My sincere congratulations to Mr Hugh Dean, Mr. Graham Maynard that could make better audio than My prefered John Lindsey Hood, model 1969.
My friends meeting evaluate again the AKSA 55 that was the winner few monthes ago, loosing only to JLH 1969.
Today i call the friends to a judgment, all conditions perfectly controled, no wind, temperature 24 degrees centigrades, no noise , no air conditionair, no one talking, sea level and many speakers used and 19 people judging, 16 audiophiles that belongs to my club and i invited my Maid my Wife and the younger daugther, those last ones do not have special interest in audio, only are normal humans.
1) AKSA 55, special for mids and brigths hi frequencies
2) Graham Maynard amplifier, the class A, because of bass and sonic image
3) JLH by the reasons you all know very well.
Despite i do not agree entirelly, my prefered still the JLH, this is the result of our meeting.
Since i told some lack of bass, Mr Hugh was in close contact with me suggesting modifications, now the bass is OK!
Related the Maynard amplifier, was not used the special transistor he insist that make a big difference...i could not find the unit and used another hi frequency one.
Related to JLH, the transistors are the normal 2N3055 and BD139 units, it may be better with some hi speed units.
Now i want to find one to beat AKSA!
hehe, the never ending novel
regards,
Carlos
My friends meeting evaluate again the AKSA 55 that was the winner few monthes ago, loosing only to JLH 1969.
Today i call the friends to a judgment, all conditions perfectly controled, no wind, temperature 24 degrees centigrades, no noise , no air conditionair, no one talking, sea level and many speakers used and 19 people judging, 16 audiophiles that belongs to my club and i invited my Maid my Wife and the younger daugther, those last ones do not have special interest in audio, only are normal humans.
1) AKSA 55, special for mids and brigths hi frequencies
2) Graham Maynard amplifier, the class A, because of bass and sonic image
3) JLH by the reasons you all know very well.
Despite i do not agree entirelly, my prefered still the JLH, this is the result of our meeting.
Since i told some lack of bass, Mr Hugh was in close contact with me suggesting modifications, now the bass is OK!
Related the Maynard amplifier, was not used the special transistor he insist that make a big difference...i could not find the unit and used another hi frequency one.
Related to JLH, the transistors are the normal 2N3055 and BD139 units, it may be better with some hi speed units.
Now i want to find one to beat AKSA!
hehe, the never ending novel
regards,
Carlos
that is a fact, i could see that your unit reproduced well
I could see your unit had no problems with the many speaker models we use.... always reproducing good sound.
But the old JLH 1969 had problems with old speakers full of coils and capacitors inside.
In my home i do not use crossover... only series condenser.... 22 to midrange and from the i capture with 1 uf the highs to the twetter, mid range and tweeter are in parallell related the signal, but only the tweeter receive hi frequencies.
I use also one 22 ohms resistor in series with the mid and high drivers.
Speaker is ported and tuned to 35 Hertz.
Your amplifier is very tollerant to strange loads i could see, also Aksa is very good in that aspect, but Aksa not happy with 1.6 ohms loads... it was made to use 8 ohms i think.
Please Graham, take a look in "testing AKSA 55, had problems testing", there you will see the test condition...only ears, no instrument except AC voltimeter to match power.
regards,
Carlos
I could see your unit had no problems with the many speaker models we use.... always reproducing good sound.
But the old JLH 1969 had problems with old speakers full of coils and capacitors inside.
In my home i do not use crossover... only series condenser.... 22 to midrange and from the i capture with 1 uf the highs to the twetter, mid range and tweeter are in parallell related the signal, but only the tweeter receive hi frequencies.
I use also one 22 ohms resistor in series with the mid and high drivers.
Speaker is ported and tuned to 35 Hertz.
Your amplifier is very tollerant to strange loads i could see, also Aksa is very good in that aspect, but Aksa not happy with 1.6 ohms loads... it was made to use 8 ohms i think.
Please Graham, take a look in "testing AKSA 55, had problems testing", there you will see the test condition...only ears, no instrument except AC voltimeter to match power.
regards,
Carlos
Carlos,
Many thanks for publishing your findings. I am pleased that the AKSA did well.
Graham, my congratulations to you - your extraordinary depth of research and math ability, together with sheer hard work, has delivered a brilliant amplifier!
