WM9711 datasheet(25/66 Pages) WOLFSON

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Production Data

WM9711L

PD Rev 4.1 April 2004

TONE CONTROL / BASS BOOST

The WM9711L 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.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

Bass Boost

0 = OFF

1 = ON

Bass Cut-off Frequency

0 = Low (130Hz at 48kHz sampling)

1 = High (200Hz at 48kHz sampling)

Bass Intensity

Code

BB=0

(Normal)

BB=1

(Boost)

0000

+9dB

15 (max)

0001

+9dB

0010

+7.5dB

…

(1.5dB steps)

…

0111

0dB

…

(1.5dB steps)

…

1011-1101

-6dB

4-2

1110

-6dB

1 (min)

11:8

BASS

1111 (OFF)

1111

Bypass (OFF)

DAT

-6dB attenuation

0 = Off

1 = On

Treble Cut-off Frequency

0 = High (8kHz at 48kHz sampling)

1 = Low (4kHz at 48kHz sampling)

08h

DAC Tone

Control

3:0

TRBL

1111

(Disabled)

Treble Intensity

0000 or 0001 = +9dB

0010 = +7.5dB

… (1.5dB steps)

1011 to 1110 = -6dB

1111 = Treble Control Disabled

Table 12 DAC Tone Control

Note:

All cut-off frequencies change proportionally with the DAC sample rate.

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