Using the envelope controls
An attack-release type envelope allows attenuation of parts of the response sample. The start position (time)
of this envelope can be set using the “Pos” knob. Setting the position will completely skip over any sample
data that comes before this position in the response sample. The combination of these three knobs allows
you to precisely focus on any specific part of the response, for instance the tail, or only the early reflections.
The position control has a precision of 1024 steps. The Release and Attack [ + Release] settings have the
same resolution, and using their exponential control curve you can achieve very short attacks or releases
and still accurately control them. The attack and release time are displayed on screen down to milliseconds.
The applied envelope attenuates the response in places. To have no attenuation at all (to actually disable the
envelope’s function) turn Attack and Pos to 0, and turn Release to its maximum. Note that the Integral uses
normalization after applying the envelope. This will preserve signal power, however it can also significantly
boost the wet signal. You can compensate by turning down the Wet knob.
Note that when attack is non-zero, you may experience a gap in the audio. Each time the envelope is
changed the convolver recomputes and restarts. Since a longer attack will result in low volume, you may
hear short gaps in the output as you continue to change the envelope. This can be compensated by
increasing Slew. See the section “Using the remaining parameters” for more information on that.
Using the remaining parameters
Predelay: 0-2.0s in with an exponential control curve. Using this often influences the perception of the size
of a reverberating space. For instance, you can make a short reverb of a small room appear bigger by
turning this up a little. Adjustment of this control causes the convolver to recompute its data. This may take a
short while. Also note that the convolver restarts after adjustment and it starts with playing back the delay.
Highpass filter cutoff [⇧ + Predelay] To keep the convolution from blowing up you can cut away some low
frequencies from the audio input. The high-pass is a 12dB per octave filter with a full range of 0 to 20000
hertz, and an exponential sweep gives fine adjustment in the lower frequencies.
Stereo width: This is a Mid-Side matrix control that either turns the input into mono (turn it down to 0), or
exaggerates the stereo effect (turn it completely right). The center keeps the stereo input audio signal exactly
as it is.
Pitch [⇧ + Stereo width] Hold down Shift and turn the Stereo width knob to pitch bend just the impulse
response. This does not change the pitch of the convolved signal itself, but changes the timing and formant,
and allows you to tune resonator-style impulses. Completely left means -2 octaves, completely right means
+2 octaves. Center keeps the response the same pitch.
Xfade: Crossfade between convolver A (left on the knob) convolver B (right on the knob). Please read the
section “Using the dual convolvers” for more information.
Slew time [⇧ + Xfade] recomputation slew time controls the crossfading time between newly computed
response and old response. Such a cross fade occurs when a new impulse response is offered to the
convolver. For instance when a new response is selected by turning the select knob, or when the envelope
or envelope position is changed. A short slew time sounds more choppy, but you’ll hear the new response
faster. A larger slew is especially useful with longer envelope attack.
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