Strange ground noises in my Carvin BB75

Discussion in 'Pickups & Electronics [BG]' started by Alvaro Martín Gómez A., Jul 14, 2005.

  1. Alvaro Martín Gómez A.

    Alvaro Martín Gómez A. TalkBass' resident Bongo + cowbell player

    Hi everybody.

    After a Bongo-induced hiatus, today I picked up my Carvin BB75 again. I wanted to record some sound clips by plugging it into my SB Audigy 2, and as soon as I connected it, I noticed a ground noise that I know it was present from some time but didn't pay attention to it until now, so used to the quietness of the Bongo. The weird thing to me is that it changes (seems louder) when I emphasize the neck pickup with the blend knob. Also changes if the position of the instrument changes (i.e. I turn with the bass on). I also noticed that the volume knob is scratchy and that the noise gets louder with full volume (not because of the full volume. It changes drastically by just turning the volume knob a little bit from full blast). I've uploaded a sound clip for you to have a better idea of the problem. You can hear the changes because I either turned the blend knob or moved with my bass on. It sounds pretty loud, but that's because I amplified the noise with my recording software.

    I appreciate your input on this, specially because I don't know a qualified guitar electronics' technician here, but maybe if I know what's causing the problem and let it know to a good tech, he/she may be able to solve it.

    Link to the audio file:

    Thank you in advance! :)
  2. luknfur


    Jan 14, 2004

    a definite if you have a scratchy pot is some pot cleaner or replacing it if that doesn't resolve it. Nothing unusual about hum becoming louder with change in position of the bass. In fact often a certain direction (and 180 degrees opposite) will eliminate the hum altogether. The hum should stop when touching strings, bridge etc. If not a meter check of the bridge and internal components and wire inspection is in order. I assume the cavity at least has shielding paint. If not, that's what I'd do next or you can just copper shield it which would be next on the list probably. Then shielding the pup cavity and running pup grounds.

    I'd also read reviews of that bass for simlar complaints or contact Carvin cause it may be inherent in the pups/pre. It's unusual the neck should be the noisier of the two. You might have to change pups or the pre to correct it.

    Battery clips and jacks are also common culprits.

    And make sure it's the bass to begin with, not amp, cord, location, etc.
  3. 90k


    May 3, 2005
    I also have had similar concerns. What i have sumissed is this.
    First the pots are have all the gain at the end of travel. the J99"s are single coil and single coil induce noise as a natural characteristic.
    If you are sitting in front fo a monitor with single coils your bassically*&^%
  4. Alvaro Martín Gómez A.

    Alvaro Martín Gómez A. TalkBass' resident Bongo + cowbell player

    I forgot to mention that the neck pickup is a J99 single coil. The bridge pup is a MM humbucker with coil splitter. Thank you for your responses, and please keep them coming. Here's a fresh link to the recording, just in case:
  5. luknfur


    Jan 14, 2004
    You can always replace the neck with a humcanceling J or stacked HB. With a dual HB setup, bart has a cool switching diagram that allows for inner singles/outer singles/dual HB operation. And you might be able to just go with half of that and wire your current neck J in with the bridge coil of the MM and in effect make the neck J a humcanceling J. Don't know, I'd have to think about it.

    At any rate, with all of the J's made, there's bound to be a quiet replacement that will get a similar tone. Usually a humbucker in single coil mode is noisy as well so I'm suprised you're not getting noise out of the MM. Basically what you have is a single J bass in that situation.

    Cleaner to the volume or replacing it altogether may alleviate the problem and needs to be done anyway so that's the first step.