The Buyer’s Guide showed up at the RMAF. At one point near the end of Sunday evening I was reading Robert Harley’s article. ‘A Survey of Amplifier Types’. One of the first covered was SET amplifiers. The final paragraph poses the question:

“How can an amplifier that performs so poorly by every ‘objective’ measure produce such an involving musical experience?” He concludes this paragraph after asking some similar questions (rhetorically), that “As of yet, no one has the answers to these questions.”

I found myself startled to see a statement like that in print. We have known the answers to those questions for some time (‘we’ meaning Atma-Sphere, but in a larger context a good number of other designers as well, particularly those that design SET amplifiers, not that that should be any great surprise), and by ‘some time’ I mean well over 20 years in our own case.

Its all about the rules of human hearing. Unfortunately, the audio industry has been for the most part ignoring the research into human perception over the last 4 or 5 decades. This has resulted in a schism in the high end industry, as there are those who *do* pay such attention, while most of the industry is asleep at the wheel. The portion that has been asleep at the wheel is the vast majority of the industry, and if anyone wonders why the industry has been shrinking over the last 10 years (it has), this is one of the reasons why- the sound of equipment must reflect the rules of human hearing in order to remain relevant and inspire people with the possibility of music!

This schism has resulted in the debate of tubes vs transistors, the need to match amplifiers to speakers, and the well-known objectivist vs subjectivist debate. One need not look very far to see these debates roiling about on the audio forums, which they have since the beginning of the Internet (well before the the www).

So- the answer to Robert’s questions (and to his credit, I appreciate that he put the word ‘objective’ in quotes, which is where that word, for the time being, belongs): The simple truth is that the ‘objective’ measurements do not measure the right things (and are thus not really ‘objective’, they are instead arbitrary for the sole purpose of looking ‘good’ on paper, sort of like the Emperor’s New Clothes). For example, our ears are tuned to use the odd ordered harmonics of any sound as a means to determine the loudness or volume of that sound. When an amplifier distorts these harmonics even by trace amounts, we hear it easily, as an artificial increase in the apparent volume and also as a brightness (you might say that our ability to discern the volume of a sound is one of the more fundamental rules of human hearing). Yet the ‘objective’ measurements look for the lowest THD, and in order to achieve such numbers, many designers will use techniques that actually *increase* these odd orders, while decreasing overall THD (this causes such an amplifier to be violating this fundamental hearing rule). This results in an a-musical amplifier, while an SET, with poor measurements, might sound very nice indeed.

SETs (and also our own amplifiers) lack these trace amounts of odd ordered harmonics where most transistor amps and push-pull tube amps tend to have larger amounts- in fact more so at lower power levels (that ’1st watt’ phenomena). SETs and our amps have lower and lower distortion as the power is decreased.

Our amps differ from SETs because when power is increased significantly, say over 1/3 full power, there is no serious increase in odd ordered harmonic content with our amps, which is why they are relaxed at high volume. SETs engage these harmonics at higher power levels, and since these power levels are mostly having to do with transients, this causes SETs to *seem* far more dynamic in a way that belies their lower power capabilities (since the exaggerated loudness cues then exist only on the transients). Its a psycho-acoustic phenomena.

You can contact us for more information about this and other phenomena. You might also read our paper regarding Paradigms in Amplifier Design. What I have mentioned here is the tip of the iceberg

While we are here at the RMAF, apparently the new review of the MA-2 Mk 3.1 has gone live at The Audio Beat. Thanks to Marc at The Audio Beat!

We are headed off to RMAF once again. We will be showing with Classic Audio Loudspeakers, Triplanar and Purist Audio in the Lupine room on the first floor. We will also have an S-30 in the Ginko Audio room and an MP-3 preamp in the ZU Audio room. See you there!

As one of the oldest hi-fi resources on the net, dating back to the early 1990s, the Atma-Sphere website has been overdue for an face-lift for some time now. So here it is, our new site, respectfully submitted for your approval.

Stay tuned for more of the same from us in the near future.

The Absolute Sound, April issue (#212), page 60: 

Dick Olsher’s Best Of CES, Best Sound (Cost No Object):
“The Sound Lab Majestic 845 ESL partnered by Atma-Sphere’s MA-1 OTL amps.
Roger West is back on top with a full range design capable of gorgeous tonality and exceptional musical realism.”

The Audio Beat has a blog review on the MA-1 Mk. III.1. In this case,

the amplifiers were an early set of MkIIIs owned by the reviewer. We had updated them to 3.1 recently (Which reactivated their warranty). The blog review comments are by Tim Aucremann.

Furthermore, The M-60 Mk. III.1 and MP-3 Mk. III.1 have both been awarded The Absolute Sound’s 2011 Editor’s Choice Awards.