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Problem with Carvin tone controls - need help

Discussion in 'Hardware, Setup & Repair [BG]' started by BassDudeSA, Oct 21, 2007.

  1. Hi guys. I recently bought a beautiful Carvin LB70P bass on Ebay. Mint condition, great price, great sound, everything is perfect except for two tone controls. The seller mentioned that the midrange knob was hard to turn. Oh yeah, you can turn it, but it takes alot of finger strength to do it, but it still works fine other than that. However, the seller did not mention that the treble knob was totally stripped. It turns all the way around without stopping and will short out and crackle during part of the turn. The treble EQ does not work well either. But if I set it to the right spot, it works fine and will not short out, but I'm not able to adjust it after that. My treble is basically shot.

    Question: Do I need a new Carvin preamp, or can I have a local guitar tech just replace the pots/posts or some other simple fix? I don't mind paying to replace the pots and for an adjustment, I just don't want to buy and pay to install a new preamp. Thanks.
  2. sunbeast

    sunbeast Supporting Member

    Jul 19, 2006
    Los Angeles, CA
    I'm fairly sure the pots are soldered directly onto the preamp board for Carvin preamps- I would try to return it to the seller!

  3. Would a tech that knows how to solder be able to change it out? I will call and ask eventually, I just wanted to get some opinions here first. I bought the bass for about $625 including shipping, new case, plenty of Carvin upgrades and a mint bass otherwise, with one of the nicest quilted Maple finishes I've ever seen, so I'll keep it, despite the problem.
  4. 202dy

    202dy Supporting Member

    Sep 26, 2006
    The pot that is hard to turn may be able to be repaired with a simple cleaning. The treble pot may respond to a cleaning or not. From your description is likely that the carbon trace is either dirty or worn. The pot that is rotating 360 degrees is probably shot.

    If it is a matter of swapping parts, any good tech will be able to handle the problem.
  5. Thanks, that is a possibility, but my Carvin has the piezo which makes it a six knobber, it looks as if there are only five knobs on these preamps that they are selling. If it comes to this I guess I'll just have to call Carvin on that.
  6. Yes, call them, I am certain that you can buy replacement parts from them. Just because it's not shown on their website doesn't mean you can't get it.

    By the way, don't rely on email for service from them. While their service is excellent, they're definitely phone-oriented. Their email communication is not good.
  7. Thanks, yeah I will call Carvin, and I'll ask THEM if the pots can be changed without a new preamp, but looking at that preamp picture, it looks as if it is all connected. I may have to go the new preamp route. Oh well, if that is the case at least I'll still have made out pretty good. REALLY nice this Carvin. But the two bad pots do really bug me.
  8. Mystic Michael

    Mystic Michael Hip No Ties

    Apr 1, 2004
    New York, NY
    As nice as it may sound to you right now, you may be very surprised with how better it sounds once you upgrade to a quality aftermarket preamp. Buying that bass with a busted stock preamp may turn out to be the best thing that could have happened for you... :meh:

  9. bowthing


    Feb 16, 2007
    I built a Carvin kit, and you can definitely replace the pots, but it is not easy, you need to remove ALL of the solder from the terminals to get the pots off, and it is very easy to pull the pads off of the circuit board. It is also hard to find pots that are exactly the same, since they have to line up machanically with the others on the board.

    I replaced the blend pot on my 501 preamp with one I like a lot better, but other that that, I highly recommend the Carvin preamp, and would either buy a new one or replace the pots. I have tried Bartolini, Audere, and Delano pre-amps in this bass and I am back to the Carvin for its simplicity (very clean - few wires!), EQ settings, and passive mode on the volume knob. It is also BY FAR the quietest preamp of any of these. It is dead quiet and sounds really good.