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Vol./Vol. => Vol./Blend

Discussion in 'Pickups & Electronics [BG]' started by KumoriNeko, Sep 5, 2001.

  1. KumoriNeko

    KumoriNeko Guest

    Mar 27, 2001
    Cincinnati, Ohio, USA
    I'm not sure if this should go in "Pickups", it's more of an electronics question.

    Is it possible to rewire my Jazz Bass so their is a single volume knob and a pickup blend knob (instead of 2 volume)? If anyone knows of any diagrams etc, it would be much appreciated. Also would this affect the output of the bass volume-wise?
  2. NioeZero


    Sep 2, 2001
    Good question... I'm looking for the same thing, and its been a pain in the arse to find.

  3. steinbergerxp2

    steinbergerxp2 Guest

    Jul 11, 2001
    I think this usually isn't recommended because it does reduce the output somewhat.

    In a "best case" scenario, both pickups will have 1/2 their signal dumped to ground and so you get half volume (or less).

    -then you add a volume control so you can reduce it further.
  4. SuperDuck


    Sep 26, 2000
    It is possible, and pretty easy, no less. I have a diagram in one of my books, but I'm not sure if I brought it to school with me. I'll check when I get back to my dorm room. If I did, I'll scan it in and make it an attachment.
  5. I think active basses have pan knobs, and passive basses have 2 volume knobs. That seems to be the case in an multi-pickuped bass I've seen.
  6. I have had some success with using a "double" pot. Its basically 2 stacked volume pots that are opposed to each other with the center detent being full for both. its very similar to the way most active circuts pan pots work.
  7. bholder

    bholder Affable Sociopath Supporting Member

    Sep 2, 2001
    central NY state
    Received a gift from Sire* (see sig)
    Check the Bartolini, EMG, and stewmac sites, I found some good diagrams on each of them. You can use a blend knob with either active or passive, but it is typically used with active setups for the very reason mentioned - used with passives, you're losing a good part of your signal strength (not a problem with active, since everything's preamped anyway). Unless of course you do something really funky with a special kind of odd taper pots, you can't get both passive pickups full on, the best you can do is half of each. Somebody might make the kind of pot you'd need to do it right with passives, but I don't think I've never seen or heard of it. I can figure out what they'd have to be like - they'd have to be stacked pots on the same shaft, with one pot increasing resistance from 0 to max up to the halfway point, then staying at max for the other half, and the other doing the reverse - staying at max for the first half, then decreasing to zero in the second half - all with the correct tapers (and a center detent would help) - but finding one is something else again. If anyone knows of a place that carries them, please post the info!
  8. bholder

    bholder Affable Sociopath Supporting Member

    Sep 2, 2001
    central NY state
    Received a gift from Sire* (see sig)
    Either I'm a moron, or it was late and I'd been drinking when I browsed the Stewart-MacDonald site. That's probably where I got the idea in the first place, duh. Of course, they have the exact item I was talking about - check out:


    Check out the bottom item - 3478 - I assume they got the taper right. (Note that audio taper on the type of blend pot used on actives will probably have a slightly different curve, being across the whole range, where I assume these are audio taper of one signal on each half of the rotation, while the other signal stays at full volume, which would yield a different curve than the other, but I'd guess they're equally usable and easy to get used to.)
  9. Do you know if Fender has ever adopted this scheme? I'm sure the Fender guys on here will know but I'm affraid I don't.

    If it has, the wiring diagram will almost certainly be found at:-


    This is a site that deals with the techy side of Fenders and its other guitars and basses.

    There was a thread on TB a couple of months ago that, as I remember, dealt with this issue or something very similar. A search might reveal something.

  10. bholder

    bholder Affable Sociopath Supporting Member

    Sep 2, 2001
    central NY state
    Received a gift from Sire* (see sig)
    I did realize one other thing about the passive blend pots vs. the active - with the actives, the overall volume stays relatively constant as the blend is moved, with the passive blend, that's not true, the overall volume changes as you change the blend. For whatever that's worth.
  11. brianrost

    brianrost Gold Supporting Member

    Apr 26, 2000
    Boston, Taxachusetts
    You can get even blending in a passive system but you need a special (expensive) blend pot.

    Many basses have this feature: Carvins, Laklands, Peavey Palaedium , Dean Berlin, etc.
  12. bholder

    bholder Affable Sociopath Supporting Member

    Sep 2, 2001
    central NY state
    Received a gift from Sire* (see sig)
    Ok, then, maybe it's possible, but someone explain to me how you can have both pots on full in the middle and still have even volume across the whole range - at the middle position, you're getting the full signal of both pickups, at either end, you're getting the full signal from one and nothing for the other (or roughly half of the overall signal strength at the center position). Or maybe do they run the resultant signal through an oddly tapered pot on the same shaft in serial with the first to flatten the volume? But the only way to do that with passives would be to cut the center to half volume, stealing half of your overall output. Just no way to do volume flat blend panning without a preamp, I just don't see how it's possible (but willing to learn, if it really is).
  13. mikezimmerman

    mikezimmerman Supporting Member

    Apr 29, 2001
    Omaha, Nebraska
    How is this different from what happens with two volume controls, rather than a blend? If you have both pickups on full, then cut out some of the bridge pickup (for instance), the tone changes, but the volume doesn't change significantly.

    No, I don't know why that is--for some reason, it didn't occur to me to wonder until now. ;-) But it has nothing to do with having a blend control vs. two volume conrols.

  14. bholder

    bholder Affable Sociopath Supporting Member

    Sep 2, 2001
    central NY state
    Received a gift from Sire* (see sig)
    I was wondering about that too, I bet the volume DOES change, but maybe not enough for it to register to the ear? It'd certainly be noticeable if you backed it all the way off (or set the blend all the way to one side vs in the middle).

    Maybe it's not enough of a difference to worry about, and it certainly seems to "lose no capability" as compared to two volume knobs, but it's still not quite the same thing as the active volume - blend setup, where the volume should stay truly flat as the blend is moved (assuming both pickups have similar signal strengths).

    But maybe it doesn't matter all that much. I think I'll probably end up trying it one one of my project basses.

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