You will note that almost ANY amp responds dramatically with a genuinely good Preamp or even better a stepped attenuator.
No news there except for the Naive.
I wouldn't worry overly about the pcbs/ I'm still wondering WHY the AKSA price more than ...doubled ..over the price point that made it successfull.. not likely due to a component price doubling
the total parts complement, even bought retail remain surprisingly inexpensive
No news there except for the Naive.
I wouldn't worry overly about the pcbs/ I'm still wondering WHY the AKSA price more than ...doubled ..over the price point that made it successfull.. not likely due to a component price doubling
the total parts complement, even bought retail remain surprisingly inexpensive 
well, my friend do not jump on me because what I will say - I will say it without anger, very calm and friendly - maybe Hugh is living from it, or maybe he made that amplifier, or maybe he had costs when making it, or maybe he had invest time to make it.......
guys - why are You so surprised that Aksa is costing something.... how much Audio Note gear costs.... take a look what is inside.... well - i can tell you - everybody has seen the schematics.... do You really think that those transformers or capacitors cost that much that we pay them.... they earn money on us.... they work for it - they work to earn money on us...... why Hugh or anybody else can't do the same.... i can't understand that .... why You or me can't make something and make money out of it to buy - lets say a better cd transport or at least an ice-cream for my child or something - or why not cover our expences for parts..... why can't we (You and me) also do the same - it is not forbiden.... guys, why is that problematic .... i think that Hugh is not earning that much out of everything.... when you take how much it will cost him to run his businness and to take care of the familly - does anyone take into account that he might live from it .... it is better to sell Aksa's than to steal.... why there are people here that think that a guy is not fair if he earns some money from what he has made with his own two arms......
please tell me nice and friendly because i am friendly here too.... i do not understand guys... can someone explain me why we are like that.....
forgive me if i was rude or something but the same thing is happening on few other forums that i can read.... people do not talk about Hugh Dean here only.... but they all have problem because somebody is making money.... and when we buy a XXX companies cd player we do not ask ourself how much those parts cost that company and is it fair or not that this company gives us the sch for that particular part that we want in our system....
- maybe Hugh is living from it, or maybe he made that amplifier, or maybe he had costs when making it, or maybe he had invest time to make it.......guys - why are You so surprised that Aksa is costing something.... how much Audio Note gear costs.... take a look what is inside.... well - i can tell you
- everybody has seen the schematics.... do You really think that those transformers or capacitors cost that much that we pay them.... they earn money on us.... they work for it - they work to earn money on us...... why Hugh or anybody else can't do the same.... i can't understand that .... why You or me can't make something and make money out of it to buy - lets say a better cd transport or at least an ice-cream for my child or something - or why not cover our expences for parts..... why can't we (You and me) also do the same - it is not forbiden.... guys, why is that problematic .... i think that Hugh is not earning that much out of everything.... when you take how much it will cost him to run his businness and to take care of the familly - does anyone take into account that he might live from it .... it is better to sell Aksa's than to steal.... why there are people here that think that a guy is not fair if he earns some money from what he has made with his own two arms...... please tell me nice and friendly because i am friendly here too.... i do not understand guys... can someone explain me why we are like that.....
forgive me if i was rude or something but the same thing is happening on few other forums that i can read.... people do not talk about Hugh Dean here only.... but they all have problem because somebody is making money.... and when we buy a XXX companies cd player we do not ask ourself how much those parts cost that company and is it fair or not that this company gives us the sch for that particular part that we want in our system....
Well, I re-read my previous post, and I realized I didn't convey much real information. I'll attempt to be more specific in a subjective sort of a way.....
I very much like a jazz album by 'The Bad Plus' called 'These are the Vistas'. But until the Aksa, I wasn't particularly fond of the first cut, 'Big Eater'. It started out nice enough, but rapidly devolved to a confused mess, which I simply couldn't follow, and I'd inevitably skip forward. That is, until the Aksa 100 N+. Via the Aksa, I could now follow and admire the interplay between the musicians, and what I'd previously thought a confused mess, turns out to be a rather interesting interplay between some very skilled musicians. This is also a characteristic of some tube amps, specifically some SE implementations. But my speakers, Alon IVs, simply required too much power for an economical SE, (or PP for that matter) tube amp.
