Abstract: A multichannel record disc recording system uses two channels of direct wave sum signals and two channels of angle-modulated wave difference signals which are multiplexed and recorded in one sound groove on a record disc. During recording, a tracing distortion compensation means imparts a reverse distortion which cancels the tracing distortion produced, with respect to the sum signals, during reproducing. Since the compensation means is in the transmission paths of the direct wave sum signals, the reverse distortion is only imparted to the direct wave sum signals. Also, phase correction signals are provided.

Abstract: A record disc cutting stylus comprises a cutting stylus body which is held at its upper end by a shank. At its lower end, there is a stylus tip portion which has a mirror surface, a relief surface with a relief angle .gamma., and a burnishing facet with a burnishing angle .beta. and a burnishing facet width d. The burnishing angle .beta. is as large as possible, and the width d and the relief angle .gamma. are as small as possible. The stylus projects distance l between the lower end face of the shank and the extreme tip of the stylus tip portion, which projection is as small as possible. The burnishing angle .beta. has a value substantially within a range of 25.degree. to 40.degree.; the burnishing facet width d is substantially within a range of 0.5 .mu.m to 3.0 .mu.m; the relief angle .gamma. is substantially within a range of 30.degree. to 40.degree.; and the stylus projecting distance l is substantially less than 2.0 .mu.m.

Abstract: A multichannel record disc recording system comprises circuits for forming first and second sum signals and first and second difference signals respectively from signals of two different channels of four channels. The first and second difference signals, are angle modulated and, a control signal is formed in accordance with the level of at least one of the first and second sum signals and the level of at least one of the first and second difference signals. The levels of the first and second angle-modulated signals are controlled in accordance with the control signals thus formed. Circuits are provided for multiplexing the first sum signal and the first angle-modulated difference signal thus level controlled, and for multiplexing the second sum signal and the second angle-modulated difference signal thus level controlled. These multiplexed signals are then recorded on a record disc.