Batteries do not sound dead and I did not hear a squeal. I would use a new battery to see how it sounds and when it wears down, you will hear the difference. I have a new active bass and have only changed the battery once. The volume started to sound low and less clear. I leave my cable plugged in since I don't want to wear out the plug just in case. The battery lasted 3 months playing it 15 to 30 mins per day most of the time and a few days not at all. I have a battery tester for most types of batteries. Now I use a rechargeable 9V battery. Been plugged in for a few weeks, no problem.I've an active jazz bass that runs on two 9v batteries. I recently changed my batteries, that is on august 1st week 2020. I practice approx. 45 mins everyday. In that ime, I'll have the preamp on for 10-15 mins. My bass is sounding like this now. Should I change the batteries?
I handle and maintain my bass very carefully. Is everything alright with the electronic part of my bass?
Do let know guys. Thanks!
Edit: I DO NOT LEAVE MY BASS PLUGGED IN. I ALWAYS UNPLUG MY BASS AFTER USING.