Carlos, the AKSA was designed for 8R loads, that is true. I use it routinely on a 4R D'Appolito speaker - that is, the impedance drops near resonance to 3.6 ohms - without problem but I agree anything below this it does not like. A 1.6R load is verbotten, and recommended only with a four output pair AKSA a couple of my customers have built. This 'special amp' delivers more than 550W into 1.62R loads with complete reliability, using only 43V rails.
My thanks again,
Cheers,
Hugh
Many thanks for publishing your findings. I am pleased that the AKSA did well.
Graham, my congratulations to you - your extraordinary depth of research and math ability, together with sheer hard work, has delivered a brilliant amplifier!
Carlos, the AKSA was designed for 8R loads, that is true. I use it routinely on a 4R D'Appolito speaker - that is, the impedance drops near resonance to 3.6 ohms - without problem but I agree anything below this it does not like. A 1.6R load is verbotten, and recommended only with a four output pair AKSA a couple of my customers have built. This 'special amp' delivers more than 550W into 1.62R loads with complete reliability, using only 43V rails.
My thanks again,
Cheers,
Hugh
Hi Hugh,
I often use the virtual Ariel 'loudspeaker' to test simulate amplifiers because it too has similarly awkward impedance dips.
550W available from an AKSA for the 'dips' - not quite a class-A capability !
Actually pure class-A can be found wanting through these impedance dips, but by then the amp would be running at its limits anyway.
Hi Carlos,
My amp is deliberately designed without any kind of input, C.dom or output filtering. Some individual listeners prefer gentle supersonic filtering, and this can be tried with my circuit, however I refuse to fit it as standard for this could limit the performance for those who prefer sharper detail. Feel free to try input filtering, also you could try a 0.22 ohm wirewound resistor in series with the output to reduce amplifier-loudspeaker damping. The reproduced sound will become subtly changed, though the amplifier would still measure similarly at audio frequencies.
One of my all-time favourite test sources is the 1986 CD by Luther Vandross. Give Me The Reason. EPC 450134 2. Apart from Luthers freshly mature voice, good backing and a decent instrumental stage without treble pre-emphasis there is magical recording of a glockenspiel. This will test any player-amplifier-loudspeaker combination, and especially show up amplifier-loudspeaker interaction and/or crossover-driver discontinuities on a multi-driver capacitor-inductor crossovered loudspeaker system.
Cheers ............... Graham.
I often use the virtual Ariel 'loudspeaker' to test simulate amplifiers because it too has similarly awkward impedance dips.
550W available from an AKSA for the 'dips' - not quite a class-A capability !
Actually pure class-A can be found wanting through these impedance dips, but by then the amp would be running at its limits anyway.
Hi Carlos,
My amp is deliberately designed without any kind of input, C.dom or output filtering. Some individual listeners prefer gentle supersonic filtering, and this can be tried with my circuit, however I refuse to fit it as standard for this could limit the performance for those who prefer sharper detail. Feel free to try input filtering, also you could try a 0.22 ohm wirewound resistor in series with the output to reduce amplifier-loudspeaker damping. The reproduced sound will become subtly changed, though the amplifier would still measure similarly at audio frequencies.
One of my all-time favourite test sources is the 1986 CD by Luther Vandross. Give Me The Reason. EPC 450134 2. Apart from Luthers freshly mature voice, good backing and a decent instrumental stage without treble pre-emphasis there is magical recording of a glockenspiel. This will test any player-amplifier-loudspeaker combination, and especially show up amplifier-loudspeaker interaction and/or crossover-driver discontinuities on a multi-driver capacitor-inductor crossovered loudspeaker system.
Cheers ............... Graham.
Yes, some monthes ago i find AKSA too much brigth on my own speakers
As this brigthness is wonderfull, i was trying some changes to reduce a little the brigth without erase it completely, without destroy all hi harmonics, that cannot be heard but can be perceived as "natural" sound, giving to the bells the characteristic sound that diferentiate it from other metals as cymbals and others "hit on metals" sounds.... this way i used your top hi frequency "Maynard modified Zobel filter"...the 2R2 resistor used in Zobel filter, and also i used one inductor with some resistance...i use thin wire and a lot of turns, one experience, but could not perceive problems related the damping.... despite of the resistance introduced together the inductor, the bass came alive, and the reduce of "brigther appearance" was not so easy to perceive.
