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2pups; Master Vol BUT only 1 NON-master Tone?

Discussion in 'Pickups & Electronics [BG]' started by merseymale, Nov 30, 2019.


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  1. merseymale

    merseymale

    Oct 28, 2018
    Hi!
    Can a Pickup 1st go just to one tone control and then into a shared volume?

    I have a P/J bass with just a master volume but I’d like to dial-in(preset?) some ‘mud’ into the shrill Jazz @The Bridge to take some edge off but am only familiar with three different set ups that include master volume with a single tone and they all seem to affect both pickups

    I want the Precision/Midd pickup to be unloaded and wide open

    does anyone have any ideas?
     
  2. merseymale

    merseymale

    Oct 28, 2018
    I got the following from DiMarzio:

    “It's possible, but the tone control will affect both pickups when they are on together. That is unavoidable. The attached diagram shows the tone control assigned to the bridge pickup.

    DiMarzio Inc.”
    upload_2019-12-2_1-21-9-png.png

    ...But I can’t help thinking that a resistor placed across a pickup’s positive and negative wires would reduce just that pickup alone so a variable resistor -a pot- would too

    it follows that adding a cap to that pot would only vary that pickup’s tone, not volume, so why is it IMPOSSIBLE?

    anyone tried anything like this yet
     
  3. sikamikanico

    sikamikanico

    Mar 17, 2004
    It could work if pickups were wired in series...

    not sure about wiring in parallel, as the two controls interact, but I understand that you get some independence with a resistor in series with the pickup.

    the big question though is whether it would practically work much different from a master tone control?
     
    merseymale likes this.
  4. merseymale

    merseymale

    Oct 28, 2018
    Sure would!
    Frinstance, imagine a Jaco situation playing on the Bridge Pup with the Tone rolled off. Going to the neck pup -a darker humbucker, remember- could be mudsville

    or settin an amp to get a clear neck sound could make going to the bridge too shrill
     
  5. sikamikanico

    sikamikanico

    Mar 17, 2004
    Oh, so you’d use one or the other pickup? Then using a switch would work best, I think. You could have tone controls for each pickup, or just one...

    I thought you wanted to roll the tone down on the J pickup while running it together (simultaneously) with the P pickup...
     
    merseymale likes this.
  6. 40Hz

    40Hz Supporting Member

    You’ll still get some interaction, even with an isolation resistor. Depending on the value of the resistor, it can also alter the resonance of the circuit. So there might be some degree of tonal shift.
     
  7. walterw

    walterw Supportive Fender Commercial User

    Feb 20, 2009
    alpha-music.com
    if you're just gonna go from one pickup to the other then yeah it would totally work!

    wire the tone directly to the bridge pickup hot itself where it hits its volume pot; the tone will affect the bridge and the combined setting but not the neck by itself.
     
    merseymale likes this.
  8. merseymale

    merseymale

    Oct 28, 2018
    Ah! I see where I miss-led you SORRY

    I have a rotary switch version of the ‘tele 4way mod’ &that’s great cos it offers either pickup or both in either series or parallel. I never use a master tone -that’s what an amps for(!)- but I would like the opportunity to tame just the bridge pickup’s tone, is all
     
  9. sikamikanico

    sikamikanico

    Mar 17, 2004
    Oh, cool, you should be able to wire the tone to the bridge pickup so that it only works in the bridge pickup setting, and maybe with the two pickups in series. I’m not sure how exactly this would be wired with the switch, but essentially you’d have the tone control before the switch.
     
    merseymale likes this.
  10. merseymale

    merseymale

    Oct 28, 2018
    I do want that!
    I want 4 sounds:
    Neck pickup with Master Volume;
    Neck pickup In Parallel with bridge (that has its own Tone) &both share Volume;
    Neck pickup In Series with bridge (that has its own Tone) &both share Volume;
    Bridge Pickup (that has its own Tone) &both share Volume
     
  11. merseymale

    merseymale

    Oct 28, 2018
    Do you have a diagram to wire this please?
     
  12. sikamikanico

    sikamikanico

    Mar 17, 2004
    all but #2 are feasible, and I think you can do it with one tone pot. My theoretical knowledge ends at how to wire it exactly, but I’m sure there’s a schematic or diagram floating around that could serve as a basis.

    with a resistor, you could isolate the pickups a bit in parallel (and thus roll off treble on just the bridge pickup), but like 40hz said above, it comes with a price. But I guess you could add another switch to dis/engage the resistor, maybe via a push-pull tone pot.
     
  13. merseymale

    merseymale

    Oct 28, 2018
    Is there somewhere I could learn more about this, please?
     
  14. merseymale

    merseymale

    Oct 28, 2018
    Thanks anyway
     
  15. SteveCS

    SteveCS

    Nov 19, 2014
    Hampshire, UK
    The original stack-knob Jazz Bass had resisitors between the volume and tone pots to achieve just the separation being discussed. As it happens, the same isolation can be achieved without the resistors just by rolling back the volume knobs a bit, provided the tone controls are wired to the wipers of the volume pots...
    20191202_130505.jpg
     
    40Hz and merseymale like this.
  16. merseymale

    merseymale

    Oct 28, 2018
    I see but as I just want a less complicated single volume & tone situation, is there a wiring that could replace the resistances & capacitance, represented by the extra components in your schematic?
     
  17. 40Hz

    40Hz Supporting Member

    Best resource IMO is this book by Helmuth Lemme:

    2FE95BB2-1319-4C7C-ADE4-7D3A7F75EF09.jpeg

    It’s a deep dive into the topic that’s very readable and easy to understand even if you don’t have an electronics background. Hardly surprising in that the electronic design of a passive guitar circuit is pretty basic. It’s only with all the little details (eddy currents for example) that things can get a little complicated.

    Note: this book periodically goes out of stock from time to time. And there’s often some price gouging that goes down when that happens. Don’t fall for the claims it’s “rare” or difficult to find. If it’s out of print it’s usually back in stock within a few months. It shouldn't set you back more than $40. I ordered mine direct from the publisher. Link here.

    Another good resource is a huge book that’s free for the download titled: Cadfael’s Small Collection of Schematics-Wiring Diagrams for Passive E-Bass. A true labor of love by Andreas “Cadfael” Kühn. It’s in German, but easy enough to follow despite that. Download link here.

    Here’s an example of what to expect:

    13B78D76-146B-485D-9793-DCEDC99D88B7.png
     
    Last edited: Dec 2, 2019
    merseymale likes this.
  18. merseymale

    merseymale

    Oct 28, 2018
    Hmmm... well, if it contains a wiring diagram for what I need then it’ll be worth it! Thanks for your trouble:bassist:
     
  19. merseymale

    merseymale

    Oct 28, 2018
    Perhaps the loading effect of a volume pot(would a trimmer be similar?) on a pickup would ‘dull the tone’ somewhat?

    If I were to crank the Bridge pick up physically closer to the strings and there is a volume control on that pickup, then perhaps that could do the trick!

    Will an individual volume for the bridge pickup also going into a master volume cause any problems that you can see?

    thanks in advance for your thoughts
     
  20. SteveCS

    SteveCS

    Nov 19, 2014
    Hampshire, UK
    I'm struggling a bit with your requirements to 1) have the P wide open and 2) to dial in the P to add 'mud' to the J. I think with just 2 knobs this will be difficult - how to dial in something that is wide open? Are you planning a selector switch?
     
  21. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
    Dec 5, 2020

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