Elektron Analog Four - Manual (Page 87)

Appendix A: SYNTH TRACK PARAMETERS A-3
FILTERS
FRQ (Filter1 Frequency) controls the cutoff frequency of Filter 1,
the 4-pole lowpass transistor ladder filter.
RES (Filter1 Resonance) controls the resonance of Filter 1.
Increased resonance introduces a peak in the spectrum at the
cutoff frequency. By design, Filter 1 has a stronger resonance in
the higher frequencies, which gives a characteristic electronic fil-
ter sound when the resonance starts sharp and then falls during
a falling filter envelope.
OVR (Filter1 Overdrive) introduces distortion in the signal path.
In mid position (0) the signal is kept clean. Increasing positive
values gives a clipping distortion after Filter 1. Increasing nega-
tive values also distorts the signal, but with a softer overdrive
inside the filter.
TRK (Filter1 Keytrack) lets the cutoff frequency follow the pitch of
the sound played. A setting of 32 will make the filter track the
oscillator frequency in note intervals, making it possible to play
the Filter 1 resonance the same way as an oscillator is played.
DEP (Filter1 EnvF Depth) controls the amount of cutoff fre-
quency modulation from the filter envelope EnvF. The knob is
bipolar, meaning that both negative and positive modulation
depth is available. Note that ENV always affects Filter1, regard-
less of which modulation destinations are chosen.
FRQ (Filter2 Frequency) controls the cutoff frequency of Filter 2,
which is the 2-pole multimode filter located after Filter 1 and
Overdrive.
RES (Filter2 Resonance) controls the resonance of Filter 2.
Increased resonance introduces a peak in the spectrum at the
cutoff frequency. (Except for the Bandstop filter type, which has a
notch instead of a peak. This notch is widest at the lowest Reso-
nance setting.) Compared to Filter 1, Filter 2 has a more uniform
resonance behavior over the whole audio spectrum.
TYP (Filter2 Type) selects the filter type of Filter 2. Seven types
are available: 2-pole Lowpass, 1-pole Lowpass, Bandpass, 1-
pole Highpass, 2-pole Highpass, Bandstop, and Peak. Techni-
cally all of them are 2-pole filters with resonance, but the "1-pole"
types have a flatter spectrum like simple 1-pole filters and can be
very useful also for equalizer duties.
TRK (Filter2 Keytrack) lets the cutoff frequency follow the pitch of
the sound played. A setting of 32 will make the filter track the
oscillator frequency in note intervals.
DEP (Filter2 EnvF Depth) controls the amount of cutoff fre-
quency modulation from the filter envelope EnvF. The knob is
bipolar, meaning that both negative and positive modulation
depth is available. Note that ENV always affects Filter2, regard-
less of which modulation destinations are chosen.
FILTERS
In the FILTERS page, settings that will affect the two track filters are found.