INTRODUCTION
As we've
discussed elsewhere in this manual, the majority of raw signals
produced by the RS Integrator are cyclic: that is, whatever shape the
waveform takes, it nevertheless repeats in a regular fashion. (The
common exceptions to this are the envelopes produced by the envelope
generators, one-shot triggers such as those produced by the RS40, and
noise.)
If cyclic
waveforms repeat rapidly (specifically, in the range 20Hz to 20kHz)
we call them audio waveforms. If they repeat more slowly, we call them
low frequency oscillations, or subsonic frequencies or, in special
cases, clocks. But it doesn't matter what the waveform looks like - it
can be a sinewave, a very narrow pulse, or a complex 'wiggly' shape -
the only thing that matters in this context is that it repeats itself
in a constant and definable manner.
There are
many occasions when you might want to take such a waveform and extract
the frequency information from it. Once you have done this, it is
often useful to reduce the frequency of the resulting signal in
musically meaningful ways. You might think that this is quite an
unusual function, but it's one that you will find on most basic
synthesisers, not just powerful modular instruments like the
RS Integrator. The difference is, it hides behind a simple name: a
"sub-oscillator".
This name
gives you a clue to an obvious but powerful use for the RS280: you
can use it to produce squarewave sub-oscillations one octave, two
octaves, or even further below the source signal. You can even produce
low frequency modulations that have an octave relationship with the
audible signal. (You can use the SLEW controls on other modules to
convert the RS280's squarewaves to other, more musical, modulation
waveforms.)
But useful as
a multi-octave sub-oscillator is, it isn't the only use for a "
frequency divider". There are many occasions when it is useful to
produce related streams of clock or trigger pulses. These can then be
used to trigger sounds, effects, or sequence steps in complex and
musically meaningful ways. The are myriad uses for this. For example, an
RS280 coupled with an analogue sequencer such as the Analogue Systems
TH48 will allow you to trigger different sequences at different rates,
thus making many harmonic and polyrhythmic effects possible.
IN USE
The RS280 is a frequency detector and divider that produces a number of
squarewave signals derived from the frequency of any cyclic signal
presented to its input. It has a single input, five outputs, and five LEDs
that give a visual indication of the frequencies of the outputs.
CK/SIG
IN
This input accepts any signal in the range ±10v. These signals may be audio
signals or CVs, and may be generated within the RS Integrator or
presented by outside sources. If an external signal amplitude is
too low for effective use as a clock or signal source, you should use
the RS70 pre-amplifier to boost it to an appropriate level.
OUT
This outputs a squarewave with voltages 0v and +10v, suitable for use as a
trigger or clock. The frequency of the output is the same as the
frequency of the signal presented to CK/SIG IN.
If the input
signal is at audio frequencies, the output will be an audio signal with a
+5v offset. You can use the RS50's DC LEVEL SHIFTER to convert this
into the range ±5v.
÷2
OUT
This outputs a squarewave with voltages 0v and +10v, suitable for use as a
trigger or clock. The frequency of the output is exactly one half that
of the signal presented to CK/SIG IN. If the input signal is at audio
frequencies, the output will be an audio signal exactly one octave below
the input. Again, this will exhibit a +5v offset, and should be SHIFTED
if you wish to use it as a ±5v audio signal.
÷4
OUT
This outputs a squarewave with voltages 0v and +10v, suitable for use as a
trigger or clock. The frequency of the output is exactly one quarter of
that of the signal presented to CK/SIG IN. If the input signal is at
audio frequencies, the output will be an audio signal exactly two octaves
below the input. Again, this will exhibit a +5v offset, and should be
SHIFTED if you wish to use it as a ±5v audio signal.
÷8
OUT
This outputs a squarewave with voltages 0v and +10v, suitable for use as a
trigger or clock. The frequency of the output is exactly one eighth
that of the signal presented to CK/SIG IN. If the input signal is at
audio frequencies, the output will be an audio signal exactly three octaves
below the input. Again, this will exhibit a +5v offset, and should be
SHIFTED if you wish to use it as a ±5v audio signal.
÷16
OUT
This outputs a squarewave with voltages 0v and +10v, suitable for use as a
trigger or clock. The frequency of the output is exactly one sixteenth
that of the signal presented to CK/SIG IN.
If the input
signal is at mid- to high- audio frequencies, the output will be an audio
signal exactly four octaves below the input. Again, this will exhibit a
+5v offset, and should be SHIFTED if you wish to use it as a ±5v audio
signal. Often, the output will be subsonic, whereupon it can be used as an
LFO.
LEDs
The five LEDs
give a visual indication of the frequencies being produced at each of the
five outputs. Because your eye cannot resolve flickering at frequencies
greater than around 20Hz, LEDs that appear to be permanently lit
indicate outputs at audio frequencies.
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