Takahashi Nobuaki, Nishikawa Kazunori, Ishigaki Yukinobu, Itoh Yasuo, Fujita Yoshitoshi: Compression and/or expansion system and circuit. Victor Company of Japan, March 5, 1974: US3795876 (33 worldwide citation)

A compression and/or expansion system comprises fixed frequency characteristic changing means having a specific fixed frequency-response characteristic which increases or decreases the level of an input signal in a predetermined frequency band. A variable frequency characteristic changing means has ...

Mawake Masaaki, Fujita Yoshitoshi, Muraoka Teruo, Sato Teruo: System for selectively receiving either 4-channel or- 2-channel stereophonic broadcastings. Victor Company of Japan, April 29, 1975: US3881063 (8 worldwide citation)

The invention relates to a system for selectively receiving either 4-channel 2-channel stereophonic broadcastings. The 4-channel signal is a composite of stereophonic signals comprising a main channel signal, a pilot sub-carrier, a first sub-channel signal, a second sub-channel signal and a composit ...

Takahashi Nobuaki, Ohnuki Katsuhiro, Fujita Yoshitoshi, Itoh Yasuo: Four channel record reproducing apparatus with muting of speakers not used for stereo or monaural records. Victor Company of Japan, October 22, 1974: US3843850 (7 worldwide citation)

A phonograph or similar apparatus reproduces a four channel record on which is recorded a multiplex signals of a direct wave signal and an angle modulated wave signal. One channel monaural or two channel stereo records, on only which a direct wave signal is recorded may also be played back on the sa ...