This guide will take you through the various materials & winding techniques used, and attempt to distill a complex art into an understandable formula. As a result, you should be able to wind your own pickups with some level of confidence as to the expected tonal qualities.
If you’re reading this, you’ve probably decided you might try your hand at winding your own custom pickups. In theory, it’s quite a simple task. That’s because pickups are fairly simple devices: copper wire wrapped around a magnet. That’s it.
So why write an entire guide about it? Because the amount of variation from one pickup to the next, in spite of such simple construction, can be quite significant. Enough to create an entire industry, thanks to the wide spectrum of tonal possibilities. These qualities go beyond simple EQ profiles, compounded by volume & microphonics.
In order to create great pickups and wind with tonal intentions, you have to know how they work. Or at least have a strong grasp of the concepts. If you don’t have any experience with physics or electronics terminology, it can be a little overwhelming.
Before we move on, it should be noted that this article’s focus remains on magnetic pickups. For that reason, we’ll just do a brief breakdown of the main pickup types that are found suitable for electric guitars (and various other instruments).
The process of turning a mechanical vibration into an electrical signal is called transduction – all pickups are transducers. The most common types of pickups are as follows:
1. Magnetic Pickups
The mechanical vibration being detected is the movement of the string itself. It is transduced by an inductor (copper wire + magnet) when changes in the magnetic field (flux) are caused by the motion. This particular process of transduction is called electromagnetic induction.
String vibration → Changes in magnetic field (flux) → Induction into copper wire as an electric field/signal → Onward to amplification
2. Piezoelectric Pickups
In common applications, Piezo pickups transduce mechanical movement not from the string itself, but rather from the vibrations the string transfers to connected parts (bridge pieces, soundboards, etc). The way the vibrations are detected is through a pressure sensor made of compressed quartz. The term “piezoelectric” refers to the rare physical property of some materials producing electrical signals in response to pressure. Other piezoelectric materials, like aluminum nitride or zinc oxide, may be found in Piezo pickups as well.
String vibration → Vibration transfers to bridge → Piezo element in contact with the bridge senses changes in pressure caused by the vibration of the part, creating electrical signals → Onward to amplification
3. Microphone Pickups
A microphone is actually very similar to a magnetic pickup. It uses an inductor that transduces the mechanical motion within a magnetic field to an electrical signal in copper wire coil. The main difference is that the magnetic flux being detected is not from the string’s vibration in the field. The coil has a very thin membrane pulled tightly over the top, creating a sort of open drum shape. When the string vibrates at a distance, it creates soundwaves by moving the surrounding air molecules. The soundwaves travel a distance and hit the thin membrane, which begins to vibrate in tandem. This vibration is within the magnetic field.
Obviously, since the signal flux is being created by any soundwave rather than just a metal string, microphones have a much wider application.
String vibration → Sound waves → Vibration transfers to membrane → Vibration inducted as an electrical signal → Onward to amplification
Note: Most microphones (including dynamic mics) rely on electromagnetic induction to convert membrane vibrations into electric signals. Transformer-less condenser microphones, however, do not.
So those are the big three transducers in the music world. Since the purpose of this guide is to have you winding your own magnetic pickups confidently, we won’t be hearing about microphones and piezo pickups again.
If you’re feeling unsatisfied with the description of magnetic pickups above, it’s probably because you want to know exactly what is occurring in the magnetic field that creates the electrical signals inducted by the copper. The next chapter will help flesh things out whilst teaching you some of the terminology you’ll need to fully understand how these pickups function.
Terms of Induction
The key to understanding the process of electromagnetic inductance is something called Faraday’s Law. It’s a fairly complex subject that’ll require some background reading in electromagnetic engineering. What you’ll be presented with in this guide is a simplified version to make things easy to understand and keep things brief. Defining magnetic flux properly is something purposefully left out here since it requires some abstract thought. We’ll stick to what’s absolutely necessary for making great pickups.
Before we move on to the actual construction and tonal implications of your materials and techniques, let’s just do some terminology. The following definitions will help you understand the electromagnetic processes at play here:
Transducer – a device that converts energy to a different form. A mechanical transducer converts electrical energy to mechanical movement, and an electrical transducer does the opposite by converting mechanical energy into electrical signals. All pickups are electrical transducers.
