an antique soviet woofer 5gd-3 from vintage acoustics symphony

symphony acoustics vintage perforation cardboard cap resonant frequency rare antique resistance gray cast case bracket cobalt alnico shielding radio soviet woofer speaker 5gd3 old cases speakers retro 1960s 60s 70s melody reportage system threeway loud listening loft tape recorder voice broadcast strut rap veneer music art disc jockey stereo helmholtz resonator musical varnished