Kalamazoo Amp Field Guide: Bass Amp


Technical Overview ] [ Schematic ] [ Photos ]

For more information on the Kalamazoo line, see the Kalamazoo web pages at http://www.rru.com/~meo/Guitar/Amps/Kalamazoo/ .

NOTE: I do not currently own one of these. These photos are courtesy of Kagang on eBay, fellow Kalamazoo lover and friend Rob Murray, and someone else on eBay whose name I have lost 8^(. Click on any photo to see a larger, more detailed JPEG.
Bass 30 and 50
Basic front shot.
Closeup of nameplate badge. Bass 50 would be the same, but say 50 instead of 30.
[Flip out]
Back with control panel flipped out.
Closeup of standard Kalamazoo controls (loudness, treble/on/off, bass). Bass 50 would be the same, but say 50 instead of 30.
[Chassis and panel]
Bass 50 chassis and panel, layout, iron, etc. Owner has already replaced the can caps.
[panel closeup]
Bass 50 panel closeup. Standard Kalamazoo Bass flipout panel.
[chassis guts]
Bass 50 chassis guts. Round, gray-green things in upper left are power supply diodes. Speaker jack is on the right.
[panel closeup]
Bass 50 closeup of pot wiring inside panel.
[Flip out]
Basic front shot. The only clue that this is the later solid state model is the badge, which doesn't even say "Bass".
Closeup of standard Kalamazoo controls (loudness, treble/on/off, bass). Again, the only clue that this is the solid state model is that no number appears after the "Bass".
Last Hurrah Bass 30
[Flip out]
When the Kalamazoo line was redesigned with the woodgrain look, they redesigned the bass amps as well, resulting in what looks like Baul Bunyan's Kalamazoo Model 2. Farewell, flip top box! This tall sucker was manufactured in 1970. Gibson also produced amps under its own name in this format, such as the Thor and at least one of the Medallist designs.
This was not a well ventilated amp, even with the back off the amp section. Note the cab is still a sealed design. Gotta love that huge transformer! Rob kept the cab to this one and installed new speakers, but sold me the electronics. This must have been top heavy, because the electronics were heavy!.
[Flip out]
Other than the power switch, the faceplate looks amazingly like the Model 2. This isn't the original switch knob; the original should match the other knobs. Note that the company headquarters is now listed on the faceplates as Lincolnwood.
[Control panel guts]
Here's the back of the control panel. The two bundles of wires go to Molex connectors that connect to the main chassis. The ceramic cap is the infamous Death Cap. Everything is original except the caps and the fuse holder and its red wire.
[Control guts detail]
Detail shot to show construction. The Loudness and Bass pots both have terminal strips soldered onto their backs. This may or may not have contributed to the Loudness pot breaking from its mounting threads.) The power switch has a regular pot switch (SPST for on/off) on the back of some sort of ceramic wafer switch that handles the polarity switching. I have no idea where the cut blue wire went.
[Chassis top]
Here's the main chassis from the top. Big iron! Six of the nine pins in this Molex connector carry signal to and from the front panel. The preamp/PI socket is at the bottom; the post-PI driver tube sockert goes in the middle, and the octal sockets are for the power tubes. Power comes out the right end of the chassis; the power connections to the front panel come out the side that is at the top of this photo, via red, black and white wires just visible at the upper right (via a three pin Molex connector). The original speaker socket is a two pin Bakelite[tm] connector on the left end of the amp; I added the phone plug you see above the output transformer to handle standard speaker connections.
[Both Chassis]
Here are both chassis together to get an idea of the relative sizes.
[Main Guts]
The usual Kalamazoo Snake Pit[tm]. It's fine for the low gain and volume of playing bass or clean guitar, but driven hard with a pedal, there are some nasty parasitic oscillations.
[Guts - amplifier]
The amplifier guts. The two prong socket on the left is the original speaker jack. (The orange and white wire between the speaker jacks is from the heaters of a Kalamazoo Reverb 12. 8^) The trim pot at the lower left is a hum balance pot for the power tube cathodes. The three dark wires at the "top" side of the Molex connector are grounds; the cable that plugs in uses three shielded wires.
[Guts - power supply]
The original PS caps were also 450WVDC, which is at the edge; the plate voltages are just over 450VDC. The green box in the middle is a full wave rectifier. I have no idea why they didn't just use two diodes.

Technical Overview ] [ Schematic ] [ Photos ]

Last updated: 31 August 2019

Copyright 2000,2007,2009 Miles O'Neal, Austin, TX. All rights reserved. Amp photo courtesy of Antonio Salvatore. Bass 50 pics courtesy of Eugene Dunn. All photos used by permission.

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