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SOUNDSHAPER: CDP REFERENCE

GRAPHIC - spectral filterbank


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SUMMARY
Retain or reject specified bands. This is a spectral version of a graphic equalizer without the graphics. Controlled by datafiles, it can have any number of bands, but none of them are time-varying, i.e. there is no amplitude control. 

MODES
 1. Single bandwidth         specified by datafile greq1
 2. Separate bandwidths specified by datafile greq2

OPTION
Reject Bands - check this option to create a bank of notch filters. (Unchecked: retain specified bands.)

PARAMETERS

 greq1  Text datafile defining a single bandwidth in octaves, followed by a list of centre frequencies, one per band.
Example: a number of narrow bands centred around harmonics of A 110Hz.
0.1
110
220

440
550
660
880
1100
 greq2  Text datafile of pairs of values, one per band, of: centre frequency and bandwidth
Example: a number of bands centred around odd-numbered harmonics of Ab 100Hz; the higher bands have progressively wider bandwidth.
100      0.25
300      0.50
500      0.75
700      1.00
900      1.25
1100    1.50
1300    1.75
1500    2.00


NOTES
This program looks decidedly old-fashioned in an era of sophisticated graphic controls. However, the ability to define a detailed filterbank in a sinmple text file is also very powerful. Soundshaper's Graph Editor has two presets which can be employed to generate 1/3-8ve and 2/3-8ve sets of data for greq2.

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