About as simple as it gets, for a three stage amplifier.
6AU6 voltage amplifier, gain of 25 drives a 6AQ5 miniature power valve, gain of 8, which drives the DHT output stage.
No feedback.
6AU6 input stage is biased with a white LED, which doubles as an "on" indicator, when placed behind a front panel, red Fender jewel lamp lens.
![Image](http://i.imgur.com/uNeBiwL.jpg)
The smoothing filters in the power supply (bottom) are duplicated on the other channel, so what we effectively have is a split power supply, once it divides in two after the rectification and smoothing choke.
Now here's an interesting discovery: on a whim, I decided to see how my NVA P20 passive would sound, feeding the SET power amplifier. All I can say is WOW!
The P20 just "goes" with the valve power amp. The sound was good with my existing switched attenuator, but with the P20, the whole passive/valve setup just hangs together superbly well. All sources have benefitted and the overall presentation and dare I say "musicality" is much better, the P20 digging out the music like a JCB.
Lovely
![Very Happy :grin:](./images/smilies/icon/biggrin.gif)