Pickup Inductance: A Useful Circuit Parameter, Not a Tone Score

Inductance describes part of the winding behaviour

A pickup winding behaves as more than a DC resistance. Its changing current produces a changing magnetic field, and the winding’s inductance contributes frequency-dependent impedance. Inductance is measured in henries. A DC ohmmeter does not measure it.

The winding and magnetic construction influence inductance. The pickup also has resistance, capacitance and losses. A useful model states those assumptions separately rather than treating the inductance number as a complete prediction of output or perceived sound.

Frequency changes the opposition to current

For an ideal inductor, inductive reactance is proportional to frequency and inductance: XL = 2πfL. The equation describes an ideal circuit element. A real pickup is a transducer with additional winding and magnetic effects, not an isolated perfect inductor connected to an ideal source.

This distinction explains why the same resistance reading can accompany different frequency response. It does not justify ranking pickups by inductance alone. Measurements need a stated method and operating frequency; two meters or test fixtures can report different equivalent values for a lossy device.

The surrounding circuit contributes to resonance

Inductance interacts with pickup winding capacitance and the capacitance presented by an unbuffered cable. A simple ideal LC estimate is f ≈ 1/(2π√LC). This is a bounded approximation, not the full response of a guitar with volume and tone controls.

Resistance and losses affect the height and breadth of the response feature. The tone network is also frequency-dependent. Adding a tone capacitor to the circuit should not be interpreted as simply substituting that capacitor for every other capacitance in the ideal formula.

Use measurements comparatively and state the setup

An isolated winding or documented pickup mode gives a more interpretable inductance test than an unknown installed harness. Record the test frequency, equivalent-series or parallel setting, fixture and whether the pickup is split, series-connected or parallel-connected.

Core and metal losses can make an equivalent inductance frequency-dependent. Published values from different test methods may not be directly comparable. A practical comparison should hold the measurement method and surrounding load constant, and report uncertainty instead of inventing excessive precision.

Turn the parameter into a useful question

• Which coil mode does the number describe?

• What cable capacitance and amplifier input are connected to the passive pickup?

• Are pot resistance, knob position and tone connection the same in the comparison?

• Does the measurement method match the maker’s stated conditions?

• Which parts of the real instrument are outside the simplified model?

Use Signal Forge to change one supported pickup or load assumption at a time. Keep its modelling limits separate from mechanical pickup placement, string motion, amplifier behaviour and listening preference.

References and scope

Seymour Duncan: pickup inductance background

Seymour Duncan: pickup impedance and response

Seymour Duncan: resistive and capacitive loading context

This guide describes passive instrument electronics. Verify the actual part documentation and disconnected circuit before changing a connection. Tool links below are for supported configurations and do not imply that every modification in this guide is modelled.