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Troubleshooting: Hum Issues - Coming from my cab?

Discussion in 'Amps and Cabs [BG]' started by illidian, Apr 23, 2005.

  1. illidian


    Jul 2, 2004
    Finished up (for now) my rig today. :hyper:

    Got home, plugged in, and my cab is humming. :bawl:

    I've got hum that goes up exponentially when I turn up the gain on my amp or the Drive on my SABDDI. And it's not too noticeable with low gain, but it's there. Just changing to my distortion channel without touching anything there's a problem -- once again, not an issue at the store.

    It is more present on the E and A strings, on the D and G strings it isn't [as] present - pickup issues?

    Yes, I turned the tweeter off, no help. I took the grill off and don't notice anything too wrong (see pictures). Am I missing something here?

    It's not my Instrument Cable, I tried both of mine. Could be speaker cable (only have one) or my bass (once again, only have one), as well.

    At the store, the amp sounded fine. No buzz or hum (only thing that's the same is the amp head). Get home and there's a nice hum.

    Will try turning up tomorrow, but it's at a some-what constant volume from what I've tried. Turning the volume way low and the strings just vibrating from setting my bass on the stands sets off the hum, but there isn't any other noise.

    I tried taking a 9V battery to my Speaker Cable to make sure the speakers are in phase, and the speakers don't move - they just crackle. The 9V battery went dead after only a few tests (I took the grill off to make sure they weren't moving, and to take pictures). Would this happen from a bad Cable, a bad battery, or a bad cabinet?

    I think I'm done... for now. Suggest something and I'll either try it tonight or tomorrow, I want to get this fixed.
  2. big evil robot

    big evil robot Supporting Member

    Feb 27, 2005
    Edmonton, AB, Canada
    do you have a power conditioner or are you running straight from the wall socket?
    it could just be a grounding issue.
  3. illidian


    Jul 2, 2004
    Straight from the wall socket. Don't own a Power Conditioner.

    Should I try other outlets around the house?
  4. Steve


    Aug 10, 2001
    speaker cabinets don't hum.

    You can get kind of a distorted fuzz from a rubbing voice coil...you can get vibration noises from loose parts....but if you have a "Hum" it's elswere.

    More than likely...most of the time...probably...IMHO.
  5. illidian


    Jul 2, 2004
    Have any suggestions?

    If it is vibration, it's low-pitched (or maybe because it's combined with the lower notes) vibration. Definately more like a hum, though.

    Speaker cone pictures are much too large (1.5 meg or so each, two cones).
  6. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    Hum would come from the amp or the bass or both and is 99% of the time caused by environmental problems. See if it hums with nothing plugged into it, then add the bass. If the hum is not there with the bass unplugged but is there when it is chances are something in your house is the cause. Don't run out and waste money on a power conditioner, most of them don't do anything. Try the rig somewhere else; if there's no problem the source is in your house, quite likely improper A/C wiring.
  7. Perfect-Tommy


    Mar 28, 2004
    Not really at home with problems like this, but could it be a shielding issue with the bass? I have a bass that will buzz/hum unless I am touching something metal on it. So if my hand is on the strings, the knobs, tunning pegs or bridge... it's fine.... :p
  8. illidian


    Jul 2, 2004
    Thanks, Bill. Nothing like the true facts, is there?

    If the problem is with my house, will it work from other jacks located throughout the house, and there's simply a bad wiring (or two)?

    Will try plugging it in somewhere else tomorrw.

    By the way, the "no bass plugged in" didn't work. The amp has a slight constant hum (near silent operation), but nothing that was coming through the speakers. Standing back a foot, I couldn't hear it.

    Could phasing be the culprit?
  9. illidian


    Jul 2, 2004
    I was thinking of that possibility as well. However, I've never had the problem until now. Maybe my current cab is simply able to reproduce the sound, whereas others couldn't?

    And would shielding be more prominant with the lower strings, rather than being constant?

    Oh, and it shouldn't be anything with the head. It was fine at the store (it was the only one they had in stock, and they unpacked it right in front of me) and no one else has played it, yet.
  10. Perfect-Tommy


    Mar 28, 2004
    In my experience the humming is a constant unless you ground it by touching something metal on the bass.

    Here's a simple thing to check before you go all crazy looking for the problem. Change the cable you're running from your head to cab. It could be something as simple as picking up interference via radio waves. I spent an hour setting up a PA system one night switching out cables between items because we were picking up the local college radio station. On the best cables, we picked up nothing. On the decent ones, we got a hum. On the Sax players, we got softball scores....
  11. illidian


    Jul 2, 2004
    I don't have another speaker cable.

    Maybe running an instrument cable for such a short period of time would not cause a problem?
  12. Plain Old Me

    Plain Old Me

    Dec 14, 2004
    Just for a minute to test the hum. It shouldn't hurt the amp so long as you aren't running it too high and only for a minute.
  13. illidian


    Jul 2, 2004
    No help.

    Not the cables.
  14. Trevorus


    Oct 18, 2002
    Urbana, IL
    What kind of amp do you have? Also, if you run the sabddi with a power supply, that can sometimes add noise as well.
  15. illidian


    Jul 2, 2004
    It's a GK Backline 600.

    And I was running my Sansamp with the only 9V battery left in the house, which is mostly dead from testing the phasing of my speakers (as per original post, last paragraph).
  16. Selta


    Feb 6, 2002
    Pacific Northwet
    Total fanboi of: Fractal Audio, AudiKinesis Cabs, Dingwall basses
    Step way back to the basics. Unplug everything that is in your signal chain except for your bass, pre and power amp. Turn it on and volume up, see if you have your hum. If you do, then it's from your pre/power or your bass. If you don't, it's something else. Add one component at a time until the humming returns, and then you'll have your solution. That is to say, that it's a grounding issue that's not from your house. If you do this, and find no fault in anything of your setup, THEN take your gear to a friends house and re-do this process. Eventually somewhere you will find a fault.

  17. illidian


    Jul 2, 2004
    Going bass -> Head -> Cab, the hum is still there.

    The only thing I'm adding is my Sansamp.

    If this is a grounding issue, could another outlet be the solution? May jam with a drummer tomorrow if I can fix this issue. If not, then I still may take my stuff over and we may jam anyway (even with a hum, will try at higher volume levels tomorrow).
  18. Tritone

    Tritone Supporting Member

    Jan 24, 2002
    Santee, America
  19. illidian


    Jul 2, 2004
  20. Selta


    Feb 6, 2002
    Pacific Northwet
    Total fanboi of: Fractal Audio, AudiKinesis Cabs, Dingwall basses
    It could be solution. If possible, try going to a complelty different area of the house and plug in and try it out. I kind of doubt that's the problem here... how old is the head? Does anything make the humming *stop*? You may have a bad ground in the head... happened in my Acoustic once.