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Poweramp sensitivity

Discussion in 'Amps and Cabs [BG]' started by Hypocrite, May 3, 2018.


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  1. Looking for advice on how to get more juice out of my rig.
    I'm currently playing an active bass into a DG B7KU - > 500W poweramp - > 800W 8x10 at 4Ohms, stereo. I find myself having to dime the volume on both pedal and amp just to hear myself between our drummer and guitarist, something easily achieved when going through the power section of my 300W 4x10.
    We play techdeath in a fairly small room, but we watch our levels and aren't too loud, considering. I have always-on distortion for some extra definition and clank, and I don't have my mids scooped or lows boosted enough to shake the walls.

    So, what gives? Is it as simple as changing the input sensitivity from 1.4V to 0.7V or 26dB, or is there some other aspect I'm missing?

    Cheers

    Edit: I'm feeding the amp an unbalanced signal, surely that can't account for the low volume, can it?
     
  2. JKos

    JKos Supporting Member

    Oct 26, 2010
    Torrance, CA
    It certainly could be. If that is an easy option, just try it.

    It may not be helping the matter. The amp is expecting a balanced signal and providing an unbalanced signal means your input level is even that much lower. That being said, many, many devices with "balanced" outputs have impedance balanced outputs which helps with the noise characteristics of a balanced connection. But, they don't actually have audio signals with opposite polarity on the two lines. Which means that when the two lines are summed at the input of a device, the audio signal is still the same level as if you ran an unbalanced line between the two.

    In other words...
    Truly balanced output to balanced input:
    a - (-a) = a + a = 2a

    Impedance balanced output to balanced input:
    a - (0) = a

    - John
     
    Last edited: May 3, 2018
    agedhorse and BasturdBlaster like this.
  3. BasturdBlaster

    BasturdBlaster

    Feb 19, 2012
    Crandon WI
    What poweramp are you using?
    If you can switch the input sensitivity from 1.4v to .7v, you should be good to go:thumbsup:
     
  4. Thanks, that is the easier thing for me to test next time.
    I thought that might be the issue, but again, I get much lower volumes than running the same signal into a lesser rig. In any case I can try with an XLR cable, see if that makes a huge difference.
     
  5. A Thomann The t.amp E-800
     
    BasturdBlaster likes this.
  6. Rick James

    Rick James Inactive

    Feb 24, 2007
    New Jersey
    It accounts for 6dB of it. Most bass amps have 100mV sensitivity for passives, maybe 1v for actives, and they also have a lot of gain before the power amp.
     
  7. JKos

    JKos Supporting Member

    Oct 26, 2010
    Torrance, CA
    If you are tapping out the knobs on the pedal and amp but not seeing any clip light indications, you certainly have more output available. Give that sensitivity switch a shot and let us know.

    - John
     
    Hypocrite likes this.
  8. Clip light comes on very rarely with both volumes maxed and extreme EQ, I'll try flipping the sensitivity and see how that goes
     
    BasturdBlaster likes this.
  9. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    What's the rated nominal output level and maximum output level of the pedal?
     
    Bob Lee (QSC) likes this.
  10. No idea. All I can see in the manual is output impedance at 1k
     
  11. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    These are essential specs, otherwise there is no way to know way to know what the real problem is.
     
    Bob Lee (QSC) likes this.
  12. BadExample

    BadExample

    Jan 21, 2016
    Injiana
    Ask Darkglass... very friendly owner I think.
     
  13. PraiseBassing

    PraiseBassing Supporting Member

    Mar 6, 2017
    California
    I agree with @agedhorse, that you need to know the output level and max output level of the pedal to set your amp input sensitivity correctly. I will also add that unless you are using the Direct Out for something else, with your setup I would use it to feed the power amp.
     
  14. PraiseBassing

    PraiseBassing Supporting Member

    Mar 6, 2017
    California
    @Darkglass
     
  15. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    I don't think the direct out has sufficient level to drive a power amp.
     
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  16. Rip Van Dan

    Rip Van Dan DNA Endorsing Artist Supporting Member

    Feb 2, 2009
    Duvall, WA
    You have checked to make sure that you don't have the input pad on right?
    And you have a fresh battery in your bass right?
    And, have you tried using other cords both to the pedal and to the amp?

    Lots of simple thing that can trip you up.

    Also, if you haven't cleaned your amp in more than a year, you need to get a can of DeOxit5 (red-label can) and clean all the 1/4" plugs both input and output that your amp has (unplug your amp first of course). Real easy for a jack, especially an unused jack, to get some corrosion on it and if the signal path of the amp goes across that jack, you can get volume drop, static, pops, etc. Just spray some cleaner on a 1/4" plug and move it in and out of each jack about 10-15 times. Do that on an annual basis to keep your amp in good shape.
     
  17. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Tiny, tiny amount of DeOxit. Don't spray it into the amp.

    Just had an amp in the shop yesterday that was ruined by a way to liberal application of such cleaner (don't know what it was), amp was so slimy and nasty inside, all the pots ruined, spray got into the high voltage parts of the switchmode power supply... cost of repair exceeded the value of the amp. Would have been a $75 repair otherwise.
     
  18. PraiseBassing

    PraiseBassing Supporting Member

    Mar 6, 2017
    California
    You’re probably right. Maybe @Darkglass can give the spec for that output as well.
     
  19. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Change the battery in your active bass if it is not fresh.

    810 at 4 ohms stereo ? Just wondering how stereo? This is a Gallien-Krueger 810 RBX isn’t it?

    Setting the input sensitivity on your power amp to 0.7v means that is the RMS voltage that is required to drive the amplifier to full power. It can help if your preamp signal is low.

    I would try the balanced out on the pre into the power amp.

    It is important that the power supply of the pedal is a full 9VDC well regulated, otherwise the pre can hum.
     
    Bob Lee (QSC) likes this.
  20. somebrains

    somebrains

    Feb 7, 2017
    They probably didn't use a paper towel to block off the area, and sprayed it like ether into a carb.
    Also decided to clean everything they could see, bc I've had a couple people tell me that's their line of thinking cleaning instruments & amps.
     
  21. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
    Mar 4, 2021

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