Not a Small Undertaking

This will be part one in a series on this amp. So...let's get started.

In early 2013, I was commissioned by local genius guitarist, Luke Polipnick, to build an nice, warm tube amp. Up to that point I had trained myself in all of the electronic skills needed to make the amp, as well as the woodworking that would be needed for the cabinet, on separate projects. This amp was the first opportunity to put of all those skills together.

Initially, this amp was supposed to be based on a Fender Princeton Reverb, only slightly larger and with a few modifications. Once Luke and I started talking about what he wanted, it became clear that the Princeton Reverb should be more of a basis for the sound of the amp, and not much else. With that goal in mind, I drafted a schematic and got to work. 

One of the biggest factors in the PR sound was a type of phase inverter called the Cathodyne. The Princeton Reverb was one of the only amps made by Fender to use this method of phase inversion. The Cathodyne gave those amps a unique tone that has become very sought after. 

By the final modification to the amp, the circuit had strayed far from the original, with a Bassman style input stage, and a Super Reverb to fill in the blanks. Though, I can't be giving out all my trade secrets so easily.

Here's some pictures of the build progress:

 All the parts are in!

 All the wiring is done at this point. This took about 6 hours and 100 feet of wire to complete.

These pictures need some explanation. In order to save costs on modern expensive transformers, we agreed to buy a vintage Hammond L100 amplifier chassis and remove the transformers for use on the new amp. These vintage Hammond transformers were some of the highest quality of their day, not to mention their wonderful tone. The second picture is a 60 watt transformer made by the good people at ClassicTone. The amp actually has two switchable output transformers: a 35 watt Hammond and the 60 watt CT. Each transformer has a distinct sound. The 35 watt Hammond has a more earthy tone with rich saturation. The 60 watt CT is solid and clean, yet it still retains the warm tone of the amp.