Bill Lawrence Microcoils Analysis

Discussion in 'Just Pickups' started by Antigua Tele, Feb 22, 2019.

  1. Antigua Tele

    Antigua Tele Friend of Leo's

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    [​IMG]

    Even though this is a Strat set, this forum in particular seem to love Bill Lawrence pickups, so I thought I'd post this analysis on TDPRI anyway.

    http://wildepickups.com/Wilde_Bill_s_MicroCoils.html

    Bill Lawrence Microcoils

    Bridge MC-A SL
    - DC Resistance: 7.406K ohms
    - Measured L: 1.462H
    - Calculated C: 69pF (79 - 10)
    - Gauss: 600G (AlNiCo)

    Middle MC-A SM
    - DC Resistance: 7.073K ohms
    - Measured L: 1.430H
    - Calculated C: 71pF (81 - 10)
    - Gauss: 600G (AlNiCo)

    Neck MC-A SN
    - DC Resistance: 6.894K ohms
    - Measured L: 1.398H
    - Calculated C: 73pF (83 - 10)
    - Gauss: 600G (AlNiCo)

    Bridge unloaded: dV: 9.3dB f: 14.8 kHz (black)
    Bridge loaded (200k & 470pF): dV: 6.5dB f: 5.36kHz (blue)
    Middle unloaded: dV: 8.5dB f: 14.8 kHz (red)
    Middle loaded (200k & 470pF): dV: 6.5dB f: 5.36kHz (green)
    Neck unloaded: dV: 8.5dB f: 14.8 kHz (pink)
    Neck loaded (200k & 470pF): dV: 6.5dB f: 5.36kHz (gray)

    Coil height incuding bobbin: 0.2185", without bobbin: 0.1375"



    [​IMG]


    I've been wanting to look at Bill Lawrence Microcoils for a long time, because arguably they're a superior single coil design, although the way the product was implemented might not make then a desirable to some.

    The superior aspect of the design is that most of the coil is placed near the string. The bobbin is very short and flat, only 0.12" tall, where as a typical Strat pickup coil is closer to 0.44", and a PAF bobbin about 0.22". Conforming to Faraday's Law, each turn of wire is responsible for generating a voltage as the magnetic field from the strings passes though them, which when combined in series as a coil of many turns, creates a sum voltage. If those turns of wire are farther away from the strings, the magnetic field from the moving guitar strings is weaker, and so the voltage for those turns is smaller. A typical Stratocaster or Telecaster pickup has a rather tall coil, so tall that the turns of wire further from the strings don't contribute much to the voltage. The turns of wire at the very bottom of the coil are essentially dead weight, increasing the inductance without increasing the output. The short, flat coil is therefore more efficient, more output for less inductance (and capacitance). Lace Sensor pickups are essentially Microcoils from this standpoint. In fact, the reason a PAF style humbucker is so much louder than single coil is not just because the pickup is wider, but because the two coil layout has the effect of ultimately placing more loops of wire closer to the strings.

    But what some guitarists might not like is that Bill Lawrence made his Microcoils very bright pickups by not putting very many turns of wire on the small coil, possibly due to the space restrictions. The result is a very low inductance of only 1.4 henries, where as ~2.4 henries is more common for a Strat pickup. I also get the sense, based on the more conventional "Keystones", that Bill Lawrence liked brighter pickups in general.

    One reason this design might not have been pursued more by other pickup makers is that it's not as simple to fabricate. Rather than having the coil former and pickup base all in one piece, as is typical, the coil former has to be a distinct section from the base, so as to be nested up inside the pickup cover. You can see from the pictures below that the Microcoil has a shorter fiberglass bobbin that is suspended above the base plate by a combination of the AlNiCo pole pieces and a black plastic retainer piece. The lead wires are soldered directly to the fiberglass bobbin, and there is very little space to work with since the coil comes right up to the edge of the bobbin. Were this geometry easier to construct, the design might have been more readily copied.

    The Microcoil is offered with screws or AlNiCo pole pieces. I bought the AlNiCo set. They don't say what grade of AlNiCo is used, but they appear to be as tall as typical Strat AlNiCo pole pieces, and fully charged they measure similar to AlNiCo 2. They have no stagger and are perfectly flush with the pickup cover. The covers are similar to the Keystones, with a very rounded edge, similar to the vintage Bakelite pickup covers. I suspect these pickups are not wax potted due to how clean the are. I'm interested to see how microphonic they are or are not, as a result. The impedance plot shows that all three coils are all remarkably alike. The middle pickups is RW/RP, but the neck and bridge pickup are interchangeable.

