Wizard wrote
I shall continue my naive / learning questions ...
No harm in that.
Why would you want a pickup to have more output, given that it's going to be amplified anyway?
Damn jolly good question! Originally it was to drive the amplifiers harder. The original guitar amps were designed to be as clean sounding as possible with the technology of the day (valves/tubes), then along came those pesky rock chaps like Ray Davies, Jimi Hendrix, Eric Clapton, Jimmy page, etc., etc., etc. who made distortion both musical and desirable. Suddenly players
wanted distortion (ironically only shortly after the invention of the transistor, which finally enabled designers to make distortion free amps). This is also why rock players usually used Gibson guitars - the Gibson humbuckers had a higher output than the Fender single coils and could make the amps distort a lot easier.
Amp and guitar manufacturers were slow to respond, but up popped Larry DiMarzio in the '80s with his Super Distortion high output humbucker (starting the replacement pickup industry) and higher output single coils too, and other guys like Seymour Duncan soon followed. The output power of the pickup was the overriding design criteria, rather than the tone.
Now of course, most amps are designed with distortion in mind and it's easy to overdrive most amps with most any guitar, but the paradigm is deeply entrenched in the psyche of many a player: More power = better, and humbuckers for distortion and single coils for cleans.
Is the principle of a pickup as simple as a coil around a magnet?
Does it work because the (metal) string cuts the lines of magnetic flux and induces a current in the windings?
Exactly.
Is a current induced in the string?
Does it only work with (conductive) metal strings?
They must be ferromagnetic, not conductive. The two go hand in hand though - ferromagnetic materials are usually conductive and this also allows you to earth the player via the strings and make them part of the guitar's shielding ?
