This is my hardware upgrade for 2010...a project which is already several years in the making. Amplifiers based on transmitting tubes are becoming popular among the DIY SET crowd, and after sitting in on a few listening sessions, I'd have to admit that some of the designs sound good...very good.
The SET circuit topology doesn't lend itself well to big electrostatic speakers; it can be done but you wind up making too many compromises that likely affect performance in some way.
In the end I penned up this design, a push-pull triode amp based on NOS Eimac 304TL's. Initial tests at low operating points have been quite exciting; even with the output stage running at < 25% under its anticipated operating range, it has far exceeded my expectations.
The goal for this year is to push it up to 90% rated power, get some running time on it, and get it into a custom chassis. The amplifier in the photo is one channel; I actually get to do this twice.
From the start, this amplifier was designed only for use with electrostatic speakers, which is not a usual consideration among those who build triode/transmitter-class amps.
If there is any interest, I could start a thread in the DIY section. I don't really recommending trying to build one of these things, but as it is slated for use with Martin Logans the information might be useful to some.
Tj