Gauge isn't extremely important here, as long as the wire is copper, the resistance-per-foot is in the mili-ohm range, meaning there will be minuscule, if any, voltage drop across the wire. Some decks stereos also offer dedicated sub-woofer outputs. Congratulations on the enthusiastic hard work of both the author and the many contributors to this instructable. This is pretty self explanatory, but for those who don't know: Then set the sub's volume control to provide the level of bass support you want. I usually spend at least a few hours listening with lots of different types of music to fine-tune the crossover and subwoofer volume settings.
If you look at all the wires coming out of the back of the head unit, there should be 1 or 2 blue ones.
Installing Subwoofers in a Car
It is for demonstration purposes and it does not sound as good as it should. The remote wire needs a 12v signal to turn on the amp. I have checked all my fuses and have even opened up the amp case to see if i can figure out whats wrong but nothing looks ab normal. Be sure to know the impedance of the subwoofer s you are using and try to match the amplifier's impedance accordingly. Set the subwoofer in the trunk of the car.