On Sat, 13 Apr 2019 13:00:37 +0100, "Dave Plowman (News)"
wrote:


Difficult to tell if the buzz is from all three speaker units, as when you
get your ear close enough to each one, it stops.

A similar problem of detecting which of a number of speakers was
producing sound from a device which changed characteristics when you
approached it was diagnosed by a length of hosepipe taped near the
device on one end and held near the observers ear at the other so you
could listen closely without interfering with the equipment. In that
case the problem was with the infamous Sinclair X10 broadband jammer
which altered its characteristics as someone across the street moved
around their lounge.