cuttting time @ 78 rpm

[prestok10]

I've done an internet search and also searched this forum, but I can't find what the recording time would be on a 7 or 8 inch disc at 78 rpm. I have a few NOS blanks at these sizes and I kind of hate it when the recording space runs out on my Presto K-10 and it re-cuts the last groove too many times.

[markrob]

Hi,

If you know the LPI of the K10, and the length of the active recording area, you can calculate the run time by the following formula:

Run Time (min) = (LPI x Area) / RPM

For example, if the K10 cuts 112 LPI and we assume the 8" diameter disc has about 1.875" of active area (4" disc radius - 1.5" radius label - .5" dead wax - .125" lead in), then the total run time at 78 RPM = 2.69 min (2:41).

Hope this helps.

Mark

[prestok10]

Thanks, Mark!