Keyboard CV

[Edu Silva]

De: jteir at cc.hut.fi
 
> Hi! I don't know if this is the correct place to send questions,

Here is the right place!

> (...) But there is
> a problem: Since the oscillator is logarithmic controlled, a linear
> resistance ladder for the keyboard doesn't sound right. But if I make a
> logarithmetric ladder the keys will only have the correct pitch ratio
> (semitone) at one particular position on the pot. That is, if i turn the
> pot, the pitch will rise/drop, but an octave on the keyboard is no longer
> an octave in pitch. 
>   Is there a simple way to solve this?

The keyboard must have a linear resistance ladder, to perform the desired
1V/octave ratio. The control voltages (keyboard, LFO, pitch wheel and
whatever else) will feed a summing amplifier and then (that's the secret!)
to an exponential converter. The output voltage will double every time the
input rises 1 volt, and everything will be allright...

Note that the modulation pot will have to be linear, as well as the other
modulations sources, since they will be processed by the expo converter.

Edu

_____________________
ES2 Audio - Som & Luz
Salvador-Bahia-Brasil