A cassette adapter has a cassette which is inserted into a cassette insertion portion of a signal playback device. The cassette is provided with an operation state detection means and a control signal output means. An acoustic device is controlled corresponding to an operation state on the basis of the...http://www.google.de/patents/US5307326?utm_source=gb-gplus-sharePatent US5307326 - Cassette adapter for signal playback apparatus