Subjectively put, the Aksa communicates, while still providing those benefits of ss, low power consumption, bass drive and control......
I do wish Hugh would produce a 300+ wpc amp with all the musical qualities of his current offerings.
I very much like a jazz album by 'The Bad Plus' called 'These are the Vistas'. But until the Aksa, I wasn't particularly fond of the first cut, 'Big Eater'. It started out nice enough, but rapidly devolved to a confused mess, which I simply couldn't follow, and I'd inevitably skip forward. That is, until the Aksa 100 N+. Via the Aksa, I could now follow and admire the interplay between the musicians, and what I'd previously thought a confused mess, turns out to be a rather interesting interplay between some very skilled musicians. This is also a characteristic of some tube amps, specifically some SE implementations. But my speakers, Alon IVs, simply required too much power for an economical SE, (or PP for that matter) tube amp.
Subjectively put, the Aksa communicates, while still providing those benefits of ss, low power consumption, bass drive and control......
I do wish Hugh would produce a 300+ wpc amp with all the musical qualities of his current offerings.
I am confident that AKSA is a VERY fine amp.....only problem I see is that Hugh has chosen to sell it with supply and cooling...so that he knows how it will work out in the end.....ok!
But what if I only want to REBUILD excisting amp/2xmono...........furthermore there is a lot of TAXes to pay
But good thing this.....expecting it fore a long time
But what if I only want to REBUILD excisting amp/2xmono...........furthermore there is a lot of TAXes to pay
But good thing this.....expecting it fore a long time
In this moment i am finishing the fifth AKSA channel, 4 of them are 55 and one is the
100 watts model (218 watts over 4 ohms).
Those amplifiier are all modified
Only one unit is almost the standard, but i supress the Black Gates, not to spend time burning them...i hate those black gates... my personal feeling is to shot them!.
The first intention was to produce a "comparator amplifier"....made for comparison, with switches to change speakers and amplifiers into a single sound source.
My earlier intention was to compare AKSA, Symassym and Gem...but i changed my mind, as now i want to test, again, the sonic differences related my changes in the 55.
The Aksa sounds great, separated listening could fooled me many times, but when i put Aksa in comparison with others, the qualities appear clear, so, i suppress the others good units, for a while, trying to repeat the incredible research Hugh made, and to understand, completelly and finally, what is that misterious thing that reproduces so nice sound with a so simple circuit.
I already have made this when i had my first stereo from AKSA....i have destroyed my boards, trying to make something better, i was searching for more bass those days, as i am boomy by nature, and brazilian music is very rich of percussions, an heritage from Africans that are a big part of our blood (Nigeria and Sudan).
I have destroyed my boards trying, and i called my audio club friends to evaluate a sample i made, a different circuit, i told them that sounded different, also informed Hugh...my friends were not happy with Hugh that dennied when was asked to give permission to me to produce some copies inside epoxi cement for them...even with erased numbers on the components and sealed was dennied by Hugh, that said clearly that people only give value for gods, when they make efforces to have, when they pay for it and also he wants his parts, special and selected inside his own boards, to avoid fake Aksas, not sounding good, reproducinhg not the best possible sound, but carrying the his brand....well, to protect the quality of their products.
They turn "on" their envy and jellows internal behavior circuit , very natural and human, in special in my place this reaction, and they start to be against Hugh...so i understand some reactions, because schematic is protected and keept hidden, and having many variations, so, someone can stolle the circuit A, the one with impressive mids, but circuit b, c, d and e will continue to be protected....the midrange circuit "a", have some identities to an old cousin called P61, and there are some guys that have it.
Even this one is not more used, there are many modifications made.
I made them the published Hugh schematic (this forum) and told them that has not the same kit's quality, as there are faulting components that increase sonics, and also there are not the parts selection, including the special components that cost a fortune if you order in Europe....This way i keep my friends less angry....but they heard mine modified, and also Hugh Standard circuit, the original, and they perceive both as better than the published version they have, and the original was considered much better than mine (what a shame for me!)...i told Hugh and ...surprise!...in 12 days new boards arrived here, for free, because Hugh had concerns that i had destroyed my boards trying to make better than he could make....a very interesting man, Mr. Dean.....when almost everybody can turn very angry, he had the idea to replace destroyed boards, not bothering that i was trying to create an other AKSA....and asked me informs if i succed to make it better.
