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Single-Channel AB763 Deluxe Reverb in a Princeton Reverb Chassis

Discussion in 'Shock Brother's DIY Amps' started by ElliotKnapp, Oct 22, 2020.

  1. ElliotKnapp

    ElliotKnapp TDPRI Member

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    You guys are clearly several levels above me here...wouldn't even know where to start or know if I was doing it right!
     
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  2. Paul G.

    Paul G. Friend of Leo's

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    You know, people have been pulling V1 from AB763s since forever. Nobody died.
     
  3. NTC

    NTC Tele-Meister

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    The solid state part is a bad idea - it would take a bit of electronic magic to make the power supply for the driver portion. You could make 5v from the heater winding, but that might not be high enough for the driver. It would work for the oscillator. Easier to use a tube.

    Ignore the man without a tele.
     
  4. sds1

    sds1 Tele-Afflicted

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    LND150 is popular in tube amps because you can drop it in for 12AX7 etc. with zero reconfiguration to power supply or otherwise. It works great in any transparent application including tremolo oscillator circuit like you suggested.

    Hardest part is mounting it. You can use a terminal strip.
     
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  5. NTC

    NTC Tele-Meister

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    I had some of those and they seemed to blow up when you soldered them down. I never got a circuit to work. Be great if the do - it really does do the same thing...
     
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  6. sds1

    sds1 Tele-Afflicted

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    Yeah those butane torches aren't the best choice for tube amps, I recommend something flameless especially when working on silicone.

    I'm kidding! Dunno why you had problems, I've had no problems soldering and even resoldering those little guys. I've not ever received a bad one either. Got them from a reputable supplier?
     
  7. zook

    zook Friend of Leo's

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    Try this:

    princeton_reverb LTP poweramp aa1164_schem clear.jpg
     
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  8. trancedental

    trancedental Tele-Meister

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    Similar to Zooks PR circuit above, 3 preamp tube Princeton Reverb, with no transformer 1 tube 12DW7 reverb, no vibrato with cathode bias (or fixed bias option).

    Using no reverb transformer / choke saves almost the same cost as an output speaker transformer.

    I saw this a while back on EL34world forum. Relevant credits are written on the circuit diagram.

    PR no transformer reverb no vibrato cathode bias .png
     
  9. ElliotKnapp

    ElliotKnapp TDPRI Member

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    This idea piqued my interest and although I own a 500 series DI that uses a 12DW7, I'd never really investigated this tube before. What I still don't understand is, if the original Fender circuits call for 2 triodes of a 12AT7 in parallel to drive the reverb, how can a single 12AU7 in the 12DW7 be a sufficient replacement? @zook are you willing to school me on this?
     
  10. elpico

    elpico Tele-Afflicted

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    When you're low on available driver power like this you can drive the tank from the OT. I know, Fender never did it that way, but other companies did and it works.
     
  11. zook

    zook Friend of Leo's

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    You really don't need the two triodes to drive the reverb tank. One will suffice, and the 12AU7 half of the 12DW7 will be just fine. If you want to hear the difference, sub in a 12AU7 in place of the 12AT7 in a fender reverb driver. You will find that you can turn the reverb up more before it becomes overwhelming.
     
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