Side wind noise questions

[Jeeves]

I'm working on a very cheap bass for a friend and hoping to clear a few things up. It's got two of these pickups in it. From what I understand it should be a pretty quiet bass, but it's not. Lots of hum coming from this one.

If I understand this design right, there are 4 bar magnets per pickup. One side has two bars with North facing in, the other has the two south poles in. With the two coils this should be hum cancelling, shouldn't it? Right now the hum is worse than a set of P90's I compared it to.

Wondering if anyone has any other ideas of things to check or to reduce the noise. Ground connections seem fine, and the hum is no better if I wire the pickup right to a jack.
And of course he knows as well as I do how cheap this bass is, but since he does gig with it for some reason I'll try to help if I can. Fun experiment if nothing else...

And yes, I have the piece of the magnet that broke off. Was planning to just use epoxy to put it back together, unless there are other methods out there

Thanks!

[big_teee]

Sounds like the polarity of the magnets are turned wrong.
The normal way is to wind both coils the same direction.
Turn both norths or both souths of each coil to the center.
Then tie one start to one finish.
You can do a search here, there has been a lot of discussion on Sidewinders.
http://music-electronics-forum.com/t34463/
T

[rhgwynn]

You're going to need a new magnet. Once they break, they don't go back together the way they came apart. It's just going to repel away from itself. Trying to force it may cause tonal problems.

[Jeeves]

Just an update here. I finally got around to finishing this one. A little confusion doing the first pickup but the second was easy. I turned the magnets so all four were facing South in. That knocked it out of phase so I rotated one coil and now they sound fine and are pretty quiet. I think the confusion on the first pickup was when I tried to reverse the wiring on one coil I must have put it back on upside down, essentially cancelling the work I just did. I hadn't considered that could happen.

rhgwynn - This whole bass is a tonal problem For fun I tried putting the magnet back together and I see exactly what you are saying. I ended up just wrapping a little gaff tape around to hold the broken piece on. He told me he'll never use the neck pickup on this bass so I put that magnet on that pickup.

Thanks again for you help!