[78-L] Calculating 78 speeds in percentages

[David Lennick]

I rely more on my ear and a good pitchpipe. Percentages aren't fixed in stone and sometimes the pitch changes subtly within a disc, and sometimes drastically. If you're playing NBC airchecks, the chimes should be G-E-C.

 

Variations of 4% aren't uncommon with some labels, especially Decca and Brunswick in the 1930s, but you'll usually have to go UP by close to that amount. Or at least 3%. Again, there's no hard and fast rule about this since Brunswicks in 1932 are usually 3% slow but may be on speed or no more than 1% out by 1938..in New York. To hear Teddy Wilson's "Blues in C Sharp Minor" in C Sharp Minor, a Chicago recording, you need to go up 2.5% as I recall. Then there's that 6 month period in 1929 where New York Victors have to go down to about 76RPM, and most of Helen Kane's Victors need to go UP about 2%....

 

Have fun!

dl


 
> From: sjones69 at bellsouth.net
> To: 78-l at klickitat.78online.com
> Date: Thu, 12 Aug 2010 23:53:45 -0400
> Subject: [78-L] Calculating 78 speeds in percentages
> 
> A math-challenged 78 collector needs your help. When using a turntable with
> a digital read-out for the pitch shifter (like a Technics SP-15), how do you
> calculate the percentage to get from 78.26 to other common "78" speeds like
> 76.59, 75, 74, 80, etc.? There's got to be a simple formula or equation,
> but my high school algebra is not coming back (even if I had it in the first
> place!).
> 
> Similarly, there should be a way to determine the playback speed in RPM from
> a record I've pitched by ear that, say, plays back at 4% below 78.26.
> 
> Many, many thanks...
> 
> Sammy Jones
> 
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