    On the sides, there is a rivet that is flattened on the bottom, but not the top. A screw holder the base to the plastic spacer piece inside, and it that screw is remove, the base plate can be carefully pried away from the two rivets on the sides.

    In the pics you can see a manufacturing defect, one strange of wire looped around one of the AlNiCo pole pieces instead of the bobbin.


    ~*~*~


    This plot shows a comparison of the Microcoil neck and a Fender Pure Vintage '56, with the exciter coil place in the same spot above both pickup, and is shows that the output is effectively identical, which is the real hat trick of the Microcoil. The 1dB difference could be attributed to difference in bobbin thickness, which causes the exciter coil to be a tiny fraction of an inch nearer or further from the surface of the coil itself.

    [​IMG]





    I'm planning to put these pickups into a 12 string Strat. The 12 strings seems to work better with really bright pickups, and it looks like here I have a pickup that is very bright, with an output that is on par with any other Strat pickup. It's definitely a unique pickup. I wish the company would consider making a Microcoils with a more standard inductance target, such as 2.4 henries.




    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]



    Comparing the Fender and the Microcoil output levels, with Ken Willmott's integrator device pictured http://kenwillmott.com/blog/

    [​IMG]
     
    Last edited: Feb 22, 2019
  2. jackal

    jackal Tele-Afflicted Gold Supporter

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    My micro-coils (Tele and Strat) have adjustable pole pieces.
     
  3. El Tele Lobo

    El Tele Lobo Friend of Leo's

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    Aren't there 2 kinds of microcoils (at least for tele)?
     
  4. El Tele Lobo

    El Tele Lobo Friend of Leo's

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    @Antigua Tele are you going to do an analysis for the tele microcoils (and if so, which sets)?
     
  5. NWinther

    NWinther Tele-Afflicted

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    These are the Alnico ones.
    The whole point with those is that you make them sound like you want....they may be "bright" but mine in my strat style guitar and Tele have never been harsh....and they do play pretty loud too!

    I love mine, have used them ever since they came out, mine are the neodynium ones with adjustable poles.
     
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  6. mistermikev

    mistermikev Tele-Holic

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    a lot of bill's amazingness is lost on the general public but not me. thank you for posting this... I'm going to have to go seek these out. I love my bill lawrence hbl, L500, L250. Admittedly all are bright. the L500 isn't very high dcr, but it sounds like it is... textbook bl.
     
  7. Derek Kiernan

    Derek Kiernan Friend of Leo's

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    The Alnico microcoils were designed to easily get the "classic Fender" tone with a larger variety of "modern" cable capacitances. Back in the 50s and early 60s, cables were much shorter, but obviously with the stage demands players had to go with longer cables. To counteract that, the inductance has to be dropped.

    Bill never wanted the resonance peak in the 3-5 kHz region, especially as you get closer to 3 kHz, which is bright/edgy/etc especially when sharp, and especially unpleasant on the bridge. He wanted plenty of 6 kHz to be delivered to the amplifier, didn't aspire to go above 10 kHz (which he called "just noise" in the realm of high impedance guitar amps), and was aware of the limits of guitar speakers and amps to reproduce the entire range cleanly.

    I think your load shows that you can reasonably hit what he was designing for with a pretty conventional cable, and that you'll easily bring what most high impedance guitar amps are able to reproduce.


    With the Alnico micros, the general impedance is in the same range as a standard Fender single, only the inductance varies. Want less highs on the neck/middle? Turn back the tone knob a bit to damp the resonance without losing the highend extension. Want warmer coloration on the bridge? Add a small 4-5 nF capacitor on the tone knob and dial in as much as you want.

    It's not the most versatile pickup he could make (which would be the neodymium microcoil), but it's very easy to get everything he could want out of a more traditional Fender single in the largest variety of setups possible, without any compromises to the impedance in the lowend or general matching to the amplifier -- just superior and more flexible highend, and with a huge portion of the noise missing in a single coil package.
     
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  8. Derek Kiernan

    Derek Kiernan Friend of Leo's

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    Other notes: the Tele set's bridge pickup has a somewhat higher inductance, so while it still might not be what some players are looking for as a "default", it doesn't privilege equal inductance in every position for the inbetweens and is easier to tonally balance.