Inductor – a device that converts magnetic flux into electrical energy, typically by using a copper coil. Copper is one of a short list of metals which can create its own magnetic field when electricity is passed through it. For that reason, a simple copper coil can be its own inductor as long as there’s electricity running through it.
Magnetic inductors don’t require any electricity because copper also has the ability to affect and become a part of a magnetic field created by a magnet.
Due to copper’s loose surface electrons, magnetic flux (movement of ferromagnetic materials like guitar strings within the magnetic field) causes these electrons to constantly rearrange themselves, creating an electric signal. This is the process of electromagnetic induction.
Magnetic Flux – A difficult concept in electromagnetism to describe, so simplified visual representations are perfectly acceptable. The most basic description would be movement of a ferromagnetic material within a magnetic field – or, in other words, changing the magnetic field.
If a magnetic field were to be visualized as a grid of arrows radiating from the magnet’s surface, the magnetic flux would be the measurement (quantification) of those lines passing through a surface. The surface area being used to measure the magnetic flux must be defined and constant to detect changes. A hall sensor can be used to measure magnetic flux. You can read more here.
Now we have a fairly good idea of what’s going on inside (and in the area just above) your pickups. The next chapter will discuss all the manners in which the inducted signal and its tonal characteristics can be manipulated by materials and construction.
Before heading on though, take a look at this monotonously narrated video for a short, succinct breakdown of the induction process. There’s a few important key facts listed at the end that’ll help you in your journey for reconciling your inductive device construction with your tonal needs!
Tonal Expectations: Construction & Materials
During the process of induction, variable materials and arrangement of parts can make all the difference in the resulting audible frequencies. If you’re paying attention, you know that we only have two functional materials in our magnetic inductors: copper wire coil and a magnet.
So what kind of variance is possible and what kind of tonal changes can be expected with each change?
1. Wire Coil
1.1 – Material
Pickups are wound with what is often sold as “magnet wire”. It’s most often a copper core with a very thin layer of insulation. Copper is used for its high conductivity and tensile strength, but you will also find magnet wire made from aluminum and silver. Aluminum wire costs about half the price of copper wire, but only has 60% of the conductive ability. Silver is significantly more expensive, but is 7% more conductive.
I’ve yet to hear of someone winding aluminum pickup coils, but silver is definitely a hallmark of a few boutique winders out there. In fact, there are quite a few people out there who will tout silver over copper for its improved tonal qualities. This is something you’ll have to research for yourself – the jury is out for the time being. It would be interesting to see a comparison of two machine wound pickups using the same specs to compare the two.
Silver is the only metal with better conductivity/lower resistance than copper. It does tend to oxidize and degrade more quickly than copper though, so without having any timelines to confirm this, it could be a potential issue for anyone wanting longevity out of their pickups. It’s also significantly more expensive. Insulation thickness’ effects on tone will apply to silver and copper wire equally though, so let’s just move on to that for now.
When it comes to insulation, you’ll usually find wire being sold with one of the following three:
- polyurethane nylon (“poly”)
Insulation material does not affect tone – theoretically, if you were to use some wire with a very thick insulation layer, like triple+ nylon, you may reduce capacitance.
This would change the tone. This would simply be due to your wire cores being spaced just a tiny bit further from each other, reducing the amount of parallel capacitance.
You may find some winders swearing by particular insulation types for their ability to resist breakage whilst winding as well.
1.2 – Gauge
Your wire gauge can make a big difference in your tone, if not simply for dictating how much of it you can get on a bobbin. The most important factor in your pickup’s tone and volume is going to be the number of winds you give it.
A thicker wire may change the resistance measurement at the end, but with the same number of turns, it should theoretically come extremely close to sounding like a thinner gauge at the same distribution.
Most commonly used in pickup winding is 38 to 44 AWG.
This is somewhere around the thickness of a hair – it can break easily, so be careful.
