Geometric mismatch between cutter head and pivot arm distorts LP playback
Evidence
LP masters are cut with a flat fronted chisel and then played with a conical or elliptical stylus, meaning that the path followed by the stylus is different from that of the cutter. The cutter also follows a radial straight-line path, while pivoted tone arms scan an arc, causing misalignment over much of the recorded surface. Signal manipulations during the disc mastering process attempt to compensate for some of these, including amplitude compression and spectral manipulations to avoid stylus mistracking (momentarily losing contact with the groove walls) in the inner grooves where classical music often reaches a climax. The bass in both channels is usually combined to mono, allowing horizontal motion only, to prevent the stylus from being thrown out of the groove. — Toole, Floyd E, Sound reproduction- the acoustics and…, 153
Categorization
Category: Causal Relationships
- DEFINE: Explains tracing distortion as a mechanical cause: flat-faced cutter vs. conical/elliptical stylus tracing different paths.