Yeah, I'd thought of a dummy load or :yikes: not turning it on without the speakers connected.Tube Amps do not like to operate with their outputs being disconnected, they will over heat. The switching that you use will need to provide a Dummy Load to your tube amp when it is not being used or you will burn it up.
Is there a reason that you don't want to use a standard switch instead of a relay ?
That's a good point about using a DC-controlled relay. The ones I was looking at had 12vac control voltage, and I can imagine that could induce some noise into the signal. The 120vac I mentioned was for contact rating.A relay is fine for switching speakers. I would use a DC relay powered with a Wall-Wart but a 120vac relay would be fine. Use a relay with the proper contact ratings to match your speaker wire to maintain full quality.
7 amps = 18 ga
10 amps = 16 ga
15 amps = 14 ga
20 amps = 12 ga
30 amps = 10 ga
If you use a 4 pole relay you would be able to do the speaker switching and add the Dummy Load all in 1 device & operation. If you need a drawing of the relay wiring I could make one up for you?
Ok, thanks; your two-relay method is a cleaner way to to it than I thought up. The one-relay way will not work for me; my tube amp (Manley Snapper) has a fully balanced circuit and a speaker terminal cannot be grounded. Thanks for taking the time and your better circuit.OK I made 2 drawings
The first drawing uses two 4 pole double throw relays, one for the left channel and one for the right channel. The picture shows only the Left Channel using 1 relay, you would need a second relay wired the same way for the Right Channel. This method totally isolates your amps from each other and is completely safe
View attachment 29828
The second drawing shows both channels using a single 4 pole double throw relay. using this method ties all the Negative speaker connections together. This should work in most cases. To make sure you would need a multimeter to make sure that all the negative speaker connections are connected to the Chassis ground of your amplifiers. Each negative connection needs to read less than one ohm to the metal chassis of the amp or do not try this method.
View attachment 29829
Please ask questions if you don't understand . . .