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How Do You "Stack" a Single Coil Pickup?

Discussion in 'Pickups & Electronics [BG]' started by CheshireCatFun, May 15, 2013.

  1. CheshireCatFun

    CheshireCatFun

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    I've seen so many complicated diagrams and whatnot, with very little info on how to go about making a stacked pickup, only to then run across vids like this, that make it look easy (tho, in this case, there's precious little explained).



    C.
  2. bassbenj

    bassbenj

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    Whats to explain? You wind the two coils (same number of turns) you solder the wires to the eyelets. You dip the thing in melted wax (wait for all air bubbles to come out) and that's it. Nice video!
  3. Bruce Johnson

    Bruce Johnson

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    Well, building pickups is a hobby/craft/art form of its own, which requires a small book to thoroughly explain. The Music Electronics Forum/Pickup Makers Sub-Forum is the best online resource that I've seen: http://music-electronics-forum.com/f11/

    But to specifically answer your question, the term "stacked single-coil pickup" is misleading. It usually refers to a humbucking pickup, which has two coils, which is built to fit into the form or shape of a standard single-coil pickup (usually a Jazz Bass pickup). To make it fit, the two coils are low in height and stacked on top of each other. To make them operate as a humbucking pair, the two coils are wound or connected up so that the current flows in the opposite directions through them. Pickup builders have different ways of putting together the coils and magnets. But the overall point of a Stacked Single-Coil pickup is to make a quiet humbucking version of a single coil pickup, that is the same size and approximately the same sound.
  4. CheshireCatFun

    CheshireCatFun

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    First, thank you for your excellent response.

    Second, can two opposing coils go around the same set of pole pieces like in that vid, without cancelling each other out?

    C.
  5. Bruce Johnson

    Bruce Johnson

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    I haven't made any stacked pickups myself, but if I understand them correctly, the magnets go all the way through the two coils. So, the North ends are in one coil, and the South ends are in the other. You have opposite coils, opposite magnets, in the standard humbucker formula. But there may be other configurations used by pickup builders. Ask David Schwab over on the pickups forum.
  6. walterw

    walterw Supportive Fender Gold Supporting Member

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    stacked coils do tend to cancel each other out a little bit; stacked pickups are as a result weaker and lower output than similar singles.

    (if you wire a stacked pickup to disconnect the bottom coil, the pickup gets louder and frankly better sounding, just with single coil hum.)
  7. CheshireCatFun

    CheshireCatFun

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    Paging Dr. Schwab . . . Dr. David Schwab . . .

    C.
  8. line6man

    line6man

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    Whenever you have equal amplitudes at 180 degree phase differences, there is destructive interference of waves. The idea with huncancelling pickups is to reverse-wind the coils, but then also swap the electric polarity, so as to put hum induced in the coils out of phase, but leave the signals transduced from the disturbances in the magnetic field, as the strings vibrate, in phase. If the electric polarity is swapped, you will cancel the signal, and end up with a very weak, "notched" output. The fix, obviously, is to flip the leads so that the two coils are back in phase, relative to the signals.
  9. Stealth

    Stealth Supporting Member

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    This is the best image I could find that explains the concept.

    [​IMG]

    Basically, the top coil is magnetized using standard magnets. The bottom coil has only ferrite cores which aren't magnetized, but are used to bump up the inductance that is mostly responsible for noise collection. The magnetic field doesn't permeate the bottom coil due to a metallic plate between the two coils, and the fact the bottom coil is further away from the strings ensures it collects most of the noise and nearly none of the signal. After it's connected in counter-phase to the top coil, it helps reject the hum both coils are sensing. Note that it can be wired in series or parallel to the top coil - in both cases it will hum-cancel equally well, however, the tone will change, for better or worse, because you still have two coils connected.
  10. khutch

    khutch Praise Harp Supporting Member

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    I've heard this explanation a lot but it does not work magnetically. If the magnets go all the way through both coils then both coils are magnetically polarized the same way and the string signals generated by the two coils, like the external hum signals they both pick up, will be out of phase because the coils are wound oppositely. You won't get complete string signal cancellation because of magnetic leakage but I have to think the designs (like the one pictured in the post just above) which make some attempt to separate the bottom coil from the magnetic bias in the top coil will work much better.

