VinylJunkie
New member
- Joined
- Jul 15, 2014
- Messages
- 4
- Reaction score
- 0
A few months ago I bought a Mark III which had an adjustable bias already installed. This bias mod has two trim pots, but it appears to be just a balance. Each pot controls one EL34 and one 6L6, not pairs, unfortunately. I'd assume that it would need a seperate bias circuit to control pairs. Anyway, I finally got around to messing with bias yesterday. After I biased the EL34’s to 35ma, the 6L6’s were only 17ma. If I run the 6L6’s up to 30ma, the EL 34’s are 55ma. I still had a long way to go before the 6L6’s were at 70% (42ma), but the EL34’s were already too high, so I went back to 35ma on the EL34’s and gave up for the time being. The high bias on the EL34’s would be normal if the EL34’s actually were running in class A, but from what I understand that’s not the case. Is that correct? What should the bias be for the EL34’s anyway? Unless I"m missing something, I don’t see any options other than trying to find a really hot pair of 6L6’s and a really cold pair of EL34’s. This is my first Simul Class amp, so it’s a bit of a learning curve.