Radio/Stereo: Description and Operation

AUDIO SYSTEM
There is one audio system available on Prowler. It consists of a corporate RBN radio with a 5 band equalizer and an external six disc CD changer mounted behind the passenger seat back. The system also incorporates an amplifier located under the passenger seat. The amplifier drives all the speakers. The speaker locations are: one in each corner of the instrument panel and one in each door.

The rear speaker enclosure which is mounted behind the seats contains 2 - 3.5 inch full range speakers, one on each side of the rear speaker enclosure, and one centrally mounted dual coil subwoofer.

The speaker enclosure is made of a very thick roto-cast plastic. The enclosure is a two-piece design, it is the housing for a 6.5 inch dual voice coil sub-woofer and 2 - 3.5 inch full range speakers. The dual coil feature allows one speaker to handle the left and right channels of a stereo signal. The sub-woofer handles frequencies from approximately 60 to 80 hertz. It is electronically crossed over by circuitry in the amplifier and also acoustically by the design of the enclosure. The subwoofer is located in a ducted port style of enclosure. The subwoofer is mounted and sealed into the back part of the enclosure while, the front of the speaker cone works into a ducted port that effectively extends the low range of the speaker and also increases the efficiency of the system. When completely assembled, the subwoofer is not visible from the outside of the housing. All of the bass from the woofer exits through the ducted port located at approximately the passengers left shoulder area. Bass is characteristically non-directional so the physical location of the port is not critical for good bass reproduction. The housing assembly with speakers weighs approximately 14 pounds.

The amplifier, located under the passenger seat, is an 8 x 40 system. That is, 8 channels at 40 watts each for a total of 320 watts. It is built by Infinity/Harman audio system. It is turned ON with an ON/OFF signal from the radio and is responsible for driving all speakers and handling the cross over internally. Internal electronic crossovers allow more efficient splitting of the frequencies without losses associated with passive crossover systems. The amplifier also has short circuit protection in case of a speaker failure.

The audio system is equipped with an auto volume control feature which allows for automatic audio volume adjustment to compensate for road and wind noise at vehicle speeds above 20 mph (33 km/h). The auto volume switch is hard wired to the body control module. The body control module provides a CCD Bus message to the radio indicating one of the following switch positions:
OFF - no volume change with speed change.
LOW - moderate volume change with speed, designed to adjust volume to road/wind noise levels with the convertible top up and windows closed.
HIGH - aggressive volume change with speed, designed to adjust volume to road/wind noise levels with the convertible top down and windows open.

There are remote control switches on the back of the steering wheel for volume up/down, seek up, seek down, and preset station selections. For this reason, the radio will be connected to the CCD bus and will allow some diagnostics of the system with the DRBIII(R).

The antenna is sandwiched between two layers of the windshield. To provide better range, it uses an amplifier that is located under the I/P top cover on the passenger side. The antenna amplifier is turned ON with the ON/OFF signal from the radio.