Classic Tube Audio

Here are a few photos of my latest guitar project, a black face Princeton reverb. This amp will have a few upgrades from the original; it will have the following added features. Individual bias for each of the power tubes, and test points on the back of the amp to measure the bias current; since I didn’t have a power transformer with a 47v ac bias tap, I did with Jim Marshall did and am taking the b+ and dropping it to 47 volts before the ½ wave rectifier. This will give me the bias current needed to run the vibrato and keep the power tubes happy. The reason I can get away with this is because I have used a very large power transformer, this should reduce any sag in the bias voltage during high volume transients.

I will post a few sound clips when it is done.

Here are a few schematics and layouts incase you want to build your own

Princeton Reverb Schematic with a GZ34 – 5AR4 Rectifier

Princeton Reverb Schematic with a 5U4 Rectifier, this is the amp that I am building since I have quite a few 5U4 tubes laying around.