Edison Executive Voicewriter

Experimental Re-recording Data

We had occasion to re-record a (7", red, transparent) Edison Diamond Disc, recorded in 1957.  These are some of our findings:

Cleaning:  Initial cleaning was done with distilled water on a (vacuum) cleaning machine.  After its first recording was completed, the disc was cleaned again using a standard alcohol-based vinyl cleaning fluid, and recorded a second time.  The second recording was markedly improved.

Setup:  Since the disc is thin and very flexible, we used a black nitrile platter with a flat surface, without machining that allows for the usual paper label.  (Rek-O-Kut's Rondine3 happens to have a reversible platter with a flat side).  An EP adapter (sometimes known as a "45 adapter") centered the disc;  the adapter was carefully removed and replaced with a center weight.  We test-recorded with this turntable successfully, and decided that the Executive Voicewriter uses a CAV (constant angular velocity) drive mechanism; obvious pitch change wasn't observed during the recording, fortunately.  Inspection of an actual Voicewriter revealed that it is, in fact, a CAV mechanism: The platter is driven by a rubber wheel, contacting the outer diameter of the platter.

Cartridge/Stylus:  We settled on the Shure V15 cartridge with 0.7mil elliptical stylus.  While a slightly larger stylus may be advantageous, we did find that a 2.0mil stylus was too large.  Satisfactory stylus force ended up around 3g, but it tracked fairly well at 1.5-2.0g.  We noticed was that the Diamond Disc was very sensitive to platter leveling and, particularly, anti-skating.  (This may be an indicator that the Diamond Disc has very shallow grooves.)  The Shure's brush was not used, since it was likely to interfere with tracking; the groove spacing on this disc may vary more than on standard pressings.  We would guess that the Executive used a linear mechanical tracking system.

Platter Speed:  We don't think that the Executive offered a choice of recording times (although it's possible, it wasn't mentioned in the user guide).  Basing the platter speed on a natural-sounding voice, our speed came in at about 24.0 rpm.

Diamond Disc:  As you might expect, the disc grooves have some noticeable crosstalk, probably due to thin or soft groove walls.  These discs are recordable on both sides (marked "A" and "B"), but the best recordings were made using one side only:  Crosstalk between sides was also noticeable.  The amplitude of this disc was somewhat low, and required a bit more amplification than standard pressings.