[sdiy] Linear detuning !

[JH.]

> Seems like a task for DCOs, anyway, because we are asking the oscs to stay
> together very, very, tightly. I mean, this Linear-FM-for-Beating effect
> works best if the 2 oscs have no beating to begin with. If you had 2 VCOs
> that tracked so perfectly (for more than a short while after tuning),
you'd
> probably declare them sterile and digital sounding. ;-) Maybe some VCOs
are
> that precise, I dunno... but DCOs are, are course.
>
> I used to think that beating would sound just like tremelo -- so why
> bother? -- but it totallly depends on the waveshapes.



Of course linear detuning _alone_ is quite boring.
It's the combination of "linear detuning" and "expo detuning" that is most
pleasant.

B = Beat frequency, f = oscillator frequency, d1, d2: constants

(1)
Linear Detuning (adding a constant current after the expo converter, causing
a fixed term of beat frequency):

B = d1 = constant ( = rather boring)

(2)
Expo Detuning (adding a constant voltage before the expo converter, causing
a
linear term of beat frequency):

B = d2 * f (tends to either sound overly detuned in high registers, or
having not
enough effect in the low register)

(3)
Combination of both:

B = d1 + d2 * f  (allows pleasant chorusing in low register, while not
sounding
out of tune at high register)

JH.