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Replacing 500k pots with 250k pots on a Jazz

Discussion in 'Pickups & Electronics [BG]' started by dabshire, Mar 4, 2004.


  1. dabshire

    dabshire

    Dec 15, 2002
    McKinney, TX
    All,

    I have a Lakland Skyline Darryl Jones Jazz bass. I love everything about this bass, but to me the overall tone is just a bit too bright. I was poking around inside tonight, and I noticed the pots seem to be 500k pots (they say "500A" on them)

    Here is the question. If I change the pots to 250k pots, the sound (from what I understand) should get darker (warmer), correct?

    The bass controls are set up like a 75 Jazz (vol/vol/tone).

    Should I replace both pots with 250k pots, or can I just replace one, and what would the difference be (if I mixed them vs if I did both)

    Thanks,

    Don
     
  2. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    Don-O,

    I've swapped pots every which way except linear and audio, and couldn't tell the difference - until yesterday. And I've seen several factory harnesses (including EMG) that use an audio pot for tone, except with a capacitor added. You should be able to tell the difference between a linear and audio volume control tho. After all, it's why they make them different to begin with.

    But yesterday I took a Bart NTMB preamp I had laying about and converted it to an outboard. But I was short a linear 50k pot. What I had was 500s. So, given my experience, I plunked that puppy into the Treble (duh) tone of the harness and fired up. Well, it was like the treble was either on or off. So I swapped the treble and mid wiring. Now the mids were on or off. So it was definitely the pot. Granted 50 to 500 may seem extreme but I've swapped 25k audio and 250 audio and couldn't tell the difference - maybe even 500, don't recall.

    So, I'm guessing you won't be able to tell the difference - but you might. If I were going to do it (which I probably wouldn't), I'd probably try one and see what happened - depending on how accessible the harness is. If you've got to jerk the entire guts out, I'd do them both. Just remember if you haven't done much of this stuff, you may be in for some unexpected grief.
     
  3. Passinwind

    Passinwind I Know Nothing Supporting Member

    Should I replace both pots with 250k pots, or can I just replace one, and what would the difference be (if I mixed them vs if I did both)

    If you do only one, you're going to get some different than expected interaction at less than full-up settings, for starters. At full-up, you will probably lose some noise cancellation compared to equal values, as well. You might get max noise cancellation at some more desirable pickup mix though, so that could be a good thing.

    Instead of going straight down to 250K, you can also solder some different value resistors across your 500K pots (try the various permutations for yourself: top lug to ground, top to wiper, wiper to ground), and play with a range of different effective values. For example, a 1 meg resistor in parallel with your 500K pot will give you a 333K pot, effectively. You will change the taper characteristics of your controls this way too, which you may or may not enjoy. You could wire small trim pots this way, and dial in exactly the balance that you like. Measure the trim pot, substitute a resistor for long term reliability; voila, a custom pot value.

    My experience with doing downward swaps is that you often lose brightness along with tightness and damping of your low end, but I'd recommend that you try it out for yourself. The tone control doesn't have to be the same value as the volumes either, necessarily. If it sounds good to you, it is good.

    You can spend many hours dweebing with this stuff. Be sure to test things in the context of a band, or how the bass sits in a mix. Too bright is often just right, if you know what I mean. BTW, what's wrong with turning down your tone control?


    --Charlie Escher
     
  4. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    BTW, what's wrong with turning down your tone control?


    --Charlie Escher

    Ah man, there it is again. The obvious.

    That's right dude, you're wanting less, not more.

    =================

    And exactly how much dirt is a 3'x3'x3' hole?
     
  5. Quick question...

    Would this be the same for a balance pot? I'm not sure what I have in my fretless right now...I believe 250K's for vol/vol and maybe a 500k for tone?

    I was thinking of wiring it to be vol/blend/tone with a Bartolini TC5 Gain Boost Preamp... any thoughts?