8.0

Included VST Instruments
Mystic
213
The synthesis method used by Mystic is based on three parallel comb filters with
feedback. A comb filter is a filter with a number of notches in its frequency response,
with the notch frequencies harmonically related to the frequency of the fundamental
(lowest) notch.
A typical example of comb filtering occurs if you are using a flanger effect or a delay
effect with very short delay time. Raising the feedback (the amount of signal sent
back into the delay or flanger) causes a resonating tone – this tone is basically what
the Mystic produces. This synthesis method is capable of generating a wide range
of sounds, from gentle plucked-string tones to weird, non-harmonic timbres.
The basic principle is the following:
• You start with an impulse sound, typically with a very short decay.
The spectrum of the impulse sound largely affects the tonal quality of the final
sound.
• The impulse sound is fed into the three comb filters, in parallel. Each of these
has a feedback loop.
This means the output of each comb filter is fed back into the filter. This results
in a resonating feedback tone.
• When the signal is fed back into the comb filter, it goes via a separate, variable
low-pass filter.
This filter corresponds to the damping of high frequencies in a physical
instrument – if this is set to a low cutoff frequency it causes high harmonics
to decay faster than the lower harmonics (as when plucking a string on a
guitar, for example).