The Pole Pieces in a Guitar Pickup
Pole pieces are the screws, poles, or posts that run through the guitar pickup’s coil to serve as a magnetic conductor for each string. Frequently you see one pole piece per string (or two, in a humbucking pickup), but many designs also employ one long pole piece, or blade, to detect each string.
The pickup’s magnet or magnets can double as the pole pieces, and in such cases are mounted within the center of the coil. Alternatively, the pole pieces can be steel rods or adjustable bolts, which run through the coil of the pickup to contact a magnet mounted beneath, thereby conducting that magnetism to create a magnetic field above the pickup itself.
Adjustable poles can be raised or lowered to balance the relative loudness of each string; fixed pole pieces are often inserted at heights intended to prebalance such output levels.
The use of steel pole pieces versus magnet pole pieces constitutes one of the most significant variables in pickup design:
Magnet pole pieces tend to have a relatively clearer, tighter, more focused sound, with crisp highs and firm lows.
Steel pole pieces tend to have a relatively thicker, meatier sound, with a little more hair around the note.
Some pole pieces are unseen beneath their covers, such as the second, nonadjustable row of steel poles in the classic Gibson humbucker, the Alnico rod-magnet poles beneath the plastic covers of a Fender Mustang, or the steel cover of a Rickenbacker “toaster top,” or the Alnico bar-magnet within the coil of a DeArmond gold foil pickup or a Gibson Firebird mini-humbucker.