1.3 – Quantity
We spoke about the number of winds already briefly, but it’s worth expanding on the subject. Normally, the number of winds a pickup has is directly correlated with its strength. This is true for the most part (taking into account the magnet and winding arrangement). But there are some tonal factors that should be considered when deciding on a wind count.
Along with magnet strength, increased wind count can produce a stronger electrical signal (higher inductance). This results in a louder signal, as expected.
As winds increase, so does the amount of DC resistance (more material for the signal to travel through). This has been found to produce a darker tone, while less winds will be brighter.
1.4 – Wind Direction & Tension
Wind direction does not have an effect on tonal qualities of a pickup. It does allow for coils to be put in phase with each other to create a humbucking effect though. So it’s very important to pay attention to your wind direction and magnet orientation. Wire tension, on the other hand, is one of a few mysterious factors that shape the tone output.
You may find multiple explanations for this, but the simplest way is to consider the capacitance.
Looser = less capacitance = more highs. Tighter = more capacitance = warmer tone. And more space for winds.
Let’s look at something else that effects capacitance though: the winding distribution!
1.5 – Wind Distribution / Arrangement
The term “unbalanced” tends to be confused in the amateur pickup winding world. So let’s just clear that up definitively: unbalanced coils refers to two coils wound with slightly different counts and placed in a humbucker configuration. Sometimes it’ll be referred to as “mismatched” coils. This method allows more high frequencies to get through, lightening up your overall tone. Technically, you’re allowing a small portion of one coil to remain out of phase with the rest of the humbucker. That means there’s a chance for noise and overhead that many people might not want.
When the amount of unbalancing is kept to a reasonable level, however, the results can be brighter, more lively, and have a microphonic overtone at times.
What “unbalanced” does not refer to is the actual shape/geometry of the distributed wire in a single coil. Winding your coils with uneven distribution in the bobbin space can yield some interesting results. The characters on this site posit a theory of Gibson’s famous PAF pickups that suggests their inimitable tone was due to their uneven distribution.
Regardless of whether or not that’s true, a top-heavy pickup is going to have a different tone from a bottom heavy pickup. Same number of winds and specs – different arrangement of coil wire. Why is this? Probably a question for a physicist, things become quite abstract when you pan into the induction zone and try to explain tonal qualities with magnetic flux or electrons.
All we know is that the arrangement of wire on the bobbin has an effect on tonal output. With that known, you can understand how people come up with their own winding theories and patterns. It’s an artform that you can leave your personal touch on – one that’s heard rather than seen.
When speaking about wire distribution, we can also talk about looseness / tightness of the coil.
In most cases, when a pickup coil is described as tight, it refers to a combination of tension and strafing of the wire. While tension was just described above, we’re now going to look at the lateral distribution of the coil as it’s wound (strafing).
You’ll find that the effects of tension and lateral wire distribution are essentially the same. This is primarily due to the distributed capacitance changing in relation to the proximity of the strings to one another. Strings that are closer together will create parallel capacitance (increased capacitance), while spreading them apart will prevent this from occurring.
Along with increased harmonic overtones, the decreased capacitance is a major factor in what makes a “scatter-wound” pickup notable.
2.1 – Material
Generally, pickups will use one of two magnet types: Alnico or Ceramic. Alnico magnets are divided into strength categories, so an Alnico II magnet is on the weaker side, while an Alnico IV is quite a bit stronger. There are two other types of permanent magnets (Neodymium and Samarium Cobalt), but they tend to be quite a lot stronger than what’s needed for a pickup.
The answer as to whether or not the magnet type affects the tone will be different depending on who you ask. It’s quite well established that a stronger magnet will induct more high-end frequencies, which can be a good or a bad thing depending on what you’re aiming for. Stronger magnets also produce more volume (higher inductance).
There’s also another factor outside of the strength of the magnet: the shape of the field.
2.2 – Magnetic Field
The shape of a pickup’s magnetic field is an often overlooked factor in tone. The size of the field and position of the strings within it are key to a pickup’s volume. But a few of the more intrepid pickup winders out there have gone out of their way to try to shape and focus the field to see how it affects tone.
By changing pole materials and shapes, or adding a bottom plate in contact with the magnet, a pickup’s sound can change significantly. It’s encouraged that you experiment with this whenever the opportunity arises.