    On paper at least the split coil designs look best to me. One of these days I am going to have to try some and see if they make any real difference. I have some split coil Barts in my passive five string and they sound great but my two stacked coil basses are also active and all three have very different strings so it is hard to compare the pickups in them. I don't really have any complaints about the sound of the Fender MIM dual coil pickups in them. I also have a passive single coil fretless that wants to have some kind of hum canceling pickups so that would be a good vehicle to use to compare with one of the other basses since I wouldn't be wasting any money if I put hum canceling pickups in it.

    Ken
  11. Stealth

    Stealth Supporting Member

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    In theory, the sidewinder design is the best; you get the magnetic aperture of a single-coil with a humbucking design.
  12. Bruce Johnson

    Bruce Johnson

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    I agree; that's why I've never played around with the stacked design. It's got inherent problems. All of the pickups that I build for my basses are side-by-side pairs or quads, identical dimensions and opposite winding and magnetic polarity. Simple and effective.
  13. CheshireCatFun

    CheshireCatFun

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    Siderwinding . . . that's what the Lace Holy Grail design is based on, and I've seen other pickup designs use that principle.

    What do you all think of that particular approach?

    C.
  14. walterw

    walterw Supportive Fender Gold Supporting Member

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    This isn't just any ol' stack, this is the breakthrough "virtual vintage" design from dimarzio, which largely solves the tone loss problem of typical stacks. (Their "virtual" and "area" stack pickups are as a result head-and-shoulders louder and more authentic-sounding than typical stacks.)

    I don't know of any bass pickups done this way, including from dimarzio, perhaps because dimarzio's split-coil designs do so well they see no need.
  15. Stealth

    Stealth Supporting Member

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    I'd say it's become a brilliant solution for the task it wasn't made to do made - making a humbucking pickup with the aperture of a singlecoil. Originally, I'd saz the design was insane enough to work - the EB-0 neck pickup is by far the hottest, fattest pickup ever. :D

    I didn't know these were Virtual Vintages. Thanks for pointing it out. I assume the difference is in the wire gauge used in each of the coils as well as the insulating element between them?
  16. walterw

    walterw Supportive Fender Gold Supporting Member

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    the main idea is a bottom coil with way less wire than the top coil (so as to reduce its tonal cost) but with the iron core to "boost" its hum back up enough to cancel the hum of the stronger top coil. (more wraps usually = more hum.)

    measure a typical V-V strat pickup and you get something like 6kΩ for the top coil and 1.5kΩ for the bottom coil.

    this is as opposed to "regular" stacks like the duncan or fender stuff, or even old-school dimarzios like their "HS" series: a dimarzio HS-3 has like 25kΩ worth of wire wrapped on it, but with so much cancellation that it's actually weaker output than a regular 6K single coil strat pickup.

    (also, V-V design pickups can't be wired parallel, because of the exceptionally low-wind bottom coil; it would essentially short out the top coil, leaving very little output.)
  17. Stealth

    Stealth Supporting Member

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    Very interesting bits of info. Thanks for the explanation. Now that you mention the actual resistances, I can see why a parallel coil wiring wouldn't go over well.
  18. CheshireCatFun

    CheshireCatFun

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    Well, we all know how a standard single coil is designed, i.e. naked pole pieces wound in copper coil; and humbuckers, i.e. slugs and screws in bobbins, pulling different poles from the same bar magnet, each wound opposing each other, and so on.

    Has there ever been any kind of basic, standard "single coil stack" design that we can refer to, or is it just catch as catch can?

    C.
  19. walterw

    walterw Supportive Fender Gold Supporting Member

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    every company does their own take on it.

    if it has one coil on top of another coil, it's a "stack"; that about it.
  20. SGD Lutherie

    SGD Lutherie Supporting Member

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    Bruce and Walter answered the question just fine. :)

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