Fixed bias for single-ended amp question

Discussion in 'Amp Central Station' started by alexwilds, May 9, 2021.

  1. alexwilds

    alexwilds Tele-Meister

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    This is a theoretical question, although I just might try it....

    Are there any fixed bias single-eded amps out there? I am looking at putting a 5F11 PT into my 5F1. It is a bolt-in upgrade to get a bit more punch into the 5881 tube I am using. It has a tap for fixed bias. The advantage would be the ability to dial in optimum bias for 6V6, or 6L6 or 5881 with the twist of a trim pot.

    What are the tonal differences between cathode bias and fixed bias, particularly when used with a single-ended amp?
     
  2. 2L man

    2L man Tele-Meister

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    I have seen quite a lot solid state constant current generators in HiFi amps but obvipusly they act more like cathode bias circuit.

    To optimise tubes to OPT impedance adjusting only cathode bias is not enough but for guitar amp it should be enough. There are many amps built which have another cathode resistor with series switch. Powerful potentiometer with series resistor is one option. Two switch/resistors which makes four different biases.
     
  3. printer2

    printer2 Poster Extraordinaire

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  4. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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