Welcome!
There are many ways to achieve this effect with a modular.
First, remember that a square wave is a "special case" of a pulse. Set the
pulse width to 50% and you have a square wave.
If you patch the pulse into a control input on a Voltage-Controlled
Amplifier, you will get the "loud/soft/loud/soft" 'tremolo' that you
describe, without period randomness. Using the VCA, you can adjust whether
the low portions of the duty cycle cut off the sound completely or just
reduce it in level.
If you wanted something a little more random, you could take some "red
noise," in other words, white or pink noise that is low-pass (or band-pass)
filtered until it is only a randomly fluctuating voltage, into the control
voltage of the Low Frequency Oscillator for either the pulse-width or the
frequency. The MOTM-101 Noise Module actually has this kind of noise
available pre-filtered as "slow random."
Another option would be to feed the random voltage into the control input of
an MOTM-700 VC Router, and adjust the switchover to taste. This would be a
"hard cut" of the sound, unless you used the router to then feed a VCA, or
used a mixer to blend in the original signal.
I'm sure there are a hundred other ways of doing this. It depends on the
exact sound you're looking for.
My thought process would be: first, get the random period down. Where can I
get it from? Noise, usually, filtered in some way. (But that's not the only
way.) So the noise module is a natural.
Next, do I want the amplitude to change to random levels, or simply between
two preset levels at random intervals? This helps determine whether or not
you use the above noise directly or to control something else. If directly,
then go to next paragraph. If indirectly, then think of what can give you
the pulse you want. As in the examples above, you can control the frequency
or the pulse-width of a pulse wave on a VC-LFO (or VCO) to get that kind of
effect, or use the Router in various ways.
Finally, what will control the amplitude? Usually a VCA, but the Router
works too, or even a ring modulator in a pinch. Anything that controls
amplitude.
After that, you can start to get crazy. What if you use pulses out of the
Multiplexer instead of an LFO? What if, instead of noise, you create
"pseudo-randomness" by having one LFO frequency (or pulse) modulate another,
with that second one controlling the VCA? What if you feed a little of that
second pulse back into a CV input on the FIRST LFO for some real chaos?
Maybe you want the keyboard gate to re-trigger the LFO or VCO so the pulse
always starts in a high (or low) state when you hit a key. Maybe you want an
Envelope Generator to control the frequency of an LFO, so the pulse changes
dramatically, but in repeatable ways. Or use the keyboard CV to control the
center frequency of a band-pass filter that filters the noise feeding the
router, so that the pitch of the note determines the stochastic parameters
of the modulation....
That's the great thing about a modular synthesizer. There are SO many ways
of creating any effect. You choose which way based on the final effect, what
kinds of modules you have (or have left, anyway, after creating the rest of
the patch), and sometimes just through serendipity!
Good luck!
Mr. T
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-----Original Message-----
From: John Parks [mailto:jpyyz@...]
Sent: Thursday, 05 April, 2001 2:02 PM
To: motm@yahoogroups.com
Subject: [motm] new member here with a question
Hello everyone. I am a newbie here in the true sense of
the word. Not only am I new to this list but to Synthesis
in general. I have never played around with modular synths
before but I have always loved the music they made. This
summer I hope to be putting together my first modular synth
from Synthesis Technology.
So on to my question. (Keep in mind I am very new to all
this and I am still learning all the terminology.)
I was wondering if there was a way to create a random gated
tremelo effect. Something that just cuts on and off. The
best way I can explain it is to think of a light bulb that
is flickering on and off at random. There is no set
pattern. Is there a way to accomplish this using MOTM
modules? I noticed that there isn't a square wave on the
LFO but there is a pulse wave. Could you somehow randomly
very the pulse width and the speed at which those changes
take place and then feed this into a VCA to produce the
gated tremelo effect? How would you go about patching this
up if its possible?
Everyone have a pleasent day,
John Parks