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Gain vs. Volume... How much of each?

Discussion in 'Amps and Cabs [BG]' started by brock29609, Dec 18, 2003.

  1. brock29609

    brock29609 4 strings, 2 wheels

    May 11, 2003
    Greenville, SC
    When I want to safely get loud, how do I know how much gain vs. how much master volume on my head? How much gain is too much?
  2. Lockout


    Dec 24, 2002
    Does your head have a clip light?
  3. VellaBass


    Aug 29, 2003
    London, UK
    Remember that the gain controls the preamp, and volume the power amp. So raising the gain does two things - it gives more of the preamp colour to your signal, and sends a hotter signal into the power amp. This is necessarily simplistic as I'm leaving speaker response out of it, but bear with me.

    A good starting point is to leave the volume at a fairly low level - say about 9 or 10 o'clock. Play with the gain control through the (say) 9 to 4 o'clock positions. Not only will the output level from the speakers change,according to the input level you're feeding the power amp, but so will your tone, as the effects of the preamp change. Try to ignore the loudness changes and listen to the tone. Do the same exercise with different EQ, fingering/ picking / slapping and pick up selections. After some experimentation you'll find some combinations which are naturally better for you.

    Once you've found those, you use the volume control to give you what you need in rehearsal / on stage. Of course as you raise the volume the power amp output characteristics and the speaker response will change the sound again and you'll have to do more tweaking, but the starting points you established will at least help.
  4. Gain: as much as possible, without clipping/distorting. This guarantees a good signal-to-noise-ratio. Keeps noise and hum away. Brings your preamp to life (if it's a tube preamp).

    Volume: as much as you need for your playing situation.
  5. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL
    well, just like the other guys mentioned, but more succinctly...

    i'll set my master at a nice and low comfortable volume. then i'll play hard on my bass' low E on my 4 string, or my low B on my 5 string, and turn up the "gain" knob, until i start to hear a raspy, farting noise. if i do hear it, i'll back off a bit, til it goes away.

    then with my power amp's volume cranked to the max, i'll use my master volume to give me the right amount of volume i need for the stage.
  6. Shri


    Feb 25, 2003
    France, Paris
    Oh i'm learning something cos some friends (usually guitarists) always told me never to put the gain louder (beyond) than the master... unless i wanted a distorted sound, some saturation. :mad: :confused:
  7. atldeadhead


    Jun 17, 2002
    I'm glad this conversation started. In the manual for my SM500 it says the same thing ya'll are saying. As much gain as possible, just down from the point of clipping, and then use the master volume. But a guy I work with says that to get the most headroom from my amp I should turn the master volume up almost all the way, say 4 o'clock of so, and then I should adjust my gain to get the volume I want???

    Is there any validity to what he's saying? It seems counter to what's being said here and in the amp manual.

  8. Shri


    Feb 25, 2003
    France, Paris
    that's what my friends told me... to put the master high and then to adjust the gain but never higher than the master.
  9. 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
    What Vella, Joris, joker, and atl said.

    There's nothing wrong with setting the master volume lower than the gain if you just don't need that much volume. So feel free to set the gain higher than the master if that works out for you.
  10. atldeadhead


    Jun 17, 2002
    What I really want to know is which way yeilds the most headroom from the amp?

    Hi gain with the volume adjusted for the volume of sound you want?


    The volume all the way up and the gain adjusted for the volume of sound you want?
  11. alexclaber

    alexclaber Commercial User

    Jun 19, 2001
    Brighton, UK
    Director - Barefaced Ltd
    Neither: six of one, half a dozen of the other.

    If you run the master volume at max and control the level with the gain control you may find the noise floor is higher. Then again, if the preamp is quiet, maybe not.

  12. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    There are two approaches. For the most headroom, turn the master volume all the way up and adjust the gain to taste. That method will always give you the maximum clean headroom the amp is able to provide.

    The other approach is, if you want to get a particular "sound" out of your amp. This approach has two examples. First example is, in a solid state amp the theory is that you get the best sound and the lowest relative distortion just below clipping. Hence the "clip led". But this is not always true in a tube amp, where some clipping and distortion may be desirable. So the second example would be, dialing in a preamp sound, and then using the master volume control to adjust its level to the demands of the gig or recording situation.
  13. 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
    The most headroom would be with little or no power from the amp. Since that would result in no loudness--in fact, no sound--I don't think that's what you mean.

    I think you probably mean dynamic range.

    To maximize your dynamic range, you want the noise to be minimized, yet want to still be able to reach all the power you need from the amp, if necessary.

    The first thing to understand is that turning the amp's master volume down doesn't reduce its maximum power capability; it just means it takes a hotter input signal to reach that point. Use that to your advantage.

    A strong signal level throughout your system will help ensure that it is always well above the noise and hum developed or picked up in the circuitry, cables, etc. The earlier you can get your signal level up, the better--at the instrument itself, if you can.

    After that, have a good amount of boost at the input gain--as much as you can without clipping anything upstream from the master volume, and if necessary adjust EQ, etc. to get the sound you like.

    Then turn up the master volume just enough to get the sound level you want. Allow yourself some room to play louder without having to rip your fingers up.

    So the concept is: gain up, master down is better than gain down, master up.
  14. Shri


    Feb 25, 2003
    France, Paris
    Thanks guys. Anyway i'll try for myself next time. :cool:
  15. Somebassguy


    Nov 5, 2003
    Everett Wa
    Agreed. I set my Master at about 9:00 oclock and adjust my gain and EQ as needed. This produces the cleanest sound on my 55-02.
  16. thelastofus

    thelastofus Guest

    Jul 3, 2002
    Bakersfield, Ca
    on my tube ampeg,gain 10, volume 2
  17. Eden WT manual calls for gain up master down approach.

  18. bassmantele


    Jul 22, 2003
    Boston MA USA
    This is a puzzling thread....

    Master volume pots were originally put in guitar amps because they had too much headroom - you'd have to turn them up too loud before you got the distortion that was popular at the time with big acts playing in auditoriums and arenas. So the whole point of a master volume is to elimiate headroom - and increase distortion - by turning it down and then turning the gain pot up until the next preamp stage starts to distort.
    If you want the most non-distorted volume you can get, you should start with the MV and gain low, turn up the gain until it starts to distort, and back it off until it cleans up. Then, turn up the MV until you start to hear power amp distortion, and back off again. That's it.
  19. Yah, that's essentially what everyone else has been saying...

    Guitarists are more likely to run their master volume dimed though and use a gain control for their actual volume as most prefer the sound of poweramp distortion vs preamp distortion.

    For me, I usually run my gain slightly beyond to point of clipping to get a nice bit of growl and overdrive from the tube preamp. Master volume on the preamp out is as hot as the poweramp input can take without clipping, and I adjust the volume on my poweramp to reflect how loud I need to be.

    Rule of thumb for bass is almost always gain as hot as possible without clipping, and control volume with the master.
  20. bassmantele


    Jul 22, 2003
    Boston MA USA
    Not really. They're saying to turn the MV down and the gain up. That's what you do to get distortion at low volumes, not to get the most possible clean volume. There's no reason why there should be a rule of thumb for which pot gets turned up more. It depends on the gain produced by each preamp stage and how much signal gets dumped to ground. And also on the pots themselves - not all log pots have the same taper. I'm just suggesting that you have to experiment to find the correct ratio of gain to MV - there's no rule.

    If they do, they're defeating the whole purpose of the MV. That's not necessarily a bad thing, but kind of a waste.