Here is a fun project we did on a 1965 Fender Princeton.

The owner of the amp complained that it sounded flat, anemic, and did not have much volume.

The main reason for this was that the amp is originally a non reverb model and therefore has only two preamp gain stages, compared to the Princeton Reverb model which has three.

As a result, there’s less drive, compression, and volume.

The EQ curve is also flatter and the amp lacks the depth of the Princeton Reverb model.

In order to correct these shortcomings the following modifications were done;

1. The tremolo circuit (which the owner wasn’t using) was removed and the “missing” gain stage was built instead, using the first triod of the second 12AX7 tube which was originally used for the tremolo
2. The RC network preceding that stage in the Blackface Fender amps and which is a major factor in the tone of those amps was added in order to give the amp the classic Blackface tone.
3. The original Oxford speaker which is very inefficient was replaced with a very efficient and great sounding Celestion Vintage 10 speaker
4. We also did some basic maintenance/upgrade work and replaced some poor quality resistors that were previously installed, replaced the original two prong power cord with a three prong grounded cord for safety and quite operation, removed the”death cap”, added a 20UF filter cap to the main filtering stage, installed new JJ pre amp and power tubes and set the Bias

All tube sockets were tightened and cleaned as well.

With all this work done the amp now sounds fantastic and is super fun to play.

It has all the tone, drive, compression, punch, and response of a great sounding Princeton Reverb amp!