@gregdude: I pulled up Will's ad. I believe they are PP mono using pairs of 811A transmitter tubes and big output trannies. Also 4 (!) 5R4GY rectifiers per chassis. Some serious plate voltage here (1200+). Looks like a nice restoration job by Will. Definitely worth the money! Imagine what you could get for them in Japan!
Has anyboidy had any experience with an 833-A single-ended triode amplifier?
One weakness of the SET is you are limited to sensitive speakers because of low power. Some people have experimented with using radio station transmitting tubes, especially the 833-A. Once you know how to do it, it is not difficult to build an 833-A final amplification stage which will work with low sensitivity speakers such as Magnepans if you prefer the sound of planar transducers to cone in box speakers and you can still have the purity of SET.
I have had success with only 1000 Volts through Hammond 1642SE output transformers. At this voltage the 833-A only draws 120 ma with zero grid bias so you can drive the grid with a 45 SET through a Lundahl LL2756 step-down transformer. The 10 Volt 10 Amp DC needed to heat the 833-A cathode is slightly tricky to build and I use 4.5 Farads in the final filter stage to do this.
Building your own, with help from someone who had experience with how to do this safely if you need it is much less expensive than buying one from a factory.
I have had success with only 1000 Volts through Hammond 1642SE output transformers. At this voltage the 833-A only draws 120 ma with zero grid bias so you can drive the grid with a 45 SET through a Lundahl LL2756 step-down transformer. The 10 Volt 10 Amp DC needed to heat the 833-A cathode is slightly tricky to build and I use 4.5 Farads in the final filter stage to do this.
Building your own, with help from someone who had experience with how to do this safely if you need it is much less expensive than buying one from a factory.