Here are diagrams for a couple of typical amp installations to help you see how all the separate components fit together to form a car audio system.
The first diagram shows a total system upgrade using an aftermarket receiver, two amplifiers, and a subwoofer. The second is more specific. It shows you how to add a subwoofer to a factory system.
How to wire a full car audio system
This wiring diagram shows how a full-blown car audio system upgrade gets wired in a car. The system depicted includes new speakers, an aftermarket receiver, a 4-channel ampfor the front and rear pairs of full-range speakers, and a mono amp for a subwoofer.
The extra gear you'll need for wiring the amps includes:
a dual amplifier wiring kit
Capacitors aren't usually necessary in a car stereo installation but we included one here to show how it would get wired into a system.
How to add a subwoofer to a factory stereo
A lot of folks want to add bass to their system without replacing the factory radio, either because it looks good or is impossible to replace. The following wiring diagram shows the additional wiring you'll need to add a subwoofer to a factory system.
Start by getting a subwoofer amplifier or powered sub with speaker-level inputs. You'll need these items for the installation and to give it that professional touch:
Use wire taps to get signal
An Add A Fuse connector plus a 2A to 10A fuse to get the amp's remote turn-on voltage
An amp wiring kit and some speaker wire