[sdiy] MIDI volume to volts formula

MTG grant at musictechnologiesgroup.com
Wed Jun 6 17:21:49 CEST 2018

Please to explain use of term "source code" in reference to the Mirage. 
I knew there were alternate OS's but have never heard anything about 
source. :)

A 6809 Fan

On 6/6/2018 12:07 AM, Gordonjcp wrote:
> On Tue, Jun 05, 2018 at 11:24:21PM -0700, rsdio at audiobanshee.com wrote:
>> All we can say for certain is that larger Velocity numbers must be louder, but only if velocity is applied to volume.
> Unless you're doing something a bit off-the-wall ;-)  Negative velocity
> values can be handy if you want to layer two sounds and crossfade
> between them.
>> Personally, I always try to consider the techniques available at the time. You have to keep in mind that bother the sender and the receiver could interpret velocity any way that they wanted. Usually, especially in the eighties, manufacturers wanted to find the easiest way to calculate these values.
> The Ensoniq Mirage maps velocity to attack peak level and sustain level
> by applying a proportion of incoming velocity converted to a signed
> value, and looking up an exponential-ish table in ROM.  I haven't got
> the right bit of source code kicking around to look at so I might not
> be remembering it properly.
> Since as you say the early 80s 6809 processor couldn't divide (but could
> multiply) then a lot of that stuff was just done by lookup tables.
> Never underestimate the power of throwing inexpensive memory at an
> expensive calculation.

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