    I would also use a tone control in the bridge position on the Strat, so some players may need to rewire, but I don't think any Strat bridge should be without a tone control anyways.
     
    Last edited: Feb 22, 2019
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  9. FrontPU

    FrontPU Tele-Holic

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    Great review, bravo!
     
  10. chris m.

    chris m. Poster Extraordinaire

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    Thanks for that excellent review. The shocker is the wayward coil loop....but for a tiny production facility I can imagine how this could happen.
    The QA/QC inspector is probably the same person that wound in the first place, and it is often hard to see the mistakes in one's own work.

    I agree that most of BL's pickups tend to be on the bright side. Some folks prefer to start with bright and then tone it down, and it is true
    that it is easier to add mud than to get rid of it. But that resonance peak can be hard to tame-- there is an inherent strident voice that
    comes through. Just my experience, YMMV of course. As people get older, especially if they've spent a lot of time playing through loud amps,
    they tend to lose sensitivity in the high end, which can be a factor as well.
     
  11. Derek Kiernan

    Derek Kiernan Friend of Leo's

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    The alnico micros are not about being bright, but having better highend extension. Taking away some of the resonance to taste is easy through turning down the tone knob a little, but if you have a bright peak closer to 3 kHz with a higher inductance pickup, you're battling between muddy and bright. By having the resonance's location in a higher place, you take away the delicate balancing act you get with a lower resonance.

    I find it much easier to take out some mid scoop and treble boost with the Alnico micros than to try to work around a lower resonance in the bright range with a higher inductance pickup. Some players won't touch their tone stack as a first response, but it is about as easy as any adjustment could be.
     
  12. hopdybob

    hopdybob Tele-Afflicted

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    i have had and used the tele micro set with adjustable pole pieces.
    it wasn't in any way harsh, with, to me, a good warm sounding neck pickup and the bridge had a good drive in it.
    at first i thought it the bridge pickup was not as loud as the neck, adjusted a lot and at last gave them to a good friend to test them to.
    his conclusion was that nothing was wrong.
    tested my hearing and in my case, there was the problem, not in the pickup ;-)
    my friend is enjoying them now, and i have the tele with l280 N and a l200N in the bridge now and works fine for me
     
  13. Antigua Tele

    Antigua Tele Friend of Leo's

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    Maybe that's true, I don't know, but the product page itself doesn't suggest pairing the product with parallel caps http://wildepickups.com/Wilde_Bill_s_MicroCoils.html , so I doubt it's often used that way, if that was what was intended.

    On this page http://wildepickups.com/Wiring___Tech_Info.html there are some diagrams that make use of low value caps, although they're hand written, some impossible to read, maybe there is a diagram that depicts using low value caps to approximate the tone of a long guitar cable, but in that case it's certainly a "mod", there's no insistence that the product should be used that way.

    On that same page they say:

    "What Capicators and Resistors should I use?

    With Bill's pickups and for simplicity, you can usually try the existing wiring in your guitar as a drop-in replacement. The standard cap is .022mf in most cases. Bill's pickups are very versatile, and most of them can be wired to either 250K or 500K pots which is an easy way to mod their sound. The models over a certain inductance range, like the L-500XL, we advise 500K pots or higher. Because Bill calculates all his pickups to avoid a certain harsh midrange peak, the sweet highs are a prominent feature! As a market standard, 250K pots are for singles and 500K pots are for humbuckers. However, Bill personally, as a player, starts with 500K pots on his guitars for both singles and humbuckers. If he needs to reduce its value, he'll wire a resistor over it. For example, a 500K resistor wired over a 500K control will reduce it to 250K."


    It looks to me like there is a general preference for higher peak frequencies. Even encouraging customers to experiment with 500k pots itself will tend to result in brighter tones. Most of the time you see advice like "250k for singles, 500k for humbuckers" because again, it seems that guitarists complain about excess treble more often than they praise it, they say it's "shrill" or "ice pick".
     
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  14. Antigua Tele

    Antigua Tele Friend of Leo's

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    I'm not sure, but I'd bet they're rather similar to the Strat Microcoils. Since they coils all appears to be about the same size, the inductance isn't bound to be much different for the Tele models.

