The Next Generation of Guitar Pickups – Part I

Guitar Pickup History Review

A couple of weeks ago I discussed a little how a standard issue magnetic pickup does its magic in converting the mechanical motion of a vibrating string into the electrical signal that is sent either to a bevy of outboard gear, like pedals and rack gear, and then to the amp; alternatively, a purist may route the signal straight to the amp.

The technology in use is approximately 80-85 years old and relied on the effects of Faraday's Law to use the perturbation of a magnetic field, in this case by a vibrating string made in part or in whole by a para or ferro-magnetic material like steel, cobalt nickel or an alloy of some sort composed of at least one of these, to disturb the magnetic flux of a permanent magnet. This results in the flow of an electromotive potential, or voltage, in the coil of wire wrapped around a bobbin and immersed in the magnetic field from the magnet or magnets that are responsible for the magnetic field in this system.

Over the years, and really more recently, there have been improvements on this design and whole other principles of physics found in the equations of Michael Faraday and Joseph Henry have been taken advantage of, in spite of the fact that the relationships were kind of obvious. Guitar players (and our bass playing brethren) are a conservative lot when it comes to our gear and we don't like change. "If it ain't broke, it don't need fixing", while an admirable philosophy to live by, can be so stubbornly held that the idea of a new, improved or neat innovation is wholly ignored because it's not the same old, same old that worked so well before.

The truth is that we willfully ignore the shortcomings and do not acknowledge that it hasn’t always worked so well, to our own detriment. Hopefully these innovative pick up designs that I'm going to discuss here are going to be part of what changes that. This is part one of a two part article.

Let us review and expand some...well, a lot. The standard issue magnetic pickup that has been the industry standard in its various and sundry forms, e.g., Fender-style single coil, Gibson-style single coil aka the P90 or the Gibson-style dual coil, aka the Humbucker.

The basic recipe consists of a pair of bobbin forms (to construct one bobbin) made from a non-magnetic, non-metallic material. Material used over the years has been everything from the ubiquitous Formvar (a thermoplastic resin), butyrate, celluloid, etc. to the DIY spare bits of thin wood, CD jewel case plastic cut to size and really thick cardboard painted with urethane, i.e., really anything that one would choose to use that fit the basic criteria of non-metallic and non-magnetic.

The magnets can be either cylindrical as has been used by Fender, one pole piece per string to the Gibson method of using a sand-cast bar magnet that rides underneath the bottom bobbin and the pole pieces, aka slugs, being made of a magnetizable material, usually ferrous in nature. The slugs, cylindrical magnets or blade “pole” piece are inserted into holes (or a transverse cut slot) into the bobbins that are spaced to the optimized distance apart, riding more or less underneath each corresponding string.

The bobbin assembly as we'll call it, is now placed on a machine and wrapped to specification with thousands of turns, customarily, of usually 42 or 43 gauge enamel insulated wire (the insulation appears to be painted on the wire because it basically is). A humbucker is just two of these coils with the magnetic polarity reversed and the wiring between the two coils configured in a way that results in an in series and out of phase wiring. This allows for the signal generated by the string to pass through, but the external EMF is electrically cancelled in the pickup's circuitry.

The coils can be stacked to allow the pickup to have the same physical geometry of a Fender-style single coil and therefore fit in a single coil sized slot without having to cut a larger hole in the pick-guard or rout the body of the guitar, or the coils can be in a tandem configuration as most are used to seeing in a guitar like the Gibson Les Paul.

The challenges with the old school methodology of manufacturing are that there are so many variables that can enter the manufacturing process, that the consistency from pickup to pickup is a challenge. This is still a significant consideration even when using the same batches or lots of raw materials from a given supplier.

One of the most difficult things to control reliably is the winding process. In the early days, there was not much thought given to the winding of the pickup. The number of turns could vary significantly, the way the turns were applied, e.g., a uniform traversing back and forth across the bobbin vs, a "scatter-wound" methodology that laid the wraps out in a seemingly random process.

The alloys of the magnets used varied, the gaussing and degaussing processes used to achieve a uniform magnetic flux (the density and distribution of the magnetic field around the pickup) were not uniform. The end result was that some of the most beautiful sounding classic pickups from the 1950's were created quite by happenstance. Some of the ugliest sounding ones were produced too.

Side note to the rookie vintage pickup collector: Just because it was veritably made in 1958 by Gibson and is a genuine, unmodified PAF from that year is no guarantee that it's not a tonal turd and the multi-G$ that one just paid netted the rookie a really expensive paper weight.

This old technology of producing a consistent, great sounding pickup from one to the next is an art as much as it is a science. The variables and potential pitfalls are known, but only one who has a few hundred winds under their belt is able to begin to understand how to really make a fine, boutique reproduction from one to the next that sounds close enough to the real deal to satisfy.

