registeredla wrote: (...) If it does indeed get that hot, why is the record recording not destroyed?
I'd figure, because it's a very punctual and short term heating, that happens in passing of the needle, and in addition it's already known from the cutting process that vinyl has a flowback effect - so that kind of heating probably isn't enough to cause significant permanent deformation of the groove modulations, at least under normal conditions. However, I remember a study that indeed shows permanent deformations for CD4 Quadro records played back with typical stereo needles - apparently one really should use a light (low ETM) diamond with extended contact area on a cantilever that doesn't resonate much for that purpose, if one doesn't wan't the CD4 information to be more and more overwritten by the resonance trail of the needle over time.
Oh, and just for your interest, here are some contact area (per side) figures from a Namiki study that recently came up in a thread over on the HiFi-Forum.de:
- conical (18 µm): 30,5 µm²
- conical (13 µm): 23,4 µm²
- elliptical (6 x 18 µm): 20,6 µm²
- LineContact (6 x 45 µm): 46,7 µm²
- MicroRidge (2,5 x 75 µm): 62,1 µm²
Unfortunately the measurement conditions weren't quoted, so I don't know whether the contact areas were measured in a blank groove or in a groove that actually contained modulations (which I'd deem more interesting).
Greetings from Munich!
Manfred / lini