gofar99 Messages: 1949 Registered: May 2010 Location: Southern Arizona
Illuminati (5th Degree)
Hi, I hope no one was holding their breath on this one...essentially it is a bust. Yes the concept works....no it doesn't do what is needed. The problem is with the 6AS7 itself. A nice push-pull amp can be made. The problem is drive voltage. One running at 250 B+ with about 50ma per triode needs...get this (from Sveltena) 250 volts peak to peak to deliver about 10 watts. Ouch. They make an audio grade version of the tube BTW. The B+ and current is easy, 250 volts of signal drive isn't. The most logical way I can see doing this is with an interstage trannie. A healthy driver something like maybe a 6V6, EL84 etc with a step up ratio of at least 3 to 1. All in all though it defeats the constant current source in the cathodes and SRPP driver stage. Back to a pretty much conventional design. I have not decided if I want to go that way or not just yet.