SSG hijinx, pt 1. (long)
2004-11-07 by John P
Hi all,
Here's a reposting of the series I did 3 years ago (!!!) on the SSG...
-----------------------------------------------------------------------
Well, some of the recent message here have prompted me to look at the
SSG with a little more detail.
The SSG is of course the Smooth and Stepped Generator module. It
consists of two sub-modules, the top being the Smooth section, the
bottom is the Stepped section. The outputs are tied together with a
comparator at the CUPL. jack - this gives a HIGH if the smooth output is
greater and a LOW if it isn't. *** CAUTION *** HIGH at CUPL is ~ 10VDC,
LOW is ~ -10VDC. This is fine for use as a trigger but be careful when
using it as a control voltage.... you won't hurt the Serge but if you're
using it to control a VCA for example you may destroy your speakers and
bring plaster raining down on your head from shattered walls.
The Smooth section is a VC lag processor with some interesting
additions:
1. Hold input. When this goes high the output no longer tracks the
input but is held at the same level that was present when Hold went
high.
2. Cycle. This is similar to GATE on the DSG but not the same thing.
It is normally not HIGH but LOW (-10V)
The Rate knob determines the rate of lag. At zero rotation the *rate*
is low, so that translates to a lot of lag.
The Stepped section is a sample-and-hold, also with interesting
additions:
1. A rate knob. This determines how big each step is at the Stepped
output. Full rotation=big steps, zero rotation = very tiny steps.
2. Cycle jack. This is also normally LOW (-10V). More on this in
another installment.
The stepped section can serve as an extremely high quality
sample-and-hold --- MOTM's sample and hold claims a droop rate of about
1mv per second - in other words, if you do a single sample driving a VCO
at 1 volt per octave, then hold it and just listen without resampling
you should be able to hear a VCO's tone drop perceptibly, without any
trouble. An informal test I did measured < 10mv droop in 400 seconds on
the SSG. Other listening tests bear this out.
First, some simple SSG applications:
1. Linear Glide
Patch the output of a sequencer or some other stepwise DC source into
the Smooth input, then patch the Smooth output to an oscillator. See
how turning the Rate control varies how fast the glide goes. Technical
note: in this application the glide has a linear slope so you will hear
a constant gliding rate from the oscillator (for a given Rate setting
the volts/second gliding thru will be constant, it won't be faster or
slower at the beginning or the end of the glide). In other words,
perfectly nice and even.
2. Exponential Glide
Same patch as above, but now also run a short patch cord between Smooth
out and its VC Rate jack. Turn the VC rate knob clockwise so the
control voltage is affecting the Rate to some degree. Now the glide
should speed up at the end, depending on the position of the VC rate
knob.
3. VC LFO (triangle) or VCO
Run a short patch cord from IN to CYCLE. You should see the LED go from
dim to bright to dim in a nice smooth progression.
Patch SMOOTH OUT into a PCO or NTO and hear the pitch rise and fall.
Vary Rate to make it faster or slower. Use VC Rate jack & knob to make
the frequency voltage controlled.
Patch SMOOTH OUT into your audio output path, whatever it is. You can
use SMOOTH as a low-end audio VCO. Note that tracking & stability are
NOT as good as PCO, NTO or DSG in this application, but it does give you
an extra audio oscillator in a pinch. This is a triangle wave.
4. VC LFO (square) or CLOCK or VCO
Same basic patch as #3. Instead of taking the signal from SMOOTH OUT,
mult a banana plug into the patch cord connecting IN and CYCLE. This is
a square wave that jumps from +10VDC to -10VDC approximately. As in #3
you can use this as an LFO for control voltage applications or as an
audio square wave. Additionally it can be used to clock a sequencer or
other module that needs a trigger or clock source.
Note: if you use it as a trigger for the Stepped module it creates two
triggers for every cycle. I don't know why exactly but this is what
I've observed. As in #3 you can vary the frequency with a control
voltage.
