What Type of Guitar Pickup is Best for You?

In the beginning, someone, somewhere plucked a taught piece of bowstring or something and realized that it made a cool noise. After experimenting and adding a few more bowstrings on the bow frame and modifying the frame some, someone who preferred art to killing turned a bow into a lyre or harp or some musical instrument of that sort.

Fast forward a few thousand years and the more contemporary stringed instruments began to appear. Cool. One of these had frets and six strings and was called a guitar. It’s called a what? I said it’s called a guitar. I can’t hear you over all the other instruments. What’s it called? Speak up son. I can’t hear ya! Ok. Another technical challenge. We need to make this guitar louder. How do we do that?

The Resonator Mechanically Amplified Guitar

Well the Dopyera brothers invented an improved acoustic guitar called the Resonator Guitar and sold it under the brand name “Dobro”, short for Dopyera Brothers. It looked like this and mechanically “amplified” the notes played.


The problem was that it did not project the sounds that much louder than the U&C acoustic guitar and only lent itself tonally to a couple of genres of music, namely the Blues and Bluegrass. Jazz and other forms of music did not play well with this amplified guitar. About the same time in the 1920’s the electric amplifier came into being.

A few inventive individuals created the first passive electromagnetic pickups. The first few attempts kind of worked and were better than nothing. A few iterations later and starting in the later 40’s we began to see the first pickups that we would recognize today; these same models have been in existence since that time. Basically we have the Fender style single coil, the Gibson style single coil, aka the P90, and the Gibson style humbucker.

We all have our favorites, whether we know it or not and I’m briefly going to describe how they differ and offer a simplistic “why” behind the reason that they sound as they do. I could write for pages as to the minutiae behind the “why” and go into all kinds of physics involving Newtonian Mechanics, Faraday’s Law, Ohm’s Law, ad nasuem, et somni. So, I’ll keep it pretty basic in this particular column and perhaps I’ll revisit the nitty gritty and fascinating details and variants at a later date.

I will throw the piezo guitar pickup in here, because although it is not a magnetic transducer, they are seen in some systems by Fishman and others on electric guitars that serve to give more acoustical kinds of tones without having to switch guitars in the middle of the set or even in the middle of a song. Basically, a magnetic pickup does what it does because of Faraday’s Law of Induction.

Simply put, the vibrating guitar string disturbs the magnetic field around the pickup; the resulting electric current induced in the pickup’s wire coil is an alternating current replica of the string’s vibrational frequency and amplitude.

The piezo effect does something analogous, but is a direct transduction of the strings mechanical energy that is producing an alternating electric current, mirroring the frequency and amplitude of the vibrating string.

The diagram below can be seen as a rough approximation of how either system can be represented to change the strings vibration into an electric current, whether it be due to the magnetic field’s perturbation inducing a current to flow in the wire coil or the changing mechanical stress on the crystal creating a current through the piezo-electric effect; both result in the creation of an electric current that mirrors the frequency and amplitude of the vibrating string to a fair degree.

Whether the pickup be single or double coils, the basic operation is the same. In all cases, the only moving parts are the strings. In terms of the magnetic pickup, the diagram can be seen for what it is with no additional explanations. In terms of the piezo, consider the black “bar magnet” AND the gray “wire coil” in the diagram to be the bridge saddle in the piezo system.

Imagine that the piezo crystals are underneath the labeled “wire coil” construct and the wires running to the piece labeled “signal” are connected to the crystals. The salient point is that either system acts as a transducer to create an alternating electric current that mimics the vibrating string’s frequency and amplitude. The only difference is the physics involved in the transduction of the vibrating string to the AC current.


The Fender Style Single Coil Pickup

One of the first kind of hugely successful, generally recognized and mass produced pickups is what I’ll call the Fender-style single coil. This consisted of a non-metallic bobbin that had holes drilled in it that allowed for the alignment and passage of the six pole pieces, one for each string. Each of the pole pieces in this design were actual magnets made from an alloy called Alnico.

Alnico has a reputation for being sort of the secret sauce in pickups that have a soft edged, warm and smooth tone when compared to pickups using ceramic or ferrite composition magnets,. Alnico is commonly available in three flavors, namely Alnico III, V and VIII.

Each one has its own characteristics in terms of the field density and this, in turn has an effect on the character of the signal produced in the bobbin and sent down the wire to the amplifier. The magnetic pole/bobbin assembly is wrapped with an incredibly thin wire that is insulated in an enamel coating. The bobbin wrap tends to be taller and it is wide, as viewed from the top.

Here is photographic representation of this kind of pickup without and with a cover. The covers are mostly for cosmetic purposes.


The distinctive qualities that these style pickups and the many, many aftermarket copies, clones, reissues, etc. are known for the clear, chimey, bell like highs and clean articulation that can be had with a clean amp.

The Gibson P90 Single Coil Pickup

There was technically another single coil pickup by Gibson. It was a single coil euphemistically known as the Charlie Christian model. Most people will never see, hear or play one of these, so in the interest of reaching out to the largest audience possible, I’ll skip it in the interest of brevity.

The significant pickup from the same era as the Fender single coils was the Gibson P90 single coil. It too has the same basic characteristics of a non-metallic bobbin, thin, enamel insulated wire, and a magnet of some sort. The differences are that the pole pieces are magnetically conductive slugs, instead of being actual magnets.

