microphonic?

[skorb]

what does it mean that a pickup has gone microphonic?
I hear this a fair amount but have no idea what this would sound like?
also, what causes this?

[sully]

Lindy Fralin says:

A microphonic pickup can plague the player, builder and repairman. It produces an uncontrollable, unmusical high-pitched squeal that makes the instrument impossible to play at stage volume. The culprit is a loose component in the pickup. Either the coil windings were improperly potted (waxed), or age and abuse have loosened the windings or some other part of the pickup. For example, a common problem with Telecaster® bridge pickups arises when the metal base loosens and vibrates under the polepieces.

[skorb]

thanks Sully!