Hi, I'm new and I have a Fender MIM Jazz and tried the parallel/series mod with a push/push DPDT switch. The sound I wound up with has great mid growl but bottom end just ain't happening. Also when in series the volume is more quiet(lower). I thought maybe I wired it wrong and went back and rewired it, hardwired in series. Still sounded the same. I have a stock neck p/u and a Quarter Pounder bridge p/u. Could this be a problem. I will eventually get the QP neck p/u. Anyway I went back and rewired it using the attached diagram. Could somebody please help me? Sorry for such a long post.

If wired properly, when in series you will be much louder than when in parallel.
Could you take a photo and/or describe how you wired it.
I'll describe how I'd usually wire it:
with the pot on top, I'd number the lugs from 1 top left, 2 top right, down to 6 bottom right.
1 connected to 2
2 connected to 1
3 input from neck ground
4 input from bridge hot
5 to ground
6 to neck vol pot input

If wired properly, when in series you will be much louder than when in parallel.
Could you take a photo and/or describe how you wired it.
I'll describe how I'd usually wire it:
with the pot on top, I'd number the lugs from 1 top left, 2 top right, down to 6 bottom right.
1 connected to 2
2 connected to 1
3 input from neck ground
4 input from bridge hot
5 to ground
6 to neck vol pot input
Just rewired it per your instructions except 6 to bridge vol pot middle prong. Still sounds the same. Even if I just hard wire it, it sounds the same as when wired to the DPDT switch. Maybe when I get the QP neck p/u it will make all the difference. I thank you though.

Problem solved! I tried the mod on my other bass (Ibanez GSR190) and it worked. I thought it must have something to do with the pups in the jazz (stock neck and QP bridge). I swaped the bridge QP with the stock pup, wired it up, and bingo, it worked. Now to just get the neck QP and swap both stocks with QP's. Thanks David. :hyper:

cool, glad you got it working!

Could it be that the stock PU and the QP have opposite windings? If that is the case, you could use these two in series by reversing the connections to just one of them. perhaps. Not sure, but it may be worth a try.

Thanks guys. It sure makes a huge difference in sound. I'm sure it will be useful at times but I really love the sound of the rear pup on my jazz soloed, maybe a little bit of neck dialed in. As for my cheap beginners Ibanez (IMHO it's really a good beginners bass), the mod turned it into a MONSTER. :D I'm not sure if the QP and stock are round opposite or what, but if the QP's are wound differently will the mod still make everything deeper or will it cut the bottom and give a snappier sound?(we're talking both neck and bridge QP's, not mixing them like I did before). If they're not going to go deeper then I won't waste my money on the neck QP, then I'll just have a lonely bridge QP sitting around my bedroom.

Thanks guys. It sure makes a huge difference in sound. I'm sure it will be useful at times but I really love the sound of the rear pup on my jazz soloed, maybe a little bit of neck dialed in. As for my cheap beginners Ibanez (IMHO it's really a good beginners bass), the mod turned it into a MONSTER. :D I'm not sure if the QP and stock are round opposite or what, but if the QP's are wound differently will the mod still make everything deeper or will it cut the bottom and give a snappier sound?(we're talking both neck and bridge QP's, not mixing them like I did before). If they're not going to go deeper then I won't waste my money on the neck QP, then I'll just have a lonely bridge QP sitting around my bedroom.

With two QPs, you'd just wire them in the usual series mod way and you'd get the deeper series sound. The comment about reversing wires applied to two opposite wound pickups.

With two QPs, you'd just wire them in the usual series mod way and you'd get the deeper series sound. The comment about reversing wires applied to two opposite wound pickups.
Cool, thanks Bill.