The mass producers know their stuff too and can get a really consistent product, but it took them a while to be able to do that and to do it well. Guys like Seymour Duncan and Larry Dimarzio started off winding or rewinding pretty much one-offs to learn the art. Even so, it’s not perfect. I have two black bobbin Dimarzio Super Distortion Humbuckers, both bridge position and identical except for one was manufactured in the mid '80s and the other in the mid'90s. They both sound great, yet I can tell which one is which from the sound, even when mounted in the same guitar and same strings. I decided to see if there was a difference, as was suggested to me by a friend who repairs pickups and sells boutiques to supplement his income. Sure enough he was right.

One last note. The old school designs have inherent limitations as deemed by the laws of physics. There are resulting tradeoffs. More windings will net a higher voltage output, but the resonance peak shifts to a lower frequency and the top end goes away yielding a darker tone. The sparkle and chime are casualties to having a pickup that pummels the front end of the amp. Depending on the winding pattern and kind of magnet used, the bottom end can end up sounding flabby in some of these over wound designs too.

Clarity and note definition are also casualties of the overwound wars that have erupted now and again. The magnetic pull that the pickup produces can interact with the vibrating string in such a way as to pull a note or chord out of tune if the pickup is parked too close to the strings. Because of the nature of the voltage driven design and all that wire in the pickup, the resulting quantities of inductance, reactance and capacitance (that are the nature of the interaction in between the pickup, the volume and tone controls and the cable used to transmit the signal to the input of the amplifier and assuming no effects lay in between) result in a beast that is a high impedance circuit.

High impedance circuits do not play well with long cable runs without all the high end going away as a longer cable is utilized. In addition, high impedance circuits are susceptible to the kinds of electromagnetic interference that are captured as a long cable run tend to act as an antennae, especially when one is using a cranked, high gain amp like ÜberAllSanity’s, Breath of Satan 200 watt head, popular among the newer extreme forms of metal guitar player, now with 13, count’em, 13 stages of gain.

One of the reasons that the spiral, telephone-style cables were so popular with some of the players in the 60's and the 70's were that the guitars and the pickups in them, especially some of the single coils of the time, tended to be spiky and shrill. The way to compensate was to utilize one of these phone cord style cables.

Were one of these to be uncoiled, the resulting cable run is about 35 feet. The resulting capacitance would kill the shrill, spiky high and warm up their tone. Still, for the most part, most players don’t want to lose their high end and that requires the use of a shorter cable and/or a line buffer somewhere in their cable run. This is not an ideal solution as some buffers can color the sound in an unacceptable way.

The Next Generation of Pickups

So, to the meat of the article. How have some of these limitations and problems been addressed? What kind of innovations have crept their way into our land of sacred, thou shalt not mess with, tonal sensibilities with new and therefore completely untrustworthy until proven otherwise tech?

Fishman Fluence
The Prince of the Piezo Pickup, veritable king of acoustic instrument electrification, aka Larry Fishman.

Fishman deliberately stayed out of the “Standard Issue” magnetic pickup arena for about three decades on account of the inconsistency factor in the traditional designs. Larry Fishman's attempt at making a better pickup initially looked at the whole inconsistent winding process. He and his team took a page out of the telecommunications and aerospace industry playbook by getting rid of the voluminous wrapping of wire around the bobbin and replacing it with a much more precise and eminently controllable means of multiplying the voltage that is the creation of the induction interaction's field perturbation by the strings.

What they did was to print the "wire", as it were, on a silicon wafer as a circuit trace that goes round and round like an oblong racetrack, but is more like the unbroken groove on a vinyl record on each wafer. The wire trace is not carrying that much current, and as this is a voltage dependent system, it can be incredibly thin and placed incredibly close to its neighbor, not unlike the traces on a circuit board in a computer’s CPU.

I'm making a bit of an assumption here as to this detail as I've not seen one of these up close and dissembled. Nevertheless, I do understand how it works and what is involved, so I reckon that if I'm not 100%, I'm pretty dang close. These wafers are then stacked one on top of another, 48 on the top as I understand it, to form one half of a bobbin. The other half of the wafers are then divided by a spacer that prevents any interaction between the halves, and stacked in a way that the current flows in the opposite direction. The result is the hum cancelling technique of yesteryear that Seth Lover patented for Gibson about 60 years ago.

The next part is equally inventive. One of Fishman's scientists, an acoustic engineer by the name of Doctor Ching-Yu Lin, PhD mapped the magnetic field of the best pickups that the team could locate. The mapping was done in 3D to render a precise topographical map that could be used as a template.

Different kinds of magnets were selected from the old school sources and the cores for the pickups were developed using the classic magnet materials and alloys. The magnets were chosen to be of the same type that were mapped. Dr. Lin's mapping now comes into play. The magnets were "supercharged" and then discharged in a precise and controlled way to yield a reproducible field pattern that was a reproduction of what Dr. Lin had mapped from these "golden age of pickup magnets".

Side note, the magnets for a pickup don't just show up at the factory, ready to use. They need to be cut to length in the case of pole pieces and sometime, in the case of bar magnets, some shaping is required, or so I've been informed. The result is that the mechanical working of the metal changes the flux. The magnets have to be "charged" with the desired amount of magnetism.