    When the resonant peak gets at or above 5kHz, it doesn't so much matter at that point, because it exceeds the range of most guitar cab speakers. The response becomes "flat" at that point, for all intents and purposes. Reducing the turn count further just causes the pickup's output to drop. The tone doesn't change, but the S/N ratio gets worse. So even if the Tele versions have slightly different inductance values, it's unlikely they differ in a way that makes them sound much different.
     
    Last edited: Feb 22, 2019
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  15. Derek Kiernan

    Derek Kiernan Friend of Leo's

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    His wife manages the site. Bill was in his 80s and couldn't type. Bill "starting with" 500k was for a test platform to insure that his pickups worked well with the widest range of values players would potentially use. The only time 500k would be "needed" for a player is if they're trying to get "more quack" out of the L280s, for example, and it's definitely not a general suggestion. Bill made most of his pickups as drop ins and didn't widely encourage anyone to use 500k pots with drop in replacements for singles.

    Bill died before the Alnico micros came out, so you can hardly expect him to have produced literature for it on the site. He didn't release them during the last couple years of his life because he wanted everything to be thoroughly prepared and explained.



    Plenty of Bill's pickups are considerably higher inductance in the bridge. His Tele wirings often include an extra resistor in parallel to the bridge pickup, so rather than recommending 500k pots, his recommendation in fact was to minimize the resonance in bridge positions since the inductance was too large to be productively manipulated with a given small cap value across the variety of cable capacitances players use.



    The original microcoils are entirely different than the Alnico micros. Their performance is generally unrelated, but of course they can easily use small caps for coloration as well.
     
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  16. Antigua Tele

    Antigua Tele Friend of Leo's

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    How are the AlNiCo and screw/neo versions different, as you understand it?
     
  17. Derek Kiernan

    Derek Kiernan Friend of Leo's

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    Completely different magnetic design (in some ways influenced by his work on the SCN for Fender), different efficiencies, different inductances, similar coil footprint.

    For the Alnicos, the Strat set is all 1.45H, the Tele has the same in the neck with ~2.2H in the bridge. For the neodymium, the Strat and Tele set are both 2H in the neck/middle, with 2.8H in the bridge.

    Both sets are capable in the highs and respond to coloration well, but the neodymium sets have a much stronger fundamental, stronger lows, stronger sensitivity to tonal and dynamic changes, and substantially stronger voltage output, with comparatively less noise after everything else. I have a 1.4H set Wilde was able to do for me while Bill was around, and everything I wrote above pans out for equal inductances, so my comparison isn't the effective difference between 1.4H and 2H/2.8H sets.

    Bill originally wanted to go with the 1.4H/2.0H sets as standard and started producing the Alnicos at that time, but saw the 2.0H/2.8H as an easy drop-in and wanted to avoid having to sell players on sub-2H inductances at the same time he was introducing a new magnetic design, with plans to release lower inductances and additional wiring suggestions later. He died before any of that was able to be done, so his wife Becky released the Alnicos as they were already produced, and the program and available literature hasn't expanded since.
     
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  18. Antigua Tele

    Antigua Tele Friend of Leo's

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    I don't agree that the magnetic design is completely different, but I can believe the inductance is lower with the AlNiCo. 2.0 henries would still trend on the bright side for a Strat, especially if it has a similar capacitance of ~60pF. Of course a pickup with a lower peak frequency willl have more fundamental / stronger lows. I'm not sure how or why the sensitivity would differ, though.

    Regarding the magnetic path, even with steel pole pieces, the aperture width is still going to be effectively the same, which is to say, narrow enough that there is no audible comb filtering effects. As for the efficiency, the steel poles increase the voltage output, but they also increase noise, so the S/N should end up being nearly the same. There's also the question of the flux density at the screw tops, the 600 Gauss of the AlNiCo's is not hard to achieve with steel and under mounted magnets, but from the pictures it looks like the components are all rather small.
     
    Last edited: Feb 22, 2019
  19. Derek Kiernan

    Derek Kiernan Friend of Leo's

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    I've already stated that I have a set with 1.4H neck/middle and that the inductance is not the factor. There's more to a pickup design than poles vs blades and a handful of inductances. You're welcome to try the neodymium microcoils and see.
     
  20. Antigua Tele

    Antigua Tele Friend of Leo's

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    Why wouldn't inductance be a factor? How can a magnetic circuit be tweaked in such a way that it yields more fundamental and low end?
     
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