Adding an extra preamp tube...

[bren-hur]

Hi...I have a hand made marshall plexi clone, pretty nice with what looks to be vintage transformers. It has the standard marshall tubery: 2 12ax7 preamp tubes, 12ax7 splitter, 2 KT66 power tubes and a thingamajig tube rectifier. Question..i want to add a swtichable gain stage in the preamp...yes I could do the hoffman hot swtich, but seeing this amp already has a master volume, I'd have a gain pot and knob sitting there all bored and stuff...SO...will the power tranny handle me adding an extra preamp tube? I would only be using half of it for a gain stage for both channels...

Thanks!

(sorry if this has been asked before...i searched but came up with nada...)

[tubeswell]

If you want to add a 12AX7, it draws about 4mA on the HT winding (shouldn't be an issue) and 300mA on the heater winding (depends on whether the heater winding is running close to max spec or not). Other than that you might have to twiddle around with the B+ supply resistors for the least disruption to the existing plate voltages.

[bren-hur]

Excceeelllent....thanks very much!!