Atma-Sphere MA-1 amps

Well then, you are used to heat - a good thing. Interesting that you are considering Atma; seems like a very different kind of amp. Obviously you have some very excellent SS amps, what is it about the MA-1s that are making you consider the move?

I own a pair of MA-1s from 1990, obviously very early in their history. I would be interested in hearing from anyone who also owns or owned MA-1s of that vintage, and either (i) upgraded them to current or near-current specs, or (ii) replaced them with a newer version MA-1. What I am looking for is some sense of a comparison between the old and new, ie to what extent the sound is the same or similar, and to what extent improved.

I agree completely with Sbank's description of the Atma-Sphere amps. With reasonable care matching speakers, the MA-1 amps are magic.

Jimjoyce25, I own Atma-Sphere MA-2 amps that were very early production MkII amps (mid-90's production). I sent them to Ralph to be updated to MkIII status with the new regulated power supply, new power supply filter capacitors, re-wiring of the output tubes, and a few other changes to bring them to current specifications. The updates should be similar to the update that would apply to your MA-1s. The result of the upgrade was absolutely astonishing in all parameters. Overall resolution improved, tonal purity improved, distortion lowered, bass impact increased materially, and there was a greater sense of "ease" across the spectrum coupled with greater dynamics. My wife and I were extremely pleased with the update; a very very significant upgrade in sound for an amp that we were already extremely pleased with. If you can afford the updates, I recommend you go for it.
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The MA-1s are teh best amps I have heard in my system. I did listen to many amps for a time. The next closest amplifier I have heard was the Pass Labs Aleph3. In may ways they share a lot in common - very highly resolving, musical without artifical euphony. Compared to the Pass, the MA-1s have a more natural midrange. I did get a couple upgrades. There were some resistors that were added to the output tubes on all new production amps that weren't in mine. I also had them make the Caddock Resistor upgrade at the same time. The result was the removal of a bit of midrange harshness that i had been aware of before the upgrade in cpomparison to the Pass, which was gone after the upgrade. They work well with my Talon Hawks without autoformers, even though the Hawks are nominally 6ohm speakers. The S30 with autoformer and M60swithout autoformer didn't do well on these speakers at all. The M60s with autoformers were OK, but not great.
Also don't overlook the physical beauty o fhte MA1s. They look stunning with their polished stainless chassis, and rows of big 6AS7G tubes. The tubes are especially nice with their finned anode plates. If only the filamnets could glow white instead of orange. Oh, well. Oh, and you cna change the color of the indicator lights on the front panel with different lenses you can buy from Fender guitar amp dealers (Musicianh's friend)