What's the Op-Amp in my Valveking?

Discussion in 'Amps and Cabs' started by midnightlaundry, Sep 12, 2008.

  1. midnightlaundry

    midnightlaundry Member

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    It's a JRC 4560D. Is it for the Reverb? What about instaling a Bias Pot? Who has a schematic?

    Shed some light on this for me Jedi's.
     
  2. Wesman61

    Wesman61 Supporting Member

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    There's a schem at schematicheaven.com. Just look under "post 70's amps." And yes the reverb circuit has a 4560. You should be able to replace R205 with a small pot to make the bias adjustable.
     
  3. midnightlaundry

    midnightlaundry Member

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  4. midnightlaundry

    midnightlaundry Member

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  5. drgonzoguitar

    drgonzoguitar Member

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    It looks like a NFB adjustment to change the bias in one of the phase inverter tubes, which would push the alternations towards one side...thus making it a little more "Class A." Some title trickery...but very interesting.
     
  6. midnightlaundry

    midnightlaundry Member

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    THanks. I wish I knew more about this stuff to figure it out.
     

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