2.3 – Polarity
Polarity and wind orientation do not affect tone. They do affect two coils’ ability to phase cancel (“humbucking”).
2.4 – Strength
Magnetic strength is most directly associated with signal strength. An increased gauss strength will have a stronger induction, creating a stronger electrical signal. Not too much to ponder there.
However, the magnet’s strength can reach points on either end of the spectrum where it may affect tone negatively. Too strong and your strings may become dampened (less sustain) by the downward pull, and if the magnets are too weak, you’ll have a very muffled, dark tone due to the field shrinking.
These issues can be addressed with other factors, such as pole size/shape/location, the closeness of the pickup to the strings, and even the wind count. It’s a great area to experiment in.
Pickup Tonal Quality Measurements
So we’ve got a healthy list of materials to choose from now, and multiple ideas for assembling it all together. And we also have a bunch of different methods we can experiment with when it comes to winding our coils. If ten people were to take this information and go off to each wind their own pickups, you would undoubtedly get ten different pickups.
There’s a lot of room for individuality in pickup-winding. Having a strong grasp of the electromagnetic laws that govern the process, or even just a general understanding of the forces at work will give you creative power. This guide seeks to give you the ability to make confident, purposeful decisions about your material selection and assembly to achieve a tone you have in mind.
Let’s take a look at the specifications for a pickup we’re all familiar with:
EMG81 Pickup Specifications:
- Resonant Frequency: 2.25 kHz.
- Average/Max Output Voltage: 1.25/1.75.
- Noise: -91 dBV.
- Output Impedance: 10K Ohm.
- Magnet: Ceramic 56x3x13mm.
- Wire: 0,06mm PE.
- Core: 54x3x12, 5mm solid steel.
- Coil: 4,18 KΩ (one coil), wax potted, approx. 5500-6000 turns, h=7,5mm.
Some of these measurements and specs are indicative of tonal qualities, while some are not. Let’s go down the list and define each measurement and its importance.
|Also called “Resonant Peak”, this is a measurement of a coil’s frequency profile that reveals a single frequency that it is most “sympathetic” to. A pickup’s resonant frequency can tell us a lot about its tonal qualities in terms of brightness/darkness and bass/treble.
Generally, the higher resonant frequencies indicate a brighter tone – though after 7k (approaching 10k), your ears become less sensitive and you enter territory that approaches inaudible ranges. So after 7k, you can expect the brightness to begin turning into a flat tone.
Measuring a coil’s resonant peak requires a multimeter and an oscillating frequency generator, among a couple other things. It’s a process best left for another article. Here’s a video explanation.
Our example pickup coil (the EMG 81) has a resonant frequency peak of 2.25khz. Let’s take a look at this chart stolen from Premiere Guitar to see what that might sound like, tonally:
So, according to Premiere Guitar, the EMG 81 should have a ‘singing’ tonal output.
Since this is a subject that deserves its own article, let’s just try to simplify things for our usage in making pickups. The resonant peak will tell how bright a pickup will sound:
**This does not take into account the other big tone factor measurements that are all intertwined with the resonant peak: capacitance, inductance, and DC resistance. Each spec affects the others.**
|Measuring a pickup’s output voltage can tell you about volume, and it can help you make some inferences about some other specifications, and it can even tell you how it might perform with other equipment. But voltage does not have a direct tonal indication.
Things that can affect a pickup’s output voltage: magnet strength, number of winds, wire gauge & distribution, and of course…the presence of a battery circuit. That last one is just to remind us that the EMG 81 example we have here is active.
Why mention this then? Well, having a high voltage pickup can help your guitar’s tone break apart sooner whilst running through an amplifier, for one. You can diagnose issues with shorted coils quicker if you know a pickup model’s general output voltage range. You can make an assumption about the way the coil was wound based on the output voltage and capacitance, or any number of other specs.
|We all know what noise is. Active pickups will almost invariably have much lower noise output due to the fact that the natural volume of the coil is much lower (lower winding, less powerful magnets).
