Phase mod with PWM

[Tony Allgood]

Hi all,

Is there a way of generating PWM without the phase modulation that seems
to accompany it? I can understand that generating your PW from the saw
output would generate a phase modulated signal. I believe, using a
triangle wave, this should not be so. However my experiments have found
that it does indeed produce a perceptible frequency shift as well.

My poly's CEM3340 VCOs sound terrible if the PW modulation is deep and
fast, just too much vibrato. I think the 3340s use the saw to generate
the pulse out. My best workaround is to use a sine LFO, but you will
still get a PM that is determined by the differential of the modulating
waveform. Other than adding a differentiated sine (-cos) to the VCO's FM
input, with approprate scaling, is there anyway to make deep fast PWM
sound more pleasant?

Regards,

Tony Allgood  Penrith, Cumbria, UK

Rack mounted moog filter and the TB3030 SuperBassline projects:

http://www.techrepairs.freeserve.co.uk/