SergeModular

John,

It is fun to reread these posts. I still have the originals archived in
my email system!

Regards, Scott
===========================================================
John P wrote:

> 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
>
>
>
>
> Keep on Patchin'!
>
>
>
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