Kalamazoo Amp Field Guide:

Modifying Tube Guitar Amps

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!

Most of these mods will work for any of the following Kalamazoo tube guitar amps: Model One, Model Two, or Model Twelve. They will probably work with the bass amp as well, but I've never touched one of those. Many of them will work for any tube guitar amp.

GALLERY

First up is Justin Belshe's <JBelshe@AOL.com> hot rod (safety, standard revamp, speaker, standby switch, solid state rectifier). Click on the photo for a 1156x823 JPEG (about 190kB).

Then we have Justin's Kalamazoo being mic'd in his home studio. (550x378, 42kB JPEG).

Then we have some photos from Steve (Steve762us AT-SIGN yahoo DOT com). of his Model Two. Links are to 640x480 JPEGs of about 60-75kB.

Full shot of the back of the amp. It's in beautiful shape. Note the foil shielding at the top of the amp.	Closer view. Nice cap job. Note speaker out jack on L bracket and quick connects on speaker lugs. Yes, that's a standby switch by the L bracket, with vacuum line over the handle.	Insider information. Note the hot glued power supply caps, Orange Drops everywhere, and heat shrink.	Close up of the speaker out jack with the top panel in place. No holes drilled in the panel, no grubbing around in the amp's guts!

MODS

• Safety First
  • Make it safe to work on (discharging the caps)
  • Make A Model 1 or 2 safe to play (three wire power cord)
  • Make a Reverb 12 safe to play (three wire power cord)
• Standard revamp (tubes, caps, transformers, etc.)
  • Replacing a multi-section Cap with individual caps
• Upgrade your speaker (and add a jack or external speaker jack) [The Reverb 12 has a jack already]
• Add a standby switch
• Add a solid state rectifier (Reverb 12 uses a solid state rectifier)
• Easy line out jack
• Hum reduction (circuit mods)
• Outside noise reduction (shielding)
• Tone control upgrade
• Reverb 12 cabinet mod to facilitate chassis removal and insertion
• Changing Gain, distortion and when the amp breaks up (circuit mods)

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 these amps.

---

Last updated: 14 September 2005

Copyright Y2K, 2004 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