Nastly little magnetic tweeter/mids ? As a 47uF NP cap is over one, for mid? Anyway nasty buzzing overtone as though a bit of steel swarf or staple has got on the cone of a larger speaker. These things have brushed aluminium inverse dome covers on them, do they work loose, swarf dislodged inside? Of course close-handling has "cured" the problem, but bound to return without proper treatment