Atma-sphere S-30 with Reference 3A?

I think an amp that might work well if there is a lot of impedance swings in the speaker would be the Pass XA30.5, which also happens to be one of the best amps I've ever heard with my Merlins, although If you believe Ralph Karsten (why woulnd't you?)all amps will work better into flat impedances, the higher the better. I don't if it is always true, but my impression is that speakers with impedance swings are best handled by SS amps.

If memmory serves, I believe that the speaker has a relatively benign impedence curve (I investigated the question when I bought them - more than a few years ago). I suspect that the problem with the S-30 may be more a simple lack of grunt. I'm no headbanger, but as spl went up (to modestly loud levels), the S-30 sounded thinner on bottom with the deCapo.
There were 2 reasons I ultimately sold the amp:

The first was that it worked best with horns (Zingali in my case) and I chose to keep my Cary 300b monos for that application.

The second was that IMHO the deCapos were skillfully designed to present a natural octave to octave balance - the low end limitations were matched with a slightly rolled top. (I always felt that they were a great dynamic alternative to Quads). In the end, those limitations were more than I cared for so I sold both amp and speaker. But the main point is, I don't think any amp is likely to change this basic characteristic of the deCapo.

Marty

Well said Marty. Sean, what does the commentary do for your "upgrade" plans?

FWIW, we always get really good feedback from Ref3A owners. This has been true for the last 15 years or so. Customer input agrees with Duke's initial assessments above.

Although the S-30 was really designed for more efficient speakers (it was intended to go after the same market/speaker combos as SETs), it *does* make 30 watts into 8 ohms, which is a lot of power in the SET world. So it gets used on a lot of lower (91-93db) efficiency speakers.

A number of those speakers have less than 'ideal' impedances for the amp, but work great anyway: Merlins and Spendors for example, and the Ref3As. You can always use a set of ZEROs, but another little trick is to run the amp input single-ended and not use the jumpers in the XLRs. This more than doubles the feedback (which reduces the gain) and lets you work with tricker loads.