[78-L] Diamond Disc mould

[Gerald_Fabris at nps.gov]

Malcolm said:
> Seems to me that an inverted groove for an Edison cut 78 doesn't look
> like my first example (which is a "normal" lateral cut)


Diamond Disc grooves (and most vertical grooves) are not flat or V-shaped
on the bottom, they are round.  The shape of the modulation sort of
resembles an hourglass.

Follow this link for a photo of a Diamond Disc negative groove:
https://www.box.com/s/01480823ba8cec9ec357

What you see in this photo is the end of a recording:
- groove with musical modulations on the left,
- then the last few turns of the groove are unmodulated,
- then blank space (with a thin line remnant from the wax shaver).


Jerry Fabris, Museum Curator
Thomas Edison National Historical Park
National Park Service
United States Department of the Interior
211 Main Street
West Orange, New Jersey 07052
tel:  (973) 736-0550, ext. 48
fax: (973) 243-7172