Now a days i will try to understand the tips and the tricks, some of them already known, and others already explained clearly by Hugh, but i am curious to see those different circuits working, this way, i will compare only those AKSAs that i am finishing the preparation, only one is the standard circuit...having all standard components on it...even the pretty coil made by a very pretty girl that works in the production...what a girl!
Symassym is wonderfull, and Gem is a precious equipment...but i am still curious how Hugh could make better than hundreds of equipments i have made, and were are the modifications that produces this or that difference.
This research is for myself, my own pleasure, of course will not publish results because i cannot...well, i will inform Hugh...he may laugh and tell me...i have already done that Carlos....well....maybe i will have one more board if some picture shows him destruction...hehe....nice idea!....sand somewere to have new boards....guaranteed man!...ahahahahahahha!.
When ready i will make pictures...with reasonable distance...using a good foto machine and will show you the "comparator".
Of course i love those Aksas and also Hugh is a personal and constant and close friend.... always confident and also strikeproof friend...we faced problems and the friendship survived to all earthquakes.
If i love to talk about Aksa sonic qualities, of course!....he is my friend!, it is delicious to give to Ceasar what belongs to Ceasar, to be fair and talk something that people can test and find the same results.
I use to exagerate.....yes..... i am exagerated...related my passions, always exagerated.
The "comparator" will be transformed , all circuits will follow my prefered sonics, and they will constitute a four channel amplifier with the 100 watts operating as a subwooffer unit.
regards,
Carlos
100 watts model (218 watts over 4 ohms).
Those amplifiier are all modified
Only one unit is almost the standard, but i supress the Black Gates, not to spend time burning them...i hate those black gates... my personal feeling is to shot them!.
The first intention was to produce a "comparator amplifier"....made for comparison, with switches to change speakers and amplifiers into a single sound source.
My earlier intention was to compare AKSA, Symassym and Gem...but i changed my mind, as now i want to test, again, the sonic differences related my changes in the 55.
The Aksa sounds great, separated listening could fooled me many times, but when i put Aksa in comparison with others, the qualities appear clear, so, i suppress the others good units, for a while, trying to repeat the incredible research Hugh made, and to understand, completelly and finally, what is that misterious thing that reproduces so nice sound with a so simple circuit.
I already have made this when i had my first stereo from AKSA....i have destroyed my boards, trying to make something better, i was searching for more bass those days, as i am boomy by nature, and brazilian music is very rich of percussions, an heritage from Africans that are a big part of our blood (Nigeria and Sudan).
I have destroyed my boards trying, and i called my audio club friends to evaluate a sample i made, a different circuit, i told them that sounded different, also informed Hugh...my friends were not happy with Hugh that dennied when was asked to give permission to me to produce some copies inside epoxi cement for them...even with erased numbers on the components and sealed was dennied by Hugh, that said clearly that people only give value for gods, when they make efforces to have, when they pay for it and also he wants his parts, special and selected inside his own boards, to avoid fake Aksas, not sounding good, reproducinhg not the best possible sound, but carrying the his brand....well, to protect the quality of their products.
They turn "on" their envy and jellows internal behavior circuit , very natural and human, in special in my place this reaction, and they start to be against Hugh...so i understand some reactions, because schematic is protected and keept hidden, and having many variations, so, someone can stolle the circuit A, the one with impressive mids, but circuit b, c, d and e will continue to be protected....the midrange circuit "a", have some identities to an old cousin called P61, and there are some guys that have it.
Even this one is not more used, there are many modifications made.
I made them the published Hugh schematic (this forum) and told them that has not the same kit's quality, as there are faulting components that increase sonics, and also there are not the parts selection, including the special components that cost a fortune if you order in Europe....This way i keep my friends less angry....but they heard mine modified, and also Hugh Standard circuit, the original, and they perceive both as better than the published version they have, and the original was considered much better than mine (what a shame for me!)...i told Hugh and ...surprise!...in 12 days new boards arrived here, for free, because Hugh had concerns that i had destroyed my boards trying to make better than he could make....a very interesting man, Mr. Dean.....when almost everybody can turn very angry, he had the idea to replace destroyed boards, not bothering that i was trying to create an other AKSA....and asked me informs if i succed to make it better.
