Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Solid State Amplifiers => Tubes and Hybrids => Topic started by: Freddie on February 07, 2010, 05:45:40 PM

Title: 12AX7 Driver in Fender 25R
Post by: Freddie on February 07, 2010, 05:45:40 PM
Wanting to hybreed My 25R Wondering where in the circuit to put the tube driver ? I am thinking of removing R55 before the final amp and putting the driver there. :loco
Title: Re: 12AX7 Driver in Fender 25R
Post by: J M Fahey on February 09, 2010, 05:31:44 AM
Basically you have to build a tube amplifier stage, send your preamp signal there, and take its output (suitably padded) into a "Master" volume pot.
That way you overdrive the tube and re-amplify its output with your original power amp.
The other way would be to copy the Marshall preamp used in Valvestates, where they drive the tone stack with a tube.
I find it somewhat buzzy but it's a very popular solution.
In any case, you will have to add a new power supply to power the tube.
Title: Re: 12AX7 Driver in Fender 25R
Post by: kldguitar on March 18, 2010, 06:13:58 PM
i don't think it is simple things, pt need change, thebetter voltage of 12ax7 is180v