Marshall 2104 mkII

[redshark]

I may pickup one of those combos with 6550's. I have read many times people replacing the 6550's with EL-34's doing a resistor and bias change. Anybody here has done that mod? just curious....If you had...how many resistors need to be changed? for what value?

Thanks!!

[M Fowler]

I believe the 6550 uses 150k and EL34 use 220k pair of bias resistors.