User Manual

3.2.3. VCF 1 (Steiner)
The Steiner filter defaults to lowpass mode in the Init patch, which means that anything
below the corner frequency is allowed to pass; anything above it is gradually filtered out.
1. Sweep the Cutoff knob through its full range while holding a note. There's no
sound when the knob is all the way down because the lowpass filter is blocking
all frequencies from passing.
2. Move the Resonance knob halfway up and sweep the filter again. Resonance
emphasizes the corner frequency of the filter.
3. Turn the Filter type knob to HP (halfway up) and sweep the filter again. Notice
how the frequencies disappear from the bottom up, and at the maximum cutoff
value there is no sound. HP (highpass) is the opposite of LP (lowpass): HP allows
high frequencies to pass and filters out the lower frequencies.
4. Turn the Filter type knob to BP (100% right) and sweep the filter again. BP
(bandpass) allows a center band of frequencies to pass and filters out the higher
and lower frequencies. Resonance emphasizes the corner frequencies. As the
filter sweeps through its range, the center band moves up and down through the
audio spectrum.
5. Set the Filter type knob halfway between LP and HP. This turns VCF 1 into a
"Notch filter", which is the opposite of bandpass: the LP and HP filters work
together to remove frequencies in the middle. Resonance emphasizes the corner
frequencies. As the filter sweeps through its range, the notch moves up and down
through the audio spectrum.
6. Now try the Filter type knob at other positions. For example, halfway between HP
and BP provides a 50/50 mix of both types.

♪: The Master Cutoff knob can be used for the above example instead. But it actually controls both
filters at the same time, which may not always be what you want.
3.2.3.1. About the other knobs...
For this overview we've only used half of the knobs in the VCF 1 module (Cutoff, Resonance,
and Filter type). Here's a quick description of the other controls, with details in the Filters
section [p.28] of the Voice Architecture chapter [p.21].
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