Kurzweil K2661, Musician’S Reference Manual

Page: 274 / 500

10-192
KDFX Reference
KDFX Algorithm Specifications
948 Band Compress
Stereo algorithm to compress a single frequency band
PAUs: 3
Band Compress is in most respects identical to SoftKneeCompress . However, Band Compress
compresses only on a single band of frequencies. Frequency band selection is based on a parametric fi lter.
You control the fi lter center frequency and bandwidth. The compressor controls the fi lter gain.
Figure 99 Band Compress filtering at full compression
The compressor reduces the signal level when the signal level 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.
With Band Compress , the side chain processing acts only on a speci fi ed band of frequencies. At the input
of the side chain is a bandpass fi lter which passes only the frequency band of interest. The side chain
output then controls the gain of a band cut fi lter acting on the main signal path. The bandpass and band
cut fi lters both are set to the same center frequency and bandwidth which you control. The depth of the
band cut fi lter is of course set by the compressor side chain processing.
You can select which channel, left ( L ), right ( R ) or the maximum amplitude of the two ( L & R ) is used to
control the compression (side chain processing) with the SC Input parameter. You can also select which
channel is actually compressed, again left (
L ), right ( R ) or both ( L & R ) using the ComprsChan parameter.
0 dB
- 20
- 40
Freq
10 Hz 100 1000 10 k
Gain