Hi all, long time bareknuckle user but only just signed up!!
Ordered some blue note P90s to go in my 56 reissue goldtop. Also got some new pots etc. So I wired up as follows:-
500k volumes (CTS TVT), 500k tones (CTS premium) and a 15 cap for the neck and 22 for the bridge (russian K40Y-9 PIO caps). Wired 50s style. Install all went fine.
Trying the pickups the neck sounded wonderful and the bridge had way too much treble and sounded very thin. Has to put tone down to about 2 to get anything usable but this then muffled the sound. This guitar has fixed "ledges" for the pickup routes so I can raise but not lower. On a humbuckered Les Paul I would change the pickup height but not possible on this guitar.
After some reading - not much out there for P90s in comparison to humbucker pickups. Anyway changed tone pots to 250K. Treble starting to go in the right direction but still a bit too much and still sounded thin and neck a bit too dark now. More reading up and seen many suggestions to use 47 caps on P90s (Seymour Duncan for one suggests this). Thought I'd give it a try. Bingo - bridge now has loads of grunt and the there is still treble but just right. Playing bridge with tone on 7 is about right so I have room to add or take away treble. Stunning sounds now from the bridge.
Neck was now too muddy with 250k tone pots so I put back the 500k for this pickup only. So I now have
Bridge: 500k volume, 250k tone, 47 cap
Neck: 500k volume, 500k tone, 15 cap
This pickup combo now sounds superb, has plenty of bite without being "ice-picky" and is very touch sensitive.
Thought I'd post this since I spent many hours reading about different options and these work really well for these pickups IMHO.