Change speed of a sound file

Carroll Grigsby cgrigs at
Fri Nov 12 05:41:51 UTC 2004

On Thursday 11 November 2004 11:35 pm, Timothy Payne wrote:

>>> snip

> I would think it would have to be at 78 rpm as who would write a program
> to convert the data coming in.  I have an old metal recording of a
> relative long gone I'd like to record but I hate to think what it would
> do to my needle on my turn table.

I'd be more concerned about the record. The standard groove for 78 rpm records 
had a .003 inch radius at the point whereas 33 and 45 rpm records used a .001 
inch tip radius, so using a more modern needle on a 78 rpm record causes the 
downward force of the needle to be borne on the bottom of the groove as 
opposed to its sides. And, the last that I heard (40+ years ago), the needles 
used at the slower speeds had diamond tips. Given that diamond is 
considerably harder than either metal or shellac (the material commonly used 
for commercial 78 recordings, my bet is that the record is at risk and not 
the needle. (There's some personal history involved here. I once trashed one 
of my father's prized 78 rpm records when I forgot to swap the cartridges. A 
heated discussion ensued.)
-- cmg

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