Strange noise

Double post ... sorry!

Our bathroom fan causes interference in the stereo .....

If it's rhythmic and intermittent I would suspect your cell phone. Move it away from the speakers.

NormF

Paranormal activity? j/k :B

A speaker is a transducer and they are installed with a speaker wire. If the wire is of the right length or the impedance of the speaker is just right, it can receive signal from other electronic devices or pick up RFI or EMI from other sources. Wrapping the speaker wire through a ferrite is sometimes enough to stop any extraneous noise.

I have heard CB radio transmissions come through my computer speakers. Could be interference from another source.

Steady hum would be DC interference. Could be converter switching to charge if happens when connected to shore power or genset is running.
If it happens when driving the rig, it could be a connection problem on the ground input to the radio.
Make and model of the radio?

Converter in desulfate mode?

enblethen wrote:
What kind of noise?
Is it possible that the paper cone is flexing against the housing? This may only show up during some tones.

No. It is a hum type noise, not a speaker rattle. The radio was OFF at the time. When the radio is on, the noise does not come thru

What kind of noise?
Is it possible that the paper cone is flexing against the housing? This may only show up during some tones.