Now a days i will try to understand the tips and the tricks, some of them already known, and others already explained clearly by Hugh, but i am curious to see those different circuits working, this way, i will compare only those AKSAs that i am finishing the preparation, only one is the standard circuit...having all standard components on it...even the pretty coil made by a very pretty girl that works in the production...what a girl!
Symassym is wonderfull, and Gem is a precious equipment...but i am still curious how Hugh could make better than hundreds of equipments i have made, and were are the modifications that produces this or that difference.
This research is for myself, my own pleasure, of course will not publish results because i cannot...well, i will inform Hugh...he may laugh and tell me...i have already done that Carlos....well....maybe i will have one more board if some picture shows him destruction...hehe....nice idea!....sand somewere to have new boards....guaranteed man!...ahahahahahahha!.
When ready i will make pictures...with reasonable distance...using a good foto machine and will show you the "comparator".
Of course i love those Aksas and also Hugh is a personal and constant and close friend.... always confident and also strikeproof friend...we faced problems and the friendship survived to all earthquakes.
If i love to talk about Aksa sonic qualities, of course!....he is my friend!, it is delicious to give to Ceasar what belongs to Ceasar, to be fair and talk something that people can test and find the same results.
I use to exagerate.....yes..... i am exagerated...related my passions, always exagerated.
The "comparator" will be transformed , all circuits will follow my prefered sonics, and they will constitute a four channel amplifier with the 100 watts operating as a subwooffer unit.
regards,
Carlos
forr said:
Hi forr,
Can I just mention my experience. Over the last 4 or 5 years I have been building quite a few amps, all quite similar with minor differences. Some EF others CFP, some bootstrapped, some with CCS and current mirrors. You get the idea, all based on the "generic" 3 stage topology. There is even 1 or 2 commercial amps for comparison, that are very similar. I have even sourced some of my components for my non-AKSAs from Hugh to try and eliminate differences.
And the result is....to my ears the AKSA is better, pretty much in line with what the others are saying.
I'm pretty sure that the AKSA's performance is a result of careful component selection and component tweaking as well as some tweaking of the original topology.
I also have a feeling that if someone with the skills and time, selected another topology and put the same or greater effort into tweaking it, they may be able to get similar or even better results.
I currently have 4 other amps to build this year in an effort to knock the AKSA off it's pedestal.
BTW: I appreciate that others will have different experiences and I do respect your opinion. We are all doing audio for pleasure and we must remember that at all times.
regards
Hi Greg Erskine,
Thanks for writing about your experience with the AKSA amp.
For years, I've loved my 1978 entirely bipolar class B Linsley-Hood amp. As I did not have much money at the time, components were of poor quality, the ones I had at hand. I wondered and wondered about its magic. The scope showed rock stability. The schock was the arrival of a distometer at home : there was a lot of crossover distorsion ! This is one of the most disturbing fact I encountered in years of audio interest. Another one, of the same kind, was an incredible low cost k7 tape recorder : very noisy but incredible detailed. From where come the magics ?
I think that, as far as passive components are of good standard quality, they have very little influence on the sound. With the use of transistors with the intended beta, I think all is in topology.
So, what makes AKSA magic ?
~~~~~~ Forr
§§§
Thanks for writing about your experience with the AKSA amp.
For years, I've loved my 1978 entirely bipolar class B Linsley-Hood amp. As I did not have much money at the time, components were of poor quality, the ones I had at hand. I wondered and wondered about its magic. The scope showed rock stability. The schock was the arrival of a distometer at home : there was a lot of crossover distorsion ! This is one of the most disturbing fact I encountered in years of audio interest. Another one, of the same kind, was an incredible low cost k7 tape recorder : very noisy but incredible detailed. From where come the magics ?
I think that, as far as passive components are of good standard quality, they have very little influence on the sound. With the use of transistors with the intended beta, I think all is in topology.
So, what makes AKSA magic ?
