Audio Damage Eos - Manual (Page 10)

Modulation Rate and Depth
The modulation RATE and DEPTH knobs apply time-varying changes to the delay lines within the
reverberators. Modulation in a reverb serves two purposes. First, when applied in small amounts, it makes the
reverb effect seem more realistic and less artificial since its timbre changes subtly over time. The modulation
also breaks up any strong resonances in the reverberation network, reducing any tendency for it to sound
metallic.
Second, when applied in large amounts, modulation changes reverberation from
a spatial enhancement to a special effect. Large amounts of modulation create
pitch changes in the reverb. While too much modulation can cause unpleasant
pitch bends, just the right amount creates a rich chorusing effect when
combined with the original signal.
Obviously, then, modulation must be applied with care, depending on both the effect you want to achieve and
the instrument(s) you’re using. Eos provides two modulation controls, rate and depth. RATE controls how fast
the modulating signal changes, and DEPTH controls how much the modulating signal affects the reverb.
The RATE knob has a range of zero to five Hertz (cycles per second). Turning up the RATE knob makes the
sense of motion in the reverb more rapid. Eos’s modulators change shape randomly to make the modulation
unpredictable and hence more interesting to our ears. The DEPTH knob has a range of zero to 100%. Turning
up the DEPTH control makes the modulation stronger and more audible. If either of these knobs is set to its
lowest position, you won’t hear any modulation at all, of course.
The modulation settings are also reflected by the wiggly line in the graphic display at the top of Eos’s window.
As the RATE increases the line wiggles faster, and as the DEPTH increases the peaks of the wiggle become
higher.
Modulation is one of the respects in which algorithmic reverbs such as Eos differ from convolution-based
reverbs. An impulse response cannot recreate the way a modulated reverb changes over time. In much the
same way that a single sample cannot reproduce the timbral repertoire of an acoustic instrument, an impulse
response cannot reproduce the sonic richness of an algorithmic reverb.