Equalization and mixing
STA309A
60/67
Doc ID 13855 Rev 4
8
Equalization and mixing
Figure 8.
Channel mixer
8.1 Postscale
The STA309A provides one additional multiplication after the last interpolation stage and
before the distortion compensation on each channel. This is a 24-bit signed fractional
multiply.
The scale factor for this multiply is loaded into RAM using the same I
2
C registers as the
biquad coefficients and the bass-management.
This postscale factor can be used in conjunction with an ADC equipped micro-controller to
perform power-supply error correction. All channels can use the channel 1 by setting the
postscale link bit.
Channel 1
Channel 2
Channel 3
Channel 4
Channel 5
Channel 6
Channel 7
Channel 8
CxMIX1
CxMIX2
CxMIX3
CxMIX4
CxMIX5
CxMIX6
CxMIX7
CxMIX8
Channel x
Table 80.
RAM block for biquads, mixing, and bass management
Index
(decimal)
Index
(hex)
Description
Coefficient
Default
0
0x00
Channel 1 - Biquad 1
C1H10 (b1/2)
0x000000
1
0x01
-
C1H11 (b2)
0x000000
2
0x02
-
C1H12 (a1/2)
0x000000
3
0x03
-
C1H13 (a2)
0x000000
4
0x04
-
C1H14 (b0/2)
0x400000
5
0x05
Channel 1 - Biquad 2
C1H20
0x000000