~~~~~~ Forr
§§§
Despite i love JLH....Aksa eat it in the breakfast
Easy!
There are 2 moments:
-The first you do not believe that Aksa could do that and you double check the connections to see if Aksa is really the winner.
-Second moment...sorry for that, but you switch off the JLH and put it to receive dust somewhere.
I made it....and friends did not believe untill they heard by themselves.
Never believe those things.... do it yourself the comparison!
I am so confident about AKSA, and there are so many guys that already told me the same i think about it, that i challenge everyone to compare with their amplifiers and return to say if AKSA winned or not..... just count the votes and i am sure that Aspen AKSA 55 Nirvana Plus will be the winner with good distance from the competition.
regards,
Carlos
Easy!
There are 2 moments:
-The first you do not believe that Aksa could do that and you double check the connections to see if Aksa is really the winner.
-Second moment...sorry for that, but you switch off the JLH and put it to receive dust somewhere.
I made it....and friends did not believe untill they heard by themselves.
Never believe those things.... do it yourself the comparison!
I am so confident about AKSA, and there are so many guys that already told me the same i think about it, that i challenge everyone to compare with their amplifiers and return to say if AKSA winned or not..... just count the votes and i am sure that Aspen AKSA 55 Nirvana Plus will be the winner with good distance from the competition.
regards,
Carlos
Tinitus
"Why so good"!
'Hmmm, maybe not from doing so much good but from doing nothing wrong'
Constant current sources and current mirrors are supposed to be electronically all good, but sonically not. Where's their default ? Or are defaults sonically better ? Seems to be a kind of Hamlet's question.
~~~~~~~ Forr
§§§
"Why so good"!
'Hmmm, maybe not from doing so much good but from doing nothing wrong'
Constant current sources and current mirrors are supposed to be electronically all good, but sonically not. Where's their default ? Or are defaults sonically better ? Seems to be a kind of Hamlet's question.
~~~~~~~ Forr
§§§
A lot of material here; I apologise in advance! 
Suffice to say that none of this thread is very meaningful unless you've heard the amplifier and know from personal experience how it sounds. This is very difficult to arrange without buying, I know, because of the distance, cost and trust factor.
Echo Wars:
Usually, I buy, particularly if someone visiting from another country seeks me out personally. Sometimes people insist they buy. One customer from the US actually sent me a 1992 Dom Perignon, which I drank only last week with friends. (Thank you very much, Stan!) Any business worth a crumpet should have sufficient petty cash to fete a customer, past or potential.
ClassD4Sure:
You may be right about the market. However, mine is a boutique business catering to the cognoscenti of the DIY world. Their tastes are more highly developed!
Joules:
The 'straight wire with gain' philosophy has served for fifty years, but has not always given us good sounding amps. If amplifiers were called 'playback instruments', then perhaps this model would not have survived so well. It persists, with some justification, but the only place where extreme linearity is useful is, IMHO, in the realm of complex orchestral works, where any non-linearity leads immediately to intermodulation, and then, rapidly, to mud........
There are other mechanisms to aural perception aside from linearity. As mentioned before, I believe it's distortion spectrum, but I cannot quantify the phenomenon because the R&D is expensive. All I can do is try to voice amps which sound good, which is merely an outcome, but not the synthesis of a theory of musical perception. I hope to remedy this in time.
Forr:
You raise many points, I'll try to answer some of them!!
You are highly technical, and experienced. Most people are not. I really have no choice but to highlight the good sonics of the amp if my product is to appeal to most; and actually, the distortion figures don't really bear much relevance to the sonics anyway. I believe it is significant that the only people who cast doubt on the AKSA are technical people, most often those who have not heard it anyway. There is a different paradigm here, and those of technical mind are highly resistant to changing their views. This is particularly true if they haven't heard the AKSA, haven't seen the full schemat, and haven't made any measurements on it. I can certainly understand that, but for marketing reasons I'm unable to enter into a full scale discussion of the techniques used.
The AKSA architecture is, in fact, attributed to Arthur R. Bailey in the mid-sixties. None of it is directly attributable to Doug Self, who immortalised himself by writing a highly readable distortion analysis of a public domain circuit during the early nineties in Wireless World. From what I have researched, Doug Self has made no significant creative contribution beyond Bailey and the public domain. In some areas he is plain wrong, such as his love of the CFP. But he does write well, and his math is very good.
