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Power amp volumes..?

Discussion in 'Amps and Cabs [BG]' started by rockstarbassist, Oct 6, 2005.


  1. rockstarbassist

    rockstarbassist Banned

    Apr 30, 2002
    The Woodlands, TX
    Endorsing Artist: HCAF
    This is an addition to the end of my post in the Schro Cabs thread, but is it really "unsafe" (as claimed by some) to run your power amp at less than 100%?? Sometimes my Demeter pre doesn't always have enough "oomph" going from the DI to the board, so I like to jack up the pre's volume and cut on the Peavey's.

    I haven't really had problems with this before, but I'm bridging my cab now, and want to make sure I'm safe cutting the volume some, or should I ONLY adjust the volume with my preamp (and now EB Volume Jr. pedal)??

    thx in advance
     
  2. I've never heard this before. If it were unsafe to run at less than 100% I doubt that amp manufacturers would put attenuators on their amps, but they all do.
     
  3. Not dangerous at all.

    Set the gains on the preamp to get best signal to noise, then adjust the power amp volume whereever it needs to be to get the volume you need.

    The power amp section has no idea where the volume control is, all it sees is how much signal its getting from it.

    Feed it 2V from your preamp, volume at -3dB, feed it 1V from your preamp, volume at 0dB, feed it 10V from your preamp, volume at -10dB, its all exactly the same stress on the power amp.


    Randy
     
  4. rockstarbassist

    rockstarbassist Banned

    Apr 30, 2002
    The Woodlands, TX
    Endorsing Artist: HCAF
    Yeah didn't make HUGE sense to me either, but just thought I'd be safe and get some clarification.

    Sometimes if we play places with lots of lights, I get tons of buzz in my cab if I run my amp at 100%, but when I cut it just a tad, it all goes away.

    Anyhow, thanks for the input!
     
  5. tadawson

    tadawson

    Aug 24, 2005
    Lewisville, TX
    Exactly! The higher you run the amp (and consequently, the lower the preamp) the worse the signal to noise ratio from preamp to amp will get. Run the preamp pretty hot, without any danger of clipping, and the power amp as needed, and you will get the best sound. Otherwise, the preamp output is so low, that all the noise on the cable gets amplified as well, due to the high power amp gain, and you get noise, as you have seen.

    - Tim
     
  6. came across this post/thread..sent you PM:
    saw your thread about the power amp & the fact that you have the 1210 & wanted to solicit your input/feedback on the cab since i'm close to pulling the trigger on a used one. have been gigging w/ 2 primary cabs lately..the a/groove 2x10 for most venues & the berg 322 for larger/outdoor gigs. went from the pre/power setup for awhile to an svt II tube..sounds good w/ the groove but so-so w/ the berg..do you find the 1210 pretty punchy & aggressive & sits in the mix well? i mainly play rock in a 5 piece band (pretty loud drummer & 2 e. guitars) even thought running the groove & 1210 tandem & saw a pic of another TB'r who's done it.. any thoughts about the cab? thanks.
     
  7. rockstarbassist

    rockstarbassist Banned

    Apr 30, 2002
    The Woodlands, TX
    Endorsing Artist: HCAF
    Will shoot ya an email tomorrow...