Saturday, July 11, 2009

The Alamo Jet Guitar Amp

Time for something completely different, music creation instead of a music reproduction! Tube instead of solid state (mostly)! Here, in Fenderish garb is the 4 tube, single ended 6V6, Alamo Jet from around '65 to '67:

Alamo Electronics was based in San Antonio (natcherly) and had an interesting history from '46 through about '82. As far as I can tell Alamo was never a premium manufacturer, but their amps have acquired a following, especially here in the Lone Star state. The Jet seems to fit nicely as a harp/practice/small venue blues amp.

This amp was in very respectable and original shape, but the last time it was used by one of the boys it was a bit noisy. That was quite a while ago, and I was nervous about firing it up without at least a basic refurb. So it was time to hit the bench.

This is a very basic point to point amp with a minimum number of caps. The 3 section main filter can was a 20@450v/20@450v/20@25v that was in marginal shape. The high voltage sections were hanging in there but the 25v section read high on the ESR meter. Forty year old electrolytics make me nervous so the can had to go. I resolved to just bypass it with caps under the hood and made the mistake of asking Mike how he would approach it. Mike whipped out the big clippers and popped the 3 tabs under the hood free. I really have to quit asking questions with obvious answers.

We resolved to up the values to 47@450v/33@450v/47@63v with Panasonics EE series caps for the high voltage caps and an FC for the other. I replaced the two 10mfd@25v caps with films @100v. Three orange drops and a Panasonic FC 47@63 brought the cap count to a very modest 9. I left the bevy of ceramic caps for another day.

The amp powered up nicely on Mike's Sencore Powerite and was stable, so tomorrow we will see how it sounds.

One note: the several solder points to the chassis were extremely tough to melt. It takes a hot gun to make headway on this amp, I guess the chassis functions as a very big heat sink.

Interestingly, I could not find a Wikipedia entry on Alamo. C'mon guys. But I did find several very useful links. Here is a part 1 of a very good history of Alamo Electronics in Vintage Guitar. And here is part 2. This article indicates '65 marked the transition to the black tolex, so the would be the earliest date of origin for my amp. The part 2 model summation seems to describe my amp cosmetically as in the '65-'66 range but it definitely has two small transistors in the tone control circuit. And it is missing from '65 line up, but I would think that is an omission. Maybe. The early '70s seems to be the transitional period for solid state, so it beats me as to the vintage of my Jet.

And here is a much more thorough restoration/augmentation of what appears to be a bit later version of the Jet, model 2564. My Jet was missing the sticker on the inside so I am not sure of my model number. Evidently Alamo was a bit cavalier with their names and model numbers.

And here are some good pictures of what I also assume is a later Jet, and please scroll to the bottom to view the reverb. Funny. I assume this is an original and not a replacement.

One last digression. In about 1982 Alamo Electronics merged with Southwest Technical Products of San Antonio. In that year I did a pilot software project on a SWTP Uniflex 6809 mini/micro for the state of Texas and demo'ed it for the Governor's office. Ahh, memories. Anyway, SWTP was also a hifi manufacturer of note and deserves some attention from the Stereo Club at some point in the future.


Anonymous said...

Nat, I have a alamo fury that could use a recap, and a general once over it sounds very nice, but the rectifier tube is a bit noisy, it also hums alot since I put in some new 7868s do know anyone who clould help me


Wolfe said...

I want to buy the name Alamo for my Instrument company BootHill here in Austin, TX. Do you owns the name? Just checking around, putting out some feelers. Please tell me if you know anything about Alamo Guitars or who owns the name.

Thank you. -Dave Wolfe (BootHill.TV)

Wolfe said...

Sorry Here is my email DW@BootHill.TV

Anonymous said...

Any chance you have a schematic for the jet? I have a newer jet with the solid state pre-amp, which is no longer working.

I'm looking to convert it to the all tube version.

Thx in advance

PS: I have found a schematic, values are mainly unreadable though.