Radio to 5F1 questions

[Grieve]

OK so I have a couple of old tube radios laying around (eg. 1 x 12AU7, 2 x 6GW8) and I was wondering what are the considerations in making the conversion to guitar amp (5F1), specifically in relation to:

- the power supply: matching the existing power supply to the 5F1 circuit. How important is the exact voltage it puts out? Is it easy to change if its not right, or would I be better off looking for a more suitable amp design to match the power supply?
- the output transformer(s): at least one of the old radios is stereo and has 2 small output transformers. Can these be used if I go with the traditional 12AX7 and 6V6?

Thanks in advance,

G

[andrew_k]

Why not work with what you've got? ie: 2 triodes in the 12AX7, 2 triodes and 2 power pentodes between the 6GW8 pair. You already know the PT can supply enough heater current for that combo, so that's one part essentially out of the equation. Replace the output transformer with an 8k push-pull transformer (15W would probably be enough, but an OT designed for a 18W clone might be a better bet), and BAM, rock and roll.

Lots of amps out there that meet that config; the blackface Princeton (non-reverb model) is one that immediately pops into my mind, and that one gives you bias-vary tremolo. The stripped down Marshall 18W clone - "LiteIIb" would be another perfect fit for the tubes you have. You might need to be a member to see this file -- http://www.18watt.com/storage/18wattLite2b.gif

Single-ended radios running 6V6 are common, I've got a couple, get one of those for a 5F1 clone. Your twin 6GW8 amp has more to offer than becoming another 4W tweed clone.

[Grieve]

Thanks for the advice. Makes sense to make the best use of whats already there. I'll check out that link at 18 Watt.com and of course post a build report once I've actually done something!

Thanks

G