Car Audio System Signal Flow
This diagram shows the layout of a common car audio system and signal flow. The dotted black line shows the path of the preamp audio signal (before it’s amplified), from a head unit, through an equalizer and electronic crossover and to the amplifier. A video signal is also sent from the head unit to a pair of video screens in the back seat area. From the amplifier, an amplified audio signal (the solid black line) goes to each speaker in the system — one amplifier powers a subwoofer. The other amplifier powers a set of component speakers in the front of the car (with the signal first passing through the speakers’ passive crossovers) and a pair of coaxial speakers in the rear of the car. The gray line shows power flowing through a power cable (protected by an in-line fuse) from the car’s battery to the amplifiers.