AKSA and other boutique amplifiers

[Gringoaudio1]

Having spent years on the DIYAudio forums I got sucked into several of the various ‘cults’ there. First it was the Fullrange driver schtick and tried for several years to understand what the appeal
was. When I finally realized that all the dudes who swore by full-range were old guys who had probably lost the top octaves of hearing I realized that I needed to build at least two-way speakers. Then it was chip amps and the cult around the clones of the 47 Labs chip amp. For under $20 one could get a couple of LM1875 or the more powerful versions and build a point to point wired amplifier. Weird topologies like making the inverting version even ensued. Thoerston Loesch was a member here for awhile was a mentor.
But there were always exotic amps like the AKSA from Aspen Labs that were seen as the holy grail. That they sounded so much better than everything else. Never got that far though I did accumulate the PCBs and almost all the parts for the P3A amp from Rod Elliot. And for one of the DIY Nelson Pass designs. Somehow got sidetracked with life work and divorce.
I’d be interested in seeing how some of these icons of diy measure and if anyone has them in their systems please send them in to Amir!

 

[pma]

You can find it at diyaudio, Vendor section. Those amps do not measure well.

https://www.diyaudio.com/community/attachments/titan-125-power-amplifier-prototype-measurements-doc.1120997/

 

[Keith_W]

I know Hugh Dean who designs AKSA. He lives in Melbourne, I have met him a few times, and he has been over to my place. AKSA amps are deliberately designed to produce a Hiraga-like distortion profile, which, according to some people, sounds better than amps with no distortion.

You can make up your own mind about whether amps that deliberately add harmonic distortion is a desirable characteristic or not. I am not against some harmonic distortion, I think it can subjectively sound more pleasant. It seems to make the sound richer and the top end more extended. However, I add my distortion via a VST plugin in JRiver. That way, it is defeatable. Distortion added by an amp is not defeatable, it is always there.

Audio cults exist everywhere. I see that you have already found a few. As always, there is a grain of truth in what they claim. However it is usually overstated and the drawbacks no mentioned.

 

[pma]

I see your point, but those amps also have tons of non-harmonic, power supply related mess, which is a sign of incompetent design.

 

[Gringoaudio1]

I see your point, but those amps also have tons of non-harmonic, power supply related mess, which is a sign of incompetent design.

Whoever did those tests and put comments on the graphs thought the results were good. All the hash on the charts provided seems unrelated to 50 or 60 hz from the Mains. Please explain the ‘power supply related mess’ ? I have a small understanding of electronics so bear with me. Thanks.

 

[3125b]

Whoever did those tests and put comments on the graphs thought the results were good

But they're not. Not awful either, but not good.
Really similar to this $200 Yamaha, actually: https://www.audiosciencereview.com/forum/index.php?threads/yamaha-r-s202-receiver-review.52587/
FR is worse with 1dB of roll-off at both ends, which is slightly audible.
You can see spikes at 50Hz and its multiples, 50Hz is the power grid frequency in Australia. It's probably a linear PS with insufficient filtering.