Kurzweil K2661, Musician’S Reference Manual

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KDFX Reference
KDFX Algorithm Specifications
10-137
746 Compress
A reverb and compressor in series.
PAUs: 2
Compress is con fi gured as a reverb followed by a compressor. The reverbs used are the same as
MiniVerb . The compressor is a soft-knee compressor and can be con fi gured as a feed-forward or feedback
compressor.
Figure 60 Simplified block diagrams of Compress
The main control for the reverbs is the Rv Type parameter. Rv Type changes the structure of the algorithms
to simulate many carefully crafted room types and sizes. Spaces characterized as booths, small rooms,
chambers, halls and large spaces can be selected. For a complete discussion on the reverbs see the sections
on
MiniVerb .
The compressor reduces the signal level when the signal exceeds a threshold. The amount of compression
is expressed as a ratio. The compression ratio is the inverse of the slope of the compressor input/output
characteristic. The amount of compression is based on the sum of the magnitudes of the left and right
channels. A compression ratio of
1:1 will have no effect on the signal. An in fi nite ratio, will compress all
signal levels above the threshold level to the threshold level (zero slope). For ratios in between in fi nite and
1:1 , increasing the input will increase the output, but by less than it would if there was no compression.
The threshold is expressed as a decibel level relative to digital full-scale (dBFS) where 0 dBFS is digital
full-scale and all other available values are negative.
In the soft-knee compressor there is a gradual transition from compressed to unity gain.
Figure 61 Soft-Knee compression characteristics
To determine how much to compress the signal, the compressor must measure the signal level. Since
musical signal levels will change over time, the compression amounts must change as well. You can
control the rate at which compression changes in response to changing signal levels with the attack and
release time controls. With the attack time, you set how fast the compressor responds to increased levels.
At long attack times, the signal may overshoot the threshold level for some time before it becomes fully
compressed, while at short attack times, the compressor will rapidly clamp down on the level. The release
L Input
R Input
Reverb Compress
L Output
R Output
Out
Amp
In Amp
Threshold