No, it's not a constant difference for every 2 rpm. It's a constant difference if the percentage of change is the same.
From: Association for Recorded Sound Discussion List [mailto:[log in to unmask]] On Behalf Of Maddie Dietrich
Sent: Monday, April 24, 2017 5:07 PM
To: [log in to unmask]
Subject: Re: [ARSCLIST] How many half-tones from 78 rpm to 80 rpm
crap. In my example I meant to say between 76 and 78. (a constant difference of 2 rpm)
On Mon, Apr 24, 2017 at 5:04 PM, Maddie Dietrich <[log in to unmask]>
> So, is there a separate logarithmic relationship accounting for...um,
> I guess the rpm to pitch, but also accounting for what the rpm is.
> Easier to give an example:
> Say the pitch difference (the resulting interval in pitch) between 78
> rpm to 80 rpm is 44 cents.
> Is the pitch difference between 76 to 80 also 44 cents? Or would it be
> less? or more? My hunch is that it would be less. And between say 70
> and 72 even less. But between 80 and 82 would be a bit more than 44
> cents. And between 90 and 92 even more. Or maybe it's the opposite?
> Stated more simply, the lower the in rpm, the smaller the pitch
> interval resulting from a constant differential (say, 2 rpms), and the
> higher the rpm, the larger the interval.
> Or maybe the opposite? Or maybe it's a constant? Am I saying this right?