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Vintage Fender bass: Remote battery box for active pick ups?

Discussion in 'Pickups & Electronics [BG]' started by WayneP, Apr 20, 2010.

  1. Hi everyone,

    Here’s the situation: I went to see a good buddy’s band the other night and spent some time chatting with his bass player. Ron has a nice late 70s Fender Precision. A previous owner added an active pre amp to the bass. Ron considered taking it out, but was advised by the owner of a local guitar shop that the active electronics are a big improvement over stock – cleaner signal, less prone to picking up noise from fluorescent lights, etc. – and he should leave them in.

    The problem is, the only way to get to the battery when it goes dead it is to remove the entire pick guard. Naturally, installing an easy-access rear battery compartment is out of the question, as this would devalue this vintage bass. Well - as we all know, there’s only so many times you can unscrew and re-screw those little pick-guard wood screws before they start stripping out.

    So – I had the bright idea (or maybe not so bright – you decide) of rigging up a remote box for the battery, that would connect between the guitar and amp. Take a look at the wiring diagram below and tell me what you think.

    Basically, I envision replacing the guitar’s stock TS input jack with a three-conductor TRS jack. The extra lead would carry the battery’s (+) voltage, and the battery’s (-) would piggyback on the audio signal (-). A standard TS guitar cable would go between the battery box and the amp.

    I originally figured on using a cable with TRS plugs on both ends between the guitar and the battery box, but I think it would be better to go with a cable with TRS plug for the guitar end, and XLR on the battery box end. This would give completely different and physically non-compatible plugs on the battery box, and eliminate the chance that someone might plug a regular TS guitar cable into the TRS jack and short out the battery, or even worse, plug it into the amp and blow out its input.

    Any thoughts or ideas are appreciated!


    Wayne A. Pflughaupt

    Pedulla Club #45


    Attached Files:

  2. SpamBot


    Dec 25, 2008
    St. Paul, MN
    This seems like a lot of effort for a little gain. Firstly, with a compact enough electronics system, a battery can be installed under the bass' control plate. This makes for a very easy battery change.

    Secondly, many pres are designed with such low current draw that you need to replace batteries so rarely it's not significant. The original Music Man preamp, for example. A single 9 volt in one of those puppies can last years.

    Thirdly, the wood of the three screw holes that attach the plate to the bass is so easily replaced with the common wood-glue-plus-matchsticks method that it's simply nothing to worry about, especially compounded with a low-draw pre.
  3. gumtown


    May 7, 2007
    New Zealand
    I would remove the preamp from the bass and try it passive.
    you could remove the preamp, make the bass original, and place the preamp in the box with the battery, and use it as an 'in-line' preamp.
    leave it as is.. the battery should last at least a year or two, if you don't go leaving a lead plugged into it all the time it is not in use.
  4. Wow, looks like someone beat me to the punch. So much for marketing my brilliant idea, making a million and retiring early!

    I still like my idea of using an XLR for the powered end of the battery box, though. It could be bad news if someone plugged a cable into that jack and dumped 9 volts into the guitar amp’s input.

    Wayne A. Pflughaupt

    Pedulla Club #45


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