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LP Thickness/Taper

If anyone has ever wondered how LP thickness varies from lead in to runout, I just measured it.  It's well known that there's a taper to LPs, but I have never seen any actual data.

This is a 120 gram record.  The thinnest part near the beginning of the first track is 0.0415", and the thickest part at the very end of the last track is 0.0470" (+/-0.0005"). 

I know there are many ways to set azimuth, but most most people tend to do it optically with a mirror on the platter.  So, if you set your azimuth like this and are confident that you have it perfect, it will automatically be 0.12 degrees off due to the taper of the record.  I'm sure all records will have a slightly different taper, but I can't see it varying too much.

ketchup

Showing 1 response by mijostyn

mijostyn's avatar
mijostyn
8,570 posts
 

Every record is different depending on the flatness of the shellac master. What does it mean? Absolutely nothing. The geometry of the groove depends entirely on the orientation of the cutting head. It stays perfectly vertical regardless of the thickness of the record.

The tip of all styluses is radiused and does not have to be perfectly perpendicular to the groove. 30 seconds one way or the other is not a problem. Some  styluses like the Replicant 100 are more pointy (the radius is smaller) and are more exacting. 

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