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Amp Volume Question

Discussion in 'Amps and Cabs [BG]' started by jcadmus, Apr 30, 2003.


  1. jcadmus

    jcadmus

    Apr 2, 2000
    I'm doing some experimentation with my amp, and recently got some advice that I find puzzling.

    Someone has suggested that I should leave the master volume up all the way all the time, and adjust gain with the volume controls on the preamp and the bass itself.

    I've heard you can/should do this with separate power amps (although I don't know why), but what about all-in-one heads.

    FWIW, I'm using a Peavey T Max amp.

    Any thoughts/suggestions/explanations/recommendations?

    BTW, I searched the threads for this and didn't find anything -- if I missed it, please direct me to the appropriate thread.

    Thanks.
     
  2. While there are a few people who like the "master gain on full" approach, in my opinion (and lots of others like Bob Lee) this is not desirable. To keep noise down, turn your preamp stage up and then keep the master at a moderate level.

    Why? Any audio section will have noise, even if no signal is being passed through. Having the post (master) up full amplifies this all-present hiss.

    Plus, if anything weird happens on your preamp side, if your master is on full volume you may have a very loud burst of energy coming through and frying your amp or speakers.
     
  3. If you prefer the tone of master volume cranked, please consider only turning it up to 7-8 over 10... Seriously, I dont think its good pushing your maximum load into the speakers WHETHER OR NOT you are playing hard, its just too risky in my opinion. That guy doesn't know what he's talking about in my opinion, screw him, he was taught wrong.
     
  4. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    It's better than running your gain high and master low, that's for sure. I've been known to use this approach. It's designed to stop people from running the pre gain too hot and clipping every note. Plus with my PA background, it seems to make sense. I don't think this approach is necessary of you understand how gain structure and clipping work.

    In fact when I bought my current amp, that's exactly what the manufacterer told me to to. However I've found the amps is too powerful, thus making volume adjustment with the gain knob a very fiddly thing indeed. So with the gain on 1 as usual (8 o'clock), I've started running the master at about 60-70% instead, leaving me with a bit of leeway for volume adjustment at the master. I'm not convinced about the signal to noise ratio concern because I don't have any noise. Maybe my amp is designed to run that way????????
     
  5. thelastofus

    thelastofus Guest

    Jul 3, 2002
    Bakersfield, Ca
    understand first that only crank the master an adjust with gain if you want a really clean signal at high volumes. if you like gain at all then this might not be right for you. i do the opposite, i crank the gain all the way and then adjust with the master (but then again i do have a tube amp). just set the gain to your liking tone wise and then adjust with the master.
     
  6. jcadmus

    jcadmus

    Apr 2, 2000
    The reason I mention this is that I've been fighting a clipping problem playing at moderately loud volumes -- preamp cranked moderately high (8), active bass turned up about 3/4s, and master at about 2.5.

    The person I was talking to suggested this as a solution to the problem.

    Thanks for the input, guys.
     
  7. Turn your per-amp down until the clipping stops. Then turn your power-amp up until you get your desired volume. I run my pre-amp (F1-X) kinda hot (12:00) because I think it sounds better up there, but, if I set it at say 4:00 the pre-amp goes into over-drive ("Jack Bruce"). I still think it's best to have the gain on the power-amp set as low as possible. That way you are protecting your speakers if something crazy happens. jmho:D
     
  8. jcadmus

    jcadmus

    Apr 2, 2000
    Hmm. So if I want to get a moderately warm tone, I should dial up the pre volume on the preamp, dial back the post volume on the preamp, and turn up the master volume?

    What about the volume on the bass? I've been told that active basses have a habit of overdriving the power amp, even at moderate volumes.

    Thanks.
     
  9. Gard

    Gard Commercial User

    Mar 31, 2000
    Greensboro, NC, USA
    General Manager, Roscoe Guitars
    As the "person" jcadmus was talking to...

    :eek:

    ...I gotta apologize for being somewhat unclear:

    I never meant to say turn the master volume ALL the way up (if I did say that, my apologies), what I meant was to set the pre volume to eliminate the problem (input clipping), then adjust the master to achieve the SPL necessary to the situation.

    i.e.: what GreyBeard said! :meh:
     
  10. Adjust the pregain to get the amount of distortion you want, then adjust the power amp gain to get the volume level you want.