The charge configured magnets were parked into the middle of the bobbin assembly. The apparent problem is that the sound is very flat with all this uniformity. What is not immediately apparent to the ear, however, is that all the required frequencies are there to make for a great sounding pickup.

The output of the pickup is sent to a custom built and configured, on board preamp. The preamps that Fishman builds are another hallmark signature of his excellence at what he and his company does. This preamp is then configured to take the entire spectrum of frequencies coming out of the pickup and shape them, cutting some frequencies and boosting others to give the signature sound of whatever highly desired tone that one wants.

In a stroke of marketing genius, each pickup has a certain core tone that is reproduced. Then the process is repeated and another signature tone is shaped and configure into the circuitry. So, when the pickup is installed in the guitar, one type can be chosen as a set and forget. The other option is to install a push-pull pot into the guitar that will allow switching between the two tones. So I can have a classic '54 Strat tone and a hot '59 Strat Texas tone a la SRV at the flick of a switch. Or in my Les Paul, I can have a '57 PAF and a hot rodded '70s tone at the flick of a switch. There are many other options in the pairings.

Fishman also realized that these "active pickups" were the nemesis of many guitar players, e.g., yours truly. I personally won't touch an active in an electric guitar anymore. Bass is another story. In a guitar, I don't like the usually compressed tones and lack of dynamics. This design might change my mind about active pickups in guitars.

From what I can tell from reviews and the video clips that I’ve seen (I’m looking to see how much the audio changes in relations to the attack that I can see in the video portion), the pickups seem to be open, breathing and quite responsive to attack. I really get the impression that they are trying to recreate the magic of the vintage pickups in all respects and in a way that is reproducible time after time so that everyone is good and there are no lemons or mass produced fliers, as I mentioned earlier.

Another aspect of active guitar pickups that I don’t care for is that I don't like to have to hassle with batteries before every gig and I hate the battery going dead in the middle of a song. Yes, it’s happened and I stopped using guitar actives for that very reason. What Fishman did is to offer an optional micro-Lithium rechargeable cell that pairs with his pickups and is recharged via a mini USB connector. The battery will keep the guitar up and running for over 200 hours on a single charge and powers down when the instrument cable is unplugged. As I can remember to plug my phone in every night, I can deal with the same “routine” the night before a gig, once a month with that 200+ hour battery life.

There is the standard 9-volt battery option for the individual who either desires such or can’t spring the $100 for the rechargeable battery. The output is also considered low impedance, so if one runs a 15 foot cable or a 50 foot cable, there should not be any high end loss and no picking up of the “Bible Bob -You’re Going to Hell ‘Cause you Play Rock ‘n’ Roll Radio Hour” that your formerly high impedance signal would facilitate picking up on that 50 foot instrument cable.

As near as I can tell, this pickup system essentially amounts to a form of pickup modeling, analogous to the modeling amps, modeling effects and the Line 6 Modeling guitars, aka the 6-string chameleon. The difference is that as near as I can tell, the signal path is all analog and there is a transformer involved in the coupling of the output signal going down the cable that serves to reduce the impedance.

Why does this matter? Because this kind of modeling has the potential to be pretty organic with the sine wave thing happening as opposed to the cold, sterile one and zero bit action that the modeling guitars and other digital gear utilize. If Fishman is utilizing CMOS transistor technology in the preamp along with the transformer, then the interactions and reactions to the input from the vibrating strings are going to be fairly analogous to the same kind of internal interplay that occurs in a vacuum tube amplifier in a fair number respects. Conceptually, this isn’t a new idea as Tech 21 of NYC pioneered the similar analog modeling of amps back in the late ‘80s with their Sans Amp pedals and rack units.

All in all, I'm liking the idea here and the YouTube videos I've watched impressed me in what I could discern in the tones produced. I need to see if any of my local or extended community of guitar playing friends have test driven these.

I'll be checking these out as best I can without having to plunk down any money and may end up overhauling my Strat. If that is a worthwhile experiment, my Les Paul and/or my SG will be next. The idea of having a built-in pickup swap at the flick of a switch is an attractive notion. For just a bit more than the what a pedestrian set of actives, e.g., EMG’s or Duncan Blackouts, would cost and realizing that the perk of an extra pair of pickups is built into the deal sans firing up my soldering iron and an hour of my time for installation…well it is more than just an attractive notion.

It’s a no brainer. If they deliver even 75% of the promised tones, I can be happy with that as the mass produced makers promising the same in their products are in that range of accuracy according to what I’ve experienced.

Next week I’ll finish this off as I have two more companies with a total of three lines of pickups between them to cover and I don’t want to be bandwidth hog. Suffice it to say that one of these lines is a very unusual approach to the Faraday and Henry mathematical sensibilities of making modern music.

I really don’t care how the note is captured, transduced into electric current and sent to the amp. The magic in that note has to be there as part of what’s captured and sent to the amp. So long as it results in a happening, inspiring and energizing experience for me that, in turn, translates to the listener getting their own mojo working, then I say, “Mission Accomplished!”

-Kirk Bolas - MU Columnist
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