Thomas_A wrote:I think I got the groove width wrong... its only in lead-in groove. Otherwise only a minimal groove width is specified, around 30-35 um, perhaps an average of 50-60 um. So I suppose a line-contact stylus with 70 um radis will be reading the groove at the surface as well, where other distortion may occur.
Perhaps thats why the line-contacts with smaller diameters (30-50 um) are preferred by some makers (Lyra?) when playing used records?
Or perhaps I got the geometry all wrong...
I've never understood what dimension eg 70um radius means on a fine line stylus, because I'm sure min groove width at top of groove is less than this.........50um? so can't mean a traditional radius as in spherical/eliptical sense, it wouldn't fit ! Perhaps its the arc radius on the contact line?
Sibilence probably mostly IM distortion landing around 3-6kHz, could be stylus or cantilever self resonance...........or mistracing hf.
I've cracked the melting calculation BTW, pretty sure can now prove there's no melting. Will post derivation and calculation once I've doubled checked.
Lastly, those contact areas lini posted seem strangely large perentage cf stylus size/wavelength, thinking about it.........are units correct?