NONLINEAR LABS C15 - 4.9 The Undo Mechanism

Sound Generation
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The Comb Filter
The Comb Filter can shape an incoming sound by imposing specific characteristics
on it. The Comb Filter can also work as a resonator and it can produce periodic
waveforms like an oscillator this way. It is an integral part of the C15’s sound gen-
eration, and it can be useful when achieving imbral characteristics of e.g. plucked
or bowed strings, blown reeds, horns, and many strange things in between and far
beyond that.
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Excursion – Comb Filter Basics
Let’s have a brief look at the C15’s Comb Filter structure:
Basically, a comb filter is a delay with a feedback path. Incoming signals pass the
delay section and a certain amount of the signal is then being fed back into the
input. The signals making their rounds in this feedback loop generate a tone that can
be controlled by various parameters to achieve specific sonic characteristics and a
dedicated pitch – the comb filter is turned into a resonator / sound source.
Comb Filter
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AP Reson
Pitch AP Tune
Decay
Hi Cut
Note Pitch/
Pitchbend
Env C
Key Trk
Env C
Key Trk
Env C
Key Trk
Gate
Key Trk
Env C
Note On/O
Delay Time
Control
Feedback Control
Center Frequency
Control
Cuto
Control
Delay
2-Pole
Allpass
1-Pole
Lowpass
OutIn