[sdiy] waveform animation (was Re: [sdiy] Imperfect VCO)

[Gene Stopp]

On the Voyager you can pick apart what the waveshaper is doing as you
transition from tri to saw to narrow pulse to square. You can modulate one
VCO with another, and crank down the mod frequency to real slow, and listen
to the pitch of the other VCO as you turn the waveshape knob on the
modulating VCO. Starts out triangle, then one slope gets longer while the
other slope gets shorter, then a little "blip" of pulse starts to edge in,
then the saw slope morphs into a vertical line as the pulse gets wider,
ending up in a square. The amplitudes adjust during all this to keep the
subjective loudness the same. The waveshape is a modulation destination.

p.s. it is a lowpass/lowpass or lowpass/highpass filter, but on separate
outputs (not mixed into mono). Best demonstrated by messing around with the
touch pad.

p.p.s. it is possible to get the Voyager to sound exactly like a minimoog.
Best if you do this with the machines side-by-side. It does take a while,
but it is possible. Just in case anybody wondered....

- Gene


-----Original Message-----
From: mark verbos [mailto:mverbos at earthlink.net]
Sent: Friday, August 01, 2003 11:05 AM
To: synth diy
Subject: Re: [sdiy] waveform animation (was Re: [sdiy] Imperfect VCO)


wait a second. I really don't think we should give credit to Bob for 
inventing voltage controlled waveshape on an oscillator. The RSF Kobol 
and the Serge NTO had that many years ago.

It is still a great feature, of course it's a bummer to lose the option 
of mixing multiple waves.

mark

john mahoney wrote:

>>Producing waveform animation by the use of non-linearities (which are
>>computed in the time domain) has been explored much less.
>>    
>>
>
>Although they do not use computer-generated non-linearities, the Minimoog
>Voyager's VCOs have the cool wave controls. To quote:
>    WAVE controls (3) provide continuous control over the waveforms of the
>    oscillators, from triangular, to sawtooth, to square, to narrow
>rectangular.
>
>There are a lot of wave shapes in between, say, a triangle and a sawtooth.
>Varying the wave shape dynamically would be more interesting. I assume (?)
>the Voyager's waveshapes can be modulated dynamically by LFOs or envelopes.
>
>Funny thing: This shaping is easy for a digital synth, but I haven't seen
it
>done before. Leave it to Bob Moog to make it happen on an analog synth.
>
>This technique could use a name. We have PWM for pulse width mod, this is
>something like ramp slope modulation (RSM) or wave shape modulation (WSM).
>--
>john
>
>
>  
>