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SERGE MODULAR
9
The Coupler (#11, #12)
The COUPLER is an internal comparator comparing the outputs of both side.
Whenever the bottom section is HIGHER in voltage than the top section, the output of the COUPLER goes HI.
Otherwise the output is LO. The COUPLER has two outputs, one of which switches between 0V and +12V, the
other switching between -12V and +12V. This is useful for generating complex control voltages and for patching
a random voltage generator. In fact, the Random Voltage Generator module is a Smooth & Stepped Generator
internally patched to function exclusively as such. Note that a Noise Source is needed for use of the GTO as a
random voltage generator. The red COUPLER OUT (11) is 0 to 5V, the black (“hot”, 12) one goes rail to rail (roughly
-12V to +12V i.e. 24V pp). Please be careful when using the black Coupler, e.g. when routing to a ADC
converter or similar.
GTO - First Steps
The GTO is a complex, highly versatile module which allows for a wide range of uses and abuses both in the
audio and CV range, so it may require some time and experimenting to familiarize oneself with it - don’t expect
the module to reveal its secrets and power in a few minutes after you rst power it up. Here are some very basic
ideas to start with:
1. Patch the Smooth side of the GTO to cycle by connecting the Cycle jack into the Input. The Smooth side
then produces a triangle wave from about 0V to 5 V (amplitude slightly depends on frequency), the LED
should indicate that. The Rate pot determines the frequency of the cycle / output - the range is very wide,
going from below 1 Hz to appr. 4 kHz. The Cycle jack provides a corresponding Pulse wave output.
2. Set the Stepped side to cycle as well by patching Cycle to IN (or turning on the Cycle switch in the
eurorack module). Unlike the Smooth side, the Stepped side will not generate an output in Cycle mode
(=LED stays dark or seems frozen) unless a Puls wave is fed into the Sample jack. Patch a pulse wave
- e.g. the Cycle output of the Smooth side - into the Sample jack to bring the stepped side to life. The
stepped side is essentially a sample-and-hold circuit, the Rate knob determines how long each step is at
the Stepped output. Changing the frequency of the pulse going into the Sample input and/or changing
the Rate affects the output.
3. The Smooth Side can be used as a Lowpass lter. Feed an audio signal (e.g. a saw or pulse wave from
an oscillator) into the In jack (Cycle switch turned off) and listen to the signal coming from the Smooth
out while you turn the Rate knob. At maximum position (full CW) the signal should sound pretty much
unltered, turning the Rate down (counterclockwise) the harmonics get ltered / smoothed out, at mini-
mum position the signal will disappear altogether.
Using the VC input jack in the same setup as before, this lter effect can be used to achieve the effect of a
Lowpass Gate / VCA. Send an CV envelope (e.g. from a DUSG or an Extended ADSR module) into the VC
jack and turn the VC knob sufciently high. Tune the Rate pot to a position so that the output is silent when no
CV is applied but clearly audible when the envelope is high. This causes a VCA effect, but the envelope not only
determines the amplitude, but also the amount of ltering applied (like a lowpass gate).
4. Try whatever you can think of and try not to distinguish between CV and audio - while originally the SSG
was primarily for control voltages, very interesting results can be found by going into audio range.
