchestral, but it is apparently true that some distortions are euphonic at low levels and that as long as the intermodulation is kept very low, which to me means H2/H3 should not be more than about 0.1%. There is also the issue of distortion masking to consider.
The fact is that from a technical standpoint we strive vigorously for very low measured distortion, yet the single ended triode beloved of a significant number of audiophiles does fly in the face of this endeavour. There is clearly a need for a psychoacoustic correlation between distortion levels/spectra and euphonic sound, if only to give guidance to those who are resolved to design a commercially successful product.
That said, I know pretty well what Stan Curtis is saying. At this stage, and until we analyse with precision what it is that people like in their amplifiers, it is fair to say that audio design is as much art as science. And this casts some doubt on the math and measure approach, and this needs to be recognised and acted upon by many in the engineering fraternity who believe the solution lies with linearity, the so-called 'straight wire with gain'.
Cheers,
Hugh
The designer, if he is to sell amps successfully, MUST sell to the market in preference to the technically correct solution, though it should be said that it may be these requirements are NOT mutually exclusive. I might add ruefully that he might get away with a purely specs-based product at the very high end, but at the mid-fi sector of the market it had better 'sound good', whatever that might mean....... Pavel, you make the point about classical music. I agree that any distortion with this genre is clearly evident, particularly orchestral, but it is apparently true that some distortions are euphonic at low levels and that as long as the intermodulation is kept very low, which to me means H2/H3 should not be more than about 0.1%. There is also the issue of distortion masking to consider.
The fact is that from a technical standpoint we strive vigorously for very low measured distortion, yet the single ended triode beloved of a significant number of audiophiles does fly in the face of this endeavour. There is clearly a need for a psychoacoustic correlation between distortion levels/spectra and euphonic sound, if only to give guidance to those who are resolved to design a commercially successful product.
That said, I know pretty well what Stan Curtis is saying. At this stage, and until we analyse with precision what it is that people like in their amplifiers, it is fair to say that audio design is as much art as science. And this casts some doubt on the math and measure approach, and this needs to be recognised and acted upon by many in the engineering fraternity who believe the solution lies with linearity, the so-called 'straight wire with gain'.
Cheers,
Hugh
AKSA said:
There is no question each individual is free to tweak listening conditions to suit his/her taste, no matter how much this deviates from accurate reproduction. This way what they are doing is a musical instrument of the last links in the chain.
That being the case, I should rather choose a setup where I can control in a defined way that tweaking instead of simply get it as it comes for mostly unknown or obscure reasons as determined by the manufacturer of certain brand.
Rodolfo
It is simply "too easy" for a competent designer to cave in to commercial demands and produce euphonic amplifiers with not only measurable but audible levels of selected distortions. It is also quite easy to go the other way and snub such aural satisfaction based goals.
I like to produce amplifiers which have all the nasty 'spray' of harmonics distortions like PS commutation, crossover and crosstalk distortions relegated to insignificance (both measured and audible) and the intrinsic stage distortions controlled to a significant degree. The HF sprays, in particular, bury the staging and timbral detail in a haze of generated harmonics which can only obscure the music.
While we don't need these distortions fogging the information, nor do we need the rose coloured glasses!
Cheers,
Greg
I like to produce amplifiers which have all the nasty 'spray' of harmonics distortions like PS commutation, crossover and crosstalk distortions relegated to insignificance (both measured and audible) and the intrinsic stage distortions controlled to a significant degree. The HF sprays, in particular, bury the staging and timbral detail in a haze of generated harmonics which can only obscure the music.
While we don't need these distortions fogging the information, nor do we need the rose coloured glasses!
Cheers,
Greg
I think it's time I championed the cause of art in audio design, as well as math.
I cannot argue more cogently than Daniel Cheever, have a read of this, it is seminal, and identifies a long history of cognitive dissonance in this field of endeavour:
http://w3.mit.edu/cheever/www/cheever_thesis.pdf
I would humbly suggest that the evidence is very strongly in favor of a smooth transfer curve, BUT NOT NECESSARILY A STRAIGHT ONE!!
Yours in low order,
Hugh
I cannot argue more cogently than Daniel Cheever, have a read of this, it is seminal, and identifies a long history of cognitive dissonance in this field of endeavour:
http://w3.mit.edu/cheever/www/cheever_thesis.pdf
I would humbly suggest that the evidence is very strongly in favor of a smooth transfer curve, BUT NOT NECESSARILY A STRAIGHT ONE!!
