Pot switch

Discussion in 'Pickups & Electronics [BG]' started by Bassy Mark, Jan 17, 2014.


  1. Bassy Mark

    Bassy Mark

    Joined:
    Sep 28, 2013
    Location:
    Littleton, Colorado
    Before and after shots replacing the volume pots on BBN5. The OEM pots were linear taper. New ones are volume taper and much more usable for fine tuning the mix between the pickups. I considered doing one volume and a mix pot but things I read suggested that this was the best solution.

    Only posted because I'm proud of it working once re-assembled!

    Before
    [​IMG]

    After. Nice shiny solder joints!
    [​IMG]
     
  2. AlarmClock314

    AlarmClock314

    Joined:
    Mar 26, 2007
    Location:
    Southern WI
    Huh, I thought that two linear taper pots would be better for pickup blending. I do prefer linear volume pots and audio tone pots though.

    Nice wiring job.
     
  3. Bassy Mark

    Bassy Mark

    Joined:
    Sep 28, 2013
    Location:
    Littleton, Colorado
    Audio taper is what makes sense for a volume pot to our ears. Our ears don't hear things in a linear fashion.

    Nice explanation here.

    [​IMG]
     
  4. line6man

    line6man

    Joined:
    Jun 20, 2008
    Location:
    Close to Los Angeles, CA
    But we're not talking about longitudinal pressure waves here, we're talking about a volume control on the first thing in a chain of gain stages.

    And of course, the goal is not to do fades, but to get pickups to mix with each other. Pickup's don't load each other in a logarithmic fashion. It's kind of like an on/off thing to our ears.

    In any case, this is another example of why audio versus linear taper is so much of a personal preference. There is no right or wrong, it seems, because there are people that swear by both sides. I suspect the quality of the taper has a lot to do with it. Note that your graph is an ideal taper. Actual audio tapers tend to vary considerably, with the cheapest pots having a taper made up of two linear segments joined in an approximation of the logarithmic curve.
     
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  6. Bassy Mark

    Bassy Mark

    Joined:
    Sep 28, 2013
    Location:
    Littleton, Colorado
    The original pots sounded very nonlinear. Between 8 and 9 they would jump in volume, making blending the two pickups difficult. The new pots seem to have a predictable slope between 0 and 10. When I read that article that I posted, it seems to be saying that audio taper are marked with an "A", and linear with a "B". I put pots marked B500K in this bass and a guitar and they seem to be Audio taper. I'm confused with the naming scheme.
     
  7. line6man

    line6man

    Joined:
    Jun 20, 2008
    Location:
    Close to Los Angeles, CA
    A is audio and B is linear, indeed. See, you've found that linear does work better.
     
  8. Bassy Mark

    Bassy Mark

    Joined:
    Sep 28, 2013
    Location:
    Littleton, Colorado
    Then none of this seems to make sense despite my best research. Oh well, I'm happy with the way both instruments sound.
     
  9. aphexafx

    aphexafx A mind is a terrible thing. Supporting Member

    Joined:
    Dec 10, 2013
    Location:
    Denver, Colorado
    Very nice job on your solder joints. I'd like to see it more organized and less excess wire but that's just a preference.

    Congrats and enjoy the new pots! :bassist:
     
  10. RobbieK

    RobbieK

    Joined:
    Jun 14, 2003
    A curve pots aren't actually logarithmic. They are usually 2 or 3 linear sections that roughly copy a log to base 10 curve (remember high school maths?). If you bust open an A pot, sometimes you can actually the see where the different linear sections start and finish in the carbon track. And as you've found they can really jump around in audio response. Personally I use A pots for vol, but I have no problem wiring my customer's vols with linear if they request. I've even suggested it for some guys too, after hearing about their playing style and the gigs they do etc etc. A vol pot in a guitar has a very different role than that in a hi-fi or studio application. Often in a strat or something, it's more a distortion control, than a loudness control. And for us bassists, it's pretty rare we run our vol below 80% of full loudness in the real world of gigs and sessions. If you need to finely tweak this region then a linear pot is ideal as half of its rotation takes you from 90 to 100% loudness.

    Just as each stick of timber that's glued together in your guitar works together to affect its response and acoustic tone, volume pots are just one part of an electronic network and, especially in passive basses, do not work in anything even resembling isolation. The effect they have on tone in passive basses is well known, but they way they work when blending two pickups is widely misunderstood.

    Congrats on the solder job! I'd use a few cable ties to neaten up the job. They don't actually do much unless you have to anchor battery clips or something, bit it makes things look a bit more pro. ;)
     
  11. Bassy Mark

    Bassy Mark

    Joined:
    Sep 28, 2013
    Location:
    Littleton, Colorado
    Thank you for the great info and feedback. I was pleased with my soldering job and thanks for the kudos on it. With the bass working well I'm unlikely to go back into the cavity again though if I do I'll clean it up. Most of the extra wire is from the pickups. The previous owner installed them. I figure the extra may come in handy if I sell them some day.
     

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