NONLINEAR LABS C15 - Page 38

Sound Generation
38
Setting up a feedback path:
As mentioned earlier, sustained comb filter sounds can be achieved by continuous
excitation of the comb filter (resonator). This can be done by using sustained oscil-
lator signals. Another way to continuously excite the resonator is feeding a certain
amount of its output signal back to its input. On the C15, this can be done by using
the Feedback Mixer, which will be introduced right now:
▶
Press Comb (Feedback Mixer).
▶
Turn the Encoder to [ 40.0 % ].
ߊ By doing so, a certain amount of the Comb Filter’s output signal is routed
back to the Feedback bus. It could also be combined with the output
signals of the State Variable Filter and the eects section.
Tß0o fully enable the feedback path, the destination of the feedback
signal needs to be determined. Available destinations can be found in the
Oscillator and Shaper sections. We will use the “FB Mix” insert point
located aer the Shaper in the signal path. Please refer to the synth
engine overview when you feel lost at this point.
▶
Press FB Mix (Shaper A).
▶
Turn the Encoder to [ 20.0 % ]. Now you can hear sustained notes.
ߊ The Comb Filter signal is tapped and routed back to the Comb Filter
input as an exciter signal through the Feedback Mixer and feedback bus.
If the loop gain is greater than 1, it will keep the filter constantly “ringing”
with self-oscillation.
Envelope A
Oscillator A Shaper A
FB Mix
FB Mix
Comb
Filter
Envelope B
Envelope C
Output Mixer (Stereo)
Feedback Mixer Shaper
Shaper
State
Variable
Filter
Oscillator B Shaper B
Cabinet
Gap
Filter
Flanger Echo Reverb
RM