Vistatones are an old pickup design that look a lot like humbuckers (the originals were slightly larger, but the new ones are hum sized) but are actually a unique single coil that's somewhat like a p90. Here's a short Premier Guitar article one them https://www.premierguitar.com/articl...pickups?page=6
Anyways the sound: they're very fat, and have more output than I expected without sounding overwound or congested. They have a very "vocal" midrange and go from polite when played soft to growling when pushed. Lots of p90-like qualities, but they also have that great glassy clarity of Fender single coils, the bridge position even has a bit of tele twang. Compared to Supro reissue "gold foils" (which are the Supro Cleartone design) they have a little less juicy roundness and a more aggressive bite. I'd highly recommend trying them if you have a humbucker equipped guitar that you're thinking about changing the pickups in, particularly if you're a fan of p90s.
