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Volume loss when blending Jazz Bass pickups

andykeating

andykeating

Oct 5, 2016
170
272
36
Manchester
www.ististmusic.com
#1
Recently installed some Di Marzio Ultra Jazz pickups into a Fender Jazz, followed the instructions down to the letter.

When either pickup is isolated, there are no overall volume issues and there are no issues with any particular string being quieter. Have been using the neck pickup soloed because of the issues below...

When I blend the pickups, the E and A remain at the same volume but the sound is slightly thinner and there's a huge drop off in volume on the D and G, plus a loss of tone. Also the volume pots seems especially sensitive with regards to how little you have to turn them to almost switch the pickups off. Have never have this issue with Fenders before - if I turned a pot down halfway the pickup would be at half volume. With this bass if I turn it halfway down it's almost off.

Anyone able to point me in the right direction on how to sort this?
 
#2
andykeating said:
Recently installed some Di Marzio Ultra Jazz pickups into a Fender Jazz, followed the instructions down to the letter.

When either pickup is isolated, there are no overall volume issues and there are no issues with any particular string being quieter. Have been using the neck pickup soloed because of the issues below...

When I blend the pickups, the E and A remain at the same volume but the sound is slightly thinner and there's a huge drop off in volume on the D and G, plus a loss of tone. Also the volume pots seems especially sensitive with regards to how little you have to turn them to almost switch the pickups off. Have never have this issue with Fenders before - if I turned a pot down halfway the pickup would be at half volume. With this bass if I turn it halfway down it's almost off.

Anyone able to point me in the right direction on how to sort this?
Click to expand...

It sounds like your pickups are out of phase, not a major issue.

low/thin output when both pickups are used
 
#3
Andy, do you still have the instructions? I'd go back over them, just to be sure... If I know there's a problem on a machine, which one of my co-workers has recently replaced a component, I can't rule out the problem may be related to a DOA component, or a possible miswiring...

... I've gotten burned a couple of times, cause it's easy to assume all is good...
 
#5
Spidey2112 said:
Andy, do you still have the instructions? I'd go back over them, just to be sure... If I know there's a problem on a machine, which one of my co-workers has recently replaced a component, I can't rule out the problem may be related to a DOA component, or a possible miswiring...

... I've gotten burned a couple of times, cause it's easy to assume all is good...
Click to expand...

Yep, have still got the wiring instructions in the box the pickups came in. I checked them early and opened up the bass to compare, all wired and soldered fine so thought I'd post here because I was at a bit of a loss.
 
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#6
It may be possible to start swapping things around, but what results is a non-standard install, which could possibly screw something up for someone else, down the road (see my post, above)...

... I'd check it, again... maybe, a fresh set of eyes?
 
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#10
andykeating said:
Thank you. Does it matter which pickup you switch them on?
Click to expand...
No. I would go with whichever wires are the easiest to access.

Also, it would be unusual for two Dimarzio pickups to be out of phase with each other, but it's pretty easy to switch the wires and see what happens. Just be prepared to switch the wires back if the sound doesn't improve or gets worse.
 
#13
Changed the hot and ground on the bridge pickup and its flipped the phase - the E and A started sounding really thin but the D and G sounded as they should.

Have tried all 4 combinations of wiring and each time whenever I blend the pickups there's the phase issue. At a bit of a loss what to do, seems like regardless of how they're wired there's phase.
 
#15
the E and A remain at the same volume
Click to expand...
huge drop off in volume on the D and G
Click to expand...

This may be a magnetic problem. The ultra jazz pickups have two coils side-by-side, right? From your description, I'd say that for some reason, one of your coils has the reverse magnetic polarity from what it should have.

The other possibility is that the wire colours are mixed up and you need to swap just two of the wires on one pickup.

Are the pickups brand new? If so, send them back for what should be a refund.

If you bought them second hand then you'll need to find out whats going on, first with a compass to make sure each pickup has one north and one south coil. If they do, then it's the wiring. You'll need to work out which wire is which so that all four coils can be wired in phase. You'll need a multimeter and a little screwdriver or something to tap the pole pieces with...
 
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#16
RobbieK said:
This may be a magnetic problem. The ultra jazz pickups have two coils side-by-side, right? From your description, I'd say that for some reason, one of your coils has the reverse magnetic polarity from what it should have.
Click to expand...

Have emailed a guitar tech in Manchester close to where I live and after explaining everything he suspects this might be the issue - the E&A a D&G are wound separately in the casing so the winding may be incorrect or they may be the wrong way round. I'm taking it in for him to take a look and also fitting new pots - mine are looking worse for wear after the amount of soldering I've done.

The pots are 250k linear taper for volume and 250k audio taper for tone - that should spark a nice debate haha :cool:
 

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