Yours in low order,
Hugh
Hi guys i have noticed that Mikeks has been abscent from the forum
and i now miss his incredible links he put up for us, especially the ones
from ew,do you guys know any good free ew links with Douglas self
artcles if you do please post them on this thread so i can collect
them later
thanks in advance
and i now miss his incredible links he put up for us, especially the ones
from ew,do you guys know any good free ew links with Douglas self
artcles if you do please post them on this thread so i can collect
them later
thanks in advance
Hugh,
Given your comments about the smooth curves in relation to sound quality, the art of audio engineering and vacuum state amps, I tend to agree with you.
Im also active in the field of designing speaker systems and over the years found a similar relation between the the sound of a speaker and smoothness of the curves as well as complexity of the xover circuit.
This is my view:
There is a strong connection between circuit complexity and smoothness of curves.
The typical tube designs are very simple and the tubes suffer less from suddenly changing parameters if compared to semiconductors. they typically also use less NFB
The typical simiconductor design uses more amplification stages and the active components tend to have less liniearity and more change of behavior over the active range if compared with tubes.
An other strong connection is global feedback over multiple stages and the related delay within the loop. I never heared a well sounding amp with global feedback over more than 3 stages.
This is where most of the well sounding amps all look alike.
I have been listening to an enourmous amount of amplifirs and bottomline concluded the following: The best performing amps for my ears were simple, had low distortion in open loop, had openloopgain constant in audio band, were unconditionally stable, could deliver undistorted signals to complex impedances over a wide impedance range, had a power supply that could deliver enough energy.
My favourites are
* JLH simple circuit and exelent dynamics
* A15 (Hawk) 15W 2 stage klass A without global feedback
* Pass Aleph 2 stage with global feedback
* D2S 2 stage ampplifier no feedback but liniarisation of the exponential fet curve.
* Ballanced circuits to cancel component related distortion no NFB.
Given your comments about the smooth curves in relation to sound quality, the art of audio engineering and vacuum state amps, I tend to agree with you.
Im also active in the field of designing speaker systems and over the years found a similar relation between the the sound of a speaker and smoothness of the curves as well as complexity of the xover circuit.
This is my view:
There is a strong connection between circuit complexity and smoothness of curves.
The typical tube designs are very simple and the tubes suffer less from suddenly changing parameters if compared to semiconductors. they typically also use less NFB
The typical simiconductor design uses more amplification stages and the active components tend to have less liniearity and more change of behavior over the active range if compared with tubes.
An other strong connection is global feedback over multiple stages and the related delay within the loop. I never heared a well sounding amp with global feedback over more than 3 stages.
This is where most of the well sounding amps all look alike.
I have been listening to an enourmous amount of amplifirs and bottomline concluded the following: The best performing amps for my ears were simple, had low distortion in open loop, had openloopgain constant in audio band, were unconditionally stable, could deliver undistorted signals to complex impedances over a wide impedance range, had a power supply that could deliver enough energy.
My favourites are
* JLH simple circuit and exelent dynamics
* A15 (Hawk) 15W 2 stage klass A without global feedback
* Pass Aleph 2 stage with global feedback
* D2S 2 stage ampplifier no feedback but liniarisation of the exponential fet curve.
* Ballanced circuits to cancel component related distortion no NFB.
Another take on the cheever thesis:
http://www.diyaudio.com/forums/showthread.php?postid=424865#post424865
and its not just me…
http://www.diyaudio.com/forums/showthread.php?postid=462457#post462457
http://www.diyaudio.com/forums/showthread.php?postid=424865#post424865
and its not just me…
http://www.diyaudio.com/forums/showthread.php?postid=462457#post462457
JCX, others interested,
Perhaps the fact that so many experts disagree is an indication more definitive work needs to be done. Perhaps then, when all the evidence has been coralled and done to death, a politically correct viewpoint can form which heretics will criticize at their peril......
And is it true that there is already a politically correct view on this and other matters audio? As it happens I disagree with Cheever that global negative feedback is the culprit - JLH's circuit uses lashes of GNFB and it sounds terrific - so there must be more to it. But that is not to denigrate Cheever for his achievement; he has worked with some passion and dedication to produce his thesis, and while there are aspects that some consider plain wrong, the fact is he was committed, he did the detail, he wrote it, and he got some things right. I was surprised that there is a popular belief here that his work is bunkum, but I guess I shouldn't be - anyone who achieves anything comes in for massive criticism in this world. What is the dignified option, I would ask? Do nothing at all but snipe from the sidelines? Doesn't Danish have a distinctive word for this, and English an apt phrase?
