Two-headed monster

[dkevin]

Hello all,
I have a phonograph/PA amp that uses 2ea 6SL7's and a 6V6 single-ended for the output. It also has a 6X5 rectifier.
I would like to make it into a guitar amp with two inputs- each one feeding a different preamp tube. I would like to use 1/2 of the 6SL7 for one channel (triode) and a 6SJ7 for the other channel(pentode). Both of them would feed the 2nd half of the 6SL7 as the driver for the 6V6.
My questions have to do with making all the connections. Is it possible to keep all the tubes connected in the circuit or would I have to switch them in or out depending on which one I was using? Is there a design already available that I could study to get some guidance?
This has been a goal of mine for some time. I would like to be able to play different preamp tubes with the same output section.
Thanks for your help!!

[Chuck H]

Well there's not so much much gain from either preamp configuration that unused channel noise would be too bad. So if you coupled the two preamps through mixing resistors you could A/B the inputs for psuedo channel switching. Just run each preamp through a 220k resistor and join them at the second half of the 6sl7. This is how all the BF Fender amps did it.