By Kevin Beller
Seymour Duncan’s VP of Engineering & New Product Development explains how this crucial component shapes your sound.
There aren’t many parts in a traditional guitar pickup: magnets, wire, and a bobbin or coil former to hold them together. But these simple components form a complex interactive system, one in which small variations in materials can have a huge impact on your sound.
Take wire, for example. During my 33 years at Seymour Duncan, we’ve spent countless hours listening to and documenting how different types of wire affect a pickup’s sound. The gauge (or size) of the wire, its insulation type and thickness, the purity and suppleness of the copper — they all influence the tone in subtle yet important ways.
The thick and thin of it. We use a wide variety of wire gauges in our pickups, most frequently in the 41 to 44 AWG range. This wire usually starts out as a big, heavy spool of 6-gauge wire as thick around as your pinky. They draw it through metal dies again and again until it’s approximately the thickness of a hair on your head.
Over the years we have determined which gauges are most conducive to certain tone categories. Here’s an example: Two pickups can have an identical number of turns and identical magnets. But by using a different gauge of wire, we can make one a little fatter sounding while having a smoother on the top end.
Aside from tonal considerations, we sometimes choose a thinner wire for space reasons. The more winds a pickup has, the hotter the output, so if you’re winding a pickup that has to be very compact, that may call for finer-gauge wire. For example, a customer who had some challenging requirements for a custom Dobro pickup recently approached us. He wanted the output as high as possible, but the overall height could not exceed 0.210”. Using a fairly fine gauge of magnet wire and a special magnetic structure, we were able to create a powerful and very compact pickup that could slide into the tight space beneath the strings. We’ve done numerous custom guitar pickups with similar challenges.
About insulation. There are at least 18 different types of wire insulation. There are polyurethanes, nylons, poly-nylons, polyester, and Teflon, to name a few. The insulation has a major effect on a pickup’s sound, and over the years we’ve learned how to use different types of insulation to refine a pickup’s tonal response. For example, we often use wire with heavier insulation to maintain more high-end detail.
While not strictly a type of insulation, bondable wires are also available. These have an adhesive overcoat that can be activated by heat or chemicals. With proper tooling, it’s possible to wind freestanding coils without having to use a bobbin structure of any sort. This can be useful in certain specialized applications, but we have avoided bondable wires because the winding and layering characteristics are inferior to conventional magnet wire.
The right stuff.Whatever the wire type, we use vendors who care as much about quality as we do, and we don’t mind paying extra to obtain wire that exceeds industry-standard tolerances. Beyond that, we test every case of wire that comes in. We measure the overall thickness to make sure it’s within spec, and we measure the resistance per foot down to three decimal places.
Of course, we use period-accurate wire in all our vintage-style pickups. One popular vintage-style insulation is Formvar, which was used on old Strats and on some Jazz Bass pickups. But the insulation vintage buffs know best is plain enamel, with its blackish-purple coating. Plain enamel wire was common in the ’50s and into the ’60s before the new insulations had been invented. It was used in all the old Gibson P.A.F.s, and many of the earlier Fender instruments. We use plain enamel wire in such pickups as the STL-1 and STR-1 Tele pickups, vintage-style PAFs like the ’59 model and Seth Lover, many Antiquity models, and of course on many Custom Shop models.
Finding quality enamel wire. Today there is little demand for plain enamel wire — except for those of us who are passionate about tone. You have to sand the wire by hand before you can solder it, and not many companies want to add that extra labor. As a result, there are only a few companies who still make true plain enamel wire.
With so few manufacturers, quality control can be a real problem. There’s one particular vendor I won’t mention whose wire is so full of voids, it’s almost unusable. Then there is a lot of wire that looks right, with that nice blackish-purple color, but it’s not even real enamel. So we buy in large quantities from a company that we have determined is the best at providing void-free, well-annealed wire. (Annealing is the process of heating and cooling the wire under controlled conditions to restore flexibility and suppleness and remove work-hardening stresses. It’s hard to wind a nice, controlled coil and get that critical layering right when the wire hasn’t been annealed properly.)
Beyond copper. We use silver in our new Zephyr pickups. Silver is the only material that has a lower DC resistance per unit length than copper.
Unfortunately, it’s brutally expensive these days, but there’s a remarkable difference between the sounds of silver and copper. Pickups wound with silver wire have powerful dynamics, explosive attack, and a complex, harmonically rich sound while producing superior individual note definition and detail in chords. Silver is more supple than copper, so it winds a very nice and regular coil. I use silver when a customer requests it, or when someone wants to extend the pickups’ response at both ends of the sonic spectrum.
Not just the wire, but the way you wind it. Voicing a pickup isn’t just a matter of selecting the right wire, insulation, and number of turns — how you lay the wire is at least as important. Among other things, this determines the pickup’s distributed capacitance, which refers to the capacitor formed between the layers as the coil is wound. This property affects the resonant frequency of the coil and dictates the high-frequency roll-off point, so it’s one of the factors that let us fine-tune a pickup’s high-end response.
Over the years we’ve developed some very interesting ways to get a variety of tones from our pickups, whether it’s hand-winding, or precisely controlling the winding pitch on our CNC production machines. Every SD pickup, whether it’s from Custom Shop or our production floor, is designed with these considerations in mind.
Crafting the perfect pickup. Voicing a pickup is a delicate balancing act of tonality, a constant give-and-take. But thanks to all those years of listening and analysis, we can control the complex interaction of wire type and winding technique. We choose the materials and production techniques to deliver exactly the sound you’re looking for.
A lifelong bassist, Kevin met Seymour through a local music shop where Seymour did repairs. “I used to take my Gibson bass to him all the time,” he remembers. “Like me, he was obsessed with getting the right sound.” Kevin joined the fledgling Seymour Duncan company in 1979 and became head of engineering a few years later.
According to co-founder and longtime company president Cathy Duncan, Kevin had the right talent at the right time: “As we started growing, we needed someone with Kevin’s level of precision,” she recalls. “A lot of technical standards were pretty loose back then, but we wanted to aim higher. They say vintage pickups vary like snowflakes, which is only okay if you’re lucky enough to get one of the good ones. Thanks to Kevin’s persistence and precision, we can give musicians a perfect snowflake every time.”