An acoustical reproducing apparatus is disclosed for high fidelity sound reproduction comprising a speaker unit in combination with a cabinet enclosure acting as a resonating chamber. The resonating chamber has a rhombic dodecahedron configuration having speaker-mounting openings located on two or more...http://www.google.com.tw/patents/US4231446?utm_source=gb-gplus-share專利 US4231446 - Resonating chamber
