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I'd like to be able to use amp's preamp out without the need to have the power section fired up and speakers connected. Is this a straight forward matter of switching off the power to the screens and OT, or is there more to it than that?
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If your only concern is not having sound getting to the speaker,you could just use a switching jack for the preamp out,wired so when you plug a jack into it the signal will be diverted to the cable you are using to connect to wherever you are sending the preamp out signal,and it wont get to the output section.Another way to take the power section out of use is to simply use a switch to lift the power tubes cathodes from ground. -
The main objective is to run the preamp into a much lower wattage power amp, and I don't really want to have the power tubes running when they're not being used.
Is lifting the cathodes effectively an off switch for the tubes?Comment
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Lift the cathodes of the power tubes from ground and or, either connect a switch across the two grids of the power tubes to mute the power tubes or lift the screen voltage.
When you lift the power tubes in any way from the B+ rail... the B+ will rise significantly so you have to watch those filter caps and the high B+ on the preamp tubes will make the preamp section sound a little different.Comment
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Thanks Bruce
Would this do the trick?
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That looks OK.
Is that a DPDT switch with a center off position?Comment
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I was thinking just a two position, power tubes on in one position, off in the other with that extra resistor compensating for the raised B+Comment
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