Preamp Tube Function(s) - Does This Sound Right?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Electric I, Jun 29, 2006.

  1. Electric I

    Electric I Member

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    I requested preamp tube functions/positions for my amp & got this email:

    "Both pre-amp tubes are 12AX7s. The tube on the right (closest to the corner) is V1. V1 is the first tube in the signal chain and it feeds the tone controls. The tube on the left is V2. Half of V2 is a recovery amplifier for the reverb and effects loop. The other half is the split phase inverter (aka cathodyne phase inverter). "

    Does this make sense? Can 'half' a tube function as a PI?
     
  2. hasserl

    hasserl Member

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    Yes it can, it is called a cathodyne phase inverter, or sometimes a concertina. This is the type of PI used in amps like Fender's tweed Deluxe and Princeton Reverb.
     
  3. donnyjaguar

    donnyjaguar Member

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    The first place I saw this type of phase invertor was on a Williamson amplifier, and I've heard it referred to as a Williamson also. The benefits of it are simplicity and equality in the amplitude of the output(s). I think its safe to say it is the most hi-fi of all types of phase inversion but the down side is it has no gain.
     
  4. Electric I

    Electric I Member

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    I see & thanks for the input.

    My next question is - would the amp benefit from a balanced PI tube, given that it's actually sharing duties with the reverb & loop?
     
  5. hasserl

    hasserl Member

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    No.
     
  6. Electric I

    Electric I Member

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    Gotcha.

    Thanks again.
     

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