Preamp/Poweramp level adjustment help

Discussion in 'Amps and Cabs [BG]' started by PolkaHero, Sep 22, 2004.

  1. PolkaHero


    Jan 5, 2002
    I just replaced my Sansamp BDDI with a real preamp, a BBE BMAX-T and am shocked at the difference in output level. I can now fully realize the capability of my QSC PLX3002 poweramp. Should I be running the channels of the poweramp full out and compensate the levels of the preamp? With these settings, I can hardly turn the levels of the BBE up at all without clipping the amp. Should I set the levels of the QSC halfway and turn the preamps levels up more? Also, which gain knob of the BBE preamp should be set higher for better signal/noise ratio? Thanks!
  2. The generally accepted school of thought for preamp gain is to turn the input gain up just to the point of clipping during your hardest notes, then back it off some. This should give you the best signal-to-noise ratio through your rig. Set your input gain and leave it.

    I generally run my gain attenuators (they're not volume knobs) on my PLX at 26, which is a couple of clicks back from full-on. I feel better about things that way. I control my master volume from the preamp.
  3. PolkaHero


    Jan 5, 2002
    I'm finding it sounds better when I set the input gain on the preamp lower while setting the output gain on the preamp higher. Does this make any sense? Is it that easy to clip the input state on these BBE preamps? :meh:
  4. DubDubs


    Aug 23, 2004
    Los Angeles
    That's how youre supposed to do it. The input gain on the pre should be lower than the output gain. I have the input gain a little lower than half way up. I have the output gain at around 3/4 and I have the poweramp anywhere between 1/2 and 3/4 of the way up depending on the volume I need.
  5. ZuluFunk

    ZuluFunk Supporting Member

    Apr 14, 2001
    I can't remember who guided me on this (the dudes from Aguilar?)...

    Run the output on your power amp all the way up, but back off a little if you get any system noise. Then adjust your pre master.

    I don't know anything about the BBE though.
  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
    Turn up the pre gain high but not so high that you get distortion. Then turn up the pre master high but but not so high that you get distortion. Then turn up the power amp as much as you need to.