pickup repair

Hi Folks, Weird one here... I installed a new set of PJ pickups into my active bass - there was no issue with the old set I just wanted a darker tone. The pickup was exactly what I wanted and it worked perfectly fine except there was sort of a low volume distortion when I used a certain...

I got an Underwood bass pickup for my upright bass recently, and it's been giving off a super annoying buzz sound that you can only hear when playing the e string. I've included an audio clip of me playing it so that you can hear what I'm talking about. As you'll hear, it only affects the e...