Noise levels can help diagnose issues with pickups if you know what sort of decibel range to expect, and it can help you perfect your craft if you take measurements of your own coils before and after potting to ensure your effectiveness.
But noise is not a tonal factor.
|Output Impedance / DC Resistance
|Output impedance is a measurement of resistance – a perfect signal is 0 Ω. This active pickup in the example here has an output impedance of 10kΩ. Since the EMG 81 is a humbucker, you can assume that each coil is about 5kΩ.
A pickup’s resistance is often the one spec you’ll see listed up front in the title of the product page, or whatever you’re reading. That’s because it’s a good measurement to make an assumption of a general output level, and is great for comparing pickups to each other. In terms of volume, oomf, breakup, presence, whatever you call it. But not tone.
Its most important value is that it’s an integral measurement for finding the resonant peak values that are more indicative of tone. This article from Lollar will help break things down (from a far more experienced perspective).
However – there is something called a low-impedance pickup which you should be aware of. While most every modern guitar pickup has a high output impedance (due to coil size and material being linked directly to its value), some manufacturers have made low-impedance pickups that utilize only one or a few winds. The claim is that you achieve a much wider frequency spectrum (in terms of frequency resonance) with a lower output impedance.
Before we delve too deep into the subject, this article from Seymour Duncan already explains things adequately. This article from Premiere Guitar on low impedance pickups helps round things out nicely by outlining some specific applications of varied impedance.
You can observe the effects of lowered impedance and wider frequency resonance range in active pickups which utilize a lower wind count / DC resistance.
Anyway…back to the matter at hand! DC Resistance is a good indicator of general output strength, useful for comparison to other pickups, and great for consideration amongst other specifications to get a complete idea of how a pickup will sound. But as an indicator of tone alone, resistance doesn’t tell us much.
|Inductance / Capacitance
|We spoke about inductance earlier, so you know it’s specifically speaking about Faraday’s law of induction, which finds that changes in a magnetic field (strings moving, flux) induce electromagnetic force (movement of electrons) in an electromagnetic conductor (magnet + coil).
So we know that the inductance process (and therefore a pickup’s measured inductance value) is indicative of signal strength / volume. And that increasing your inductance (by using stronger magnets, for instance, or moving the pickup closer to the strings) will directly increase output volume.
Now we need to get an idea of how a pickup’s inductance can affect tone. A while ago when we spoke about the capacitance generated between two parallel wires in a coil, something referred to as self-capacitance. A coil that is wound more tightly with the wire distributed uniformly will have a higher capacitance (and a warmer tone, consequently). A more loosely wound pickup will have a lower capacitance (and a brighter tone, though at the risk of some microphonic overtones when distribution is randomized).
So we know that capacitance can affect tone in a general manner, but let’s come back to the relation of capacitance to inductance. This excerpt from Wikipedia sums up the tonal changes:
“The turns of wire in proximity to each other have an equivalent self-capacitance that, when added to any cable capacitance present, resonates with the inductance of the winding. This resonance can accentuate certain frequencies, giving the pickup a characteristic tonal quality. The more turns of wire in the winding, the higher the output voltage but the lower this resonance frequency.”
So, what we’re speaking about is the result of two build specs working together. Inductance and capacitance each have their own separate variation possibilities: inductance (and output voltage) is based on magnet strength and wind count, while capacitance comes from parallel winding, wind count, and wire material/insulation thickness.
Only when you consider these two factors together can you make an assessment about the pickup’s resonance frequency. From there, you may make adjustments to your inductance and/or capacitance to focus your pickup’s overall tonal output.
|The manner in which your magnet selection affects tone is two-fold. First, as the magnet strength increases, so does the coil’s induction level, and along with that comes an increased capacitance. As we know, higher capacitance means a warmer, bassier tone with less high frequencies.
Secondly, a magnet’s strength, shape, size, location, and any conductive parts within its field changes the shape of the magnetic field itself. This changes the magnetic flux when the string is plucked and can be responsible for different frequency ranges as well as dynamics (volume, overtones).
The variance between different magnets is distinct enough for people to become die hard fans of particular magnet types, and you can go so far as to attribute particular guitar tones as being dependent on their pickup magnets.
