Lineup,
Nice to have some explanation from the Variac, who I thought was very moderate, operating well below mains on this occasion.....
Thank you for your comments, yes, a couple of children, Soraya 21, and Alessandra, 19. The eldest is a girl racer, a real petrol head, like me.
P-A,
You must be tolerant of your own countryman. Lineup and Carlos both add something and dilute the objectionable egos which are a part of all forums!
Tony,
Possibly. However, it's innocent enough. BTW, how is it that your written English is magnificent, right down to the slang - I have a friend married to a high class Mexican lady and her English is better than most Australians. Spanish is reputedly the best language of all to express strong emotion; English is much more functionally oriented, without the intense color of your language. This clever lady is now a high powered executive here in Melbourne. I conclude that you have enjoyed a wonderful education, and we are privileged to talk with you, particularly if you like Pass gear.
On AKSAs,
This amp was deliberately designed to very slightly color the sound with typical levels of 0.04% H2 and H3. The principle was the known psychoacoustic masking of these harmonics on the higher order harmonics spuriously created in most SS, feedback amplifiers. The design is very, very simple, but no one looking at the circuit has ever been able to figure out precisely how it's been achieved, which has protected the IP better than any patent. But the amp definitely sounds a bit like a tube amp, but with the slam and sheer grunt of solid state, something the tube amps struggle to achieve.
I'm still selling them, but my latest amp has gone all out to reduce distortion to vanishingly low levels. I do not have figures, as I don't own an AP1, but THD should now be below 0.005% at all levels to full power. Nested feedback, phase lead and superlinear circuit blocks have brought improvement in resolution, with much more spatial information and almost zero congestion with heavy orchestral works, focussing deficiencies squarely on the speaker and source.
P-A, I've started using surface mount; the DMMT5401 supermatched pair for the LTP. You must be very careful not to draw breath while mounting them - they are so light they can be disturbed by air flow!! With six leads on a chip 1.6 x 2.7 mm you cannot do this job on a bad hair day........ I'm not sure I'll be able to mount these components if Parkinsons ever sets in!!
Cheers,
Hugh
Nice to have some explanation from the Variac, who I thought was very moderate, operating well below mains on this occasion.....
Thank you for your comments, yes, a couple of children, Soraya 21, and Alessandra, 19. The eldest is a girl racer, a real petrol head, like me.
P-A,
You must be tolerant of your own countryman. Lineup and Carlos both add something and dilute the objectionable egos which are a part of all forums!
Tony,
Possibly. However, it's innocent enough. BTW, how is it that your written English is magnificent, right down to the slang - I have a friend married to a high class Mexican lady and her English is better than most Australians. Spanish is reputedly the best language of all to express strong emotion; English is much more functionally oriented, without the intense color of your language. This clever lady is now a high powered executive here in Melbourne. I conclude that you have enjoyed a wonderful education, and we are privileged to talk with you, particularly if you like Pass gear.
On AKSAs,
This amp was deliberately designed to very slightly color the sound with typical levels of 0.04% H2 and H3. The principle was the known psychoacoustic masking of these harmonics on the higher order harmonics spuriously created in most SS, feedback amplifiers. The design is very, very simple, but no one looking at the circuit has ever been able to figure out precisely how it's been achieved, which has protected the IP better than any patent. But the amp definitely sounds a bit like a tube amp, but with the slam and sheer grunt of solid state, something the tube amps struggle to achieve.
I'm still selling them, but my latest amp has gone all out to reduce distortion to vanishingly low levels. I do not have figures, as I don't own an AP1, but THD should now be below 0.005% at all levels to full power. Nested feedback, phase lead and superlinear circuit blocks have brought improvement in resolution, with much more spatial information and almost zero congestion with heavy orchestral works, focussing deficiencies squarely on the speaker and source.
