Problem with series/parallel/single wiring. Buzz/Hum

[jacobass4]

This is my first post and would love any help anyone may have. I have a custom made bass with a SD BassLines Jazz style as the neck pickup and a Basslines MusicMan style pickup as the the bridge pickup. Both pickups are wired with 3 way switches for series/parallel/single coil, and then to a bartolini NTMB-918F preamp with midrange control, bass, mid, treb, blend. the volume pot also goes passive.

The problem i am having happens in both passive and active modes and when either pickup is in the center position of the three way switch, i think its the single coil setting though i don't know for sure. There is a bad hum and buzz that sounds through the speaker that is amplified with the treble knob. When i tilt the bass in different directions while plugged in, the buzz/hum will diminish and rise and may even disappear when tilted in one direction only to return when the bass is tilted again.

What can i do about this problem and am i correct to think this is happening on the single coil setting of the three way switch??? thanks for you help.

 

[jacobass4]

The pickups are AJJ-2 and SMB-4D or 4A, i'm not sure which one though. anyone know how i could find out which one it is, 4D has Ceramic bar and 4A has Alnico V rods. anyone know the difference??

 

[newfuture]

If that's the single coil position, that's the nature of the beast. You could try shielding the bass better (copper tape / conductive paint) if it's not been done, but single coils are inherently noisier than humbucking designs, stacked or side-by-side.

One thing you might be able to do is adjust the wiring so that when both PU's are in single coil mode the noise cancels. Call SD, they'll be more than happy to help, great Tech Support department, and they'll let you know how to do this and how well it might work. Calling them is more effective than email in my experience.

good luck

 

[Jazz Ad]

Perfectly normal. In split mode the coils stop acting like humbuckers.
Not much to do about it.

 

[jacobass4]

i kinda figured that may be the case. thanks for both of your replies, the bass sounds great, and i love that single coil sound, i think i may look into making them work together in single coil mode to cancel the hum. thanks.