5. Lowpass Filter/Lowpass Gate
Same patch as #1. Instead of patching a DC control voltage into the
input, patch an audio source in, say, any PCO waveform. Send SMOOTH OUT
to your audio output path. Notice that the sound is more or less intact
at 100% rotation of the Rate knob, and as you turn Rate counterclockwise
the harmonics and harshness get filtered and Smoothed out. Keep turning
Rate counterclockwise, the sound will disappear altogether. So you can
use this to filter harsh harmonics out of audio, or to create an unusual
filtered effect. Use the VC rate knob and jack to make this filtering
effect voltage controllable.
You can employ this effect to create an audio Gate. What's a Gate? A
gate is a general name for a device that lets you either permit or close
off an audio signal. That's usually what you use a VCA for, and VCA's
are very high quality examples of gates. You can use this patch,
especially under Voltage Control, as an unusual substitute VCA: First,
set the Rate knob at around 10 o'clock to 12 o'clock, just so your audio
is no longer audible at the output. Now send a note envelope from DSG,
DTG, or Envelope Generator to the VC rate jack, with the VC rate knob
turned sufficiently high. You are creating low quality unusual
envelopes where the harmonics are varying with amplitude. Using
harmonic rich input, you have an unusual effect. Using purer input such
as sine or triangle wave yields a more usual or typical result.
6. Sample and Hold
Now we'll use the Smooth section to create a sample and hold effect!
Send a varying signal from LFO or Random Source into Smooth In. Using a
DSG or DTG create a rectangular clock pulse with a 99% duty cycle, that
is, mostly 'on,' with a tiny 'off' part. Send that pulse into Smooth
HOLD. Turn Smooth Rate fully clockwise. Send Smooth Out to a VCO or
some other module that needs a control voltage. Play with the DSG
rise/fall times and Smooth Rate. While HOLD is low the Smooth section
takes a 'sample', when HOLD is high that sample is held.
This should be enough to get you going for a while!
More will follow later.
John P.
--
m/n/m/l
surreal electronic music, sound, noise
http://mnml.soulcatcher.net
Here's a reposting of the series I did 3 years ago (!!!) on the SSG...
-----------------------------------------------------------------------
Well, some of the recent message here have prompted me to look at the
SSG with a little more detail.
The SSG is of course the Smooth and Stepped Generator module. It
consists of two sub-modules, the top being the Smooth section, the
bottom is the Stepped section. The outputs are tied together with a
comparator at the CUPL. jack - this gives a HIGH if the smooth output is
greater and a LOW if it isn't. *** CAUTION *** HIGH at CUPL is ~ 10VDC,
LOW is ~ -10VDC. This is fine for use as a trigger but be careful when
using it as a control voltage.... you won't hurt the Serge but if you're
using it to control a VCA for example you may destroy your speakers and
bring plaster raining down on your head from shattered walls.
The Smooth section is a VC lag processor with some interesting
additions:
1. Hold input. When this goes high the output no longer tracks the
input but is held at the same level that was present when Hold went
high.
2. Cycle. This is similar to GATE on the DSG but not the same thing.
It is normally not HIGH but LOW (-10V)
The Rate knob determines the rate of lag. At zero rotation the *rate*
is low, so that translates to a lot of lag.
The Stepped section is a sample-and-hold, also with interesting
additions:
1. A rate knob. This determines how big each step is at the Stepped
output. Full rotation=big steps, zero rotation = very tiny steps.
2. Cycle jack. This is also normally LOW (-10V). More on this in
another installment.
The stepped section can serve as an extremely high quality
sample-and-hold --- MOTM's sample and hold claims a droop rate of about
1mv per second - in other words, if you do a single sample driving a VCO
at 1 volt per octave, then hold it and just listen without resampling
you should be able to hear a VCO's tone drop perceptibly, without any
trouble. An informal test I did measured < 10mv droop in 400 seconds on
the SSG. Other listening tests bear this out.