I have heard SETs which categorically underwhelmed me; others which were just sublime. The design differences are still not fully evident to the cognoscenti after all these years.
I am convinced that complexity does make it more difficult to design for good sonics, but the specs often look very good. Is it reasonable that through all the smoke and haze we continue to judge the worth of an automobile by reading off its licence plate at 100 yards?
Cheers,
Hugh
Perhaps the fact that so many experts disagree is an indication more definitive work needs to be done. Perhaps then, when all the evidence has been coralled and done to death, a politically correct viewpoint can form which heretics will criticize at their peril......
And is it true that there is already a politically correct view on this and other matters audio? As it happens I disagree with Cheever that global negative feedback is the culprit - JLH's circuit uses lashes of GNFB and it sounds terrific - so there must be more to it. But that is not to denigrate Cheever for his achievement; he has worked with some passion and dedication to produce his thesis, and while there are aspects that some consider plain wrong, the fact is he was committed, he did the detail, he wrote it, and he got some things right. I was surprised that there is a popular belief here that his work is bunkum, but I guess I shouldn't be - anyone who achieves anything comes in for massive criticism in this world. What is the dignified option, I would ask? Do nothing at all but snipe from the sidelines? Doesn't Danish have a distinctive word for this, and English an apt phrase?
I have heard SETs which categorically underwhelmed me; others which were just sublime. The design differences are still not fully evident to the cognoscenti after all these years.
I am convinced that complexity does make it more difficult to design for good sonics, but the specs often look very good. Is it reasonable that through all the smoke and haze we continue to judge the worth of an automobile by reading off its licence plate at 100 yards?
Cheers,
Hugh
Sorry, but I wasn't given the opportunity to be on Cheever's committee or I might have made the basic objections known earlier in his research process. What other choice does one have when critiquing a piece of fatally flawed work than to do it from the sidelines?
Being passionate, committed, and writing up the work doesn't mean that there's any value in what ends up being produced; believe me, I've been on the wrong side of that one more times than I care to remember.
Hugh, you're always a true gentleman.
Would you disagree with my notion that commercial magazine reviews from people of questionable qualifications and motivations and a total lack of controls might not be an accurate metric for an engineering paper?
I remember reading an analysis by an engineer in The Audio Critic correlating reviews with circuit topologies. As you might expect, he found no correlation.
Would you disagree with my notion that commercial magazine reviews from people of questionable qualifications and motivations and a total lack of controls might not be an accurate metric for an engineering paper?
I remember reading an analysis by an engineer in The Audio Critic correlating reviews with circuit topologies. As you might expect, he found no correlation.
Truth?
I have been reading this thread since the beginning. I have kept silent because the people making the posts have much more experience than I. I have learned a great deal and I thank all of you.
This leads me to make a small comment concerning magazine reviews and how much faith we as a reading public should place in them.
To many people have what they call "truth". When there is no benchmark to stand before it is all too easy to make statements and say that they are true. As a young man I fell into that quicksand. It didn’t take to long before I figured out that brand X was not all that much better than brand Y. The true difference was that it was a new month and the magazine had a new set of advertisements and companies behind them to keep happy. I got the crash course in reality during the late eighties when I tried to market some speakers. The reality and the illusion came crashing together. The aftermath some a somewhat cynical person with his eyes a little more open to what was what.
From what I gather about the term "truth" is that it is something that stands the test of reason. A truth is something that when challenged and questioned by anyone stands up to that questioning and says so. It is not a point of view or a best guess. It is born from facts and experience. Therefore the facts support the truth. Black is black and white is white. ( not getting into philosophical discussion please )
There is a general delusion amongst many of the reviewers that makes no sense when held up to the light of reason. Someone like that tends to believe what they do through blind credulity. A good example is a client that I had who was listening to a newly installed system. He asked me to turn up the bass which I did. A smile of approval came over his face. I sat down and listened to the music . There was no apparent change in the bass levels. It turned out that the tone defeat was engaged. When I pointed it out his whole illusion collapsed. Prior to that knowledge he was happy. When facts come up and question that credulity it makes such a person uneasy. They don't like it. A truth should actually be liberating in the sense that we now have an answer to a question that we were seeking.
