Kurzweil k2500 User Guide

 

FXAlgs #4-11: Classic ¥ TQ ¥ Diffuse ¥ Omni reverbs

 

              

 

 ÒClassicÓ 2; others 3

 

This set of 2 and 3 PAU sized algorithms can be divided into 2 groups: Verb and Place. Verb effects allow user 
friendly control over medium to large spaces. Their decay times are controlled by Rvrb Time or LateRvbTim 
parameters, and Room Types range from rooms to large areas. Place algorithms on the other hand are optimized 
for small spaces. Decay time is controlled by the Absorption parameter, and Room Types offers several booths.

Each of these reverb algorithms combines several components: a diffuser, an injector, predelay, an ambience 
generator with feedback, and various filters. These components provide sonic building blocks for both the early 
reflection portions and the body of the reverb.

The ambience generator is the heart of each reverb algorithm and creates most of the ÔlateÕ reverb in algorithms with 
an Early Reflections circuit. It is comprised of a complex arrangement of delay lines to disperse the sound. By using 
feedback in conjunction with the ambience generator, a reverb tail is produced. The length of this reverb tail is 
controlled by the Rvrb Time parameter in the ÒVerbÓ algorithms, or the Absorption parameter in ÒPlaceÓ 
algorithms. 

In order to create reverbs that are smoother and richer, some of the delays in the ambience generator are moved by 
LFOs. The LFOs are adjusted by using the LFO Rate and LFO Depth controls. When used subtly, unwanted artifacts 
such as flutter and ringing that are inherent in digital reverbs can be reduced.

In the feedback loop of the ambience generator are filters that further enhance the sonic properties of each reverb. 
A lowpass filter is controlled by HF Damping. Its action mimics high-frequency energy being absorbed as the sound 
travels around a room. A low shelving filter is controlled by LF Split and LF Time, which are used to shorten or 
lengthen the decay time of low frequency energy.

At the beginning of each algorithm are diffusers. A diffuser creates an initial ÒsmearingÓ quality on input signals 
usually before the signal enters the ambience generating loop. The DiffAmtScl and DiffLenScl parameters 
respectively change the amount and the length of time that the sound is smeared. The Diffuse reverbs, however, 
implement diffusion a little differently. See the section on Diffuse Verb and Diffuse Place below for detailed 
information.