Reported as fuzzy sound on the bass guitar E string even at relatively low levels but otherwise fine sound rendition or backing off the bass control . Feeding a signal generator in then indeed a distinctly fluttery distortion in the range 50 to 70 Hz on top of the wanted output, ok above or below that range. No external speaker output on this cube and before getting inside to scope it or run an external speaker I took the front grille of in case of parasitic rattling but no change. But putting a sock in the front/back vent tube in the speaker surround cured it. Where to go from here ? sci.acoustics.repair ? charge for an old sock ?
-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on