FXAlg #956: Compress 3 Band
Algorithm Reference-152
FXAlg #956: Compress 3 Band
Stereo soft-knee 3-frequency band compression algorithm
Allocation Units:
4
The 3-band compressor divides the input stereo signal into 3 frequency bands and runs each band through its own
stereo soft-knee compressor. After compression, the bands are summed back together to produce the output. You
may set the frequencies at which the bands are split.
The compressors reduce 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 infinite ratio, will compress all signal levels above the threshold level
to the threshold level (zero slope). For ratios in between infinite 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.
3-Band Compressor
For details about the compression action, see the section in this book on FXAlg #950.
Parameters:
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In/Out
In or Out
Out Gain
Off, -79.0 to 24.0 dB
FdbkComprs
In or Out
Crossover1
16 to 25088 Hz
Signal Dly
0.0 to 25.0 ms
Crossover2
16 to 25088 Hz
Atk Low
0.0 to 228.0 ms
Ratio Low
1.0:1 to 100.0:1, Inf:1
Rel Low
0 to 3000 ms
Thres Low
-79.0 to 24.0 dB
Smth Low
0.0 to 228.0 ms
MakeUp Low
Off, -79.0 to 24.0 dB
Low Band Reduction
-dB 40 20 12 8 6 4 2 0
Band
Split
Filters
Compressor
Compressor
Compressor
L Output
R Output
L Input
R Input
2
2
2
2
2
2
2