This thread has for the most part dealt with facts. Some opinions are present, but the greater majority are backed by experience of realities seen and experienced that are not fully understood but are nonetheless present. It means that we all have a way to go to find out the truth about distortions in sound and how we perceive them. It also means that our methods of describing them and measuring them are not up to the task.
Hats off to you gentlemen. The emperor has no clothes and there are many here who are not scared to say so!
Mark
I have been reading this thread since the beginning. I have kept silent because the people making the posts have much more experience than I. I have learned a great deal and I thank all of you.
This leads me to make a small comment concerning magazine reviews and how much faith we as a reading public should place in them.
To many people have what they call "truth". When there is no benchmark to stand before it is all too easy to make statements and say that they are true. As a young man I fell into that quicksand. It didn’t take to long before I figured out that brand X was not all that much better than brand Y. The true difference was that it was a new month and the magazine had a new set of advertisements and companies behind them to keep happy. I got the crash course in reality during the late eighties when I tried to market some speakers. The reality and the illusion came crashing together. The aftermath some a somewhat cynical person with his eyes a little more open to what was what.
From what I gather about the term "truth" is that it is something that stands the test of reason. A truth is something that when challenged and questioned by anyone stands up to that questioning and says so. It is not a point of view or a best guess. It is born from facts and experience. Therefore the facts support the truth. Black is black and white is white. ( not getting into philosophical discussion please )
There is a general delusion amongst many of the reviewers that makes no sense when held up to the light of reason. Someone like that tends to believe what they do through blind credulity. A good example is a client that I had who was listening to a newly installed system. He asked me to turn up the bass which I did. A smile of approval came over his face. I sat down and listened to the music . There was no apparent change in the bass levels. It turned out that the tone defeat was engaged. When I pointed it out his whole illusion collapsed. Prior to that knowledge he was happy. When facts come up and question that credulity it makes such a person uneasy. They don't like it. A truth should actually be liberating in the sense that we now have an answer to a question that we were seeking.
This thread has for the most part dealt with facts. Some opinions are present, but the greater majority are backed by experience of realities seen and experienced that are not fully understood but are nonetheless present. It means that we all have a way to go to find out the truth about distortions in sound and how we perceive them. It also means that our methods of describing them and measuring them are not up to the task.
Hats off to you gentlemen. The emperor has no clothes and there are many here who are not scared to say so!
Mark
Stuart,
I do not disagree at all with your comments about magazine reviewers. I regard much of their writing as convoluted, subjective marketing. There is an underlying economic equation in many reviews and too few people realize how interwoven they are with the advertising budget. I would laugh out loud at some of the articles I've read in Stereophile from JS in particular if I knew that no-one was paying any attention, but tragically these guys have sinister influence over sales, and that really worries me.......
However, you are being a little uncharitable with Cheever. He is not taking reviewers too seriously either, and he is using reviews to point up some of the cognitive dissonance to which I refer.
You must speak with my wife as soon as possible. I am touched your opinion should be so much at odds with hers, and I'm hoping you are a good salesman........
Cheers,
Hugh
I do not disagree at all with your comments about magazine reviewers. I regard much of their writing as convoluted, subjective marketing. There is an underlying economic equation in many reviews and too few people realize how interwoven they are with the advertising budget. I would laugh out loud at some of the articles I've read in Stereophile from JS in particular if I knew that no-one was paying any attention, but tragically these guys have sinister influence over sales, and that really worries me.......
However, you are being a little uncharitable with Cheever. He is not taking reviewers too seriously either, and he is using reviews to point up some of the cognitive dissonance to which I refer.
You must speak with my wife as soon as possible. I am touched your opinion should be so much at odds with hers, and I'm hoping you are a good salesman........
Cheers,
Hugh
Re: Truth?
A balanced a well thought post Mark.
Perhaps the key to understand the cacophony of opinions about what is right in audio, is that as you hint it is a personal perception experience.
We grew with sound reproduction systems sorely lacking in accurate performance and grew accustomed to tweak tone controls and mix and match speakers, phono cartridges, amplifiers of all designs and so on, to attain a pleasing experience.
So much so we grew accustomed more to concote setups pleasing to hear rather than to reproduce what looked allways farther and farther away, a neutral reproduction of what the actual thteater or whatever is, and which we find so surprisingly different to amplified audio each time we have the opportunity to witness.
Now, if we (mostly uncknowingly) strive for a pleasing experience in line with what is our experience in audio reproduction, it is no surprise there will be as many "ultimate" setups as people putting them toghether.
