BMW E46/4 (sedan) HK 2-channel Subwoofer Amplifier


TL431 is a adjustable shunt reference most likely used to set up a virtual ground of around 6 Volts since normally you would want + and - voltage for the audio circuits.
LM3900 is a generic op-amp with 4 in one package
LM13700 is a transconductance amplifier with linearizing diodes and buffer with two independant circuits in one package. This is most likely used as a VCA or voltage controlled amplifier to handle the boosting of the bass in response to the vehicle speed.
LF347 is a general purpose J-FET input opamp with 4 in one package.
LF353 is a general purpose J-FET input opamp with 2 in one package.
TDA8563Q is a 2-channel power amplifier with up to 40 Watts per channel into a 2 Ohms load.

The amp is from NXP, and even though it's advertized as 40 Watts x 2, it's probably more realistically like 20 Watts per channel into 3 Ohms.

X18774 Description Wire Size and Color
1 SUB_IN+ 0.5 GN
2 SUB_ON 0.5 WS
3 no connect
4 Ground
5 Fuse 41 - 30A 2.5 RT/GN
6 SUB_IN- 0.5 BL/GN
7 TAA, Speedometer signal 0.35 SW/GN
8 no connect
9 Ground
10 no connect