Hegel Design Flaw?

The Atma-Sphere S-30 drives the Raidho C1.1s with more than enough headroom thanks to Paul Speltz Zero-Autotransformers.

I never understood why adding a transformer to an OTL just to make it work. Either buy a bigger OTL or different type of amp IMO.

I auditioned Atma-Sphere M-60 with Paul Speltz Zero-Autotransformer driving Acoustic Zen Crescendo. It sounds fantastic on less demanding material but overall had trouble controlling the speaker. Acoustic Zen Crescendo is much easier to drive than C1.1.

Knghifi,

Ralph Karsten or Paul Speltz may want to chime in with a technical explanation. The fact is that without the Speltz Zeros the Raidho C1.1s are hard to drive. But with them the sound is stunning and there is loads of headroom.

Knghifi,

You stated, "I auditioned Atma-Sphere M-60 with Paul Speltz Zero-Autotransformer driving Acoustic Zen Crescendo. It sounds fantastic on less demanding material but overall had trouble controlling the speaker."

There are 3 or 4 levels of adjustment with the Zero-Autotransformers. Perhaps the level was not the correct one. Is that possible? I am puzzled about your lack of success with the Speltz. How did this control problem manifest itself in terms of SQ?

There are 3 or 4 levels of adjustment with the Zero-Autotransformers. Perhaps the level was not the correct one. Is that possible? I am puzzled about your lack of success with the Speltz. How did this control problem manifest itself in terms of SQ?

I know there are different levels of adjustments.

I was at a BM and the dealer setup the system. I was considering Atma-Sphere MA-2 and wanted to reacquaint myself with their sound again.

I only demo with Zero-Autotransformers in the chain but dealer told me with Zero-Autotransformers, SQ and transparency suffered a little but has better speaker control. I forgot his reason not getting MA-1 so he needed Zero-Autotransformers.

Knghifi,

With my system, SQ and transparency improved a lot with the S-30. I can think of 2 possibilities here -- the driver tubes and system synergy. It took me months to find the best tubes for the S-30. And it has taken years to optimize the S-30 with cables, tweaks and accessories. So, the reason for this happening in your case may not be apparent.