RMAF12: Atma-Sphere goes Classic

OTL amps are something of a hidden art. Joule Electra’s Jud Barber, David Berning, and Atma-Sphere’s Ralph Karsten are a trio of designers carrying various implementations of the technology into our listening rooms these days, and from my own experience with OTLs, I can honestly say that they really do sound different. And yes, that’s a good thing.

There’s just something incredible about the treble on an OTL. I’m not a treble guy, per se, as my obsessive behavior tends to fixate a bit lower on the frequency scale, but I’ll never forget what my old Marquis monos sounded like. Unreal.
It’s enough to permanently bias me in that direction — so when I stumble across the Novacron amps from Atma-Sphere at RMAF, I was not only tickled, I was intensely curious. I really want to play with these amps at home! From the Atma-Sphere blog:

We are showing the Novacron amplifier, which we have updated and are reissuing as a limited edition!! For those of you not familier with the Novacron, it uses four of the Russian 6C33 power triode per channel. It features a very curvatious chassis, one of the prettiest amps made by anyone, which is no doubt why used examples get into bidding wars on eBay when they turn up (which is not often- the original amplifier only saw two runs of production and is quite rare). The chassis are done in left and right-hand pairs. Here is the original photo:

We have updated the original amplifier with an improved voltage amplifier and individual bias controls for each power tube. It uses V-Cap copper foil Teflon coupling capacitors and Teflon power tube sockets.

Shown here with loudspeakers from Classic Audio and digital gear from Stahl-Tek, the sound was light and airy and piercingly sweet.

  • Classic Audio T-1.4 Reference speakers ($36,500/pair)
  • Atma-Sphere “Novacron” monoblocks $12,000/mirrored-pair
  • Atma-Sphere MP-1 preamp ($16k, as shown)
  • Stahl-Tek Opus CD transport ($37k)
  • Stahl-Tek Ariaa D/A converter ($12,900), a new async-USB converter that supports 24/192 via USB 2.0.

Ask me about sponsorship!


  1. The Stahl Tek Ariaa Dac has turned out to be the best money ive ever spent on my system! It will compete with any dac on the market regardless of price.If you plan on spending 5 times its price dont spend that kind of money until you hear it. it really is that good.

  2. I’m curious about the Ariaa, as far as Stahl-Tek pricing goes its a bargain, and could be an interesting Debussy competitor. On the bottom shelf is their “A.B.C” (audiophile bridge to computer) that’s a battery powered asynchronous USB to S/Pdif or I2S converter.

  3. You must try those Atma Sphere’s (and some other models) at your home.
    Let them glow for one hour and then……. Set sound with balls.

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