This way, some theories that using hi emitter resistor or series resistance between amplifier and speaker, do not create problems in bass reproduction as i expected, i could have a better bass, when i was waiting loss of bass.
I turn myself confused.... i am already confused.
Resistance in series with the speaker, will that reduce bass or not, as a effect of modified amplifier damping?
regards you and all guys
Carlos
As this brigthness is wonderfull, i was trying some changes to reduce a little the brigth without erase it completely, without destroy all hi harmonics, that cannot be heard but can be perceived as "natural" sound, giving to the bells the characteristic sound that diferentiate it from other metals as cymbals and others "hit on metals" sounds.... this way i used your top hi frequency "Maynard modified Zobel filter"...the 2R2 resistor used in Zobel filter, and also i used one inductor with some resistance...i use thin wire and a lot of turns, one experience, but could not perceive problems related the damping.... despite of the resistance introduced together the inductor, the bass came alive, and the reduce of "brigther appearance" was not so easy to perceive.
This way, some theories that using hi emitter resistor or series resistance between amplifier and speaker, do not create problems in bass reproduction as i expected, i could have a better bass, when i was waiting loss of bass.
I turn myself confused.... i am already confused.
Resistance in series with the speaker, will that reduce bass or not, as a effect of modified amplifier damping?
regards you and all guys
Carlos
Carlos,
Let's consider this output inductor thang.
You wind it with 0.5mm wire, 53 turns, to give around 0.1 ohms. The output impedance of an AKSA at 1KHz 20W is around 20 milliohms; this is a nominal damping factor of 400. You could argue that for many speakers this is overdamped, and the bass will sound very tight and rather dry, with very limited decay. With the 0.1R introduced outside the feedback loop, the Zout is now 120 milliohms, giving a damping factor of 67, six times less. This should have the effect of diminishing control, particularly decay, and the bass will wetten out somewhat, sounding fuller and arguably more musical.
Your modification is probably a good idea!
Cheers,
Hugh
Let's consider this output inductor thang.
You wind it with 0.5mm wire, 53 turns, to give around 0.1 ohms. The output impedance of an AKSA at 1KHz 20W is around 20 milliohms; this is a nominal damping factor of 400. You could argue that for many speakers this is overdamped, and the bass will sound very tight and rather dry, with very limited decay. With the 0.1R introduced outside the feedback loop, the Zout is now 120 milliohms, giving a damping factor of 67, six times less. This should have the effect of diminishing control, particularly decay, and the bass will wetten out somewhat, sounding fuller and arguably more musical.
Your modification is probably a good idea!
Cheers,
Hugh
I feel ashamed sometimes in our forum, i have not this knowledge
I am one "changeneer"...i go changing till the sound turns agreable to my ears.
Sometimes i change so much, that i did not realise "what was the main change" that produce this or that result.
I need that capacitor that put things "on focus", the one you told me.... i have not good focus.
I changed so much your amplifier that i am really do not know if increase the quality or decrease..... i will make one more, 100 percent "standard" AKSA to compare to my "clone".
Your circuit board is wonderfull...hehe, i have one that never receive solder...not to destruct the "purity"... wonderfull board.
regards,
Carlos
I am one "changeneer"...i go changing till the sound turns agreable to my ears.
Sometimes i change so much, that i did not realise "what was the main change" that produce this or that result.
I need that capacitor that put things "on focus", the one you told me.... i have not good focus.
I changed so much your amplifier that i am really do not know if increase the quality or decrease..... i will make one more, 100 percent "standard" AKSA to compare to my "clone".
Your circuit board is wonderfull...hehe, i have one that never receive solder...not to destruct the "purity"... wonderfull board.
regards,
Carlos
My dear Mikeks and his batteries
hehe, you incredible.
John Lindsey Hood was a very nice guy, he could be ahead for long, long time, one example to be followed.
He teached to all of us that simple is good, and sometimes better too
He loose, in my point of view, but was not something to be ashamed, the advantage was clearly perceived to ASKA, but JLH is already a very respectable amplifier.
