A phenomenon where physical shocks, taps, or acoustic vibrations cause internal elements of an electronic component to move, altering its capacitance or resistance and generating a spurious electrical signal. It is a notorious problem in vacuum tubes, where grid wires physically vibrate, but it also affects ceramic capacitors and certain inductors, introducing ringing or howling noises into high-gain audio and RF circuits.
Tap the chassis lightly with the handle of your screwdriver; if you hear a pinging noise in the speaker, you've got a bad case of microphonics in the preamp stage.
High-K ceramic capacitors are highly piezoelectric and prone to microphonics; use film or C0G/NP0 ceramics in sensitive analog audio paths to avoid the issue.
Also heard as
- microphony
Related terms
Vacuum tube
An evacuated glass or metal envelope containing electrodes used to control electron flow.
Capacitor
A passive two-terminal component that stores electrical energy in an electric field.
Hash noise
A harsh, wideband electrical interference that sounds like a buzz or static on an audio output or looks like thick fuzz on a trace.
Valve amplifier
An electronic amplifier that uses vacuum tubes instead of transistors to boost a signal.
Coil whine
An audible, high-pitched noise generated by magnetic components vibrating under load.