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Input Gain versus Master Volume Gain?

Discussion in 'Amps and Cabs [BG]' started by GRoberts, Mar 8, 2004.

  1. GRoberts

    GRoberts Supporting Member

    Jan 7, 2003
    Tucson, AZ USA
    I am confused about which volume controls to adjust for maximum tone and power. What are the rules for setting Input channel gain versus Master Volume gain? Is the one 'best' way to do it?

    1.) Should I adjust the Master Volume on my Amplifier for maximum volume so I don't over drive it? Do I need to keep the Master Volume control as wide open as possible so it can deliver the power on transient peaks.

    1a.)If I keep the Master Volume knob down, am I limiting the power that can be called on to deliver to my speaker?

    2.) Or should I adjust the input gain volume control on my Amp for maximum volume before clipping (VU Meter shows signal strength) and then adjust the Master Volume control for my overall Front of house volume? When I do it this way, the Master volume is usually set to less than 50% of its total adjustment. It seems to me that I could potentially be limiting the volume available to my speaker cabinet. (Bergantino HT322)

    3.) Is it possible to overdrive the input of my amp (active input) with too much bass boost? I have EMG's and EMG preamp in a recent Modulus Quantum 5.

    4.) Should I leave my onboard bass preamp controls as flat as possible and try to get the tone from the preamp controls on my amp instead? Sometimes I bump up the bass boost almost full to get the thick fat round tone out in the room. But it occurs to me that maybe I would be better served to feed a leaner signal to the input channel on my amplifier and use the boost/cut on the amplifier tone controls for the best result.

    Confused - anybody have any general rules. I realize we may approach this differently. Looking for a consensus, if there is such a thing.
  2. Mike Money

    Mike Money In Memoriam

    Mar 18, 2003
    Bakersfield California
    Avatar Speakers Endorsing Hooligan
    Well, the input gain controls the signal coming from the instrument, so you probably want as much of this as possible so you are getting the sound of your bass, and not the sound of the amp.

    I usually have my input gain at 50% and then adjust the master volume accordingly.
  3. inazone


    Apr 20, 2003
    Dont know if this helps or not, try and leave the bass knob on the ashdown flat or cut a little. Then use the sliders (the first a little, second one a little more, about 3/4 up, before the middle knob) to boost the bass. To me, live on stage the bass 'boom' sounded about the same but took less power. Also add a little drive in about 1/3 up before you get the grind.
  4. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    DFW, Texas
    All approaches mentioned are valid as long as you avoid clipping all along the way.

    I suggest experimenting (preferably in a live gig type situation) with different approaches and try to decide what sounds best to you.

    Lately, I've been running my bass volume maxxed, setting my preamp at 50% gain, and using the power amp gain as the final level setting (a few venues I've played required maxxed power amp gain + above 50% on the preamp).

    I like to do as much with the bass' tone controls and leave the preamp as flat as possible, but with a different bass &/or preamp that could change.

    Good luck.
  5. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL
    with the master of the amp or the power amp down at a very low level, i'll push up the initial stage's gain or volume on the preamp section, until i hear distortion or a little clipping. then i'll back off until it goes away. gives me the best signal to noise ratio. with the master down low, at least i'll know the distortion is coming from the initial preamp stage.

    then i'll use the master volume or the power amp's volume for overall volume control.

    keep in mind, that usually fiddling with the EQ controls will change the amount of signal being pushed thru the initial gain stage. so, if you add more bass or lower mids, you'll end up hitting some distortion. if you cut some of that bass or lower mids, you'll lose some signal, and may have to raise the preamp's gain/volume.
  6. GRoberts

    GRoberts Supporting Member

    Jan 7, 2003
    Tucson, AZ USA
    I was recently told the same thing Joker; To adjust the input level gain for maximum signal before clipping to maximize the signal-to-noise. Then use the Master volume for Volume. I was just not clear if the Master volume control limited the power that could be delivered to the cabinet. Especially since my Bergie HT322 is allegedly power hungry.

    Thanks for the feedback. I've tried it both ways and am still undecided which method gives the best punch. Love to hear from others. Especially from Bergie HT322 owners.

    I am also beginning to question whether the Ashdown ABM500 is my Sonic Nirvana. Would love to check out an EA iamp800 for comparison to the Ashdown.
  7. lo-freq

    lo-freq aka UFO

    Jan 19, 2003
    DFW, Texas
    P.S. I have an HT322.
    I can't tell any difference in punch or low-end grunt between the max S/N approach or using the power amp section fully up and setting the final level with the preamp.
    I believe that all the power section's headroom is still there even if the gain is not maxxed (Bob QSC Lee) could tell you for sure.

    I'd love to be able to A/B a WW Ultra and an iAmp-800 with the HT322.
  8. Arranger


    Mar 9, 2003
    One thing is certain. If you leave the master power amp maxed and control the volume with your preamp, you will have noticable hiss the whole time. It doesn't make much sense to choke your input signal.

    If you have your preamp/input signal near clipping and can't turn your master power amp volume loud enough, it's time for some more wattage. Trying to get more volume by turning the input past clipping won't help the sound.

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