WM9715L
Production Data
TONE CONTROL / BASS BOOST
The WM9715L provides separate controls for bass and treble with programmable gains and filter
characteristics. This function operates on digital audio data before it is passed to the audio DACs.
Bass control can take two different forms:
•
Linear bass control: bass signals are amplified or attenuated by a user programmable
gain. This is independent of signal volume, and very high bass gains on loud signals
may lead to signal clipping.
•
Adaptive bass boost: The bass volume is amplified by a variable gain. When the bass
volume is low, it is boosted more than when the bass volume is high. This method is
recommended because it prevents clipping, and usually sounds more pleasant to the
human ear.
Treble control applies a user programmable gain, without any adaptive boost function.
Treble, linear bass and 3D enhancement can all produce signals that exceed full-scale. In order to
avoid limiting under these conditions, it is recommended to set the DAT bit to attenuate the digital
input signal by 6dB. The gain at the outputs should be increased by 6dB to compensate for the
attenuation. Cut-only tone adjustment and adaptive bass boost cannot produce signals above full-
scale and therefore do not require the DAT bit to be set.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
08h
15
BB
0
Bass Mode
DAC Tone
Control
0 = Linear bass control
1 = Adaptive bass boost
Bass Cut-off Frequency
12
BC
0
0 = Low (130Hz at 48kHz sampling)
1 = High (200Hz at 48kHz sampling)
Bass Intensity
11:8
BASS
1111
(OFF)
Code
0000
0001
0010
…
BB=0
BB=1
15 (max)
14
+9dB
+9dB
+7.5dB
(1.5dB steps)
0dB
13
…
0111
…
8
(1.5dB steps)
…
1011-1101 -6dB
4-2
1110
1111
-6dB
1 (min)
Bypass (OFF)
6
DAT
TC
0
0
-6dB attenuation
0 = Off
1 = On
4
Treble Cut-off Frequency
0 = High (8kHz at 48kHz sampling)
1 = Low (4kHz at 48kHz sampling)
Treble Intensity
3:0
TRBL
1111
(Disabled)
0000 or 0001 = +9dB
0010 = +7.5dB
… (1.5dB steps)
1011 to 1110 = -6dB
1111 = Treble Control Disabled
Table 12 DAC Tone Control
Note:
1. All cut-off frequencies change proportionally with the DAC sample rate.
PD Rev 4.0 December 2007
26
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
