
They're called Filtertrons, and are a type of "humbucking" guitar pickup designed the the Gretsch company in the 1950s. There are two basic types of electric guitar pickups -- single coils (think Fender Statocaster/Telecaster) and humbuckers (think all things Gibson, including the Les Paul). Single coils tend to be bright. Humbuckers tend to have a big, warm sound with a higher output, that is somewhat muted in the highs. Filtertrons, though they've been around for years, are a new discovery for me. They have a rather low output for a humbucker, which is fairly easy to deal with, but a sound that is...well, I'm going to sound like an audiophile..."magical." They have this big warm, fat, powerful lower midrange like the best Gibson humbuckers, with a lovely, complex chime on top. Pixie dust glittering on a sledghammer. Just magnificent clean tone, and the nicest, most clearly articulated overdrive when used to hit a tube amp hard. I like the ones that came on my recently acquired Gretsch so much, I put one on one of my Fenderesque guitars, and I'm thinking of having another.
Just thought I'd share for the few who care.
Tim