Your comments concerning stability, noise immunity, phase margin, current linearity, etc are all correct but you are wrong if you suspect the AKSA is very neutral sounding. It is not a straight wire with gain, and not designed as such, though the distortion figures are good.
The customer is indeed the target! I really cannot sell enough AKSAs - I want more customers. There!! I've said it!
The 'capricious nature of human physiology and psychology' as you colorfully put it is indeed at the core of my design. But by describing it as such, you indicate there is much work to be done in aural perception, and you are exactly correct. This is the key. Humans like their music with a sprinkle of truffle - to use a convenient French metaphor - they really don't like it too bland (like English cuisine, to use another!).
Your experience with tape recorders and crossover distortion on the JLH amp is very interesting. JLH is a design model for me; I love his approach and creative designs. Your experience should demonstrate clearly that the key is aural perception, rather than extreme linearity. However, linearity does help, and in any given design I have found that subsequent improvements in linearity always enhance the sound. That's a significant clue, of course.
Gracious Terry and Exuberant Carlos:
Thank you for your lovely, tolerant and enthusiastic posts! It is regrettable we can't all meet - it would be great pleasure to talk to you both!
Per Anders:
Thank you for your comment on the pcb! No-one designs better double sided pcbs than you - not even PMA comes close!
It may be that a full double-sided pcb with ground plane would sound even better. I don't know about this yet. I need to do more R&D to verify the virtues of double sided pcbs.
BTW, the quality is outstanding. I have all my pcbs made in Australia by a professional, and the latest ones are wonderful.
Bare:
The original AKSA did not include power supply UFSR diodes, a custom pcb and filter caps. These days it does. These caps are very expensive, as you probably know.
I don't believe the AKSA is expensive for what it is sonically. You will have no idea of the service I give, or the grade of components I use, or the R&D costs behind the design. You may not have heard the AKSA. Naturally I won't bore you with those details, but like anyone in this difficult business I have not even fully recovered my costs to date, nor will I debate how I arrive at my prices. Nough said.
Tube Dude:
You may be right about topology!! However, I prefer to think of it as one third topology (including dimensioning), one third component choice, and one third layout. Everything seems to matter. There are hundreds of hours in the AKSA pcb layouts, I regret to say.
To all those not mentioned here, thank you for the positive, encouraging comments. Much appreciated.
Cheers,
Hugh
Suffice to say that none of this thread is very meaningful unless you've heard the amplifier and know from personal experience how it sounds. This is very difficult to arrange without buying, I know, because of the distance, cost and trust factor.
Echo Wars:
Usually, I buy, particularly if someone visiting from another country seeks me out personally. Sometimes people insist they buy. One customer from the US actually sent me a 1992 Dom Perignon, which I drank only last week with friends. (Thank you very much, Stan!) Any business worth a crumpet should have sufficient petty cash to fete a customer, past or potential.
ClassD4Sure:
You may be right about the market. However, mine is a boutique business catering to the cognoscenti of the DIY world. Their tastes are more highly developed!
Joules:
The 'straight wire with gain' philosophy has served for fifty years, but has not always given us good sounding amps. If amplifiers were called 'playback instruments', then perhaps this model would not have survived so well. It persists, with some justification, but the only place where extreme linearity is useful is, IMHO, in the realm of complex orchestral works, where any non-linearity leads immediately to intermodulation, and then, rapidly, to mud........
There are other mechanisms to aural perception aside from linearity. As mentioned before, I believe it's distortion spectrum, but I cannot quantify the phenomenon because the R&D is expensive. All I can do is try to voice amps which sound good, which is merely an outcome, but not the synthesis of a theory of musical perception. I hope to remedy this in time.
Forr:
You raise many points, I'll try to answer some of them!!
You are highly technical, and experienced. Most people are not. I really have no choice but to highlight the good sonics of the amp if my product is to appeal to most; and actually, the distortion figures don't really bear much relevance to the sonics anyway. I believe it is significant that the only people who cast doubt on the AKSA are technical people, most often those who have not heard it anyway. There is a different paradigm here, and those of technical mind are highly resistant to changing their views. This is particularly true if they haven't heard the AKSA, haven't seen the full schemat, and haven't made any measurements on it. I can certainly understand that, but for marketing reasons I'm unable to enter into a full scale discussion of the techniques used.
