04/10/2020
We not only build our own custom amps and pedal boards, but we do refurbishments/rebuilds of vintage amps. This is a long read - but ya'll have the time, right? We received an “as is” Valco Tremo-Tone that was not functioning and the speaker cones were rotted from age. These are very nice sounding amplifiers in a nice pine box. Rebuilt the amplifier replacing the rectifier and power tubes. The phase inverter (6SC7), preamp tube (6SQ7) and oscillator (6SQ7) were in good shape but the signal capacitors (paper/wax/foil) were all defective. The oscillator capacitors were replaced with SOZO capacitors and the signal capacitors were replaced with Copperhead Audio Engineering hybrid capacitors (Paper/Polypropylene/Tin) for a vintage tone and tight mid-bass. The 10/10/10 UF@450 for the DC supply are not available, so a 10/10/10/10 UF@450 was used and one section was unused. The space in this amplifier is tight and the supply capacitor is much bigger in diameter than the original, so some parts had to be removed to fit a punch to the chassis to make the hole bigger. The panel potentiometer/switch for the tremolo had to be disassembled and cleaned as there are no suitable replacements. Next, the speakers were rotten so they needed replacement. They are 6”x10”. There are no recone kits or direct replacements available. One company makes a ceramic 6”x’9” for Valco amplifiers but they leave a huge gap around the hole in the baffle, because they use clips to mount them. This was not acceptable as the gap around the edge of the speakers would not allow proper coupling to the baffle, and bass response would suffer greatly. The original speakers were 4 Ohm, so any replacement speaker(s) needed to be 2 x 4 Ohm or 1 x 2 Ohm. There is not a lot of space for speakers in this cabinet. No 10” would fit that was suitable, and no 8” speakers are available in 2 Ohm. We considered purchasing a Jensen 8” ALNICO speaker and reconing it with a 2” coil, but found the Jensen ALNICO P6V sometimes used in Champion 600 speaker replacements. We made a new baffle from good plywood and installed a pair to get 2 Ohms, good bass and volume. We had to remove the output transformer from the original speakers and mount it to the cabinet. For a little fun, we added a vintage cloth power cord. We are all blown away buy the tone of this amp. We named it the mini-twin.
