GC_ET_APC_F8AFQ.html

2021-07-16   16:20:27
2021-12-11   08:48:14

          APC_F8AFQ

***   Two Variable MFB Filters with 8 All-Pass stages in the middle 

An effective combo-design, which is simpler
...  but not as effective as the AFV-3RL-V4F-D-VQ version

***  Below:  Schematic shows 8 All-Pass filters
used to experimentally replace two MFB Active PassBand Filters. 

*** Compared to the "AFV-3RL-V4F-D-VQ" version 
(1) BW @ -3dB is wider ; 160 Hz vs 80 Hz.
(2) Dual Notch BW is wider ; 380 Hz vs 330 Hz.  but the FX Q20 will narrow to 35Hz. 
(3) Variability of f(0) is much narrower ; +/- 75 Hz  is  good, vs +/- 100 Hz for the AFV-3RL-V4F versions. 
(4) Variable f(0) controlled physically by a Single Panel-Mounted Pot (very important).  

*** Plots show f(0) varied +/- 50 Hz  
*** Q20 35Hz Filter is shown shifting inside master BandPass signal, down -1 dB. 
 
 
    

*** Magnitude Plot clearly shows the Notch Depth while shifting f(0) +/- 100 Hz
*** Notch depth is basic= -52 dB,  F(Q20)= -82 dB
       Lo Notch = 530 Hz    and   Hi Notch = 900 Hz
*** Notch Generator freq tracks with f(0)   at +/- 100 Hz   
***      Fx(100Hz) is -0.5dB
***      Fx(35Hz)   is -1.0dB
***

                     ***  Little table at left of plot shows each Hi-Notch value.  

                       
***  Little table at left of plot shows each Hi-Notch value.  ***  Little table at left of plot shows each Hi-Notch value. 

     



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*** Results:
    Notch-Hi depth basic= -52 dB,  F(Q20)= -82 dB
       Lo Notch = 530 Hz    and   Hi Notch = 900 Hz
 
       f(0) shifting +/-   50 Hz  , with loss of -1 dB .
       f(0) shifting +/- 100 Hz  , with loss of -3 dB .
       Good Peak is required at +/- 100 Hz master shift, with variance of -3 dB ,

 

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