Speaker interference...

[Swanny_UK]

Guys,

Ive noticed, well Ian pointed it out before I bought the car, that I\'m getting interference in the centre dash speaker as you drive.  The tone increases and decreases with the cars revs.

Also - when you operate the dimmer switch for the dash illumination - the more you dim, the more of a tone can be heard.  This is in addition to the above tone.

I take it this *isnt* normal?  Im assuming its interference between the loom or a high current circuit and the little speaker wires.  Just wanted to make sure it wasnt an interesting model feature before I go on a wild goose chase!