One for the Tube Guys!

[PRR]

> the effect goes away immediately.

Grid coupling caps will hold charge and delay recovery.

Transformer drive avoids that but has been unpopular since 1939. A few old-skool Gibsons(?), the cheap Fender BassMaster(?), and the over-the-top Fender 300. Oh, and Garnett messed with transformers, but he messed-around a lot.

I'm having a hard time with 6BQ6/EL84 self-bias at 25 Watts, but whatever.

[amptramp]

The EL84 is a 6BQ5, not a 6BQ6.  A pair of 6BQ5's would be good for 14 watts.  Guitar amp manufacturers might push it to 18 watts, but life would be short.  I happen to like sweep tubes - they are cheap, plentiful, they require low screen voltages and it does look butch to have plate caps going to the output transformer.  You can't do an ultra-linear connection because of the low screen voltages, but that doesn't get used much in guitar amps anyway.  Transmitting tubes look even better but they usually require very high plate voltages and high output transformer impedances to get their rated power.

[craigmillard]

Well i have got 6 Russian 6v6 the 6P6S that im going to use in this build and i bought a 50-100w output transformer from Merlin (Nice one Merlin) that has 3k25! I also used the second 400va transformer i had which has slightly different voltages, 40 + 32 which creates about 398 offload with the above quadruppler.. It does have a 10v secondary spare which i could use for the bias but was wondering if i could get a bias voltage from the main secondary.

I was building this as a play amp to mess with hence wanting to try fixed bias and a sextet of tubes Its a part bin build..

I will try those 6BQ6's next though! Look good:)

Im currently thinking of using some zenors to drop the extra voltage from merlins idea or putting a quadruppler on the 10v line too which will get 54v ish

[merlinb]

Im currently thinking of using some zenors to drop the extra voltage from merlins idea or putting a quadruppler on the 10v line too which will get 54v ish

Bias supply need practically no current, so a potential divider might be all that is required.