The History of the Fender Princeton Amp
Part I: The Early Years Woody and Tweeds

The Princeton amp has been around almost since Fender's inception. The Princeton haas remained a popular amp in Fender's line. Over the years the Princeton has undergone many circuit and cosmetic changes.  For the purposes of our discussion we will only consider the classic Princetons made from 1946 to 1981. This covers the Woody Princetons, Tweeds, Brownface, Blackface and Silverface Princetons. These are the quintisetial years for the Fender Princeton that most interest players and collectors. I will briefly discuss the Princeton models, circuits, sounds and basic modifications. Part I will concentrate on the Woody and Tweed years from 1946 to 1960. 
 

If you would like on of these models built let me contact me and I'll send you quote! 

 

Note on Early Models:
All these early Princeton models are 5 watt cathode biased amps (no need to bias these when changing tubes).  They were intended for students rather than professionals.  All models use 5Y3 rectifer tubes but a GZ-34 or 5V4 can be substituted for more punch and volume.  All models came with 8 inch Alnico Speakers but these amp sound much bigger with larger speakers.

The  Woody Princeton, TV Front Princeton and 5B2  Wide Panel Princeton 1946-1953:
All three of these models used the same cicuit but had different cosmetics.  The tube setup was a 5Y3, 6V6, and a 6SL7 for about 5 watts of power into a 8 inch Alinco Speaker. These amps had a high and low input and Volume and Tone Controls. This version of the Princeton used a grid leak biased first gain stage giving the sound a distictive grit and brightness but making it unsafe to use higher gain pedals with (why would you want too?).  The 6Sl7 has a fat, jangly and gritty quality that really make these amps sing. 
   The power section is flawed in these amps. Increasing the filtering and some other slight changes can great reduce hum and increase punch.  Adding a 3 prong grounded cord is a necessity.  I also recommend adding   2 watt 1K screen resistor and replacing filter caps over 10 years old for the best sound. 

I have built of of these amps into a suitcase amp format and combos for  customers.  It's relatively low volume affair but is bright gritty and very usable. It's highly similar to many other small amps from that era.

Wide Panel 5C2 1954-55
These amps are very similar to the the early models with two exceptions. They use 6SC7 rather than 6SL7 which are very similar tubes. The 5C2 uses a cathode biased first gain stage allowing for better headroom and slightly more refined sound. This is the model that inspired my Octal Princeton that garners rave reviews and can use 6V6 or 5881 power tubes and has 12" speaker. 
Again the power section is flawed in these amps and uses the configuration as the previous model. Increasing the filtering and some other slight changes can great reduce hum and increase punch.  Adding a 3 prong grounded cord is a necessity.  I also recommend adding  2 watt 1K screen resistor and replacing filter caps over 10 years old for the best sound. 

  Carl's Custom Amps Octal Princeton is based on the 5C2 but with larger speaker and numerous improvements. 


Carl's Custom Amps Octal Princeton is based on the 5C2 but with larger speaker and numerous improvements. 

Wide Panel 5D2 1955
This the first Princeton to use the  12AX7 rather than the 6SL7 or 6SC7 of previous models.  Fender went back to a grid leak biased first gain stage giving the amp a gritty sound. This is rare one.


Again the power section is flawed in these amps and uses a similar configuration as the octal models. Increasing the filtering and some other slight changes can great reduce hum and increase punch.  Adding a 3 prong grounded cord is a necessity.  I also recommend adding  2 watt 1K screen resistor and replacing filtaer caps over 10 years old for the best sound. 

I've also tried this circuit a but found I prefer the cathode bias of the 5F2A  later tweeds in a 12AX7 pre-amp.

 

 

Narrow Panel 5E2 and 5F2 1955-56
These rare versions were made with a cathode biased first gain stage. They also introduced negative feedback which gave them a smoother more even sound. Both used a choke transformer in the power section with rather minimal filtering. So additional filtering is helpful here to give amp punch and reduce hum.  Adding a 3 prong grounded cord is a necessity.  I also recommend adding  2 watt 1K screen resistor and replacing filter caps over 10 years old for the best sound. 


Narrow Panel 5F2A 1957-60
This is the classic Tweed Princeton model. Fender improved the power section with better filtering and dropped the choke giving the amp more punch, volume and definition. Again it has a 12AX7, 6V6 and 5Y3 as it's tube compliment.  The 12AX7 is cathode biased and the sound is clear at lower volumes and get a nice crunch when turned up. This is model people are generally referring to when they talk about a Tweed Princeton. 
 Adding a 3 prong grounded cord is a necessity.  I also recommend adding  2 watt 1K screen resistor and replacing filter caps over 10 years old for the best sound. 

 

I've built a number of these over the years.  They are great sounding little amp and more versatile than a champ. One trick I like to do it add push pull pot to switch out the tone control so it can behave just like a 5F1....two amps in one!