Results might vary with discs from different recorders.  Some of the 
grooves will be deeper on some discs than others depending on the weight 
put on the embossing head, and that would effect the ease of tracking as 
well as the width of the groove.  I wouldn't be so sure that the size of 
the diamond ball which embossed the grooves was standardized.  Both Doug 
Pomeroy and Elizabeth McLoud seem to have the most experience with these 
recently.

Mike Biel  [log in to unmask]

On 8/24/2011 12:47 PM, Kurt Nauck wrote:
> Brian and I are working our way through a stack of mid-30s 
> Speak-O-Phone aluminum recordings. Most of these appear to be air 
> checks of dance bands and vocalists.
>
> Condition is pretty good on most of them, but we're having trouble 
> finding the ideal stylus to play them with. Best results seem to be 
> obtained with a standard LP stylus.
>
> Does anyone have any experience with these? (And yes, we're riding the 
> groove, not the landing between them.)
>
> Kurt Nauck