[sdiy] MIDI volume to volts formula

[Adam Inglis]

> On 7 Jun 2018, at 5:02 PM, rsdio at audiobanshee.com wrote:
> 
> 
> On Jun 6, 2018, at 6:07 PM, Adam Inglis <21pointy at tpg.com.au> wrote:
>> On 7 Jun 2018, at 4:48 AM, Ben Bradley <ben.pi.bradley at gmail.com> wrote:
>>> On the other hand, I think a piano is a roughly linear function of
>>> input velocity (or force) and "signal" output. This may require
>>> "original research."
>> 
>> There must be a stack of research out there, possibly some of it in-house/proprietary by the big instrument makers, regarding this.
>> I would’ve thought you be better served by a sinusoidal function, rather than log or linear, but of course it is going to depend mostly on the qualities of the particular tone or patch you are controlling at any one time (even more than personal playing style).
> 
> Why sinusoidal? Are you suggesting the volume should eventually decrease and then go negative as velocity increases?
> 

Aaah, sorry, that should be sigmoidal, not sinusoidal!! Duh.

As in this 
https://en.wikipedia.org/wiki/Sigmoid_function

These sorts of shapes are very useful when tailoring velocity to “playability” on a per patch basis.