I have been looking at gut shots of some Two Rocks on the Pro guitar site. I have noticed that they have high/low power switching on the rear, JM signature has 2 different types of power switching.
Also appears to have 2 x bias adj pots?
Pentode / triode switching???........Turning 2 tubes off perhaps ( as done in ODS's )??
The other one being the custom reverb sig 3 50 which has fixed/Cathode bias switching.
I have searched extensively in this forum for any previous discussions on this subject that may have appeared but have not had much luck.
I am always looking for different ideas to experiment with for future builds. I would greatly appreciate some feedback from the wealth of knowledge that is abundant in the TAG.
Thanks in advance,
Crafty
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Two Rock got bought by Premier Builder Guild, who's been buying up guitar and amp shops (Tone King, Baker, Koll, Fano) over the last year or two.
As far as power switching goes: turning off two tubes when there are four will give you half power. Triode pentode connects the screen to the plate, instead of the screen supply, and also cuts power by about 1/2 and also darkens the tone. The cathode/fixed switch lifts the cathodes through a resistor and cap (like your average cathode bias amp) and it turns off the bias supply, grounding the grid leak resistors for the power tubes. One switch will do it.
There are tons of diagrams on this forum covering each of these mods, which can be combined as well.
