Faulty Acoustic Bass Pick-up

Discussion in 'Pickups & Electronics [BG]' started by Cochise, Feb 21, 2005.

  1. Firstly, if this is posted in the wrong forum, then I apologise

    I have a Hohner TWP600B acoustic bass which is fitted with the CPA 200 preamp, which I believe to be stock, and what I think in a piezo pickup, which looks like a thin strip of foil which sits under the one piece string saddle (which in turn pushes into the top of the bridge. Nothing at the bridge end is adjustable. My problem is that the output from the E and G string is massively higher than that from the A and D string when played through an amp. I have dismantled and reassembled the bridge as far as I can, and checked the wiring and all seems OK. I lowered the action by sanding a little from the bottom of the saddle assembly but this is flat and in contact with the piezo all along its length. I don't know if this coincided with the problem occurring as I usually only play this bass acoustically for practice, but now I'm in an acoustic duo it's a fault I need to rectify. Any advice gratefully recieved...
  2. ColonelZulu

    ColonelZulu Not Impressed By Those Who Flaunt “Authority” Supporting Member

    Apr 14, 2001
    I had a similar problem when I got my Martin. The D and G were way quieter than the E and A. Luckily, I live a few blocks from the plant. I took it back and they diagnosed that the bridge slot wasn't routed properly. They took a small sanding tool and opened it up a few microns. This allowed the bridge to float better and make solid contact with the transducer (thin metal strip thingy).

    The only other possible culprit would have been an uneven face of the bottom surface of the bridge saddle. If that thing that fits into the saddle slot on top of the transducer is not making even contact with it, you can lose the signal from a string or two.

    I'd give an uneducated guess that this is your issue. Take it to a pro to make sure the bottom of this piece is completly flat.

    As in every case, confer with the manufacturer to ensure you don't screw up the warrantee.

    Good luck.
  3. DubDubs


    Aug 23, 2004
    Los Angeles
    Do you have the bass eq'd so that the highs and lows are much higher than the mids? If it's the lowest and highest strings that's a possibility. If you do try setting it more flat. The more likely problem is what ZuluFunk said but eq could be causing the problem if you have some really drastic boosts and cuts.
  4. Thanks for the input fellas. It is definately NOT an eq related problem. Things have become markedly worse since my first post. I took off the strings and removed the saddle doohickey. The base which rests on the transducer was not flat so I got some 1500 wet and dry (laid on a surface plate), and began to sand the saddle flat. At the first (very gentle) push forward on the paper the saddle broke into 3 pieces. OOPS...
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