Wolfson WM8978, Manual, Page: 111 / 119

Production Data
WM8978
w
PD, Rev 4.5, October 2011
111
5-BAND EQUALISER
The WM8978 has a 5-band equaliser which can be applied to either the ADC path or the DAC path.
The plots from Figure 58 to Figure 71 show the frequency responses of each filter with a sampling
frequency of 48kHz, firstly showing the different cut-off/centre frequencies with a gain of

12dB, and
secondly a sweep of the gain from -12dB to +12dB for the lowest cut-off/centre frequency of each
filter.
10
-1
10
0
10
1
10
2
10
3
10
4
10
5
-15
-10
-5
0
5
10
15
Frequency (Hz)
M
agni
tude (
dB
)
10
-1
10
0
10
1
10
2
10
3
10
4
10
5
-15
-10
-5
0
5
10
15
Frequency (Hz)
M
agn
itud
e (
dB
)
Figure 58 EQ Band 1 Low Frequency Shelf Filter Cut-offs Figure 59 EQ Band 1 Gains for Lowest Cut-off Frequency
10
-1
10
0
10
1
10
2
10
3
10
4
10
5
-15
-10
-5
0
5
10
15
Frequency (Hz)
M
agni
tude (
dB
)
10
-1
10
0
10
1
10
2
10
3
10
4
10
5
-15
-10
-5
0
5
10
15
Frequency (Hz)
M
agn
itud
e (
dB
)
Figure 60 EQ Band 2 – Peak Filter Centre Frequencies,
EQ2BW=0
Figure 61 EQ Band 2 – Peak Filter Gains for Lowest Cut-off
Frequency, EQ2BW=0
10
-2
10
-1
10
0
10
1
10
2
10
3
10
4
-15
-10
-5
0
5
10
15
Frequency (Hz)
M
agni
tu
de (
dB
)
Figure 62 EQ Band 2 – EQ2BW=0, EQ2BW=1