[sdiy] Synthesizers...

[Ian Fritz]

At 12:19 PM 2/18/2009, Scott Nordlund wrote:

>I've never seen any synth-related reference to this (guess it would be
>in electronotes if it's anywhere), but saw-derived PWM and tri-derived
>PWM do have different spectra.  PWM from a sawtooth wave results in an
>upward (or downward) sideband shift proportional to the modulation
>frequency, while PWM from a triangle wave results in a simultaneous
>upward and downward sideband shift.  This is why saw-derived PWM can
>sound "out of tune", especially at low frequencies.  Using a triangle
>wave should sound much better.  Unfortunately synths usually use the
>saw wave for PWM, even when a triangle is available.


Well, that's been discussed here at least a couple of times before.  The 
Saw-based PWM is much stronger sounding than the Tri-based effect, because 
it is more "phasey".  My original DPWG works off of a Tri and has a more 
subtle sound than a similar unit I have that works off of a Saw.  It is 
just a personal preference thing as to which one sounds "better".  They're 
just different, that's all.

Ian