[78-L] Calculating 78 speeds in percentages

[martha]

 The math is simple:   take what you want (74, for instance) and divide it 
by what you have (78.26)  - that's your percentage  ( .94556 ) .  So, 78.26 
x .94556 = 74 .   Or,  you can take the difference  (78.26 - 74 = 4.26 ) 
and divide that by 78.26 -  5.4433%  drop is needed to reduce 78.26 to 74  .


----- Original Message ----- 
From: "Sammy Jones" <sjones69 at bellsouth.net>
To: <78-l at klickitat.78online.com>
Sent: Thursday, August 12, 2010 11:53 PM
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