Biasing a tube?..

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  • 01-20-2007, 04:18 AM
    Bingo
    Biasing a tube?..
    :17: I am considering buying the new Raysonic CD 128 CD player. This player has four tubes in the output stage. I have read that in a tube amplifier that tubes need to be 'biased' from time to time by a technician. Does anyone out there know if that applies to the CD player as well? I'd appreciate advice on this.
  • 01-20-2007, 04:34 AM
    SAEA501
    The electrical properties of any tube changes with time an use. So ideally you should do this periodically. I don't know the application of the tubes in the CD player so what sonic effect it will have if you don't I can't tell you.
  • 01-20-2007, 05:16 AM
    mlsstl
    Typically the only tubes in an audio circuit that need biasing are the final stage outputs to the speakers. Most preamp circuits (which would include the gain stages in a CD player) do not require biasing.

    Many of the modern tube power amps that do require biasing include a built-in system to help you bias. The Conrad Johnson MV-60 I used to own had a small potentiometer and a red LED next to each output tube. You periodically turned the pot until the LED lit up and then backed off until it just went out and you were done. However, as noted before, this is generally not required for line-level output tube equipment.
  • 01-20-2007, 05:29 AM
    Dusty Chalk
    Quote:

    Originally Posted by mlsstl
    Typically the only tubes in an audio circuit that need biasing are the final stage outputs to the speakers. Most preamp circuits (which would include the gain stages in a CD player) do not require biasing.

    What he said -- you shouldn't need to do so with a tubed CD player.
  • 01-20-2007, 07:19 AM
    Bingo
    Biasing tubes
    TO SAEA501
    MISS1l
    DUSTY CHALK

    Thanks! I appreciate the prompt and direct answers. Keep up the good work!

    Nolan