1/2 power switch?

[rockon1]

I'd like to install a 1/2 power switch on my Crate VC50. Its fixed bias with 4 EL84"s. Am I correct in assuming all Id need to do is wire a STDP switch between pin three and ground on two of the EL84'S ? (after of course cutting the trace to pin 3 on those two tubes) If so what minimum rating should the switch have? Thanks Bob

[tubeswell]

I'd like to install a 1/2 power switch on my Crate VC50. Its fixed bias with 4 EL84"s. Am I correct in assuming all Id need to do is wire a STDP switch between pin three and ground on two of the EL84'S ?

Or you could try a triode/pentode switch that works on all four EL84s at the same time.

[mac1amps]

I remember on the EL84 model Matchless amps, they had a power cut switch that was rigged so that, in the lower power mode (eliminating two of the four EL84's), there was additional cathode resistance (I think it was around 50 additional Ohms). The two remaining power tubes in ckt. wouldn't have the additional "strain" that occurs when two of the tubes are taken out of "the mix". The added resistance would also help in cutting the overall power. A word of note though.....Don't expect the ½ power mode to be ½ as loud (a common misconception.......it doesn't really work that way).