P-A, I've started using surface mount; the DMMT5401 supermatched pair for the LTP. You must be very careful not to draw breath while mounting them - they are so light they can be disturbed by air flow!! With six leads on a chip 1.6 x 2.7 mm you cannot do this job on a bad hair day........ I'm not sure I'll be able to mount these components if Parkinsons ever sets in!!
Cheers,
Hugh
Times they are changing 
Have you also started to make double sided boards? It's time you to upgrade your Nirvana kit to "Outer Space" kit.
Hugh,
Sorry but I couldn’t resist and of course you are right on with the comment.
I like class A amps for what they bring to the table but find them terribly inefficient, the AB’s I’ve made over the years (mostly Borbely designs) did not cut it, they were no AKSA of course which I haven’t had the pleasure to hear.
I do have some Zen and Aleph’s but drive them with vacuum line amps and in no way I’m married to Pass designs but like them for their simplicity and good sound. Time may come to try AKSA, been tempted for some time after hearing comments from many DIYaudio members.
BTW, my user name here is an acronym of my name Antonio Passalacqua with the added “gear” which many think it implies that I’m a Pass nut so to speak.
I appreciate your kind words, you are a real Gentleman
Sorry but I couldn’t resist and of course you are right on with the comment.
I like class A amps for what they bring to the table but find them terribly inefficient, the AB’s I’ve made over the years (mostly Borbely designs) did not cut it, they were no AKSA of course which I haven’t had the pleasure to hear.
I do have some Zen and Aleph’s but drive them with vacuum line amps and in no way I’m married to Pass designs but like them for their simplicity and good sound. Time may come to try AKSA, been tempted for some time after hearing comments from many DIYaudio members.
BTW, my user name here is an acronym of my name Antonio Passalacqua with the added “gear” which many think it implies that I’m a Pass nut so to speak.
I appreciate your kind words, you are a real Gentleman
Gaetan,
E. Larsen and R.M. Aarts (2004), Audio Bandwidth extension. Application of Psychoacoustics, Signal Processing and Loudspeaker Design., J. Wiley.
E. Larsen and R.M. Aarts (2002), Reproducing low-pitched signals through small loudspeakers, J. Audio Eng. Soc., March, 50 (3), pp. 147-164.
Hugh
E. Larsen and R.M. Aarts (2004), Audio Bandwidth extension. Application of Psychoacoustics, Signal Processing and Loudspeaker Design., J. Wiley.
E. Larsen and R.M. Aarts (2002), Reproducing low-pitched signals through small loudspeakers, J. Audio Eng. Soc., March, 50 (3), pp. 147-164.
Hugh
Hugh,
your WebPages - especially with details and prices - are completely unreadable to me (using Firefox). The characters are way too small sized. Can you please let your webdesigner check your layouts also with different browsers? Or was it designed on a Mac perhaps (this can also cause problems of this kind)?
all the best
Klaus
your WebPages - especially with details and prices - are completely unreadable to me (using Firefox). The characters are way too small sized. Can you please let your webdesigner check your layouts also with different browsers? Or was it designed on a Mac perhaps (this can also cause problems of this kind)?
all the best
Klaus
Yes... saturation in colour....and i was thinking in Black and white.
Into black and white. some modification in deepness happens, as constrast reforce the black shadows, that turns hidden some small gray detais... shows also dinamics to me.
Well....as you see,...each one of us feel different about the word "contrast" applied to audio.
There are so many variables into our communication, as we are persons, things are subjective and language not precise or not absolutelly standard.... this makes people run to instruments.
Because there, the language is standard...easy of communication.
regards,
Carlos
Into black and white. some modification in deepness happens, as constrast reforce the black shadows, that turns hidden some small gray detais... shows also dinamics to me.
Well....as you see,...each one of us feel different about the word "contrast" applied to audio.
There are so many variables into our communication, as we are persons, things are subjective and language not precise or not absolutelly standard.... this makes people run to instruments.
Because there, the language is standard...easy of communication.
regards,
Carlos
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