Dave Smith Instruments EVOLVER - Manual (Page 26)

Lowpass Filter
The analog (real analog!) lowpass filter is actually two different filters; one for the Left
channel and one for the Right channel. This allows true stereo processing of external
audio signals run through Evolver. However, for simplicity and consistency the two
filters are driven together in tandem, so they normally respond the same way.
Exceptions are when using the Spilt parameter as noted below, and when using the
separate filter cutoff and resonance modulation destinations, which allow the two
filters to be modulated independently. Note that though they are normally controlled
together, since they are analog there will always be some subtle differences between
the two filters, which gives Evolver a more natural sound.
Frequency: 3 1 0…164 Selects base filter cutoff frequency over more than 13
octaves. There is special smoothing on the operation of the filter knob to eliminate
stepping as you turn the knob for clean manual filter sweeps.
Env Amt: 3 2 -99…+99 Amount of filter envelope to the cutoff frequency. This
can be positive or negative, allowing inverted envelope control of the filter.
Attack: 3 3 0…110 Attack time of the filter ADSR envelope generator
Decay: 3 4 0…110 Decay time
Sustain: 3 5 0…100 Sustain Level
Release: 3 6 0…110 Release time
Resonance: 3 7 0…100 Sets the Resonance level of the filter; at high settings
the filter will self-oscillate in 4-pole mode. If the filter does not oscillate, make sure that
4 pole mode is selected.
Key Amt: 3 8 0…100 Amount of keyboard (MIDI note) to the filter cutoff. A
setting of 72 will step the filter one semitone for each MIDI note, 36 would be half-
semitones, etc. Also, the MIDI note is derived using Oscillator 1 Glide, allowing Glide
tracking.
2/4 Pole: 3 1 S 2 P, 4 P Selects either 2 or 4 pole operation for the filter.
Velocity: 3 2 S 0…100 Amount of MIDI velocity controlling the level of the filter
envelope.
Audio Mod: 3 3 S 0…100 Amount of audio modulation from the analog
oscillator to the filter, separate in left and right channels.
Split: 3 4 S 0…100 Split separates the cutoff of the left and right filters by
raising the left and lowering the right. Normally the filters track in both channels; this
allows a way to unlock them.
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