Atma-Sphere MA-1 amps

This is a very interesting thread. Trcnetmsncom, I looked up the impedance curve of the Avalon Eidelon. It's below 5 ohms (closer most of the time to 3 ohms) between 50Hz and 20kHz, except for a narrow "peak" in the midrange, where it gets up to 7 ohms. This is not an optimal match for any OTL (like the Atma MA2) that does not use negative feedback to achieve a low output impedance. However, the MA2 has such huge power capability that you are able to overcome the impedance matching problem to a large degree. Nevertheless, I wager that if you were to interpose a pair of Paul Speltz's Zero autoformers between the amp and the speakers, the perceived unpleasant treble distortions would disappear. Given the large investment that you have already made in the amps and speakers, the Zeros amount to a trivial additional expense. I don't think one can ever talk about how an amp "sounds" without considering the speaker load.

Lewm,

Thank you! That is very interesting. In fact I wanted to research the same, but then was too busy to do so. By the way, it was the cable breaking in not the Atmas after all, when I began to seem to hear the same "thinness" through the Sound Labs, which Trcnetmscom had described hearing through the Avalons with them. Wanted to report that anyway.
Cheers,

Since we are on the topic, sort of, what are your preamps of choice with the Atma amps. I assume the Atma pre would be a natural pairing. Was that best for you? Have you preferred something else? Why? Or tried others and decided the Atma pre was best for mathcing with their amps? Why? Your thoughts?

Hello Lewm,

Thanks for the research and posting a response. I'm sorry if you got the impression from this thread that I own the Atma's. To be clear, I do not. I came awfully close though!

However, I was fortunate enough to have spent time hearing the MA-2 with the speakers I own and speakers I previous owned in three different systems for a total of 5 lengthy listening sessions. Thankfully I was able to get over the things I thought they did so well and hear IMO what did not jive to my ears.

When I talked on the phone with Ralph he mentioned to me that there were many Eidolon-Eidolon Diamond/MA-2 users in the field. I don't know for certain, but I didn't get the impression from talking with him that any of them were using the Zeros. If this helps, the MA-2's amps were able to drive the Eidolon Diamond to extreme volume levels without signs that the amps were running out of gas. Also, it might be of help to know I heard the IMHO texture thinness and treble abbreviations at low or loud volumes. But from the little technical knowledge I have of OTL's, tonal abbreviation is independent of volume. In other words, if the speaker in question is not a good match for an OTL, tonal coloration will be apparent at all volume levels. Is this correct?

I would like to point out once again I think the Atma's are in certain ways .... "extraordinary" .... exceeding the competition. I also encourage others to audition them to hear the certain areas of cutting edge performance I feel Ralph has achieved with his design.

Having lived and learned over the years from owning five different sets of electrostatics from Acoustat, Quad, and Martin-Logan, these also in certain ways were ....extraordinary.... and in my view, above, exceeding that of the competition. But they also lacked in certain ways, and for me in the long run their faults took away the enjoyment, that magic, the escape, the thrill of being fooled if only for a second that this could be real. Through my experience and from the mistakes I felt I've made, I have learned a balanced approach of choosing all components is what has endured for me.

Best to all,
Tom