FXAlgs #4-11: Classic ¥ TQ ¥ Diffuse ¥ Omni reverbs
Algorithm Reference-9
Some algorithms use injector mechanisms when feeding a signal into the ambience generator. An injector creates
copies of the input signal at different delay intervals and feeds each copy into the ambience generator at different
points. This results in finer control over the onset of the reverb. By tapering the amplitudes of early copies vs. late
copies, the initial build of the reverb can be controlled. Inj Build controls this taper. Negative values create a slower
build, while positive values create a faster build. Inj Spread scales the length of all the copies as a group. Inj Skew
(Omni reverbs) delays one channel relative to the other before injecting into the ambience generator. Negative
values delay the left side while positive values delay the right side. Inj LP controls the cutoff frequency of a 1 pole
(6dB/oct) lowpass filter associated with the injector.
Predelay can give the illusion that a space is more voluminous. Separate control over left and right predelay is
provided which can be used to de-correlate the center image, increasing reverb envelopment.
In addition to filters inside the ambience feedback loop, there also may be filters placed at the output of the reverb
including a low shelf, high shelf, and/or lowpass.
Algorithms that utilize Early Reflection circuits use a combination of delays, diffusers, and filters to create ambience
that is sparser than the late portion of the reverb. These early reflections model the initial near-discrete echoes
rebounding directly off of near field surfaces before the reverb has a chance to become diffuse. They add realism
when emulating real rooms and halls.
The starting point when creating a new reverb preset should be the Room Type parameter. This parameter selects
the basic type of reverb. Due to the inherent complexity of reverb algorithms and the sheer number of variables
responsible for their character, the Room Type parameter provides condensed preset collections of these variables.
Each Room Type collection has been painstakingly selected by Kurzweil engineers to provide the best-sounding
combination of mutually complementary variables modeling an assortment of reverb families. When a room type
is selected, an entire incorporated set of delay lengths and diffusion settings are established within the algorithm.
By using the Size Scale, DiffAmtScl, DiffLenScl, and Inj Spread parameters, you may scale individual elements away
from their pre-defined values. When set to 1.00x, each of these elements are accurately representing their preset
values determined by the current Room Type.
Room Types with similar names in different reverb algorithms do not sound the same. For example, Hall1 in Diffuse
Verb does not sound the same as Hall1 in TQ Verb.
The Size Scale parameter scales the inherent size of the reverb chosen by Room Type. For a true representation of
the selected Room Type size, set this to 1.00x. Scaling the size below this will create smaller spaces, while larger scale
factors will create large spaces.
The InfinDecay switch is designed to override the Rvrb Time parameter and create a reverb tail with an infinite
decay time when ÔOnÕ. However, certain HF Damping settings may reduce this effect, and cause the tail to taper
away. This parameter is an excellent candidate for a KDFX Modulation, using a switch pedal as a source.
