The RQ-4746 a is an updated version of the RQ-3746 which was released in 1973.
Changes include an internal CD-4 De-modulator, removal of the Aux Input for a CD-4 Phono Input, and a red indicator overlay.
Stereo Bridge Mode
Joystick Orientation/Balance controls
4 Channel modes supported internally include Discrete, SQ Matrix, SQ Blend, and CD-4
Supports two sets of four speakers while in 4 Channel mode or two sets of two speakers while in Stereo Bridge mode
Two 4 Channel Discrete Tape Monitors
Magnetic Phono Input
CD-4 Phono Input