[sdiy] Q: oscillator bank

[john mahoney]

----- Original Message ----- 
From: "Mike Hall" <m3ha11 at rcn.com>


> Just a general question about making an oscillator bank and
> using only one exponential converter to drive the oscillators:
> Is it possible?
>
> My thoughts on this:
> - sum the various control voltages: keyboard key, plus modulation,
plus
> pitch-bend
> - apply to the exponential converter
> - use the converted Hz/V value to drive several oscillators
> - each oscillator has octave switching via a resistive divider
> - each oscillator (but one) has scaling to allow relative tuning +/-
> some interval
[snip]

I'm glad that you asked, because I don't understand how octave
switching and relative tuning work with linear oscs.

With 1V/oct expo VCOs, octave switching is done with 1V increments.
Relative tuning also uses certain voltage increments -- for example, a
certain voltage will always raise the pitch a fifth. These voltages
work no matter what the initial pitch of the VCO may be.

With linear oscs, the voltage to increase from frequency X to
frequency X+N varies depending on the values for both X and N. That's
why I've never understood how octave switching worked with linear
VCOs. Am I confused or has this problem been glossed over?
--
john (confused one way or the other)