ステレオディスクレコードの再生ひずみ(I)
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概要
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The motion of phonograph pickup stylus in a stereo disk record groove is analyzed with consideration for the effects of elastic contact between the stylus and the groovewall, using the Hertz's equation for elastic deformation, and the expansion method by Lewis and Hunt is used for the tracing distortion. Namely, expanding ΔΖ, which the lateral component of distance between the origin of stylus tip and the stylus-wall contact point, and the elastic deformation δ in powers of the amplitude, as the general formulus expressing the motion of stylus sliding on the elastic wall modulated by any arbitrary recorded signal was obtained, as an expansion in powers of the amplitude and its derivatives; that is, Considering tha alteration of δ by mechanical impedance of pickup, it was driven that relative response at any frequency is affected by the impedance of pickup and the compliance of wall. As for the fundamental wave, the amplitude of stylus motion S_1 is given by and as for the second harmonics, S_2 is given by where Z_m1 is the mechanical impedance and Z_m2 is that for second harmonic frequency, including the compliance of wall, and f is tracking force acting on this wall. The distortion response at harmonic frequencies is governed in part by Z_mn embodying the effect of resonanse similar to the fundamental frequency, and moreover is controlled by not only scanning loss but a sort of translation loss. In the case of 45/45 stereo system, the crosstalk of reproduced signal including harmonic distortion between both channels doesn't appear, even if the groove is elastically deformed by force acting on the groove-wall, as long as the force is circularly symmetrical in the surface which cross vertically the direction of groove movement. For the sake of analysing the distortion in stereo disk record, it ts suggested to describe the displacement of stylus tip as conjugate quantity.
- 社団法人日本音響学会の論文
- 1962-01-30