Operation Manual

THOR POLYSONIC SYNTHESIZER
212
State Variable Filter
This is a multi-mode filter which offers 12 dB/octave slope Lowpass (LP), Bandpass
(BP), Highpass (HP), plus Notch and Peak filter modes which are sweepable be-
tween HP/LP states, similar to the vintage Oberheim SEM filter.
The filter modes are as follows:
D LP 12 (12 dB lowpass)
Lowpass filters let low frequencies through and cut off high frequencies. This filter
type has a 12dB/Octave slope.
D BP 12 (12 dB bandpass)
Bandpass filters cut both high and low frequencies, leaving the frequency band in
between unaffected. Each slope in this filter type is 12 dB/Octave.
D HP 12 (12 dB highpass)
Highpass filters let high frequencies pass and cut off low frequencies. This filter
type has a 12dB/Octave slope.
D The “Notch” and “Peak” filter modes employ a combination of two out-
puts from the same filter combining LP and HP set to the same the filter
frequency.
The “LP/HP” knob associated to these two filter modes can modulate the state of
the filter from low-pass to high-pass. If the knob is in the mid-position, you get a
Peak or Notch filter slope (depending on the mode). The HP/LP parameter can be
assigned as a modulation destination.
D This filter can self-oscillate and will produce a pitch with high Resonance
settings if this is activated.
Self-oscillation can be switched on or off by using the “SELF OSC” button. The
“KBD” knob governs how the frequency tracks the keyboard, turned fully clock-
wise will produce 12 semitones/octave tracking.
Comb filter
The Comb filter can add subtle pitch variations and phasing-like effects to sounds.
D Comb filters are basically very short delays with adjustable feedback
(controlled with the Resonance knob).
A comb filter causes resonating peaks at certain frequencies. Comb filters are
used in various signal processing devices like flangers, and produces a character-
istic swooshing sound when the frequency is swept.
D The difference between the “Comb +” and “Comb –” modes is the posi-
tion of the peaks in the spectrum.
The main audible difference is that negative Comb mode causes a bass cut.
D The Resonance parameter in both cases controls the shape and size of
the peaks.
This filter will produce a pitch with high Resonance settings combined with low
frequency settings.
Formant filter
The Formant filter type can produce vowel sounds. There are no Frequency or Reso-
nance parameters, instead you have a horizontal “X” parameter slider and a vertical
“Y” parameter slider that operate together to produce the various filter formant char-
acteristics.
D You can alter the settings of both the “X” and “Y”parameters simulta-
neously by moving the “dot” inside the gray rectangle on the filter panel.
Horizontal movement changes the “X” parameter, and vertical movement the “Y”
parameter.