Car audio specialists Assemble.

Right, I’ve got audio hum coming through some stand alone powered speakers in my motorhome when the solar panels are generating. The speakers are powered directly from the 12V leisure battery and receive a signal via an aux cable from the telly.

If I power the speakers through the original 240 transformer this eliminates the noise as does unplugging the aux cable. I installed this Audio Filter but it’s made no difference. A filter that goes in line with the aux cable is available but apparently they’re dire and reduce the sound quality.

Anyone on here know about filtering noise out of DC?

Ta in advance, Dave.

Try an RF choke on the 12v power lead to the speakers. If that doesn’t work try a ground loop isolator to rule that out. I’ll bet it’s the ground that’s causing the hum. You could try a better earth for the speakers.

+1 for a ground loop isolator. Usually sorts it. The cheap ones on eBay are fine

I’ve got a male-male 3.5mm lead with some sort of filter on it.

Got rid of the horrendous whine from the engine in my van, and haven’t noticed much in the way of reduced sound quality (albeit its a Ford Transit and standard Spotify!)

Lots of cables have like a long fat cylinder at one end, which I now understand is a carbon choke to avoid interference, so probably fitting one of those would alleviate the problem.

Probably a bad earth.

Make sure all earths are connected to the bare metal in the car, scrape or sand a bit of paint off to make a good contact.

That’s the black cable.

Also,, keep negative cables as short as physically possible.

Ok, lots of good ideas to work with, many thanks. I’ll have another look tomorrow 😀

Is the carbon choke the magnetic cylinder? I bought some retrofit ones where you wrap the cable round a couple of times and then clip the device shut. Made absolutely no difference…but I think its intended to do the same as the cylinders you often see moulded into one end of the lead.