pickup mix knob: weak at center

[Peejhunt]

Hello all!
I am new to the forums and I really like what I see here. Lots of useful info! So on to my question:
I picked up a Washburn bass body used. It is P/J style. I have assembled it with a nice neck and really like how it plays. BUT, there is a pickup mix knob that selects well but when set in the center, the signal gets very weak. Almost completely gone. Could this be a phase problem? It acts that way but I wanted to ask before I go playing with pickup polarities. Any thoughts?

Thanks!
peej

 

[Pacman]

The pickups are probably wired out of phase

 

[JRA]

The pickups are probably wired out of phase

my first thought, too. blend knobs can be really useful --- shouldn't sound like what you're describing. good luck with the fix!

 

[dwizum]

"Almost completely gone" is definitely not typical, I would third the suggestion that the pickups may be out of phase with each other. If that doesn't fix it, check for markings on the blend pot - if it's A/C taper, try swapping to an M/N taper.

 

[Turnaround]

It sure sounds like a phase problem. But with conventional P and J pickups it's impossible to get the combination in phase. Here's why...

A P pickup is two coils reverse wound with respect to each other. That makes it noise cancelling. The conventional J pickup is a single coil. It will be in phase with one side of the P pickup and out of phase with the other no matter how you wire it. So it is important to use a noise-cancelling J pickup which will balance better with the two coils of the P pickup.
I have no idea what's in your bass, but unless the two pickups were designed to work together you may get some unwanted cancellation. You condition sounds extreme though. I'd try disconnecting one pickup and seeing if the blend control diminishes the remaining pickup's output in the centre position. If so I would suspect a problem with the control.

 

[sissy kathy]

...and welcome to TalkBass.

 

[Gilmourisgod]

If it comes down to a faulty pot, ive had good luck with this Bourns blend pot, but im using it with two single coils. It gives me a nice smooth transition with a solid detent at center. I'll defer to the more knowledgable as to compatibility with your bass.