Mikeks, hehe.... will put some batteries on you....my dear Mikeks, can you show to us some amplifier you design, assemble and test... can i have the honor to evaluate, together with my friends, and also our forum friends, the excelence of design you could made?
hehe.....waiting you design Mikeks.
May have some art there....but please, i know all wide worlds designs, the published ones and the ones turned into reality, some exception may exist, of course, hehe, can be your schematic.... show us the one you made that is new.
regards,
Carlos
hehe, you incredible.
John Lindsey Hood was a very nice guy, he could be ahead for long, long time, one example to be followed.
He teached to all of us that simple is good, and sometimes better too
He loose, in my point of view, but was not something to be ashamed, the advantage was clearly perceived to ASKA, but JLH is already a very respectable amplifier.
Mikeks, hehe.... will put some batteries on you....my dear Mikeks, can you show to us some amplifier you design, assemble and test... can i have the honor to evaluate, together with my friends, and also our forum friends, the excelence of design you could made?
hehe.....waiting you design Mikeks.
May have some art there....but please, i know all wide worlds designs, the published ones and the ones turned into reality, some exception may exist, of course, hehe, can be your schematic.... show us the one you made that is new.
regards,
Carlos
Destroyer..
This:
http://www.meridian-audio.com/p_559.htm
..could be demonstrably better than the JLH...No?
This:
http://www.meridian-audio.com/p_559.htm
..could be demonstrably better than the JLH...No?
Yes, there's some possibility, it seems pretty good
Also US enormous cars seems pretty good too.
But could not beat the Toyota Corolla, or the Suzuki Swift, even the uncle Sam brothers had to accept that, it is turning hard to see american car's in the US now a days...hehe...maybe in Japan we can find some.
My grandfather told me, Mikeks; " the more complicated the thing, more possibility of defects you will have. "
Related audio, as you know better than big Charlie, each circuit causes some small problem, and now we have the "correctors", circuit to correct this or that..... something non sense to my Grandfather....alike a fire soldier putting gasoline and ignition material inside some wooden house, and after that run to extinguish the fire he create. Only usefull as one exercise.
I could see new amplifier models ashamed in comparison to some "stupid" old designs.
People is working in silence, sometimes when hardly challenged, they turn nervous and talk a little bit more than usual, some big Doctors, i think can incluse you too, are working taking into account the human perception joined with the standard instruments.
Sony did that since long time ago, when i first entered their factory i could confirm that they evaluate calling a lot of people , selected from the "parts stock" people to the high staff.... and together, they stayed all day long hearing and making notes.
When this hearing tests where finished, the Engineers gone to instruments.... they do not confirm that if you ask them, but they were learning the distortions that people like to hear!..... to keep them there!....not to remove!....learning how to make amplifiers to people.
What we can see today....a Market reference of those sinthetic multichannels amplifiers...take a look inside... see that they are using transistors..... check the supply, not a complicated switching supply, you will see a transformer.... voltage goes down.... and the pleasant effect of that appear in your sound reproduction.....distorts when you push hard, and some people smile and tell you full of pride:
- "What a power!.... did you perceive the brigth in that reproduction?"
I'm turning confident that we will going fast to better sound amplifiers, as i could perceive that people alike Mr. John Curl, are using some old studies of human perception as reference for something he may be doing.... i would like to be some fly or ant, to go there, and see what Curl is doing rigth now!
I was very sad related the "direction" the amplifier's designs were going, only few people telling that researching something adequated, as amplifiers made for people. A lot of good guys going to instruments....wrong way in my mind.
Now i am feeling much better.
regards,
Carlos
Also US enormous cars seems pretty good too.
But could not beat the Toyota Corolla, or the Suzuki Swift, even the uncle Sam brothers had to accept that, it is turning hard to see american car's in the US now a days...hehe...maybe in Japan we can find some.
My grandfather told me, Mikeks; " the more complicated the thing, more possibility of defects you will have. "
Related audio, as you know better than big Charlie, each circuit causes some small problem, and now we have the "correctors", circuit to correct this or that..... something non sense to my Grandfather....alike a fire soldier putting gasoline and ignition material inside some wooden house, and after that run to extinguish the fire he create. Only usefull as one exercise.
I could see new amplifier models ashamed in comparison to some "stupid" old designs.
