GF82.62-P-3009FAA Sound Amplifier, Component Description
GF82.62-P-3009FAA Sound Amplifier, Component Description
MODEL 203.7
- with CODE (810) Sound system
MODEL 203.7 as of model year 09/Modification Year 08 model refinement package
N40/3 Amplifier for sound system
Location
The amplifier for sound system is mounted on the right, rear inner panel.
Task
- Processing (sound settings) and amplification of all audio signals
- Dynamic volume adaptation (dynamic range optimization (DRO))
- Muting (MUTE)
- Reception of additional signals
Processing (sound settings) and amplification of all audio signals
- Reception of audio signals from each available audio sources over Media Oriented System Transport (MOST)
- Processing of audio signals in accordance with sound settings and amplification of the audio signals
- Transmission of processed and amplified audio signals to following speakers over direct lines:
- Left front door speaker (H4/1)
- Right front door speaker (H4/2)
- Left rear door speaker (H4/5)
- Right rear door speaker (H4/6)
- Left front door speaker, mirror triangle (H4/23)
- Right front door speaker, mirror triangle (H4/24)
- Center cockpit speaker (centerfill) (H4/27)
- Subwoofer speaker (H4/29)
- Left rear surround speaker (H4/54)
- Right rear surround speaker (H4/57)
For vehicles with code (525) MB Audio 50 APS radio or with code (527) COMAND APS with single DVD drive (with navigation), the sound system amplifier receives the signals over MOST for voice output with navigation for processing and amplification.
Dynamic volume adaptation (DRO)
- Reception of signals from sound amplifier microphone (B25/6) over direct line.
- Dynamic adaptation of audio signal volume to match background noise in vehicle interior. The background noise here is determined by comparing the output signal on the sound system amplifier with the input signal from the sound amplifier microphone.
- Transmission of adapted audio signal volume to the listed speakers over direct lines.
Muting (MUTE)
- Reception of muted switching signal over MOST
- Interruption of current audio playback
Reception of additional signals
- Additional direct input signals
- Additional MOST signals
Additional direct input signals
- Circuit 30
- Circuit 31
- Electrical wake-up signal (wake-up)
Additional MOST signals
- Control signals from each audio unit (radio (A2), with code (523) MB Audio 20 radio, radio and navigation unit (A2/56), with code (525) MB Audio 50 APS radio or COMAND operating, display and controller unit (A40/3), with code (527) COMAND APS with single DVD drive (with navigation))
Design
- MOST interface
- Connection for sound amplifier microphone
- 8 linear amplifier stages
- 8 high-resolution digital filter structures
- Electronics for digital signal processing (digital signal processing (DSP)), improves the acoustic sound properties using mathematical algorithms
- 8 speaker outputs
- Electrical wake-up signal (wake-up) and bidirectional optical wake-up signal (wake-up)
Function
- Data exchange over MOST
- Digital signal processing
- Sound processing with high resolution
- Individual sound optimizations
- Bose fader
- "Baby sleep"
- Suppression of disturbing noise
- Diagnosis
Data exchange over MOST
The data exchange between the sound system amplifier and the other audio components takes place over MOST. All the control information and audio signals (e.g. radio, CD, navigation voice output) are transmitted via this fiber optic cable.
Digital signal processing
In order to make possible the diverse adjustments to the sound, the sound system amplifier is equipped with a digital signal processor which carries out the complete signal filtering. In comparison to analog filters, digital filters exhibit the following distinct advantages:
- The filter parameters (sound settings) do not change over the course of time. Thus, all settings can be reproduced exactly.
- Lower noise.
- Lower expenditure in components with higher number of possible filter settings. This is achieved by setting the filter parameters by software and not by varying the component values (resistance, capacitance or inductance).
Sound processing with high resolution
Digital filters of higher order are used to provide an individually configured frequency-response compensation for each particular vehicle acoustics for every 8 amplifier channels.
Individual sound optimizations
Further sound optimizations and effects such as voice-emphasized, driver-optimized, or room sound can be called up. Bass, treble, volume, balance, fader and the dynamic volume function can be individually configured.
Bose fader
The Bose fader maintains the full sound quality, even if the sound playback is controlled more to the front or to the rear. As the bass is generated at the back on the rear shelf, without the Bose fader the bass would be faded out, the more "fading" (regulating) is done to the front. The full bass playback is retained with the Bose fader.
"Baby sleep"
When the system is regulated to the front, the bass playback remains fully active during the first 9 regulation steps. Only in position 10 is the bass completely faded out and no more sound shares come from the rear area (no bass as well), i.e. from the speakers behind the B-pillar.
Suppression of disturbing noise
A dynamically controlled limiter function monitors the output signal and adapts the level so that a maximum permissible sound pressure is achieved. Any distortions are largely suppressed.
Diagnosis
The sound system amplifier provides the following messages that are relevant for the diagnosis:
- Operating status
- Undervoltage
- Internal error on sound system amplifier
Messages are sent over MOST to each audio unit, and they can be read out over the data link connector (X11/4).
To test the MOST system during installation and to localize any sources of fault or to reproduce any faults that occurred during operation, a diagnostic mode is implemented (installed) in the sound system amplifier.
