hair or bit under the slip cover, that is touching the panel, or an intermittent separation of panel and support structure. Possibly a few other things...(on the list of potentials)
You’d have to play the offending part on repeat and then listen to find out exactly where it is coming from, note that..and then the cover comes off to inspect the offending area..
a fairly common experience when trying to diagnose panel speaker problems. (apogee ribbons and Martin Logan, others) the Martin Logan thing is fun as it can be a short/open on the given stator....(exceedingly rare, though)
You’d have to play the offending part on repeat and then listen to find out exactly where it is coming from, note that..and then the cover comes off to inspect the offending area..
a fairly common experience when trying to diagnose panel speaker problems. (apogee ribbons and Martin Logan, others) the Martin Logan thing is fun as it can be a short/open on the given stator....(exceedingly rare, though)