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HELP...need diagnosis of bad noises

Discussion in 'Amps and Cabs [BG]' started by adouglas, Nov 2, 2003.


  1. adouglas

    adouglas

    Jun 23, 2003
    Bridgeport, CT
    I dramatically upgraded my rig a few months ago.

    Suddenly, I'm getting wierd noises at random.

    The noise sounds EXACTLY like wind blowing across an open microphone. Not crackling. Not popping. It's that blustery sound.

    If I yank the cord out of the bass it vanishes.

    I seem (SEEM) to be able to induce it by rotating the pots on the bass, but this is not reliable. And I get the noise from time to time even if I don't touch anything at all.

    I've ruled out cable noise by swapping cables.

    I suspect dirty pots in the tone section of the bass, but a dirty pot doesn't make any noise if you don't touch it, right?

    Here's the rig:

    -1997 Carvin LB75A
    -1991 SWR Grand Prix preamp, probably with the original tube
    -Unknown vintage Stewart 1.2
    -New Avatar B212

    Could this possibly be a preamp tube crapping out? Or is it more likely a dirty tone pot on my bass? I suspect a dirty pot on the bass, but it doesn't have the staticy, crackly sound that you'd expect from a dirty pot.

    HELP! HELP!
     
  2. Toasted

    Toasted

    May 26, 2003
    Leeds, UK
    sounds like a blown speaker or horn to me

    thats the sound ashdown was making and i mailed and and they sent me a new one. sorted in 5 mins
     
  3. Try changing your battery and cleaning the pots (if applicable). Visually inspect the wiring and solder joints for any noticable problems as well.:D
     
  4. adouglas

    adouglas

    Jun 23, 2003
    Bridgeport, CT
    Happens at random. A blown speaker would make noise all the time.
     
  5. adouglas

    adouglas

    Jun 23, 2003
    Bridgeport, CT
    ...this is an intermittent problem, not a constant one.

    A blown component would make noise continuously, right?

    i.e. a bad battery would not cause an intermittent problem, it would cause a continuous problem. Ditto a blown speaker (I really doubt the blown speaker, since the cab is brand new and has not been abused).

    Last time I looked at the solder joints (about a month ago) all seemed okay.

    I favor the dirty pot but am not certain because the noise is intermittent. A dirty pot makes noise consistently, right?
     
  6. I posted what I did because I had a similar problem and that is what it turned out to be (the battery). I spent a lot of money figuring that out. I bought an entirely new rig ($3000) and still had the problem (imagine my embarrasment). I finally took the bass to a luthier. After switching out both PUs (EMG's) and all the wiring, pots, etc... We changed the battery and the sound went away. Keep in mind this was a fairly new battery (a week old?) and my problem was intermitten as well. So take it for what it's worth. Just thought I'd see if I could save you a lot of headaches.:D
     
  7. adouglas

    adouglas

    Jun 23, 2003
    Bridgeport, CT
    the battery's fresh, but I'll change it anyway.

    What's the next-most-probable thing?
     
  8. Clean the pots, inspect the wiring, solder joints, etc...
     
  9. notanaggie

    notanaggie Guest

    Sep 30, 2003
    A noisy part in the active circuits of the bass is a very possible cause.

    Sometimes they are quiet for a long time and then make noise for a while. And it sounds just like you said.

    It might be a bad solder joint, that is possible, something that needs to be re-soldered, but isn't rattly-type loose, just not a good connection.

    A last possibility, since in some places its getting colder, is some form of static electricity issue. Mostly that goves sparks and sharp pops, but it can also make the noise you describe.

    If the bass does it when sitting on a chair and you havent moved it for 5 min, I'd quit worrying about staic though, and start thinking about the other possible causes.
     
  10. 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
    You said the noise vanishes when you unplug the bass. That's a very big clue there!!

    I assume it's an active bass? Something's not right with its circuitry. Sure, try a new battery to see if that helps, but I suspect there's something more to it than that, like a bad component or a circuit defect.
     
  11. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA
    Yep, that could typically be caused by a bad part in the onboard preamp. Do you have an active/passive switch on your bass?
     
  12. Toasted

    Toasted

    May 26, 2003
    Leeds, UK
    its got all the sympoms of when i blew my horn. . .
     
  13. MauriLii

    MauriLii

    Jan 19, 2003
    Kent, England
    I agree about the soldering issue. Often a visual inspection will reveal nothing. As a last ditch effort to repair a problem, some technicians will resolder every solder connection on a board. (I'm not saying that they necessarily apply more solder, but they will re-melt the connection to ensure that there's no problems.) Also look at the board with a magnifying glass. Once in a while there will be a hairline crack that hasn't quite broken the traces on the board, but is significant enough to cause a problem. This is quite rare, but worth looking for.

    Let us know what the problem turns out to be.
     
  14. 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
    Are you a trumpet player, too?
     
  15. Petebass

    Petebass

    Dec 22, 2002
    QLD Australia
    :)

    I'm with Bob, it sounds like a problem with the bass. Is it possible to try out the rig with another bass guitar?
     
  16. MauriLii

    MauriLii

    Jan 19, 2003
    Kent, England
    As much as I appreciate puns, I'm not touching this one with a ten foot pole. (I could go in one of about a dozen directions with this one--none of them appropriate for this forum);)