Does anyone know of a simple mod to increase the headroom in a PRRI. I've seen mods on the net but they all seem to be done by amp techs or by someone skilled in electronics.
Is there anything as simple as a speaker/tube change that anyone knows of?
All ideas are appreciated. Thanks.
Yep, upgrade to a deluxe reverb 
J/K. You could try using 12AT7 tubes in the preamp. Those don't break up as soon as the 12AX7 that are stock in the preamp.
I'm sure some others will chime in here with lots of ideas.
There's a phase inverter mod that's all over the internet, look for the "Paul C mod".
Also, a very efficient speaker will help, and you could even put a 12" speaker in it if you put in a different baffle.
Also, but that's pretty involved already, you could put a bigger output transformer in it, Allen amps has the one you need.
See if you can find a JBL D110F speaker. You will gain a ton of headroom and a tone to die for. I played a Princeton Reverb from around 1966 that came from Fender this way and it is to this day the best sounding amp I have ever heard.
EDIT: Found one on eBay JBL
I actually have a bunch of JBL D110F's, and they're great speakers, but not for everyone or any kind of music/playing. But they are great speakers, that's for sure.
But yes, by all means, replacing the speaker in a Princeton reissue seems like a good idea, as the reissues have the Jensen C10R, which is probably about the least efficient, ballsy speaker you can get these days.
Almost anything would be louder and bigger sounding. I'd recommend Eminence's Copperhead or Ragin Cajun speakers, they're not expensive at all, and they'll give your Princeton more punch and headroom while still maintaining that "Fender character".
Plug in a solid-state recitifier & you'll gain a few watts. The Cathodyne phase splitter is the weak point. If you lower the grid resistor on the phase inverter to about 75K, you can keep the tube from pulling reverse grid current. Then raise the plate and cathode resistors to around 68K. With this setup, the phase inverter actually has enough current swing to drive the output tubes to full power, and without the charateristic farty sound when it clips. BZ
That is the most perfect possible answer, and I have no idea what the hell it means.
