David McGown wrote:
Stuart,
Since you are committed to PP amps, the natural thing is to keep everything balanced (differential) to the power amp. No more phase splitter. It makes no sense to convert back to single ended out of the preamp and then split phase again at the amp. I know the OddWatt amps do the phase splitting in the output stage, so it would require a little rework to convert the SRPP driver into a differential, but hey, it is only resistors and perhaps another signal capacitor. But that is a system wide change and upsets everything including interconnects (right after you upgraded to RCA Audio Envy!). You should really look at Allen Wright's designs for a fully differential preamp/amplifier. Some really interesting and good stuff there.
All you are doing is executing in vacuum tubes what the Topping does with an opamp when it converts from balanced to SE after the DAC. The most basic circuit is a summing amplifier executed with a single opamp. Maybe the tube circuit will sound better, but maybe not. It is cheap to put something together with what Tom is suggesting. A pair of transformers is another solution that is easy to try without upsetting everything. Jensen and Cinemag makes some. I think I may even have a pair of Cinemag transformers that may work, I will have to dig around.
I have been toying with balanced in explorations of powerful versions of First Watt amplifiers (converting a stereo 25W Class A to a 100W monoblock), but have backed off because I realize that (1), I prefer tubes, and (2), a 30W tube amplifier does almost everything I need or want for the music I listen to.
David
Site keeps logging me off and erasing my reply! Dammit