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SNR/noise figures

Discussion in 'Amps and Cabs [BG]' started by Funky Doctor, Sep 6, 2004.

  1. Funky Doctor

    Funky Doctor

    Aug 28, 2003
    Ok, here is one for the "techie" type people. Maybe even Bob Lee himself could clear this one up for me.

    I have 3 volume knobs on my amp (pre/power set up, gain, preamp volume, power amp volume). I was wondering, what kind of setting(s) would give me the best signal to noise ratio? Would I maybe, set gain to max. without clipping, turn power amp volume all the way and control the overall voume with the preamp volume knob? What would be the best way?
  2. Mcrelly


    Jun 16, 2003
    Minnesota, USA
    well, I hope I can help. I have a preamp with gain and volume, and I have a poweramp with a level control.

    here is how I normally set my controls, but this may work differently for you. with my amp volume full and preamp volume slightly on, guitar full, I raise my pre gain until I get some distortion, then I back off a little. I turn my pre volume up to the loudest volume I think I'll need during the performance. I use my guitar from that point to lower my volume. sometimes running a little under full on the guitar to turn up a little if necessary.
  3. CamMcIntyre


    Jun 6, 2000
    Here's how i run my setup. I've got the following: on my preamp i've got a drive knob and a level knob, power amp 2 gain knobs. I run my power amp full open. Preamp drive to suit [adds a bit of well-drive, it's a SansAmp RBI], and adjust the overall volume with my preamp level. If i'm running the BassMaxT, i get the master gain to suit [e.g. not distorting], and adjust with the volume/level.

    That's all
  4. 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
    For optimum signal-to-noise ratio, get your gain--your signal boost--up front, as close to the source as possible.

    That means:
    • Preamp input gain up high, but not so much that the preamp circuitry clips.
    • Preamp master or output gain mid to fairly high; adjust to avoid clipping the preamp output.
    • Power amp turned up only as far as you need it--not up to full unless you actually need that much gain.
  5. I usually keep my power amp cranked, the pre gain as high as it'll go before peak lights, and adjust the volume with the pre volume level.

    Worked fine for me.
  6. Funky Doctor

    Funky Doctor

    Aug 28, 2003
    Well thanks everybody. Especially thankyou Mr Lee, because that's exactly what I have been doing. Thanks for the replies.