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Adding a gain control to an amp?

Discussion in 'Amps and Cabs [BG]' started by subdude67, Nov 10, 2019.

  1. subdude67


    Jan 18, 2010
    This tiny practise amp I have tends to distort even on low volumes unless I dial down the bass volume by quite a bit.

    Can I add a small trim pot into the signal chain just after the amp's input jack and would that help me to reduce the distortion?
  2. Stumbo

    Stumbo Wherever you go, there you are. Supporting Member Commercial User

    Feb 11, 2008
    Song Surgeon slow downer. https://tinyurl.com/y5dcuqjg
    Which amp are you using?
  3. JimChjones


    Aug 6, 2017
    SE England
    Wouldn't that be exactly the same as backing the volume off on the bass/pedals (if any) a bit?
  4. subdude67


    Jan 18, 2010
    The Artec Cubix
  5. subdude67


    Jan 18, 2010
    Isn't that how a gain knob works?
  6. Warpeg

    Warpeg Supporting Member

    Jun 20, 2005
    I could be wrong, but I believe that gain is not a cut-only control like a potentiometer is. Gain adjusts voltage by adding and/or subtracting voltage. It sounds like you just need a potentiometer, like the one that’s already present on your bass.
    JeezyMcNuggles likes this.
  7. SamanthaCay

    SamanthaCay Like bass guitar OMG!

    Nov 16, 2008
    Denver, CO.
    Gain is typically a pot placed after the first gain stage in an amp before the signal goes on to the next stage (usually your eq)

    @Warpeg the volt is a SI unit of electromotive force, the difference of potential that would drive one ampere of current against one ohm resistance, ie anywhere there is the flow of electrons there is voltage and anything that varies said flow will also have an effect on the voltage.
    HolmeBass and dabis like this.
  8. SamanthaCay

    SamanthaCay Like bass guitar OMG!

    Nov 16, 2008
    Denver, CO.
    Also FWIW I'd say if ya want a cleaner sound you're gonna want a bigger amp. I've got probably half a dozen practice amps and they all distort. Also as was stated backing your bass volume off is probably your easiest semi solution here. Also also worth noting here, if you have an active bass it may have an internal level/gain trim as many do and would be worth a looksy.
    rollie 55 and bassliner50 like this.
  9. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    It depends entirely on the design of the amp. There are many ways to design a gain control into an amp.

    Generally, it's not easy to retrofit a gain control because it depends on the rest of the amp's circuitry/design as to how it might be done.
    BassmanPaul and Al Kraft like this.
  10. Coolhandjjl

    Coolhandjjl Supporting Member

    Oct 13, 2010
    Just use the gain knob on your last pedal in your chain.
  11. subdude67


    Jan 18, 2010
    Thanks for all your replies, I appreciate your input:thumbsup:

    I first suspected the speaker to be the culprit so I disconnected it and hooked the amp up to my eden cab but that didn't make the distortion go away. So I started wondering if the input signal was too high and if a gain control would alleviate the deficiency.

    Now I learned that the gain isn't just a pot before the preamp and that there is no shame in having the volume on my bass on a position other than 0 or 100. I will do just that.
    Kro likes this.
  12. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    I suspect that you’ve reached the limit of your practice amp. The input signal level and the bass setting go hand in hand. A balance of the two might allow you to optimize what you can get out of the amp.

    If you have a high pass filter pedal, try that at the input of the amp. This will lower the energy in your signal and might allow more headroom. With a typical practice amp, don’t expect miracles though.
    BassmanPaul, agedhorse and quickfix like this.
  13. BogeyBass


    Sep 14, 2010
    people have used volume pedals in effects loops to control amp saturation
    but that is more post gain.

    As far as the practice amp, you probably are reaching speaker distortion or hit the end of the road of the amplifier.

    its not easy to just toss in pre gain control. specially on a pcb type amplifier

    cutting volume on the bass itself will cause tone changes.
    be easier to use a active volume control in a pedal or outside box.

    you could build whatever circuit you want in a box, so technically its very easy depending on electronic knowledge

    unless you have a active bass. Simple as, turn down your bass volume or lower the output level on the pre inside the bass if its adjustable
    Last edited: Nov 10, 2019
  14. byacey


    May 16, 2008
    Alberta, Canada
    Often the volume control is after the first preamp gain stage, so if your signal at the input jack is too high, the first preamp will clip, regardless of how the volume control is set.

    I would try reducing the level at your pedals, or the bass itself, if it's got an an onboard preamp.
  15. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    I completely agree. You're trying to turn a practice amp into a silk purse. Enjoy it for what it is, respect its limitations, and use something bigger and better for gigs and jams. Otherwise you're throwing good money after bad and you still won't get the results you want.
  16. vvvmmm


    Dec 6, 2016
    One other idear - probably won't give ya what you really want, but you could try, particularly if it's tone as the issue at available volume, is some kinda pad after the bass before the amp

    I do the J. Mascis thing in a similar manner to adjust volume on distortion-pedal guitar, running the hi-gain pedal (and guitar) on "10" into a boost pedal that is set on, say, "3". The net effect is that I get the blown-out distortion sound of the full volume guitar into the cranked distortion pedal, controlled.

    But it's not gonna add volume, just allow for the blown pedal sound at the same volume the amp has.

    But I think likely Jimmy M.'s post above is a better evaluation of the issue(s).

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