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Bartolini MK2 preamp popping?

Discussion in 'Pickups & Electronics [BG]' started by lossfizzle, Dec 2, 2018.

  1. lossfizzle


    Jul 8, 2013
    Hey all. Got an Ibanez BTB575FM this weekend - normally wouldn't be my style, but it was part of a mutually fair / beneficial trade and I've never had such a beast, so I thought "what the heck." I like the bass more than I expected to like it, and am actually very pleasantly surprised with the sound of the Bartolini MK2 setup installed, but I am getting an occasional series of little DC pops from the preamp at idle. Waveform zoom attached, and a brief direct-captured FLAC file typifying the troublez can be heard / downloaded here.

    The amplitude of the little pops seems to increase with a bump up on the board's low EQ, and they don't seem to start until the bass has been plugged in for a few minutes.

    For those who have a much greater mastery of electronics theory than myself, what are some things I might look for when I finally pull the preamp board?

    Attached Files:

  2. Usually, problems with onboard preamps are due to faulty electromechanical parts; jacks, battery snaps, pots, switches. So I would definitely check all these out, especially the battery snap and jack because if the power supply is intermittently cutting in and out, you'll get large pops like this.

    If you still have a problem, I'd start to trouble shoot the circuit (if you have access to it). Use a magnifying glass to look over the board for dry solder joints. Check the electrolytic caps on the power rails. There's more you can do, but this is a good start.

    I have to warn you that even for experienced electronics guys, finding the source of intermittent pops and crackles can sometimes be difficult and frustrating. Best of luck mate, and keep us informed...
    lossfizzle likes this.
  3. lossfizzle


    Jul 8, 2013
    Right, I should have mentioned that I've scaled up / normalized the pops so they're more visible / audible in the file. They're actually not all that loud, which doesn't necessarily rule out the power supply cutting in and out, which is what it looks like to even a n00b like me. The FLAC file starts out with a couple of open strings played very quietly, interrupted by a couple of these as they just begin to kick in, and those are by far the loudest pops I captured.

    I know this could be a real fun time, and ultimately I may just end up buying another preamp board. Unfortunately I already know well enough from vast past experience not to take it to any of my local "professional" techs unless I want to be without the bass for a year, pay 3x the cost of a replacement board, and probably still end up with the same symptoms on return. :( I will advise as the plot thickens, thanks for the moral support!

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