I have an RV with a 150 Ah battery bank and SureSine 300W 115V inverter. Due to space constraints, the inverter and the rest of the DC loads share about 6 ft length of wire to the batteries, but otherwise it’s a fairly typical setup.
The media center and speakers are running on the 12V and they pick up high pitched noise when the inverter is running, it gets worse the more AC loads I have.
The inverter probably already has bypass capacitors, but would it help if I added more? How do I choose the correct size? Would it help if I added a big ferrite bead on the positive rail going to the inverter? The peak current there is about 60A.
Also, does it make sense to filter the noise just at the media center as it uses a fraction of the power the inverter does?
Edit: I have a multimeter, but not much besides that to diagnose this.