quick bias question?

Discussion in 'Amps and Cabs' started by gtrplr71, Jun 28, 2008.

  1. gtrplr71

    gtrplr71 Supporting Member

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    sorry for the silly ques. but I had a bias mod done to my amp and have not rebiased in 6 months. On my multimeter it should be on 200 on the V or the A side I just can't remember. thanks in advance!:jo
     
  2. 5E3

    5E3 Member

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    Depends on if you are measuring plate voltage (V-DC) or current (Amps). Where and how are you going to take your measurement? If you have a bias probe like the following, set for Amps.
    [​IMG]
     
  3. gtrplr71

    gtrplr71 Supporting Member

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  4. KeithC

    KeithC Silver Supporting Member

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    On my Allen I would have it on V and use the test points with my multimeter

    In fact on the back of the amp by the test points is says to get a reading from 30-35 mV DC
     
  5. gtrplr71

    gtrplr71 Supporting Member

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  6. KeithC

    KeithC Silver Supporting Member

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    Sure!
    Kind of a bad pic but you can see here what the Allen says at least

    [​IMG]
     
  7. VaughnC

    VaughnC Supporting Member

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    Most bias mods insert a 1 ohm resistor in the cathode circuit of each or both power tubes. So said 1 ohm resistor will drop a voltage across it that's numerically equal to the amperes through it...so, for instance, if there's 30 millivolts dropped across the 1 ohm resistor, that means there's 30 milliamps going through the resistor.

    Set your multimeter for the lowest range that will read 100 millivolts.....with most multimeters, that would likely be its 200 millivolt or 200 mv scale.
     

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