[78-L] Fwd: Skating force, was Re: 78-L Digest, Vol 64, Issue 17

[Doug Pomeroy]

Dave,

In my opinion, the difference in speed between the left and right groove walls would likely be far too small to explain the tendency of the 
arm to skate toward the disc's center.  I always thought it was caused by the fact that the disc had been cut from outside to inside, thus 
the right side of the groove is constantly pushing the arm toward the center.  Also, IIRC, a tangential-tracking arm with tend to skate 
more than a lateral-tracking arm.

But I agree with you that setting anti-skating when playing a blank disc is not to be trusted because it ignores the effect of playing an actual 
modulated groove.

Doug Pomeroy
Audio Restoration and Mastering Services
193 Baltic St   
Brooklyn, NY  11201-6173
(718) 855-2650
audiofixer at verizon.net


> Message: 4
> Date: Tue, 14 Jan 2014 20:57:12 -0500
> From: Dave Burnham <burnhamd at rogers.com>
> Subject: Re: [78-L] 78-L Digest, Vol 64, Issue 17
> To: 78-L Mail List <78-l at klickitat.78online.com>
> Message-ID: <3CF094D3-2B72-4A68-A9D0-DB9F64070A8F at rogers.com>
> Content-Type: text/plain;	charset=us-ascii
> 
> 
> I think it's a matter of what causes the skating. As I've said elsewhere, I don't believe it has anything to do with centrifugal or centripetal forces;  my mind accepts the notion that it is caused by the fact that the outer groove wall is travelling faster than the inside groove wall, tending to push the stylus towards the centre. I've never seen this theory in writing but if it's true, it means skating forces will be much higher on a 78 with a larger stylus and hence a higher speed differential between the groove walls. Also if this theory has merit, it doesn't matter which direction the turntable is spinning. 
> 
> I remember that there was a theory back in the '60s that the most accurate way to set anti-skate was to put the arm on a blank disc, (I found that a blank Columbia 78 side was the smoothest), and adjust the anti-skate control so the arm didn't move either towards or away from the spindle. I don't believe this actually worked because I think skating forces are created by the actual groove, not a flat surface. 
> 
> db


Begin forwarded message:

> (But I'm not sure this is correct, either.)

Doug Pomeroy
Audio Restoration and Mastering Services
193 Baltic St   
Brooklyn, NY  11201-6173
(718) 855-2650
audiofixer at verizon.net