Subwoofer Feedback

[LeatherDog]

This past weekend the stereo system developed a very bad feedback whenever a dimmer equipped light was on or any of the fans running. The feedback occurred on battery or shore power and all of the stereo modes (AM/FW/Bluetooth/TV). Prior to this trip, the system worked very well with no issues under these same conditions. I removed the main stereo control panel and check tightness of all connects, all good. In looking for more loose wires, I found that the feedback stopped if I disconnected power to the subwoofer. Is this a sign that the subwoofer is blown? The roads we traveled were quite rough, so the trailer was tossed a bit so maybe something came loose inside the subwoofer? Maybe this is a good time for an upgrade?

Stereo is a Polk marine unit linked to Polk speakers. Cannot see the subwoofer brand or model.

Any suggestions would be appreciated!

[panamerican]

Make sure it's ground (neg) is firmly connected. Also make sure that all the connections are tight, even if you have to move the RCA cables a bit by twisting.

I'm kind of a novice audiophile and when I get that happening, it's typically been a loose RCA or just twisting slightly sometimes gets them to connect better and the feedback goes away.

[SYC2Vette]

Our unit has an RF filter can I noticed. Different brand head unit but the filter is used on the Airstream side of the harness.

Another thing you might consider is just leaving the subwoofer disconnected that way you can use the sound system when you have neighbors in close proximity with much less chance of annoying them.

[richard5933]

I agree about the ground connection. Same thing happens in our house if the sub woofer loses its ground connection.

In my experience, a large number of electrical issues in RVs stem from bad or weak ground connections.

[LeatherDog]

Thank you for the feedback! The only RCA connectors I could find are on the subwoofer and I removed and replaced them a couple of times. They seemed tight and messing with them did not change the note of the feedback. I will track down the ground next time I have enough time to sort through the wiring.
Thanks!

[richard5933]

You might not see a ground wire, but likely on the back of the subwoofer there will be a screw/lug intended for one. On my subwoofer at home I used a screw which was holding the back of the case on the subwoofer - with a spade terminal on a wire I attached to the screw, and then the other wire went to the case on the stereo. Since we have the advantage of a metal chassis nearby, you can make sure that the subwoofer and the stereo are properly grounded to the chassis and hopefully this will take care of the problem.

I'd suggest pulling the manuals for both the subwoofer and the stereo and looking to see what specifics they provide for grounding in case there is a special technique used.

When I worked on audio equipment decades ago it was common to have a 60-cycle hum present on poorly grounded devices. Simple to fix and darned annoying till it is.

[switz]

I found in both our 2014 Classic and 2015 23D International Serenity that the sub-woofer is a power hog and is "ON" all of the time that the battery is connected. So I put an on/off switch inline of the power cord to the sub-woofer and removed the parasite power draw when the trailer is parked without shore power.