Reverb Parameters; Decay; Low Pass Filter; Pre-Delay - Alesis 4 Reference Manual

Overview of Effects – Chapter 3

Reverb Parameters

Most of the reverb effects in the MidiVerb 4 operate under the same set of control
parameters, which are listed and described in this section. However, reverbs which
use more processing power (i.e. the Single Configuration reverbs) provide more
parameters which take advantage of their extra processing power; parameters which
are not found in the other, smaller reverb algorithms. For example, Reverberation
Swirl is a parameter found only in the Single Configuration reverb types. Here are
the reverb parameters:

Decay

The Reverb Decay determines how long the Reverb will sound before it dies away.
When using the Reverse Reverb effect type, the Reverb Decay parameter controls the
Reverse Time.

Low Pass Filter

The lowpass filter that can be set between 059 Hz and 36.2 kHz, and attenuates all
frequencies above this value by 6dB per octave. The lower the setting, the less high
frequencies of the input are allowed to pass thru to the reverb effect.

Pre-delay

All the reverb effects have pre-delay parameters. Pre-delay slightly delays the reverb
itself up to 175 ms, so that the dry signal more easily stands out from the reverb. A
bit of pre-delay can make certain instruments (such as snare drums) sound bigger.

Pre-delay Mix

This allows you to balance the amount of Pre-delay to Direct Signal as a percentage
of each. This gives you the ability to hear a bit of the Reverb before the loudest part
of the Reverb (the Pre-Delayed Reverb) sounds, and makes for a bigger, smoother
sounding Reverb.

Density

Density controls how the first reflection of the reverb effect will appear. When set to
0, the first reflection is heard alone without any other reflections. When set to 99, the
first reflection appears to "fade-in" and then "fade-out". This is because a number of
reflections will occur just before and just after the first reflection, in addition to the
remaining reflections heard after the first reflection. Thus, the reverb sounds more
"dense".

Diffusion

Diffusion determines the "thickness" of the reverb sound by adding more reflections
to the reverb's decay. With lower diffusion settings, you may be able to actually hear
the individual echoes that make up the overall reverb sound. With higher diffusion
settings, the echoes increase in number and blend together, washing out the reverb's
decay. Greater diffusion works better with percussive sounds, whereas less amounts
of diffusion work well with vocals and other sustained sounds.
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