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Re: [ARSCLIST] Archaeological 78 Fragments
At 11:17 AM 7/22/2004 -0500, Aaron Russell wrote:
A friend of mine is an archaeologist who is currently excavating a
historical lumber town in North Carolina. Among the artifacts he is
recovering are fragments of 78 RPM records, and he is wondering if
there is any way to get sound off of these fragments. He says they are
generally pretty small (about the size of a quarter - I haven't asked
yet if he's checked for cross-mends between any of the fragments), but
is hoping that he could get some diagnostic snippets to let him know
what people in the town were buying and listening to. Has anyone on
the list had experience with this kind of thing of have any ideas about
how to go about working with these?
Okay, let's begin with some rough arithmetic.
The mean radius of the music on a 78-rpm disc is of the order of 4". The
length of one revolution at that radius is around 14", so a fragment an
inch across will be about a fourteenth of a revolution. 78 rpm makes that
about a milli-minute <G> or a sixteenth of a second. So to begin with,
quarter-sized fragments are not going to help.
If there's a fragment large enough to be useful, retrieving information
will be a major adventure. For example, if the shard includes some of the
center hole (for location) and has some groove in an arc of perhaps twenty
degrees, it might be worth experimenting to get an idea of the final sound,
hence insight into the recording. But remember that a full rotation of the
disc is less than one second; it takes a lot of that rotation to get sense
out of the recording.
Mike
--
mrichter@xxxxxxx
http://www.mrichter.com/