The difference between an Alnico II and a Ceramic magnet is significant – you should be familiar with each of them.
You can find some general differences in tonal qualities in the chart below, but external research and sound comparisons are recommended for a better understanding:
To close things out, here’s a poignant quote from that Dylan character (you’ve seen him on Youtube if you’ve looked up anything to do with pickup winding) that attempts to place these specifications in a hierarchy:
Finally we reach the end….of Part I.
What did we learn? If you read everything, you just absorbed a lot of data. Hopefully, there was enough semblance in how it was presented to you to give you an idea of how to manipulate a pickup’s tonal output. That’s the end goal, put simply.
Here’s a couple potential scenarios to consider:
- A client wants a custom-made bridge pickup for his rock & roll band that has a strong midrange and a decent output for overdriven tones. What kind of magnets and winding specs/materials should you use?
- A client brings a neck humbucker with Alnico 5 poles and a 6500 wind count. He feels the sound is too “shrill” and “tinny”. On top of that, he’s disappointed with the output, which has declined over the ten years he’s had it. What are some options you can give him to address this?
- You want to build the ultimate high-gain humbucker that has a fairly high output and retains an organic tone profile. What could you do to achieve this?
You’ll note that there’s multiple ways to address each of these things – some of them may work out better than others. It’s up to you to experiment and learn. You’ll also want to do a little more reading from other sources, because in tonal matters, one voice is never going to satisfy everyone. There are a couple pickup winding “gurus” on Youtube – some of them take a more scientific approach, while others seem to draw everything from experience.
Something that wasn’t covered in this article is wind counts and resistance measurements – this is a subject more suited for Part II. The second chapter to this pickup winding saga will go over the actual winding process, techniques, machinery, testing, and everything else you were probably hoping to find in this one. It will also include a large list of manufacturer’s pickups with wind counts, measurements, and materials to help you base your own work around. So be sure to check back soon for that – and feel free to put yourself on the mailing list (on the front page) if you’d like to receive an update when it’s published.
Regarding Alnico IV Magnets
Previously, in this article, it was stated that Alnico IV magnets do not exist. And that is 100% correct in the eyes of the MMPA, who have no designation for it. However, you’ll still find almost every pickup manufacturer building pickups with Alnico IVs…how is this possible? There’s a lot of theories and rumors floating around as to the composition and existence of this magnet type, so here’s a few you’re likely to run into:
- Alnico IV magnets are flawed Alnico V magnets, created due to bad mixtures of the ingredients that comprise an Alnico magnet.
- Alnico IV magnets are simply de-magnetized Alnico Vs.
- They are a combination of Alnico II and Alnico V ingredient ratios.
Alnico IV was a designation used in the 50s alongside I, II, III, and V. It was just as valid as any other, with its own specific ingredient ratios. According to Tim from Bareknuckle Pickups, the correct mixture to create an Alnico IV is as follows:
- Al 7%
- Ni 14%
- Co 24%
- Cu 3%
- Ti 0%
Tim also provides us with some handy specs and notable qualities of the Alnico IV magnet, having taken the formula directly from Alnico IV samples from the 50s:
- Br: 8000 Gs, Hcj 660 OE, BHmax 2.0 MGOe
- Alnico IV is Isotropic and is made specially for us based on original samples from the 50s.
- Alnico IV is definitely not sub standard or low charged Alnico V-Alnico V, VDG and 5-7 is also heat treated differently.
So, there you have it – Alnico IV may not have an official designation anymore (not sure exactly why, perhaps the MMPA just couldn’t find a practical industrial need for it), but it did exist. And it does exist today too, because people like Tim are having this formula specially made for them.
The downside to there not being an official designation for this grade of magnets is that virtually anyone can sell Alnico IV magnets without being held to any standard of quality. Perhaps that is why you hear many people complaining of the hit or miss quality of these pickups, or frequently describing them as slightly weaker Alnico 5s. You can trust that a reputable brand such as Bareknuckle or Seymour Duncan will be making an effort to retain the standard established long ago for these magnets, but even then, there is a chance that they’re working with slightly different formulas.
Feel free to direct angry emails to the author using the contact form.