Ulti-Coil Prototype - Wal-Style Pickup For Guitar

Discussion in 'Luthiery, Modifications & Customizations' started by KhzDonut, Sep 7, 2016.

  1. KhzDonut

    KhzDonut Freelance Nutjob

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    My background is 50% guitar & 50% bass, more or less. My first instrument was a bass, and shortly after had to play both for recording purposes.

    I'm a big Tool fan, and Justin Chancellor has always been a big influence as a bassist. Consequently, I have more than a passing interest in Wal Basses, Multi Coil Pickups, and Filter-based Preamps.

    My taste in guitar tones tends to run on the "dark" side, with lots of low-mid "chug" and a tight low end for the "djug" and then several other vague adjectives ;)

    Anyway, some of the qualities I've seen described by using multiple coils sounded like I could probably capitalize on a few of those qualities for guitar tones. I'm actually not 100% confident that it will fit my goal, but I have a feeling that it may work well for the technical/progressive metal acts that use a lot of tapping and articulation.

    We'll see :D

    I started out by testing to see what it's like to wind a mono-coil.

    [​IMG]


    This is a .125" steel rod as a pole piece, the coil is a little under .350" tall, and bit over .400" wide. I got 10,000 turns of 44 AWG wire on the coil.

    I'm planning on doing a taller coil and adding an insulator around the pole piece, and probably try 8-9,000 winds to start out with. Not sure yet. I also want to see if I could manage a standard .195" pole piece so I could use some off-the-shelf Alnico 5 rods.

    To start with I'm using steel rods and varying sizes of neodymium discs (mostly .25" and smaller)

    I've also got some .125" neodymium rods, but I'm anticipating them being significantly overpowered. Figured it was worth a fair test, at least.

    A more typical coil geometry seems like it would be possible given tight-enough tolerances, but for rough prototyping the taller coils will give me a larger margin of error for getting the coils perfectly placed on a fabricated backplate. All I've got to drill with at the moment is a Dremel so it's a little hard to get things perfect.

    My plan is to wire everything up like a more recent Wal, with each string being a "column" wired in series, and then each "column" wired together in parallel.

    When this is finished I'll make another one where each "row" is wired in series as a unit, and each "row" can then be wired in either series or parallel like a standard humbucker.

    (PS - Sorry if this belongs in the Pickups section. I couldn't decide which would have been more appropriate.)
     
  2. dpm

    dpm Oni Guitars Contributor

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    Interesting. I've done a little of this but haven't had time to really get into it. Steel poles are the way to go for sure if you're after good guitary humbucker kind of tone. The next thing I was going to try was a normal humbucker magnet position. In fact, that's probably the best way to refine the coil voicing - stick with a normal humbucker magnet and pole arrangement to see how the multiple small coils sound in regard to tone and output, then look at how alternative magnet arrangement effect them.
     
  3. ImBCRichBitch

    ImBCRichBitch SS.org Regular

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    Ive honestly questioned for a while now why there arent single coils for each string wound differently to optimize the sound of each note. maybe different magnets on certain strings for different harmonic response and whatnot
     
  4. kindsage

    kindsage SS.org Regular

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    What are multi-coil pickups?
     
  5. KnightroExpress

    KnightroExpress Guitar Nerd Vendor

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    This is really cool, I'm looking forward to seeing how your experiments turn out.
     
  6. KhzDonut

    KhzDonut Freelance Nutjob

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    I'm concerned about microphonics, being into high-gain amps and music, so potting is definitely something I'm intent on getting right. I don't have access to a proper vacuum chamber ($$$) so I picked up a little manually operated vacuum thingamajig for testing break lines or whatever the hell (I'm sure someone who knows about cars could explain it) It doesn't do a full vacuum (30 inches of mercury or whatever) but I thought it will probably do a good enough job for wax potting, considering that many of the tutorials I've seen don't even mention vacuums, they just say to leave the coil in the wax for a few minutes.

    [​IMG]


    I drilled a hole in the lid of a mason jar to attach the hose for the vacuum pump, and for the wax I just used some beeswax from a block I've had for the last 10 years. I know paraffin or a paraffin/beeswax mix is preferred, but I figured for testing purposes this would work fine.


    [​IMG]

    I couldn't really take a picture of the process (I'll try to get one at some point) but the results were positive. I cut through the coil after it was potted with a dremel and an abrasive/cutting wheel, and the coil was solid *almost* all the way through. At the very center of the coil it started spitting out tiny bits of wire, which indicated to me that probably the last 10-20 layers at the center of the coil didn't get full wax penetration.

