There is some controversy as to why the spectral content of vinyl records contain frequency "information" above what the analog tape recorder was capable of capturing. A thought experiment: If I have a piano that has a key which plays 15khz (primary freq. of that key's piano string), what happens to the harmonics as they: (1) go thru the analog tape deck (with 18khz top freq.)? (2) go thru the record cutting lathe (yes: the cutting lathe is downstream of the analog tape deck)? For example, note the spectrogram here: http://www.channld.com/vinylanalysis1.html The author claims: (Above) Spectrogram (Loudness vs. Frequency vs. Time). Bell percussion, showing harmonic overtones extending to 96 kHz, which is the ADC Nyquist Limit at a 192 kHz Sample Rate Bottom line: if the original tape recorder could only record up to, e.g., 20khz, why does the spectrogram show "harmonic overtones"? Some audiophiles claim that "harmonic overtones" is mechanical distortion produced (ringing) from the vinyl cutting lathe and./or the playback system (i.e., turntable/cartridge/stylus). Others claim that harmonic overtones propagate electrically. If a tape recorder plays that 15khz piano key (see Thought Experiment above), it will still ring in the "electrical domain" (e.g., in amplifiers and circuits of the cutting lathe) and produce higher-order harmonics (as seen the spectrogram above). Thoughts?