The AKSA architecture is, in fact, attributed to Arthur R. Bailey in the mid-sixties. None of it is directly attributable to Doug Self, who immortalised himself by writing a highly readable distortion analysis of a public domain circuit during the early nineties in Wireless World. From what I have researched, Doug Self has made no significant creative contribution beyond Bailey and the public domain. In some areas he is plain wrong, such as his love of the CFP. But he does write well, and his math is very good.
Your comments concerning stability, noise immunity, phase margin, current linearity, etc are all correct but you are wrong if you suspect the AKSA is very neutral sounding. It is not a straight wire with gain, and not designed as such, though the distortion figures are good.
The customer is indeed the target! I really cannot sell enough AKSAs - I want more customers. There!! I've said it!
The 'capricious nature of human physiology and psychology' as you colorfully put it is indeed at the core of my design. But by describing it as such, you indicate there is much work to be done in aural perception, and you are exactly correct. This is the key. Humans like their music with a sprinkle of truffle - to use a convenient French metaphor - they really don't like it too bland (like English cuisine, to use another!).
Your experience with tape recorders and crossover distortion on the JLH amp is very interesting. JLH is a design model for me; I love his approach and creative designs. Your experience should demonstrate clearly that the key is aural perception, rather than extreme linearity. However, linearity does help, and in any given design I have found that subsequent improvements in linearity always enhance the sound. That's a significant clue, of course.
Gracious Terry and Exuberant Carlos:
Thank you for your lovely, tolerant and enthusiastic posts! It is regrettable we can't all meet - it would be great pleasure to talk to you both!
Per Anders:
Thank you for your comment on the pcb! No-one designs better double sided pcbs than you - not even PMA comes close!
It may be that a full double-sided pcb with ground plane would sound even better. I don't know about this yet. I need to do more R&D to verify the virtues of double sided pcbs.
BTW, the quality is outstanding. I have all my pcbs made in Australia by a professional, and the latest ones are wonderful.
Bare:
The original AKSA did not include power supply UFSR diodes, a custom pcb and filter caps. These days it does. These caps are very expensive, as you probably know.
I don't believe the AKSA is expensive for what it is sonically. You will have no idea of the service I give, or the grade of components I use, or the R&D costs behind the design. You may not have heard the AKSA. Naturally I won't bore you with those details, but like anyone in this difficult business I have not even fully recovered my costs to date, nor will I debate how I arrive at my prices. Nough said.
Tube Dude:
You may be right about topology!! However, I prefer to think of it as one third topology (including dimensioning), one third component choice, and one third layout. Everything seems to matter. There are hundreds of hours in the AKSA pcb layouts, I regret to say.
To all those not mentioned here, thank you for the positive, encouraging comments. Much appreciated.
Cheers,
Hugh
Hi Jorge,
Yes, to some extent, though not completely, you are right!
If you are well used to the speakers and the source, and know how they 'sound', you can generally pick differences IFF you have a good audio memory, or a mental checklist.
However, it is wise to swap things around to check, and to this end I have five sets of speakers, and three sources, all different. Of course, speakers vary widely and to produce a universal amplifier you need to know how it reacts with different loads anyway..... But with many different sets of speakers and three different sources, you can generally voice an amp so that in all cases it sounds better than stock.
This is highly empirical, and fills the objectivists with horror, but it's what the consumer does all the time, so you'd better do it too....
I try hard not to take things personally, and play the situation, not the man. Thank you for your kind suggestion, but these days I am no longer insecure about the AKSA, and not much I read either insults or surprises me.
Cheers,
Hugh
Yes, to some extent, though not completely, you are right!
If you are well used to the speakers and the source, and know how they 'sound', you can generally pick differences IFF you have a good audio memory, or a mental checklist.
However, it is wise to swap things around to check, and to this end I have five sets of speakers, and three sources, all different. Of course, speakers vary widely and to produce a universal amplifier you need to know how it reacts with different loads anyway..... But with many different sets of speakers and three different sources, you can generally voice an amp so that in all cases it sounds better than stock.
