This is what started it all.
Ive always believed and liked the way electric guitars sound thru a tube amp. Maybe its the way the older recordings sounded, but solid-state amps dont quite capture that tone. Not that solid state is bad – its different sounding. Tube amp purists deride it, since compared to tube amps it sounds too sterile. There is no “warmth” to its tone. I call them snobs.

In defense of solid state amplifiers, theyre safer to use,require very little maintenance, and far cheaper! These days there are modelers and effects processors that can emulate ANY tone you wish, and yes, even  that “tube sound”. Solid state amps can provide quiet and clean operation, and can crank out much higher wattages, and are far more versatile soundwise. Its nt easy to get really good metal riffs on tube amps – solid state amps can get meaner and nastier. If thats your cup of coffee.

But going back to my point – why bother trying to emulate a tube sound, when you can get tube sound with, uhm, TUBE AMPS? With that in mind, ive found that there simply is no substitute for the real thing.

After my very first tube amp (a 2008 Peavey Valveking 112), i decided to check out the used section in a store chain. On  the back wall stood this old Kalamazoo Bass 50 amp along with other older amps. It was relatively cheap compared to the marshalls and fenders and musicmans that are priced 3 to 4 more times higher. I did not pay any attention to it until i got home, and looked it up.

In a nutshell, these Kalamazoos were old and (or in the guitar amp vernacular) vintage. Made in the mid to late 60’s, they were in a limited run, as the parent company CMI (which also produced the more expensive Gibson amps) had been sold, which effectively ended the line immediately. They were Gibson’s economy line then.

The website created by Miles O’Neal dedicated information regarding these amps, and thats when i found out that Bass 50’s are not that easy to come by. I immediately went back the next day and bought the amp.

October 13, 2009, 11:58:54 AM
The Bass 50s are admittedly a beast to tame! that being said i now have 3 (theyre that fun to work on and play on!).
I find that they always have quite a bit of hum, but changing out the electrolytics help. The first 2 i replaced with values TWICE the schematics/original can cap values. The third i kept as close as i can.

but heres something i found that helps A LOT – replace the non-electrolytic POLARIZED caps under the chassis. Theres 2 of them, i think. one is close to the 6EU7’s and another is right on one of the EL34’s.

The rest of the non-polarized caps can be left alone, in my opinion. i kept them intact on the third. i replaced ALL of them in the first using orange drops, and the second one i replaced them all with polyprop caps. Again this is just my preference then, and now im going back to restore what i can. Although Paper-in-oil caps is an interesting alternative…

Definitely look for those POLARIZED (non-electrolytic) caps and replace them.  I used the same values. Not sure what tonal difference or effect it will make if the values are greater, but im more than satisfied with the greatly reduced hum.

i recommend also going to the Kalamazoo Amp Field Guide Site, by Miles O’Neal. Its THE bible for the kalamazoo amps. I gathered most of what i knew from there.

December 08, 2009, 02:39:05 PM
Of the 3 Bass 50s i have, one of them ive turned into a head also. I picked this one since the OT started to go. I was able to locate an OT replacement from www.tubesandmore.com (with a selector for 4/8/16 ohm taps), and its been fine since. Im using it to switch from EL34 to EL84 with the help of yellowjackets. A lot earlier breakup as expected. Gives me this real nice fizzy/buzzy/industrial top end sound (while still retaining a good bottom end) when i place a combined dano coolcat transparent overdrive and metal stompbox in front of it (using a 95 P-Bass Special “cowpoke”). EL34’s are just too dark to produce that sound.

I used an old empty Gibson head i found on ebay. I forget the model of the gibson head (it was i think for a solid state amp), but it was perfect since its handle matched the Bass 50’s original handle (those handles are HARD to find – no one makes a replica of them anymore!). There was even a rectangular hole cut in the bottom to accomodate the bass 50 cab’s protruding handle. Its about the length of the Bass 50, making it look like it was made for the Bass 50 when it sits on top of it.
Tolex was different though – the head used what looked like a basket weave pattern/texture. Im still looking for a matching grill cloth, or at least similar shade/color. The head was constructed out of MDF board (yeah, it wasnt even thick plywood or solid wood). Pretty sturdy though.
What i liked about it most is that the ease of access to the chassis and tubes now. Plus it now has the height to accept ANY EL34. JJ’s dont fit in the original cab, i had to find EH tubes to make it barely fit (as im sure youve experienced). A little long compared to the Bass 50 chassis, but the head give it plenty of space now, even for the standard sized yellowjacket converters with EL84’s.

Ive toyed with the idea of dispensing with the flip top control panel, as the harness (as you suspect also) can add hum. But i do have one Bass 50 thats relatively quiet (it starts to do so only when the treble is turned up at higher volume levels) so im keeping the harness for now (less of a project, plus i kinda like its fliptop quirkiness). Im putting the control panel on the front this time, but im debating if i should keep the fliptop action or just have the panel permanently set facing forward. that should allow me to shorten the harness, less chance of wires shorting or having a break due to a constant fliptop action.