Swapping rectifier

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Matt Phillips, Jun 23, 2019.

  1. Matt Phillips

    Matt Phillips Member

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    Jun 23, 2019
    Hi all

    I’m currently running a Tweedle Dee Modulus amps kit with a gz34 and 6v6s

    Am I right in thinking that I could just drop in a 5y3 for earlier break up?

    Thanks
     
  2. pdf64

    pdf64 Member

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    That should be fine, better for the 6V6 really, especially if russian made 5Y3 are not used, as they are reported to put out a higher HT Vdc than real 5Y3.
     
  3. HH1978

    HH1978 Member

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    I think a 5Y3 would be plenty enough to feed two 12ax7 and two 6v6GT.

    A 5R4GA would be another possibility : about the same voltage drop but with more current available. Probably overkill in this case though.
     
  4. HH1978

    HH1978 Member

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    +1, I tried one, and the voltage drop was about the same as the GZ34
     
  5. Matt Phillips

    Matt Phillips Member

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    Thanks chaps, I’ll give it a go!
     
  6. bulbasaur_85

    bulbasaur_85 Member

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    Is this amp fixed or cathode biased? Just curious.

    Are you measuring the plate voltage when you reference voltage drop? (Ie off of pin 3 on your 6v6)?
     
  7. Matt Phillips

    Matt Phillips Member

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    It’s cathode biased.

    I haven’t referenced voltage drop
     
  8. HotBluePlates

    HotBluePlates Member

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    "Tweedle Dee" is supposed to be a Dumble-modified tweed Deluxe circuit.

    You can certainly install a 5Y3, but the amp may be about as-loud when it distorts.

    The somewhat lower voltage from the 5Y3 will reduce the voltage across the output tubes, as well as their bias voltage. However, that may not significantly change the clean power output of the amp. And since the output tubes are the first thing to distort in this amp, the onset of distortion will probably happen around the same volume-in-the-room (though you may see it as occurring on a slightly lower number on the Volume dial).
     

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