Master Volume Mod for Silvertone 1484 "Twin Twelve"
Disclaimer: The voltages present inside the 1484 amplifier can kill you. The following text assumes that you understand how to work on amplifiers safely, and that you assume full responsibility for any risks you take in modifying your amplifier.
| I chose to use a power amp master volume described in Kevin O'Connor's book, "The Ultimate Tone" (right). For this mod you will need a 1484 schematic. You will be inserting a dual (ganged) 1M audio taper potentiometer between coupling caps C14 & C15 and resistors R35 & R36. According to O'Connor, the new cap values should be 10x the values of the original coupling caps; in the 1484 that's .02uF x 10 = .2uF. He suggests at least a 100v rating (I used bigger ones because I had them). |  |
| Here's how it looks. I cut the leads between C14/15 (which are taped together in the original layout) and the two resistors; I soldered the shortened leads from the caps to a piece of terminal strip. The pot goes in the second input hole for CH2 (remove the existing jack). Ground the pot (pin 3) to the ground pin on the other input jack. I mounted the two new caps on another piece of terminal strip. Since I used stiff solid core wire, the whole thing stays put fairly well. You could also drill a hole in the fiberboard running down the center of the chassis and screw the terminal strip down. You may have to re-route some other wires to make room if you use big caps like I did. |
(Click on the image for a full size blow up.) How Does It Sound? Great. It's nice to be able to max the gain on the two channels, and jumper them with the MV turned down - great blues tone at bedroom volumes! Caveat: Because of the way the reverb return is mixed on the 1484, the reverb seems to be less audible when the master volume is turned down. Since I'm not a fan of the 1484's 'verb this didn't bother me. |
