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MITCHELL
STEREO ANALOG ELECTRONIC CROSSOVER
REVISION P
RB
– DECEMBER 2020
Copyright © 2020, M2Tech Srl
22
8.1. Set commands
8.1.1. Set Filter (SF)
Sets the frequency and Q for a filter block in one or both channels in a way.
Five parameters are required: w is the way, c is the channel, b is the filter block to be set, f
is a coefficient related to the frequency and q is a coefficient related to Q. For first order
filter, Q must be specified but its value is “don't care”.
The following formulas can be used to derive f and q from the desired frequency and Q:
f = Int(1024*(1-44.21/fre0.5) b=[1,2,H,L]
f = Int(1024*(1-79.58/fre0.5) b=A
q = Int(1024*(1-10000/(3*Q-1))+0.5)
Both parameters must be converted in hexadecimal.
Syntax:
#SF
,w,c,b,f,q
where:
w = [A,B,C]
c = [B,L,R]
b = [1,2,A,H,L]
f = [000..3FF]
q = [000..3FF]
A,B,C indicates the way the command is applied to (w).
B means “Both channels”.
L means “Left channel” (c).
R means “Right channel”
1 means “State Variable Filter 1”.
2 means “State Variable Filter 2”.
A means “All-pass” (b).
H means “1-pole High-pass”.
L means “1-pole Low-pass” (b).
Example 1:
#SF,A,L,L,045,1FF
OK
Selects the cut-off frequency of the 1-pole low-pass filter in the left channel of way A. as Q
is not defined for a 1-pole filter, q may be any allowed value.
