Fender Pro Junior --> Matchless Spitfire

[imbuedblue]

I have a blonde Fender Pro Junior fitted with a Weber 10A125 that I'm considering gutting to build a Matchless Spitfire-based circuit.

I'd like to use the stock Fender transformers. Will they do the job? Has anyone done this?

I'll keep the Fender solid-state rectifier, replace the choke with a resistor, and remove the Tone and Master Volume controls. Otherwise, I'll follow the Spitfire schematic.

Any considerations I need to make?

Here are the schematics for the Pro Junior and Spitfire.

http://www.ampwares.com/ffg/schem/pro_jr_schem.jpg

http://www.freeinfosociety.com/elect...ssspitfire.pdf

[withnail]

The Voltages on the Pro Jr. PT are probably much higher than the stock Spitfire voltages ?, plus you'll be raising the plate voltage even more if you use a solid-state rectifier .... it will work, but the tone won't be quite as nice as the original Spitfire. You could also go with a Weber 5Y3 or 5U4 copper cap module instead of solid-state to drop the voltages down to where they need to be.

[mac1amps]

The stock Fender transformers in a Pro Jr. leave a bit to be desired (that's the first place they "cut corners" to reduce cost), that point alone already puts the Matchless "one-up". Why would you intentionally want to leave out the "choke"? Granted, the trannys are the most expensive components on the amp, but it can oftentimes make the biggest difference between a "student" amp vs. a "real" one. I replaced the O.T. on my Pro Jr. with a sweet Hammond 1615 (also adding a small "choke" from a DR) and the difference is outstanding.

[imbuedblue]

Why would you intentionally want to leave out the "choke"? ...

Here's my situation. I own two amps, the Pro Junior and a silverface Twin Reverb. The Pro Junior is my main gigging amp for obvious reasons. Anyway, 10 years of hard gigging has played its toll on the amp and many of the solder pads on the PCB are starting to lift.

I have the components, minus upgraded transformers and choke, on hand to rebuild the amp point-to-point. I just bought a house and am getting married in 2 months so its hard for me to justify buying new transformers at this point. I've always wanted a Vox amp and knew the Spitfire was based on the AC15 but used the same tubes as my PJ, so I thought I'd go in that direction. Maybe tweak a few values here and there so the frequency response is more Vox than Matchless.

I plan on eventually upgrading the transformers--especially the OT--and adding a choke at a later date--like after the wedding.