Q: What is the difference between P-90 and P-100 pickups? The “soapbar” P-90 appears quite similar to the pickups on Fender’s Jazzmaster. Are they the same basic design?
A: The main difference is that the P-90 is a single-coil pickup that was originally introduced in 1946, well before the first true humbuckers appeared in 1957. Meanwhile the P-100 is actually a stacked humbucker. It delivers some of the character of a P-90 because the coils are wired in parallel (a standard humbucker has coils that are wired in series). The parallel wiring helps the P-100 retain more high frequencies than are present in a humbucking pickup. As far as the pickups found on the Fender Jazzmaster, these have magnets that pass through the coils, giving a narrower magnetic field, and thus it sounds more similar to a Fender-style single-coil than any of the Gibson-style P-90s, as Gibson magnets are placed underneath the coils, which produces a much broader magnetic field.