120w valve amplifier.

[Diabolical Artificer]

I tried to Terry. The problem's I had were due to changing position of ground terminations on the bus. When I built the amp I couldn't see a way round putting the bus in, too many widely spaced valves etc. I was in touch with a bloke in Oz who has built a similar amp/s, and have heard the same from other sources; high power amplifiers with high open loop gain are buggers to keep from oscillating. Guitar amps of around 100w in the past on the whole didn't suffer too much from this as they didn't have NFB I presume.

Been working on the protection board all weekend. Pics soon.

A.