I was asked to do a complete electronic restoration of this ca 1961 Ampeg Reverberocket guitar amplifier. In this case, the client wanted me to completely re-cap with new polyester capacitors and new production tubes, rather than keep as many vintage parts as possible intact. Who am I to argue?
As received this amp was fairly rough physically. Lots of dirt and corrosion on the chrome top panel, incorrect knobs, torn and painted over Tolex, damaged speaker, a mixed bag of tubes, and user added internal cooling fan, and external speaker connection, poorly installed.
Cleaning and polishing of the chassis came out better than expected. During the re-capping process, found a few resistors badly out of tolerance which were replaced. The line to ground capacitor was replaced with a proper updated Y2 safety capacitor. The main filter capacitor can was dented, so replaced with a similar sized unit from stock, but re-stuffed with quality up to date electrolytic capacitors.
A new, 3 conductor line cord was installed to replace the old 2-conductor unit.
A complete new set of JJ tubes was installed, making sure the 6V6 output tubes were factory matched, and the 6SL7 preamp tube was selected for low microphonics. The bias for the 6V6 tubes was adjusted to allow them to run a bit cooler than in the original design, which had them biased very close to their maximum plate dissipation.
I had to add a metal shield over the section which housed the preamp circuits, to reduce hum pickup.
A new speaker was required, and I decided on a Jensen C12R, which, rated at 25 watts, will easily handle the 14 watt RMS output from the 6V6 tubes. I thought it also to be the best value for money in this case. This speaker is also very similar to that used in the original design of this amplifier.
The client was extremely pleased with the sound of the amp, despite the use of new production tubes and capacitors and speaker in the rebuild.
Total time span of the restoration: 22 hours.
