In article , RJH
wrote:
[snip inner groove distortion]

Don't follow that - I'd have thought the distance travelled would be
less, but the disc speed the same? Actually, having written that I start
to get it (disc/stylus-time/distance), but I thought the inner groove
thing was related to tracking anomalies caused by the geometry of the
various bits.

It occurs for both reasons. In principle, you can deal with the tracking
geometry with something like a parallel-tracking or articulated arm. But
the groove 'wavelength' for a given frequency still reduces as you get
nearer the center as the actual velocity (in m/s) falls. Thus the wall
curvature increases and 'pinches' the stylus.

Anyhoo, and FWIW, I've found that 'inner groove' poor quality sound
could be all but solved by certain types of cartridge. Not sure why/how,
but in my case an AT 440, and AT OC5

Stylus shape is critical here. And also being able to track at low playing
weight to avoid groove deformation for the best shapes in geometric terms.
These don't prevent a rise in end-of-side distortion, but can reduce how
severe it becomes.

Its a shame none of the current hifi mags ever print full explanations of
such 'technical' issues. I've been going though my early Hi Fi News issues
putting together a searchable index.[1] And they are full of careful and
detailed explanations of such matters. Alas the work by Kelly, Crabbe,
Walton, etc, seem to be long out-of-print. Maybe time for a new book or
some reprints.

Also, the old mags had lots of DIY/constructional features which - even if
you never built them - are a mine for info for anyone wanting to understand
such details. Again, such things are hen's teeth these days. :-/

Editor's seem to have decided that such things would frighten off
wooden-header readers. Personally, I suspect some would be put off, but new
readers would be attracted.

Jim

[1] If anyone wants a copy there is a zip of a csv version here
http://jcgl.orpheusweb.co.uk/temp/HiFiNewsIndex7.zip
As yet only up to volume 7 and I lack most of volume 1. But I am
slowly adding more volumes.

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