Originally Posted by ncapone
I have noticed today that when I turn both of the pickups in my Jazz bass to full, there's a decrease in volume.
This is completely normal for a Jazz, you just never noticed it before.
Also, if they're both on full and I play a note and turn one of them down, I get a sort of a "mwah" sound that I've never noticed before. Is that normal?
Don't know about this but I have never tried it so it may be normal.
I'm using Super 55 split coil pickups. I did notice today in the original wiring diagram that the tone pot output is wired on the outer lug instead of the middle lug like normal. Why is that? There's something else also wired to it (the big white circle). Is that another capacitor? If so, what value would it most likely be, and why is it there?
I don't think there is any reason you cannot use a normal tone control with these pickups. The Fender diagram appears to show a Greasebucket tone control
. Kinda. They seem to have left off the 4.7k resistor between the small cap and ground. Years from now someone will read this and Fender will have moved or deleted that diagram so the big cap would be 0.1uF, the small cap would be 0.02uF, and the one lead of the small cap should go to ground through a 4.7k resistor instead of directly to ground. Of course Fender uses those exact same values for the Greasebuckets in their regular guitars so one could argue that the values need to be adjusted for a bass. Seems like bass players routinely rip out their Greasebuckets and replace them with regular tone controls which might also argue that the values should be adjusted if one is going to use them on a bass. I'm just guessing but you might want to go 0.22uF and 0.047uF on a bass. You might want to play with the 4.7k value too. Or just use a regular tone control....
My guess is that someone at Fender picked up the Greasebucket diagram to use with these pickups and then someone else told him/her to eliminate the resistor, not realizing the rest of the circuit needed to be modified too if it was going to be a normal tone control.