Fender bass pickup question

[StarryNight]

According to Sam Lee Guy's response to a thread a while back, the length of rod for a Fender J or P pickup is .78". I have a P bass cover that measures .54" deep which leaves a hell of a lot of rod below the coil (assuming the bottom of the bobbin is set flush with the botom of the cover and leaving a bit above the coil to sit flush with the top of the cover). Can one get by with a shorter rod or is part of the Fender mojo having that length of rod below the coil?

[David Schwab]

That's not right.. I have a '74 P bass pickup and the magnets are 0.532" tall. They extend out the top of the flatwork 0.071" and out the bottom 0.026".

Maybe he meant the single coil P bass pickup?

Stew-mac now has P bass kits:

STEWMAC.COM : Parts Kit for P-Bass Pickup

You can get assembled bobbins with charged magnets from GJ:

P-Bass Bobbin-#1564

[StarryNight]

Yes, sorry! I shouldn't read these threads too late at night!

http://music-electronics-forum.com/t6896/

It seems the J Bass pickups are .78" while P Bass are .53" in length. Appologies for the mis-quote. I guess single coil Js needed longer magnets? Any theories as to why?

[David King]

The J pickup uses a different geometry, it's a narrow, tall coil that keeps more of the wire close to the poles for maximized output and treble content.
The P coil is flat and wide, slightly less efficient probably and it's got a different tonality. I think most of the tonal differences we hear are due to placement vs the pickup's design. If you stick a J pickup in the P location you'll hear more P bass than J bass...

[David Schwab]

The split coil P bass has squat coils to get a different tone from the Jazz or other single coils.

Another example is comparing a Strat pickup to a Jazzmaster.

The wider squat coils have a mellower tone.

[StarryNight]

thanks guys. this is giving me ideas around playing with different coil depths. I guess winding a deeper coil will put more wire on the bobbin (possibly boosting mid range) but also closer to the rods which inherently makes for a brighter pickup(?) i think i remember seeing a thread or two about the subject. Another arguement for an LCR meter me thinks.