New amp build - how to deal with a 12AX7 using only one triode?

[che_guitarra]

I'm building a 6G2 brownface Princeton based project, but it's being housed in a modified 5F-2A chassis. I did plan to build a tweed Princeton, but I just feel the basic 6G2 sound is a better overall tone for my style.


Anyway, I've had to do away with the tremolo part of the circuit as there's only home for a volume and tone in the chassis. This has left me with a 12AX7 only being half used. My query is - i'm not sure if I have to adapt the socket wiring at all to deal with this, and am looking for advice as what the next step would be.


Here's the schematic i've modified to suit my build - as can be seen pins 1, 2 and 3 are empty on the 12AX7:



And here's where i'm up to in my build:






Anyway - i'm by no means an expert at amp building, so any advice how to deal with this is much appreciated

[hamerfan]

Re: New amp build - how to deal with a 12AX7 using only one triode?

You can opt between Tweed/6G2/Blackface if you create a switch in the feedback loop between the stock 56k and a rude 1 meg. I know this is just one difference but a important one to an early tweed sound. i made my champ scwitchable between 22k and 1 meg (nearly off).
Blackface should be around 5k for a 6G2 circuit, because the junction to the preamp tube is before the cathode bias resistor on blackface Princetons.

[glassman]

Re: New amp build - how to deal with a 12AX7 using only one triode?

Just connect pins 1, 2 & 3 of V2 together and hook them to ground; it will null that triode and make certain it has no effect on anything else in the amp.