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crazy micro tube amp for 12$

Discussion in 'Amps and Cabs [BG]' started by thobbinghotrod, Jun 8, 2007.

  1. I bought a tube powered reel to reel tape player at a thrift store. It has an input, amp out and speaker out. It sounds great for bass, not quit as good with guitar because it's voice too low. I has six tubes.

    two 12au7
    one 12ax7
    one 12ab5
    one 12x4
    and one crazy green eye type of thing that must be for looks.

    which one is the power tube and how much power could it be putting out?
  2. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    12AB5 shows a max plate dissipation spec of 12 watts, so it'd be considerably less than that, given inefficiencies of a Class A tube power stage.
  3. I forgot to mention, It's a Webcor brand, made in the sixty's, and has a huge power transformer, but hardley a capacitor to be seen.
  4. A9X


    Dec 27, 2003
    Caps were very expensive in the 60's so designers found other ways of getting the circuits to work with the minimum number possible.

    Power output will likely be under 4W, but that's a guess based on plate dissipation as I'm unfamiliar with this particular tube and can't se a datasheet on it in my library..

    The round indicator tube is likely a 6U5 or similar and was probably used for setting levels or monitoring them.
  5. Thanks for the replies. I used it in practise last night and it was amazing. I plugged my bass into the in jack, and ran a cord from the "amp out" jack into the effects return of my GK 700RBII. I couldn't believe how smooth and warm the sound was. It was louder than I've ever had my amp, and I had to turn down for the first time ever. One curious thing, the GK ran cold instead of the usual heat it puts out. The fan didn't turn on that I noticed in an hour of playing. My only concern is that the motor for the reel to reel part is always running and squeeks, you can only hear it if you kneel down to it's level, so not really a problem.
  6. Get it to a tech and have him trace out a schematic of it...
  7. It has a complete schematic inside the case. And I called my tech but he might be on vacation or something. I would like to take any unused parts out to lighten the thing up a bit.
  8. Primary

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