wm9714l Wolfson Microelectronics plc, wm9714l Datasheet - Page 39

• Manufacturer Part Number: wm9714l
• Description: Ac?97 Audio Codec
• Manufacturer: Wolfson Microelectronics plc

Pre-Production
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TONE CONTROL / BASS BOOST
The WM9714L 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:
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 (i.e. bass and treble gains ≤ 0) and adaptive bass boost cannot
produce signals above full-scale and therefore do not require the DAT bit to be set.
Table 17 DAC Tone Control
Note:
1.
20h
DAC Tone
Control
REGISTER
ADDRESS
•
•
All cut-off frequencies change proportionally with the DAC sample rate.
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.
15
12
11:8
6
4
3:0
BIT
BB
BC
BASS
DAT
TC
TRBL
LABEL
0
0
1111 (off)
0
0
1111 (off)
DEFAULT
Bass Mode Control
0 = Linear bass control
1 = Adaptive bass boost
Bass Cut-off Frequency Control
0 = Low (130Hz at 48kHz sampling)
1 = High (200Hz at 48kHz sampling)
Bass Intensity Control
BB=0
0000 = +9dB
0001 = +9dB
… (1.5dB steps)
0111 = 0dB
… (1.5dB steps)
1011-1110 = -6dB
1111 = Bypass (off)
Pre-DAC Attenuation Control
0 = 0dB
1 = -6dB
Treble Cut-off Frequency Control
0 = High (8kHz at 48kHz sampling)
1 = Low (4kHz at 48kHz sampling)
Treble Intensity Control
0000 = +9dB
0001 = +9dB
… (1.5dB steps)
0111 = 0dB
… (1.5dB steps)
1011-1110 = -6dB
1111 = Bypass (off)
DESCRIPTION
PP, Rev 3.2, October 2008
BB=0
0000 = +9dB
0001 = +9dB
… (1.5dB steps)
0111 = 0dB
… (1.5dB steps)
1011-1110 = -6dB
1111 = Bypass (off)
WM9714L
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