[sdiy] CV from soundcard

Paul Schreiber synth1 at airmail.net
Fri May 8 17:13:16 CEST 2009


>
> Also 'gain error', 'offset', 'temperature coefficient'.
>
> Looking up the datasheet of a random audio codec (Wolfson WM8590) gives 
> typical 1.16% (0.1dB) gain error between the channels. The absolute gain 
> error is not even specified! Assuming the same figure (probably 
> unrealistically good assumption), that gives tuning error of 70 cents for 
> highest note in a 5 octave converter.
>
> Now let's pick a dirt cheap 12 bit DAC (MCP4821). Gain error is 0.1% 
> typical, which gives tuning error of 6 cents. And this for the cheapest 12 
> bit DAC I could find in a pinch.
>

I forgot about absolute gain channel-to-channel. Because in audio, this is a 
relative VOLUME change that now we want to map into an absolute PITCH 
change. Huge difference to the ear!

Volta is cute and clever, but it's NOT the same as a true MIDI-CV converter.

Paul S.




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