NONLINEAR LABS C15 - Page 36

Sound Generation
36
Using “Fluctuation”:
▶
Press Fluct (Oscillator A).
▶
Sweep the Encoder slowly across the entire range while playing some notes.
Then dial in approx. [ 60.0 % ].
ߊ At various pitch ratios between Oscillator A (exciter) and Comb Filter
(resonator), the frequency boosts and attenuations are very strong and
limited to narrow frequency bands. Consequently, the peaks and notches
are quite diicult to handle, and oen it is diicult to achieve musically
useful results, e. g. a steady tonal quality across a wide key range.
The Fluctuation parameter is a welcome aid at this point: It randomly var-
ies the oscillator pitch and thus produces broader frequency bands with
matching ratios. The peaks and notches are evened out, and the sound
is becoming more consistent. The sonic character also changes – in our
example, it is shiing from a reed instrument towards a string orchestra.
5
Recap: Using the Comb Filter as a resonator
• The Comb Filter is a delay line with feedback loop, driven into oscillation and
thus generating a tone.
• The Pitch parameter of the Comb Filter determines the delay time and thus the
pitch of the generated tone.
• Frequency boosts and cancellations in the feedback loop create a complex
frequency response that determines the timbral character.
• The Decay parameter controls the feedback amount and, by that, the number
of repetitions of the input signal. This determines the decay time of the tone
generated by the resonator.
• An oscillator signal (exciter) stimulates a response of the comb filter (resonator).
• The qualities of the exciter determine the timbral character of the resulting sound
to a large extent.
• Short, percussive exciter signals produce sounds like plucked strings. Sustained
exciter signals produce sounds like bowed strings or (over)blown woodwinds.
• Key Tracking and a Gate (on Decay) as well as a lowpass filter (“Hi Cut”) produce
natural sounding characteristics of “plucked strings”.
• An allpass filter (“AP Tune”) can shi the overtones and provide sonic characteris-
tics of “metal tines” or “metal plates”.