andyhaines

I'm keeping an eye on this - seller has 0 sells/purchases and it seems a very low price to start such a rare bass. Seems too good to be true...

Good call, thanks!

Worth a look - thanks! I suspect not as I didn’t have this problem in the previous bass these pickups/electronics were in, but that was some years ago so I may be mis remembering!

Interestingly, swapping the pickups around on the blend pot reversed the issue - the pronounced hum is now on the opposite side, indicating that the issue follows the pickup.

Thanks everyone- really good advice all round! I’ll probably try to swap the pickups on the blend to confirm whether it’s a blend or pup issue, but sounding like a new blend pot may be required.

Thanks, good to know. I’m assuming the blend pot was wired by bartolini (part of a pre wired harness)

Yes, they’re mid 90s bartolini jazz pickups (passive). The undersides are marked N and B so designed for neck and bridge.

Thanks - so the yellow and blue wires that cross over behind the lugs should be soldered to the lugs and not to the rivets?

No. The hum is not present when 100% bridge. Turning the pot back then gradually introduces the hum, through 50% blend increasing hum as you get to 100% neck

No problem -pic of the blend pot before I disconnected the neck pickup - hot wire goes to centre lug and the ground braid is soldered to the same lug as the bridge ground. 2nd pic of the wider control cavity. Hope that helps!

Hi All, Recently had two Bart Jazz pickups and early NTMB preamp (pre-wired harness) moved from an old bass to another -all works fine except that when moving the MN250K blend pot away from 100% bridge towards the neck where there is a steady (ground?) hum. When fully on bridge it's silent (as in no hum). Both pickups work fine and you can clearly hear the neck pickup tone coming through, just with the added hum! I've disconnected the neck pickup from the blend pot just as a test and (as expected) turning the blend pot to 100% neck results in silence (no pickup or hum). Touching strings and bridge makes no difference so I'm assuming there's no ground problem there (otherwise the bridge pickup setting would also hum) and the ground wire is making contact below the bridge. Any clues as to what's going on? Possible failing blend pot? Thanks! Andy

I have the bubinga version of this bass, exactly the same bridge -yes there’s a small allen key screw on the top and bottom of the bridge. Loosen these up then move your saddle pieces and tighten again. Andy

Very useful stuff, thanks, much appreciated. i’d also found the same fender link to the spellbinder schematics so at least I’ve got something useful to give to an amp tech if I can find a good one locally! Andy

Thanks for the tips - phantom power is off. Yes it has a tube preamp but as I’m very new to tube stuff I don’t know what a tube warming up sounds like. Power socket is earthed. with everything down apart from the master, the popping sound is quiet but certainly there - almost like a high pitched heartbeat, with the mute light flashing every other ‘pip’. Slowly turning the gain up increases the sound of the pips (as well as a 50z hum I think). Any of that help? cheers! Andy