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Author Topic: 12AX7 Driver in Fender 25R  (Read 4375 times)


  • Chipper
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12AX7 Driver in Fender 25R
« 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

J M Fahey

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Re: 12AX7 Driver in Fender 25R
« Reply #1 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.


  • Chipper
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Re: 12AX7 Driver in Fender 25R
« Reply #2 on: March 18, 2010, 06:13:58 PM »
i don't think it is simple things, pt need change, thebetter voltage of 12ax7 is180v