Kalamazoo Amp Field Guide:
Converting an Amp to Use a Solid State Rectifier
DISCLAIMER:
Tube amplifiers contain potentially lethal, high voltages even after they are unplugged, that may cause personal injury or death. Do not attempt to repair, modify, or work on any amplifier unless you are absolutely certain you know what you are doing.
NO GUARANTEE
These mods are all things I have tried, someone I know has tried, or are recommended by people who work on amplifiers for a living. Nevertheless, if you try any of these, you assume all responsibility for anything that happens, whether the amp explodes, you get zapped, or the amp suddenly increases in value because everyone falls in love with it. The glory, the pain, whatever, they're all yours. If you can't live with that, don't mess with the amp!Why convert to a solid state rectifier? There are several potential (pun intended) reasons. First off, you will get higher voltages and very little ``sag'', resulting in a punchier, cleaner sound until the volume is really cranked (far more with the Reverb 12 than the Model One or Model Two). Additionally, solid state diodes will probably outlast everything else in your amp. They run far cooler than tube rectifiers, and don't pull any heater current, so your amp will run quite a bit cooler.
If you like the way your amp starts distorting now, and the volume level this happens at, you may not want to do this conversion. Of course, you can always convert back by simply removing the diodes and replacing the rectifier tube! If you do, leave the standby switch in; it's still a good idea.
This one is verbatim from email by Justin Belshe. Thanks, Justin.
``Get a pair of 1N4007 diodes and solder the leads from the striped ends to pin 7 of the rectifier socket (remove the tube). Solder the other ends to pins 1 & 6.''
It's crucial to install a standby switch with this mod to avoid cathode stripping by applying high voltage before the tubes are properly warmed up.''
I would add that you don't have to use 1N4007 diodes; anything from a 1N4005 (600 PIV, 1 amp) on up will work. But the higher the rating the better, and 1N4007s are cheap!
Thanks!
Special thanks to Justin Belshe <JBelshe@AOL.com> (who would like to thank Tim Swartz <TimTube@AOL.com>) for lots of ideas on rebuilding this amp.
Last updated: 14 September 2005Copyright Y2K Miles O'Neal, Austin, TX. All rights reserved. Miles O'Neal <roadkills.r.us@XYZZY.gmail.com> [remove the "XYZZY." to make things work!] c/o RNN / 1705 Oak Forest Dr / Round Rock, TX / 78681-1514