Weird noise from Nordstrand pickups

[bassdudestevo]

I've searched this site and could not find anyone with the same problem as I have. Here's the scoop, Lakland 55-01 with Nordstrand 3B-5a pre and Nordstrand Big Split pickups. Excellent sound but after a few minutes of playing I get this really soft rumbly-mumbly noise when quiet(in between my tasty bass lines of course). Almost like a volcano is erupting many miles away and all you can hear is a low rumble noise.
When the preamp is active, it doesn't matter what pickup I chose or any EQ adjustments I get the rumble. It's not a hum or hiss, just a low but noticeable noise. When the preamp is bypassed it's as quiet as the exosphere. I've had many very nice active basses but never had this issue. I checked the wiring as well, everything looks clean.
Any thoughts or experiences with this issue? Carey could you spare a few minutes from your mojo making to help a fan out?

You all rock.

[dino777]

Hi , recently i have installed 3b-4b in MIA fender deluxe p,
i think i had the same problem with yours (rumble noise), i modified 9v to 18v power, i try to check the wire and solder points and nothing wrong,

finally i replaced new batteries and the problem solved, so you can try this. anyway i think this issue is not only related to battery, the preamp itself may take part

cheers

[bassdudestevo]

Hey Dino, sorry for the late repsonse. When I read your post I went and bought some new batteries to try and everything seems to be working great now. I think I was over analyzing the situation when I should have checked the basic areas first.
Thanks for the help!