Audio Channel Mapping: Amplifier
DESCRIPTION
There are three amplifiers (1) available, two stand-alone and one integrated into the radio, and are dependant on the speaker package installed in the vehicle. Both stand-alone amplifiers are located in the same location for the speaker system to which they belong; behind the right quarter trim on a bracket secured to the right rear inner wheelwell.
The Premium I Sound System has a 6-channel amplifier with Active Noise Cancellation (ANC) built into the radio and includes six speakers in the system.
The Alpine Premium II Sound System uses a 12-channel 506 watt amplifier (1) and includes nine speakers plus a subwoofer in the system. The McIntosh Premium III Sound System uses a 17-channel 960 watt amplifier (2) and includes 18 speakers plus a subwoofer in the system.
The 12 channel amplifier has three integral connector receptacles (4) that connect the amplifier to the vehicle electrical system through dedicated take outs and connectors of the body wire harness. The 17-channel amplifier has four integral connector receptacles (3) that connect the amplifier to the vehicle electrical system through dedicated take outs and connectors of the body wire harness.
Both separate amplifiers use internal circuitry and software to provide the ANC for the Alpine Premium II and McIntosh Premium III sound systems.
OPERATION
The amplifier receives fused battery current from a fuse in the Power Distribution Center (PDC) at all times. The internal circuitry of the amplifier switches the amplifier on based upon a Controller Area Network - Interior High Speed (CAN-IHS) bus message that is received from the radio whenever the radio is turned ON.
On vehicles equipped with a separate amplifier, the radios use a different strategy for the four channel output. The left front channel is used for Voice Recognition (VR) and navigation turn-by-turn direction audio, the right front channel is used for cell phone audio. The rear channels are used for stereo, right and left channel, output to the amplifier. The signal data from the antenna, USB or AUX inputs on the rear channels is split logically so that it appears to the occupant to be surround sound. With this channel strategy, there is the possibility of additional symptoms of "no audio" from either the navigation system or the cell phone that will not set a Diagnostic Trouble Code (DTC).
The amplifier receives information from the Body Control Module (BCM) and radio that communicates the correct channel setting for optimum speaker sound and output. The amplifier receives signals from four Active Noise Cancellation (ANC) microphones in the headliner. This data is used to reduce or eliminate undesirable noise in the passenger compartment.