Resistance is useless!
Resistance is useless.
Most guitar pickup manufacturers will list a specification for their pickups. The most common spec given is a DCR reading (Direct Current Resistance) taken from the coil. The listed value is typically "K" or Kilo-Ohms (tens of thousands of Ohms). A typical traditional single coil pickup will read around 6.0K (+/- 0.5K), and a typical P.A.F humbucker around 8.0K (+/- 0.8K). Higher or lower figures may be quoted. If all factors are created equal (coil wire diameter, insulation type & thickness, bobbin dimensions, number of turns) then some very basic idea of the "hotness" of your pickup may be offered.
To see say 7.4K on a Tele bridge, and then 7.4K on a Tele neck pickup and think they are identical winds will not tell the full story. The neck pickup will usually have fewer turns of a thinner gauge wire, so this neck pickup is actually less powerful in terms of the coil wind. This is what you want from a Neck pickup in most cases. So, extrapolating DCR figures in K can be fraught with peril! DCR figures won't tell you much about the tone of the pickup, so it is always best to get an audio or video demo of the pickup you're looking to use.
What DCR readings don't tell you: In a guitar, the pickup is working in an AC (Alternating Current) circuit, not a DC circuit. Instead of DC Resistance, AC circuits use something slightly different called Impedance. Impedance changes with frequency and a range of other factors. DC resistance may be useful in DC circuit architecture, but not so much in the AC audio path (speakers, amps, preamps, microphones and guitar pickups)
Inductance. This may indicate how much metal there is in a pickup. Inductance rises with wire turn count but also with the addition of baseplates or different alloys used in slugs, blades and rod magnets. Some metal pickup covers may also shift inductance values.
Gauss. This is the level of magnetic flux density your magnets produce. A typical AlNiCo magnet when it is made, is not yet a magnet, it must be first charged. This is something we do in-house. How you charge it, how much you charge it and also how much you un-charge (degauss) it each have a huge influence on tone. This adjustment can and does affect Inductance, output and most importantly, the final tone you hear. We have in place proprietary self-built equipment and procedures to achieve very specific gauss levels.
Capacitance. Different winds can change capacitance, but not by much. Your guitar pickups run in a complete and complex system of guitar strings, potentiometers, capacitors, cable and amp (a lot of variables in preamp and amp design) to your speaker. The capacitance of your guitar cable will outweigh capacitance variables in a guitar pickup.
Every one of these factors, AC Impedance and Reactance, Flux area density (B & H), coil dimensions, Inductance (of coils, magnets and any metals) influences the final outcome and your tone.
It's not rocket science! I hear you say. Rocket Science and Guitar Pickup technology do have a lot in common, they're both sharing the principles of Quantum Electro-Dynamics.
Cheers, Ben Bailey.