Rodolfo
mwmkravchenko said:
A balanced a well thought post Mark.
Perhaps the key to understand the cacophony of opinions about what is right in audio, is that as you hint it is a personal perception experience.
We grew with sound reproduction systems sorely lacking in accurate performance and grew accustomed to tweak tone controls and mix and match speakers, phono cartridges, amplifiers of all designs and so on, to attain a pleasing experience.
So much so we grew accustomed more to concote setups pleasing to hear rather than to reproduce what looked allways farther and farther away, a neutral reproduction of what the actual thteater or whatever is, and which we find so surprisingly different to amplified audio each time we have the opportunity to witness.
Now, if we (mostly uncknowingly) strive for a pleasing experience in line with what is our experience in audio reproduction, it is no surprise there will be as many "ultimate" setups as people putting them toghether.
Rodolfo
It is very interesting (or out of my rationale
) how people who have money, but do not understand electronic, willing to pay USD27.000,- for active Xover, USD40.000,-for power amp, etc.
What is the "magical" sound that makes them willing to pay that so..so...soooo.... much money for audio equipment?
OK, the gears are "FM Accoustics" from Switzerland. I have a friend, who is audio maniac here in Bandung, have loads of money, can buy any audio gear.
He buys so much FM Accoustics gear, that Manuel Huber himself will visit his house here in Bandung this late August/September. (I'm invited to his house that day, what should I ask Manuel Huber about how to make good sounding amplifiers?)
From the gears that he used, I think my friend likes the "coloured" sound (masked with low order harmonics). He prefers the "dirty" Airtight twin monoblocks compared to "very low thd" Gryphone. He doesn't know electronic, he doesn't know harmonic, but he can say he prefer this amp than that amp.
Now he changes everything to FM Accoustics. From Phono stage, preamp, eq, active Xover, power amp, all from FM Accoustic.
When I (and my friend) look inside those gears, it is not filled with expensive stuff at all. The PCB is single layered. For signal coupling it uses polarized (+/-capacitor), don't think about using Hovland or any expensive, it does not. All FM accoustic gear are full of "Black Box" modules with "ordinary" components.
This is the "Magic Part". My friend who knows what is inside FM Accoustic looks like, STILL willing to pay loads and loads and loads of money for each FM Accoustic gear.
What makes a customer willing to do so? It is incredible.
So, I think the difference between a "technically correct" power amp and with "technically incorrect / not good perfect enough technically" power amp not only in technical discussion only.
This will make a VERY BIG DIFFERENCE in making money. And big chance is, the "not perfect technically" power amps have much more chance to sell to these guys (who doesn't know electronics, but have tons of money)
) how people who have money, but do not understand electronic, willing to pay USD27.000,- for active Xover, USD40.000,-for power amp, etc. What is the "magical" sound that makes them willing to pay that so..so...soooo.... much money for audio equipment?
OK, the gears are "FM Accoustics" from Switzerland. I have a friend, who is audio maniac here in Bandung, have loads of money, can buy any audio gear.
He buys so much FM Accoustics gear, that Manuel Huber himself will visit his house here in Bandung this late August/September. (I'm invited to his house that day, what should I ask Manuel Huber about how to make good sounding amplifiers?)
From the gears that he used, I think my friend likes the "coloured" sound (masked with low order harmonics). He prefers the "dirty" Airtight twin monoblocks compared to "very low thd" Gryphone. He doesn't know electronic, he doesn't know harmonic, but he can say he prefer this amp than that amp.
Now he changes everything to FM Accoustics. From Phono stage, preamp, eq, active Xover, power amp, all from FM Accoustic.
When I (and my friend) look inside those gears, it is not filled with expensive stuff at all. The PCB is single layered. For signal coupling it uses polarized (+/-capacitor), don't think about using Hovland or any expensive, it does not. All FM accoustic gear are full of "Black Box" modules with "ordinary" components.
This is the "Magic Part". My friend who knows what is inside FM Accoustic looks like, STILL willing to pay loads and loads and loads of money for each FM Accoustic gear.
What makes a customer willing to do so? It is incredible.
So, I think the difference between a "technically correct" power amp and with "technically incorrect / not good perfect enough technically" power amp not only in technical discussion only.
This will make a VERY BIG DIFFERENCE in making money. And big chance is, the "not perfect technically" power amps have much more chance to sell to these guys (who doesn't know electronics, but have tons of money)
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