    Simple as that. If you want distortion, then turn the pregain up really high. If you want really clean, turn the pregain distortion not-so-high.

    If you have a clipping light on your preamp, then for clean you'd want to adjust the pregain until it was just under making the clip light flash every once in a while. This would mean very little distortion, but maximum signal to noise ratio.

    Chris
     
  11. FunkySpoo

    FunkySpoo Supporting Member

    Feb 6, 2002
    SWRs' web site says to turn the gain up till the clip light lights up on only your loudest notes. Then adjust your volume with the master. That what I do and it seems to work for me. If I have the pre amp volume cranked and use the amps volume then I get clipping. As for the bass I have it up all the way.
     
  12. Steven Green

    Steven Green

    Jul 25, 2001
    Pacific NW
    I think jcadmus was asking about how to set the knobs for:

    preamp: pre-gain & post gain

    &

    poweramp: gain


    I usually set my pre's master at 12:00 and adjust my pre-gain to taste. My power amp is then adjusted to get the volume I need. And I can clip that sucker, even when it's set to about -20.

    FYI, I'm using a Stewart 2.1 and Aggie DB 680.
     
  13. This discussion has perplexed me for sometime now. I've asked many knowledgeable people their opinions. I have QSC2402 and always run it mono/stereo mode full up on the gain. Sometimes I cut it back some, but usually end up turning it up later on. I run my Demeter VTBP201S on around 11:00 or 12:00 usually in the Passive input even with my Active Bass. I know this sounds like a real hot signal but it works for me. I don't have and noise problems either, so the signal to noise ratio concern isn't one. I have also been told by some pros that the hotter preamp signal can be far more dangerous to speakers and other equipment than worrying about the s/n ratio thing. Therefore it was recommend to me to run my amp-gain full, getting the most out of my power and supplying it to the hungry speaker cabinet.

    I see the respectable answers here indicate to set the preamp to just under clipping (I agree), then set your amp gains to the desired volume (that changes as the gig goes on, at least for me). So, again this question interests me. Please feel free to tear me a new a-hole if I'm wrong.

    The best advise is to KNOW about all of your equipment and then take all of the tips/advise/suggestions you get (after reading your manuals) and experiment. It can be real frustrating, but the research and experimentation will help you find your sound and how to "fit into the mix", of your band/bands.

    Know your equipment. (the whole signal chain)
    Basses
    Amps/preamps etc.
    DI
    Cabinets
    Effects
    Cords
    Proximity/Location of you and equipment.
     
  14. FunkySpoo

    FunkySpoo Supporting Member

    Feb 6, 2002
    I copied this from SWR's web site about the volume control on their power 750

    VOLUME CONTROL
    The Volume control affects the amount of signal driving the power amplifier. With the knob indicator in the full counter-clockwise
    ("MIN") position, turning the control clockwise will gradually increase the level the power amp sees and thus increase the overall
    volume. In most cases, we suggest you run the Power 750 with the Volume control set near maximum and control the level from
    your signal source
    (i.e. preamplifier, console, etc.). This will result in less knobs to worry about and insure repetitive gain structures. In any event,
    always keep an eye on the dot bar display to make sure the Power 750 is not being overdriven (+3 red LED continuously lighting)
    as this can result in damage to your speakers due
    to DC content in a clipped waveform. Turning down the Volume control will correct this situation.
     
  15. jcadmus

    jcadmus

    Apr 2, 2000
    No, dude, it wasn't you -- I asked you about the tone stuff, and your advice was real helpful.

    I asked someone else about the clipping thing (not on this board), and he gave me the master volume advice.

    Sorry for the confusion -- didn't want you to think I threw you in the trick bag.
     
  16. 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
    That's a sensible way to do it. Bravo to SWR for the very simple and straightforward instruction.

    However, SWR is not infallible, since they repeat the "clipping = DC" myth. :rolleyes:
     
  17. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    Can I just add that this works for Tube amps but not Solid State. If you're using solid state and you want distortion, buy an effect pedal. Don't overdrive or clip. SS clipping isn't musical anyway, but it's more likely to hurt your speakers than tube clipping.