Strange noise accidentally repaired

[tauzero]

While practising with Positive Grid Spark NEO wireless headphones, I noticed a twittering (for want of a better term) from my Sei Flamboyant when it was in active mode. It stopped when in passive mode. None of my other active basses did the same, and when I used a wireless dongle plugged into the headphones and the Sei, it went away. The preamp is a Delano Sonar 3 - I have a Delano Sonar 2 in the Sei fretless which didn't do the same thing. Battery was showing 8.75V when the bass was switched on - not 9V but should be enough, and anyway I haven't got a spare battery (got some on the way now though). I wondered it there might be some strange issue with the jack socket, which fortunately isn't a barrel type, so I extracted it and the battery negative wire immediately fell off the ring terminal. Looks as if it was either fatigued or had been stripped rather too carelessly and only held on with a couple of cores. Stripping and resoldering the wire solved the problem.

 

My conclusion about what had happened is that the dodgy wire was presenting a certain amount of resistance to the 0V line and therefore reducing the effective battery voltage. Why it only showed up on the Spark NEO dongle is another question - possibly it's a low impedance and consequently a higher current draw for the preamp, but that's just a wild guess. Obviously a low battery is the most likely cause of low battery issues, but this does show another possible (albeit unlikely) cause.