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Volume control with a rack rig?

Discussion in 'Amps and Cabs [BG]' started by HeavyDuty, Jan 16, 2002.

  1. HeavyDuty

    HeavyDuty Supporting Curmudgeon Staff Member Gold Supporting Member

    Jun 26, 2000
    Suburban Chicago, IL
    Now that I'm graduating to a component rack rig - a SansAmp RBI preamp into a Carvin DCM1000 power amp - what's the "best" way to control output SPL?

    Logic would tell me to run the power amp dimed to maximize headroom, and control volume with the output level on the RBI. Am I nuts?
  2. ZuluFunk

    ZuluFunk Supporting Member

    Apr 14, 2001
    I have no clue, but I would have thought instinctively to drive the pre-amp at max and control the volume on the pwr amp. kind of like keeping the volume on my bass all the way up and backing off on my head.

    Then again, I find if I back off on my on board to about 2/3, I can get a cleaner tone.

    Wouldn't you use the same logic either way?

    Sorry if I didn't help.
  3. mikemulcahy


    Jun 13, 2000
    The Abyss
    I crank the amps and the post gain on the pre amp and adjust volume with the pre gain control.

  4. Ditto
  5. Steve


    Aug 10, 2001
    FWIW, Per SWR.... Run your power amp wide open, set you tone controls then increase your pre-gain volume until the edge of tube saturation. This will give the best signal to noise ratio, reproduction of harmonics and the "fullest" tone. Use the post gain to control overall volume.

    How hot you run your tube does to my ear, seem to make a tonal difference. It's also a pain in that as you tweak tone, you have to monitor the pre-gain to avoid audible distortion.

    If you have an all transister front end, I doubt it would matter.
  6. arfur


    Nov 26, 2001
    London, UK
    Turn all the gain controls on your Power amp up to maximum. In effect all these are is a couple of variable resisters and by leaving them on max you should be taking them out of the circuit. (This is probably a gross simplification and some amps may be configured differently). The exception to this is when you have to balance the volume between two different cabs running off of the two channels. Then you can turn down the one that is too loud.
    I set pregain at a couple of clicks below the overload light for my loudest sound and then control the volume through the pre-amp output. Everything else stays the same.
  7. jasonbraatz


    Oct 18, 2000
    Oakland, CA
    so for me - i'd adjust everything on my IOD how i want it, turn the power amp up all the way, and adjust volume with the "master volume" knob, right?

  8. Steve


    Aug 10, 2001
    Uhhh, I just looked at the IOD user manual on the SWR website. It's one whole helluvalot more involved than that. You may want to scoot over there and take a peek. How you run it depends on what you want to get out of it.

    Aparently it ain't no ordinary preamp...
  9. Did I misunderstand the question?

    I run my power amps dimed and control the loudness with the preamp volume control on the F-1X.

    When the SWR IOD comes online tomorrow night, I plan on running it the same way. The Drive and Blend will be set according to the manual for clean, fat tube tone, and the volume will be controlled by the master volume on the preamp.

    The IOD is capable of putting out 12 ~15 Vrms to the XLR LINE OUT, depending on how you interpret their specs. My QSC needs 1.0 Vrms to reach maximum amplification, so I should have beaucoup noise capabilities tomorrow night.
  10. HeavyDuty

    HeavyDuty Supporting Curmudgeon Staff Member Gold Supporting Member

    Jun 26, 2000
    Suburban Chicago, IL
    OK, the Carvin is here. I'm finding running the Carvin wide open and controling volume with the line out of the RBI works just fine.

    Thanks, everyone!
  11. chucko58


    Jan 17, 2002
    Silicon Valley, CA, USA
    I paid for all my gear myself. Well, me and MasterCard.
  12. lowfreqguy


    Oct 18, 2000
    Baltimore, MD
    Power amp and bass dimed, control overall volume via preamp volume control. Once I set it, I just play harder or softer without changing the volume setting. That is, until the last set when the #$%& drummer is hitting way too hard and I have to turn up to hear myself.
  13. jasonbraatz


    Oct 18, 2000
    Oakland, CA
    cool, i was doing it the other way around - having the master dimed and then adjusting from the power amp - but i will try this new way.

  14. Jeff Moote

    Jeff Moote Supporting Member

    Oct 11, 2001
    Beamsville, ON, Canada
    HeavyDuty: how are you doing with that rig? Are you using the XLR or 1/4" from the RBI to the poweramp?

    Are you still using the power maxed and using the out of the pre as volume?
  15. FalsehoodBass


    Jul 22, 2001
    Denver, CO
    nono.. you use the poweramp to control your volume.. here's why....

    increasing the volume on the powearmp also amplifies any hiss or noise created by the preamp, so it is quieter to crank the preamp, and then use the poweramp's volume.

    This method worked best with my Ampeg SVP-Pro and Mackie poweramp, so i assume it would be the best for you too. The reduction in hiss was pretty noticable, so just try it for yourself.
  16. Jeff Moote

    Jeff Moote Supporting Member

    Oct 11, 2001
    Beamsville, ON, Canada
    Yes, that's what I thought, but the others havr different views.

    bgavin, can you clarify what you do: you wer unclear before.
  17. HeavyDuty

    HeavyDuty Supporting Curmudgeon Staff Member Gold Supporting Member

    Jun 26, 2000
    Suburban Chicago, IL
    So far, so good. I'm using 1/4" for now, but may switch to XLR if I go to a deeper rack bag.

    I'm trying volume setting all different ways - with the amp, with the preamp, with the bass. The jury is still out on what's the best way for me.

    I like the Carvin, I love the RBI, and the Korg tuner reminds me of the Cylon Warriors from Battlestar Galactica...

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