nestedap

  ar  nestedap  asig, imode, imaxdel, idel1, igain1[, idel2, igain2 [, idel3, igain3]]

Description

Three different nested all-pass filters, useful for implementing reverbs.

Initialization

imode - operating mode of the filter:

• 1 = simple all-pass filter
• 2 = single nested all-pass filter
• 3 = double nested all-pass filter

idel1, idel2, idel3 - delay times of the filter stages. Delay times are in seconds and must be greater than zero. idel1 must be greater than the sum of idel2 and idel3.

igain1, igain2, igain3 - gain of the filter stages.

imaxdel - will be necessary if k-rate delays are implemented. Not currently used.

Performance

asig - input signal

If imode = 1, the filter takes the form:

If imode = 2, the filter takes the form:

If imode = 3, the filter takes the form:

Example

instr 5
  insnd     =           p4
  gasig     diskin      insnd, 1
endin 

instr 10
  imax      =           1
  idel1     =           p4
  igain1    =           p5
  idel2     =           p6
  igain2    =           p7
  idel3     =           p8
  igain3    =           p9
  idel4     =           p10
  igain4    =           p11
  idel5     =           p12
  igain5    =           p13
  idel6     =           p14
  igain6    =           p15
  afdbk     init        0

  aout1     nestedap    gasig+afdbk*.4, 3, imax, idel1, igain1, idel2,\\   igain2, idel3,    igain3      
  
  aout2     nestedap    aout1, 2, imax, idel4, igain4, idel5, igain5

  aout      nestedap    aout2, 1, imax, idel6, igain6

  afdbk     butterlp    aout, 1000

            outs        gasig+(aout+aout1)/2, gasig-(aout+aout1)/2
  
gasig     =           0

endin 


;Score

f1 0 8192 10 1

; Diskin
;   Sta  Dur  Soundin
i5  0    3    1

; Reverb
;   St  Dur  Del1 Gn1  Del2  Gn2  Del3  Gn3  Del4  Gn4  Del5  Gn5  Del6  Gn6
i10 0   4    97   .11  23   .07   43   .09   72    .2   53    .2   119   .3
e

Author

Hans Mikelson
February 1999
New in Csound version 3.53