The actual magnets in the P90 are a pair of sand cast bar magnets, differing between Alnico III and Alnico V in the early days and possibly Alnico VIII in recent years. This is something I learned by reading some of Seymour Duncan’s missives on the subject. In case the reader is unaware, Seymour Duncan has forgotten more about guitar pickup design and construction than most will ever know. His company, Seymour Duncan of Santa Barbara, California is a preeminent winder of guitar pickups and is really second to none, in my honest opinion.

The P90 is wound to be wider than it is tall, the opposite of the Fender single coil. This gives it a seemingly higher output, more midrange bark and a generally more, in your face kind of snarl or crunch sensibility. Part of this tone is due to the pickup “sensing” a wider expanse of the vibrating stings as its magnetic field “sees” more of the length of the strings as compared to the Fender single coil which has more of a focused sense of the vibrating strings.

Here are a couple of examples, one with the bobbin exposed and the cover to the side and then the bobbin “wearing” the cover. Note the adjustable pole piece screws and the “blind holes” between screws 2 & 3 and 4 & 5 that allow for adjustment of the height of the pickup.


The Gibson Humbucker aka PAF Pickup

The final very common form is the dual coil or “Humbucker” pickup. There is a flaw in the design of the single coil pickup. That flay is the propensity of the pickup to receive stray electromagnetic field energy in the form of radio wave and 60 cycle hum from adjacent AC circuitry.

In the early 1950’s, Ted McCarty, the head honcho at Gibson tasked Gibson Engineer Seth Lover with coming up with a pick up that would reject this extraneous noise. Mr. Lover came up with the Humbucking, aka PAF (Patent Applied For) pickup. It is as if the Fender single coil and the Gibson PAF had a love child. There is some controversy as a Mr. Ray Butts at Gretsch filed a patent much later than Lover did, but Butts’ patent was issued by the USPTO before Lover’s. In any case, most recognize Lover as the inventor.

It has the same salient elements of fiber, non-metallic bobbins, non-magnetic ferrous slug pole pieces, sand cast magnets, enamel insulated wire and the coils are wound more high and tight like the Fender coils (and most haircuts of the period). The coils are wired in series but out of phase as the magnetic polarity is configured to be reverse wound, reverse polarity. This achieves what the Dilbert engineering types call “common-mode rejection”.

What this means is that there is a bunch more output and a cancelling of the obnoxious hum and extraneous noise that a single coil pickup experiences. Here’s uncovered from the side and top and with a chrome plated cover. The cover can change how the pickup sounds a little, especially if it is metal as it changes the eddy currents of the magnetic fields. It matters not if it is non-magnetic.


Basically, the Humbucker pushes the front end of the amp harder and into overdrive more easily than a single coil owing to its hotter output. It accentuates the midrange more and tends to be less airy and, darker in terms of tone. The Humbucker is what shaped the hard rock and acid rock of the late 60’s and early 70’s. Humbuckers are also described as being more warm and corpulent in terms of tone.

The humbucker is what gave the sound that most recognize as Southern Rock, The Allman Brothers Band, Lynyrnd Skynyrd, Molly Hatchett, .38 Special and Blackfoot. The British Electrified, Hard-Edged Blues invasion of the late ‘60s, ZZ Top and early Rush are more examples of the Humbucker.

The Piezoelectric Pickup

There is an effect in the realm of physics called the Piezo electric effect. In the most basic of terms, it is an effect that when certain crystalline materials are subjected to pressure or vibration, an electric potential is generated.

Basically, what is happening, when the crystalline material is imbedded into a plastic rod element and placed under the bridge saddle on the guitar and a string is plucked, the vibration is transferred and causes the crystal to produce a weak electric current that is proportional to the string’s vibration. This minute current is routed down a wire and to a preamp that is often housed in the electric or acoustic-electric guitar and then to the amplifier. It is not a magnetic pickup and is responding to mechanical vibration, so the character is more like an acoustic instrument in tone and is often preferred for this reason when amplifying an otherwise electric guitar.

It’s also a way, although certainly not the only way, to amplify an acoustic guitar. It lends itself well to the nylon string classical guitar as there is no requirement for the strings to be of a ferromagnetic nature. Here is the element and the wire pigtail that feeds a signal to the chrome-plated output socket.


Conclusion

I realize that this was just a basic glossing over of what makes these pickups what they are and why they sound the way that they do. I’m throwing this out there just as a general information piece and as a foundation for perhaps a more in depth treatise later in the year.

There have been some new developments in pickups over the last few years that change the game a little. I thought about taking that up here; still if I don’t look at the basics first, I’ll most likely lose some folks in talking about the newer innovations.

The lowly pickup is really the most significant and inexpensive bit of gear that one can change if one is looking for a significant change in their tone. Sure, changing strings and using a different kind of pick are cheaper options in the changing of one’s tone, but changing out a pickup can often be done for under $50 and it will completely change the nature of the instrument’s tone far beyond what a different kind of string or pick material can ever hope to do.

There is a lot to be gained, or lost, for that matter with a pickup change. It helps if one understands what is going on before attempting such alterations. Hopefully the reader has a little better idea as to what is going on underneath those plastic or metal pickup covers. I know this material has been gone over before, but hopefully my approach, being a wee bit different than the usual, will allow for a few nuances to be considered.

Going forward in another article, I’ll bring forth some of the newer and different approaches that do not rely on the attempt to capture the Golden Era of vintage pickups. I think that is a dead, well beaten horse. Lace, Fishman and Lawing are companies that have a different take on pickups that is not an attempt to capture what was done fifty to sixty years ago. With this foundation here, I’ll write a future article about what these companies are doing and what’s different, fun and exciting about their approaches.

-Kirk Bolas - MU Columnist
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