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Need to borrow a design for a low wattage amp

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  • Need to borrow a design for a low wattage amp

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    I am getting ready to start my next build using the chassis(?) pictured here as the basis for the amp. I envision a low wattage living room amp with one tube mounted, pointing up and visible, on each tier of this lovely piece. It used to be a 40s/50s cover for a coin-op radio in a motel, I imagine. There was a little 6 tube radio inside and I hope to mount a power transformer and an output transformer on that little chassis. There is also tons of room inside for caps resistors etc, with a pilot light behind the dial opening and off/on and volume controls. A small speaker can be mounted at one end where a suitable grill already exists.
    I have been searching and can't find a suitable schematic or wiring diagram, as I will need details on suitable transformers et al. I could use just about any tubes, but I see possibly a 12a?7 as a power tube and a 6X4 as a rectifier, with another 12a?7 as a preamp.

    Can anyone point me in the right direction? I have been recapping and restoring amps for some time now, as well as building a few, from kits and from scratch, but I don't have the electronics knowledge to kick start this one.
    Thanks

  • #2
    Sniff around ebay or similar and see if you can find suitable out and power transformers.
    In this forum everyone is entitled to my opinion.

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    • #3
      Of course, the bigger and weirder-looking the tubes are, the more visual impact the thing will have. You could mount some oddball tubes on top with just the heaters connected if you wanted to go that route.

      A design with a 12AX7 preamp, a 12AT7 power tube (for about 1-2 Watts output power max) and a rectifier could also certainly work, but the mini tubes IMHO lack the visual impact that you might desire. Good luck with this, I'll be watching to see how it progresses!
      If it still won't get loud enough, it's probably broken. - Steve Conner
      If the thing works, stop fixing it. - Enzo
      We need more chaos in music, in art... I'm here to make it. - Justin Thomas
      MANY things in human experience can be easily differentiated, yet *impossible* to express as a measurement. - Juan Fahey

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      • #4
        I thought of big bottle tubes, but I built one of those already, and they would likely blow up a 4 inch speaker. I want the thing to work and, one hopes, to sound okay. Big tubes would look cool though.

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        • #5
          I will need a design first to determine what transformers are suitable.

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          • #6
            Big bottle tubes like a pair of 6SN7's? Or a 6SL7 into a 6SN7? http://music-electronics-forum.com/t16661/
            And you could use a solid state rectifier with a sag resistor to eliminate the tube rectifier.

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            • #7
              No, the big bottles I was thinking of, and used in my last build, were coke bottle 6V6 and 5Y3. I really want just a low watt 3 glass tube design that will power a small speaker. Simply a fun little thing that looks cool and sounds okay. Here is a pic of my last one that you have already seen, MadKatb

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