QSC PLX question. Bob? you out there?

Discussion in 'Amps and Cabs [BG]' started by Steve, Apr 10, 2004.

  1. Steve


    Aug 10, 2001
    If you run in bridged mode.....Shouldn't the signal LED's light up exactly the same?

    I'm wondering because...mine don't. And it's not consistant. sometimes the right side will flash higher and decay faster, sometimes the left.

    And yes, I have RTFM and re-RTFM. I have also checked and re-checked the wiring....

    It's a little hard to tell because I've never run it past the point where the third green LED gives any more than the occaisional flash but it is a little disconcerting.....
  2. Phat Ham

    Phat Ham

    Feb 13, 2000
    No. While the signal amplification circuitry is made to be very accurate, the LED circuitry isn't. So don't worry if the LEDs don't light up exactly the same.
  3. Steve


    Aug 10, 2001
    That takes a load off the old mind bone
  4. Schwinn


    Dec 4, 2002
    Sarasota, FL

    My leds in bridged mode aren't completely sychronized either. I'm sure it's normal.
  5. Phat Ham

    Phat Ham

    Feb 13, 2000
    I forgot to mention in my first post that my PLX does the same thing.
  6. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    So does mine. ;)

    The LED meters are just to give you an idea of your headroom--that is, how much gas is left in the amp.

    It's not precision circuitry driving those. Especially at the "signal" (approx. 30 dB below full power) and "-20 dB" levels, which are respectively 0.1% and 1% of full power, you may see some mismatch in the metering response due to just slight tolerance variations in the comparator circuitry. And the electrolytic capacitors that hold the LEDs on so you can see them more easily also have normal tolerances of something like +50 / -20%, so you may also see that some LEDs hold slightly longer or shorter than others.