Spatial Sound Function

HiFi/Top HiFi Amplifier

The HiFi/Top HiFi amplifier is designed as an amplifier with active frequency gates. With such a system, better acoustic results can be achieved than with passive frequency crossover networks.

The active crossover networks transfer the frequencies which are reproduced by the relevant connected speaker system to an amplifier module (output stage) to which a corresponding speaker (tweeter, mid-range, woofer) is connected.

On the E83, the subwoofer speakers are also connected to the amplifier module (final stage).

Operating characteristics

Switching on
The amplifier is connected directly to continuous positive and ground as the power supply. It is switched on and off by the radio via the control input. If the amplifier detects a voltage greater than 9 volts at the control input and a voltage which is greater than the voltage at the control input at the continuous positive input, it is activated after approx. 2 seconds.

Switching off
The amplifier is connected directly to continuous positive and ground as the power supply. The amplifier is switched off if the voltage at the control input drops below the lower operating voltage limit of 9 Volt for a short time (approx. 25 ms).

Undervoltage
The amplifier is connected directly to continuous positive and ground as the power supply and operates within a voltage range from 9 Volt to 16 Volt. If the voltage drops below the lower operating voltage limit of 9 Volt for a short time (approx. 25 ms) during the start procedure for instance, the amplifier is switched off and the switch-on procedure is restarted once switch-on conditions have been reestablished.

Speed-dependent increase in volume
In contrast to the Top HiFi amplifier, the HiFi amplifier does not feature a speed-dependent volume boost function to compensate for the noise produced by the vehicle acoustics. This general increase in volume takes place via the radio.

Top HiFi Amplifier
The Top HiFi amplifier features the same operating characteristics as the HiFi amplifier. In addition to the output stages for the tweeters, mid-range speakers and woofers a subwoofer amplifier with two channels is also connected which, in the same way as the Top HiFi amplifier, controls speed-dependent equalization of the noises attributed to the vehicle acoustics.

"Speed-dependent equalizing"
In contrast to the HiFi amplifier, the Top HiFi amplifier facilitates speed-dependent equalization of the noises attributed to the vehicle acoustics by increasing the volume in a defined sound range. For this purpose, the Top HiFi amplifier features a signal connection (speed signal, output) from the instrument cluster. This equalizing function does not cause a general increase in the volume but rather the volume is increased depending on the sound pitch. The low frequency range in particular is boosted at high driving speeds.

Subwoofer Module
Apart from in the E46 Sport Wagon and E83, the top HiFi amplifier features an additional two-channel subwoofer module. It is attached to the subwoofer housing, it has its own power supply and is switched on by a signal from the Top HiFi amplifier (> 8 V = ON / < 6 V = OFF). In the same way as the Top HiFi amplifier, the subwoofer module features speed-dependent equalization of the noise attributed to the vehicle acoustics. For this purpose, the subwoofer module is equipped with a signal connection (speed signal, output) from the instrument cluster via the Top HiFi amplifier. The low frequency range in particular is boosted at high driving speeds.

Interior sound
The Top HiFi amplifier features a spatial sound function which enables improved space acoustics. The spatial sound effect is particularly effective in conjunction with "pure" sound sources (CD mode). The spatial sound function is not recommended for predominantly voice reproduction or poor radio reception. After equalizing the noises created by the vehicle acoustics, the indoor sound function is switched on and can be switched off using a button.