First, some simple SSG applications:
1. Linear Glide
Patch the output of a sequencer or some other stepwise DC source into
the Smooth input, then patch the Smooth output to an oscillator. See
how turning the Rate control varies how fast the glide goes. Technical
note: in this application the glide has a linear slope so you will hear
a constant gliding rate from the oscillator (for a given Rate setting
the volts/second gliding thru will be constant, it won't be faster or
slower at the beginning or the end of the glide). In other words,
perfectly nice and even.
2. Exponential Glide
Same patch as above, but now also run a short patch cord between Smooth
out and its VC Rate jack. Turn the VC rate knob clockwise so the
control voltage is affecting the Rate to some degree. Now the glide
should speed up at the end, depending on the position of the VC rate
knob.
3. VC LFO (triangle) or VCO
Run a short patch cord from IN to CYCLE. You should see the LED go from
dim to bright to dim in a nice smooth progression.
Patch SMOOTH OUT into a PCO or NTO and hear the pitch rise and fall.
Vary Rate to make it faster or slower. Use VC Rate jack & knob to make
the frequency voltage controlled.
Patch SMOOTH OUT into your audio output path, whatever it is. You can
use SMOOTH as a low-end audio VCO. Note that tracking & stability are
NOT as good as PCO, NTO or DSG in this application, but it does give you
an extra audio oscillator in a pinch. This is a triangle wave.
4. VC LFO (square) or CLOCK or VCO
Same basic patch as #3. Instead of taking the signal from SMOOTH OUT,
mult a banana plug into the patch cord connecting IN and CYCLE. This is
a square wave that jumps from +10VDC to -10VDC approximately. As in #3
you can use this as an LFO for control voltage applications or as an
audio square wave. Additionally it can be used to clock a sequencer or
other module that needs a trigger or clock source.
Note: if you use it as a trigger for the Stepped module it creates two
triggers for every cycle. I don't know why exactly but this is what
I've observed. As in #3 you can vary the frequency with a control
voltage.
5. Lowpass Filter/Lowpass Gate
Same patch as #1. Instead of patching a DC control voltage into the
input, patch an audio source in, say, any PCO waveform. Send SMOOTH OUT
to your audio output path. Notice that the sound is more or less intact
at 100% rotation of the Rate knob, and as you turn Rate counterclockwise
the harmonics and harshness get filtered and Smoothed out. Keep turning
Rate counterclockwise, the sound will disappear altogether. So you can
use this to filter harsh harmonics out of audio, or to create an unusual
filtered effect. Use the VC rate knob and jack to make this filtering
effect voltage controllable.
You can employ this effect to create an audio Gate. What's a Gate? A
gate is a general name for a device that lets you either permit or close
off an audio signal. That's usually what you use a VCA for, and VCA's
are very high quality examples of gates. You can use this patch,
especially under Voltage Control, as an unusual substitute VCA: First,
set the Rate knob at around 10 o'clock to 12 o'clock, just so your audio
is no longer audible at the output. Now send a note envelope from DSG,
DTG, or Envelope Generator to the VC rate jack, with the VC rate knob
turned sufficiently high. You are creating low quality unusual
envelopes where the harmonics are varying with amplitude. Using
harmonic rich input, you have an unusual effect. Using purer input such
as sine or triangle wave yields a more usual or typical result.
6. Sample and Hold
Now we'll use the Smooth section to create a sample and hold effect!
Send a varying signal from LFO or Random Source into Smooth In. Using a
DSG or DTG create a rectangular clock pulse with a 99% duty cycle, that
is, mostly 'on,' with a tiny 'off' part. Send that pulse into Smooth
HOLD. Turn Smooth Rate fully clockwise. Send Smooth Out to a VCO or
some other module that needs a control voltage. Play with the DSG
rise/fall times and Smooth Rate. While HOLD is low the Smooth section
takes a 'sample', when HOLD is high that sample is held.
This should be enough to get you going for a while!
More will follow later.
John P.
--
m/n/m/l
surreal electronic music, sound, noise
http://mnml.soulcatcher.net