People is working in silence, sometimes when hardly challenged, they turn nervous and talk a little bit more than usual, some big Doctors, i think can incluse you too, are working taking into account the human perception joined with the standard instruments.
Sony did that since long time ago, when i first entered their factory i could confirm that they evaluate calling a lot of people , selected from the "parts stock" people to the high staff.... and together, they stayed all day long hearing and making notes.
When this hearing tests where finished, the Engineers gone to instruments.... they do not confirm that if you ask them, but they were learning the distortions that people like to hear!..... to keep them there!....not to remove!....learning how to make amplifiers to people.
What we can see today....a Market reference of those sinthetic multichannels amplifiers...take a look inside... see that they are using transistors..... check the supply, not a complicated switching supply, you will see a transformer.... voltage goes down.... and the pleasant effect of that appear in your sound reproduction.....distorts when you push hard, and some people smile and tell you full of pride:
- "What a power!.... did you perceive the brigth in that reproduction?"
I'm turning confident that we will going fast to better sound amplifiers, as i could perceive that people alike Mr. John Curl, are using some old studies of human perception as reference for something he may be doing.... i would like to be some fly or ant, to go there, and see what Curl is doing rigth now!
I was very sad related the "direction" the amplifier's designs were going, only few people telling that researching something adequated, as amplifiers made for people. A lot of good guys going to instruments....wrong way in my mind.
Now i am feeling much better.
regards,
Carlos
Your class A sounded better than JLH too Maynard, but it is some
Technological developed clone....something alike a clever cousin, or the brigther family's brother...i am including your development, upgradings and correction in JLH family because of same audio characteristics.
I am looking to a "magic mistery tour"... without marijuana, cocaine, and other brain exciters..... some contact with alive music.... and that is the real fun!....because will never realise that....because alive is alive!...and recording is recording.... they cannot be the same.
If someday that magic happened to me, have sure that i will be completely depressed..... because the interesting game will be finished..... reach the unreachable.
AKSA, your amplifier Graham, some JLH designs give enougth satisfation.... but we can be more and more close the reality.
There are some circuit in AKSA, that you could perceive some singer out of tone..... when hearing Wagner (receiving people to a party).... without the AKSA, i cannot hear this guy, and if you discover what is doing that!!!!!, you may hit your head into the wall, alike our forum smilies.
So, there are some "magic" some detail, some focusing, and could not understand why?
And those things goes making differences.
Yesterday i was seeing "troy" DVD.... and my six AKSA pumping 8 speakers around me.... inside small room.....operating amplifier almost all the time in class A, as i increased the bias against Mr. Hugh advise. There's a moment that "Aquiles" hit some giant man, i could heard the sound efect of the spade entering the flesh.... i runned to other equipment to check.... and where"s that sound?.... mufled it was.
So, let's go tweaking guys..... Long life to the King!
regards,
Carlos
Technological developed clone....something alike a clever cousin, or the brigther family's brother...i am including your development, upgradings and correction in JLH family because of same audio characteristics.
I am looking to a "magic mistery tour"... without marijuana, cocaine, and other brain exciters..... some contact with alive music.... and that is the real fun!....because will never realise that....because alive is alive!...and recording is recording.... they cannot be the same.
If someday that magic happened to me, have sure that i will be completely depressed..... because the interesting game will be finished..... reach the unreachable.
AKSA, your amplifier Graham, some JLH designs give enougth satisfation.... but we can be more and more close the reality.
There are some circuit in AKSA, that you could perceive some singer out of tone..... when hearing Wagner (receiving people to a party).... without the AKSA, i cannot hear this guy, and if you discover what is doing that!!!!!, you may hit your head into the wall, alike our forum smilies.
So, there are some "magic" some detail, some focusing, and could not understand why?
And those things goes making differences.
Yesterday i was seeing "troy" DVD.... and my six AKSA pumping 8 speakers around me.... inside small room.....operating amplifier almost all the time in class A, as i increased the bias against Mr. Hugh advise. There's a moment that "Aquiles" hit some giant man, i could heard the sound efect of the spade entering the flesh.... i runned to other equipment to check.... and where"s that sound?.... mufled it was.
So, let's go tweaking guys..... Long life to the King!
regards,
Carlos
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