[sdiy] Living VCOs - single VCO PWM sound

[JH.]

First of all, a big thank-you to all those who have pre-ordered PCBs for my 
"Living VCOs" project!

The huge request for this has taken me by surprise. I never had so many 
pre-orders coming within the first couple of days for *any* of my other 
PCBs, and if it goes on like this it may be the first project that could be 
sold out before I even get the boards from the factory. :) - Ok, but I don't 
really expect that.

Anyway: Even though the strength of these VCOs lies in the animated bass 
range of three of them playing together, there is another feature I've built 
into them, and that's the CS-80-style PWM. Like the Yamaha CS-80, the Living 
VCOs have a limited pulse width. Even with strong pulse width modulation, 
you never "lose" the VCO signal, because you never get down to 0% or up to 
100% pulse width. What may sound like a limitation at first, actually opens 
the possiblitity of "overmodulation": You can modulate the pulse width with 
a triangle LFO of rather slow rate, and with a depth that would normally be 
bigger that 100% modulation index. As a result, the modulation is clipped, 
becomes trapezoid-shaped. Musically, this is like a periodic "push" of the 
modulated oscillator's pitch - something that sounds less detuned than 
ordinary PWM and allows a sonically very rich modulation. I've made a short 
demo to demonstate this:
http://www.jhaible.de/living_vcos/living_vcos_single_vco_pwm.mp3
(One VCO thru wide open filter + VCA + reverb)

Project description and a 3-VCO-demo is here:
http://www.jhaible.de/living_vcos/jh_living_vcos.html

JH.