This is highly empirical, and fills the objectivists with horror, but it's what the consumer does all the time, so you'd better do it too....
I try hard not to take things personally, and play the situation, not the man. Thank you for your kind suggestion, but these days I am no longer insecure about the AKSA, and not much I read either insults or surprises me.
Cheers,
Hugh
AKSA said:Hi Jorge,
I try hard not to take things personally, and play the situation, not the man. Thank you for your kind suggestion, but these days I am no longer insecure about the AKSA, and not much I read either insults or surprises me.
Hi Hugh.
That is the giving of some years living in this planet with eyes opened... I call it maturity.
Cheers
Just so we dont get misled by one set of highly selective quotations!!
Hubert also observed:
>>
here is THE problem: inner details (micro details) are not on par with my tweaked valves-amp Rogers E40a: i.e. the lack of reverberations and prolongation of musical notes is obvious, not only in the upper range but also in the low-mid. Thus, timbres are affected, but not the musical flow; fluidity is preserved even if a few harmonics are "breaked down".
>>
and
>>
> To summarize:
> An almost perfect amp; if the lack of inner details could be avoided
>>
also
>>
Others (me included) may prefer less accurate electronics, with different listening characteristics
>>
These comments pose interesting questions to me!!
How can something NOT be distorting if:
" the lack of reverberations and prolongation of musical notes is obvious"
"timbres affected" ,
"harmonics are breaked down"!!
Certainly does seem "warts & all"!!
But then again, I'm just lover of old fashioned tube technology which despite its multitude of technical faults doesnt chop off everberation or ruin instumental timbre!! Rather important I would have thought and an area in which ( compared to most SS amps ), my listening tests confirm, the AKSA excells, which is why I like it!!!.
cheers
Hubert also observed:
>>
here is THE problem: inner details (micro details) are not on par with my tweaked valves-amp Rogers E40a: i.e. the lack of reverberations and prolongation of musical notes is obvious, not only in the upper range but also in the low-mid. Thus, timbres are affected, but not the musical flow; fluidity is preserved even if a few harmonics are "breaked down".
>>
and
>>
> To summarize:
> An almost perfect amp; if the lack of inner details could be avoided
>>
also
>>
Others (me included) may prefer less accurate electronics, with different listening characteristics
>>
These comments pose interesting questions to me!!
How can something NOT be distorting if:
" the lack of reverberations and prolongation of musical notes is obvious"
"timbres affected" ,
"harmonics are breaked down"!!
Certainly does seem "warts & all"!!
But then again, I'm just lover of old fashioned tube technology which despite its multitude of technical faults doesnt chop off everberation or ruin instumental timbre!! Rather important I would have thought and an area in which ( compared to most SS amps ), my listening tests confirm, the AKSA excells, which is why I like it!!!.
cheers
pmkap said:
I find this an interesting detail.
Use of a 'simple resistor' to give current to input differential pair.
Like Mr. Dean there is another one using resistor instead of transistorized current source.
This is EE professor Mr. Leach in his 'Leach amplifier'.
We have had a discussion of this in
about ccs of Leach Amp
started by john-china
It is my opinion, that in an amplifier using a great deal of negative feedback,
the input pair topology will considerably effect overall result at output.
Interesting to find two experienced amplifier designers using a non-active current source.
And in both cases resulting in amplifiers that are very much loved for their performance.
When in reality there are ways to use a more precise topology.
Also bootstrap is 'an old technique',
that many, including myself, do not use at all.
But logically, what worked well yesterday,
will not suddenly stop working well today.
Do note, however, that the reason Leach uses a resistor instead of a CCS is that a resistor has lower noise (his claim). It should be no problem to design a CCS with sufficiently low noise today, so his reason is no more, if it ever was.
Edit:
Also remember that Leach used the triple T output configuration because it had the lowest distorsion in his Spice simulations. No mentioning of what sounds best anywhere in his writings, as far as I can remember.
Edit:
Also remember that Leach used the triple T output configuration because it had the lowest distorsion in his Spice simulations. No mentioning of what sounds best anywhere in his writings, as far as I can remember.
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