In the 1/31 issue of MMD,  Jim Hendershot wrote:

> Was there more than one groove standard?  On first playing, I noticed
> that my Ediphone was tracking faster than the cylinder.  Was there
> perhaps a change in the number of grooves per inch on later machines?
> If someone knows, drop me a line.  Thanks.

Prior to 1909, Edison cylinders were cut at 100 grooves per inch, which
at the (post-1900) standard speed of 160 rpm, yielded about 2 minutes
of playing time.  About 1909, Edison introduced 4-minute cylinder
records (called "Amberols") which still played at 160 rpm, but were cut
to 200 grooves per inch.

Edison sold conversion kits so that owners of older phonographs could
upgrade them to play the new, longer records.  These kits included a
gear changing device to slow down the tracking of the feed-screw (which
propels the reproducer across the record), and also a second "4-minute"
reproducer: the most common version is the H reproducer.  There were
also models like the K and O, which featured dual styli for both 2- and
4-minute records.

From 1909-1912, all new Edison phonographs played both 2 and 4 minute
cylinders.  After 1912, they played 4-minute only, until the demise of
Edison cylinder machines and records in 1929.  The early Edison 4-minute
records (called "Black Amberols" by collectors) are brittle black wax,
which crack easily and wear out rapidly.  The later, plastic "Blue
Amberols" are wonderful-sounding, sturdy records, best heard by using
a Diamond reproducer (sold by Edison from about 1912 onwards).  Other
manufacturers made "indestructible" 4-minute records too.

One of the great things about Edison, especially admirable today in
the days of throwaway technology, was that whenever he came out with
improvements to his phonographs -- from longer-playing records to
better reproducers to bigger horns -- he always made conversion kits
available for owners of older machines.  So, your grandmother may have
bought her Home early on, and later added various upgrades.  The
variations make phonograph collecting a lot of fun!

If your Home has a dual speed switch, be sure you use the proper
reproducer to play the appropriate cylinder -- you risk ruining your
stylus AND your cylinders if you don't!

By the way, a bit of terminology: your Edison Home is a "phonograph"
as opposed to an "Ediphone".  Ediphone was a term applied to Edison's
office dictating machines.

Hope this helps!

Jim Canavan
http://members.aol.com/cybrflash