    Still, I was pretty happy with the results. By reducing the amount of empty volume in the jar (by either putting in more wax or using a smaller jar) I should be able to get a better vacuum. I also thought about drilling a small pilot hole in the Forbon flatwork near the center of the coil so that there is a more direct-route for the wax to get to the center of the coil. I have a few other ideas if that fails, so I'm sure I'll figure something out :D

    Super fun project so far.
     
  7. KhzDonut

    KhzDonut Freelance Nutjob

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    Thanks for the info, and for taking a look. I'm a big fan of your work :D

    I think I'm going to try an augmented magnet placement with the first prototype, because I can't help myself but try it out, but I think you're right; at some point I need to do some more direct comparisons using a smaller number of changed variables.


    I know ZexCoil makes single-coil style pickups with single coils, and I think the Cycfi (sp?) pickups use a similar, modular-style coil configuration, but I don't know anything about how they work. It seems like those are more of a low-impedance style coil, more like Alumitones.


    Pickups with a single coil used for each string, or with two coils per string for a humbucker. I suppose you could do more than that as well, though I dunno why you'd want to.


    :D
     
  8. stevexc

    stevexc Laura Like Butter

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    So here's a stupid idea. Would there be a point into mounting each coil seperately so you could have each one at a different position along the string? Almost like an adjustable-angle pickup.

    Definitely some cool work, though!
     
  9. KhzDonut

    KhzDonut Freelance Nutjob

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    My plan is to get creative with coil placement, so let's hope it doesn't turn out to be a stupid idea ;)
     
  10. stevexc

    stevexc Laura Like Butter

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    Nice, I feel like this is gonna turn out really neat!
     
  11. KhzDonut

    KhzDonut Freelance Nutjob

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    So I made a few sketches of how to wire all the coils together (they're messy and unreadable, so if anything this picture makes them look BETTER)

    [​IMG]


    And in the process realized how much room I'd have to move coils around, which was much more than I expected. The tolerances are pretty tight side-to-side, but along the length of the string I could move things around quite a bit. So I did.

    [​IMG]

    Just some old-school Forbon I cut with a Dremel and filed the edges smooth with some of the Stew Mac nut-shaping files. (Those things are fantastic)

    The idea is that it keeps the coils under the thin/plain strings roughly the same distance/aperture as a normal humbucker, but narrows underneath the lower/wound strings.

    I usually tune C standard with something in the ballpark of 12-56 set (for the br00talz and ye olde doomy stoner metal) so a focused low end is the order of the day. How much will this facilitate that? Who knows. Certainly not me. My one experience with a pair of Seymour Duncan Mini Rails led me to believe that a narrow aperture humbucker would sound focused, but it was in a Tele with an angled pickup that put the magnet underneath the lowest string the furthest away from the bridge, which does NOT facilitate a tighter low end.

    So... Many... Variables...

    But that's what empirical testing is for, so here we go :D
     
  12. KhzDonut

    KhzDonut Freelance Nutjob

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    The complexity of wiring a pickup like Wal does leaves me with a few challenges that, without more information about how Wal did it and how pickups are designed in general, lead me to believe that life would be really easy if I just had a circuit board printed. Obviously, that's a bit ambitious for a project like this :p

    I took some brass eyelets, the vintage Fender ones that are usually used in making singlecoils with Forbon flatwork, and sanded them down so they'd be more like the solder terminals on a printed board. Mostly I just wanted them to be small so that they would be easier to work around.



    [​IMG]


    The next challenge is figuring out how to wire the coil to the board, AND have connections going from each of those solder points to OTHER solder points. The inability to make actual traces is a problem. It would be a little tricky trying to solder the super tiny coil wire AND a regular sized wire in the same hole (and do it like 24 times)

    So I had the idea to just run the copper wire used for the "traces" through the eyelets, and make loops for the coil wire to attach to. It's not elegant, exactly, but I think it should work.



    [​IMG]


    Obviously it's not pretty, but the majority of it is a single piece of bent wire looped through a couple dozen holes, and then a few auxiliary pieces.

    This way when I'm soldering the coil to the board, I ONLY have to worry about the coil wire. The rest of the wire is soldered into the eyelets, and should be very rigid and stable, even if part of the wire becomes loose/unsoldered during the process, it's connected elsewhere and should remain rigid and easy enough to work with.

    It's a lot of work for a prototype, but the first time I was wiring things together on a Stew Mac Humbucker Kit I had some trouble with breaking the coil wire while trying to solder it to things (because I'm clumsy and kind of a pickup n00b) This seemed like an easy way to compensate for being meat-fisted and inexperienced.

    I wouldn't want to have to build more than a few prototypes this way, though. It's a lot of work.
     
  13. Hollowway

    Hollowway Extended Ranger

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    This is super cool stuff! Durero did something similar to this on his protos.
     
  14. Mehnike

    Mehnike SS.org Peruser

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    Very excited about this one!
     

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