This app simulates an analog stylus tracing a vinyl groove in slow motion, using microscopic physics rather than a visual approximation: Hertz/Winkler contact, viscoelastic damping, and rigid-body dynamics. All core quantities use SI units, and the observable SNR, distortion, and resonance frequencies are checked against real-world orders of magnitude.
Pink noise (a music-like long-term spectrum) passes through a 20Hz rumble filter, an 80Hz music LF shaper, bass mono filtering, HF cutoff, RIAA recording pre-emphasis including the Neumann 3.18µs pole, and velocity-to-displacement integration. The result drives 45/45 left and right wall normal displacement. The 0dB reference is a 5cm/s peak wall velocity.
At 2g VTF, each wall carries roughly 14mN of normal force and the contact pressure reaches about 0.4GPa, well above the yield stress of PVC. Microscopic asperities inside the ~5×7µm contact patch are therefore crushed and averaged. The simulation separates visible roughness from the roughness actually felt by the stylus with an analytic patch-averaging factor.
At each step, the simulator evaluates the stylus scanning-radius parabola against the wall gap, so inner-groove treble loss and pinch-effect distortion emerge from geometry rather than from an added distortion formula. Use sine mode to inspect it directly.
The ruler divides a ±15µm wall displacement full scale along each 45° modulation axis. The default roughness σ=13.17nm is calibrated to SNR 60.0dB, or 9.7 effective bits; at the default +12dB peak level this corresponds to DR 72dB. White markers show the instantaneous wall displacement.
The main noise source is three-scale AR(1) groove roughness representing stamper precision and molecular-scale placement error. Dust follows a physical deposition model with flakes, fibers, and grit; only particles actually pressed by the stylus deform. Static is injected as an electrical pulse, as in a real playback chain, not as a mechanical vibration.