Kontakt implements a wide range of synthesis controls, including envelopes, LFOs, filters, and other processors.
envelopes
An envelope is a function that changes over time, applied to some audio parameter. The most common envelope you will use is the amplitude envelope, but envelopes can be applied to any parameter, including pitch, filter frequency, filter resonance, speed of sample playback, amount of an effect to be applied, etc.
The most common envelope type is the ADSR: Attack, initial Decay, Sustain level, Release. A, D, and R describe time values – S is an amplitude level. Kontakt uses AHDSR envelopes, with H standing for Hold time at the end of an attack, before starting the initial decay. In its most simple terms, it can be visualized as pictured below.
The attack starts when a key is pressed, taking the specified attack time to reach full amplitude. After reaching the attack, Kontakt inserts a hold time before starting the initial decay. The initial decay time specifies the time it will take to change from full amplitude to the sustain amplitude specified as the sustain level. Once the key is released, the release segment is triggered. The release time describes the the time it takes to go from the sustain amplitude to zero amplitude. Note that the release segment will start whenever a key is release, even if previous envelope segments have not completed.
low frequency oscillators (LFOs)
LFOs are oscillators that have frequencies below the range of human hearing. Although human hearing goes down to 20 Hz, these oscillators typically have frequency ranges from 0 – 100 Hz. Kontakt LFOs go above 200 Hz — not exactly an LFO, but it still limited in its frequency range. LFOs can provide periodic fluctuations, such as those you find with pitch or amplitude vibrato. Most LFOs have changeable, or selectable, waveforms. These waveforms are named after the shape of their amplitude function over time — sine, triangle, sawtooth, square. You can also have random LFO waveforms, which output random amplitude values at a specified frequency.
filters
Filters take a complex signal and attenuate or boost amplitudes of designated frequency ranges. Filters apply something similar to sonic sculpting, taking away parts of the sound and/or accenting parts of a sound. Filter types are named after the type of signals that are passed through unchanged.
- Lowpass filters allow frequencies below a specified cutoff to pass through unchanged. Frequencies above the cutoff are reduced or eliminated.
- Highpass filters allow frequencies above a specified cutoff to pass through unchanged. It is the opposite of a lowpass filter.
- Bandpass filters allow frequencies around a specified center frequency to pass through unchanged.
Filters do not allow one frequency to pass through, and then fully eliminate an adjacent frequency. Instead, filters have attenuation slopes that describe their amplitude reduction over a frequency range. A first order filter (or 1 pole) has a slope of 6 dB per octave. A second order filter (2 pole) has a slope of 12 dB per octave. Bandpass filters combine the slopes on either side of the center frequency, so a second order bandpass filter has the same slope as a first order lowpass or highpass filter.
Although it would seem intuitive that you would want the steepest slope to your filter cutoff, this is not always the best musical situation. Filters work by using delay lines to mix current and past output together. The steeper the slope, the longer the delay line. Longer delay lines can start to affect transient clarity and can create phase problems.
In Kontakt, a 2, 4, or 8 slope filter uses feedback to produce a resonant amplitude peak around the cutoff or center frequency, which can accentuate the filter frequency.
effects
Kontakt provides you with a range of effects to change a sound in playback that are similar in many ways to the plugins available in DAWs like Digital Performer. For now, I’m going to stay away from these processors to focus time on learning how to use envelopes and LFOs in interesting ways.
modulation
Modulation means change. Envelopes and LFOs are modulators, because when they are applied to a sound parameter, that parameter changes according to the parameters of the envelope or LFO. In Kontakt, you can also modulate sound parameters, and even modulator parameters, with MIDI information. It is typical to modulate amplitude through the use of Key Velocity (how hard/fast you press a MIDI key). Key Velocity mixes with an amplitude envelope to produce the actual amplitude for a note. You can set filter frequencies to respond to MIDI note number (Kontakt calls it Key Position), so that a cutoff frequency will always be the same distance from a played MIDI note.
You can also use Continuous Controllers (CCs) to change parameters using rotary encoders (knobs) or sliders to change parameters. You can have a CC change envelope attack times, for example, or change the intensity (amplitude) of an LFO, or the frequency of an LFO.
Using modulation sources will be crucial to creating interesting sounds, as interesting sounds change over time.
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