andro wrote: ↑Wed May 27, 2020 1:41 am
@honki-bobo, having myself just written a volt meter, I am surprised to see yours. I can't find it on the store. That's worth releasing (in competition with my upcoming one).
I haven't released that one yet. And it is going to be free, since it doesn't really do anything
andro wrote: ↑Wed May 27, 2020 4:59 am
So I end up with y = 65.406398*2^x whereas you have the vastly more elegant y = 55*2^(x + 0.25). The 0.25 is of course the negative voltage offset at 55 Hz based on A440, the voltage for 55Hz being -0.25V.
Hat off to you. Sometimes I wonder why I am so dumb! Did you derive that yourself or is it well known and I am just ignorant of basic things?
You are far from dumb, my friend. Your formula is absolutely correct, as 0V maps to C2, which is 65.40639... Hz (at a 440 Hz A4). Since frequency doubles every octave (2^1, this is why 1V/oct works so well) and we have 12 tone equal temperament (at least in western music) the distance between two half tones is 2^(1/12). Now since 65.40639... is actually an irrational number and will never be exact, no matter how many decimal places you enter, I simply shifted the exponent by 3 halftones, ergo 3/12 = 1/4 = 0.25, as you have correctly stated.