Power distribution importance
Sometimes it feels like I am banging my head against a wall, when I am talking to my fellow car audio fanatics. If you know me, then you will know that most of my theories are based on physics, or at least on my interpretation of the those laws.
When it comes to today's high-power audio systems, there is one area that is constantly overlooked, proper power distribution.
I have reviewed single amplifiers that can draw more than 400 Amps of current. Imaging what some of these dB Drag competitors must be drawing when they have 10, 20 , 40 or 80 Amplifiers?
Even in moderately sized street systems, the important of flowing electrons to your amplifier can not be overstressed. It is this flow of electrons that allows the amp to perform properly.
Since car audio systems really started to take off back in the early to mid eighties, everyone has taken the same route when it comes to wiring up an amplifier. Run a big wire from the battery, through a fuse holder, then to the positive connection on the amp. Run a short wire from the negative terminal of the amp to the chassis of the car.
If you are really paying attention, you may be smart enough to upgrade the wire from the negative terminal of the battery to the chassis of the car, since we still need to complete that loop and get those electrons back to where they started.
There are several problems with this concept.
First: Modern cars are full of computers, sensors and complicated multi-plexed signals, all of which use the chassis as it's ground. Dimming dome lights, lower-output daytime-running-lights and dimmed dash lights create havoc in terms of electrical system noise. Sure, car audio products have improved a great deal, and they can reject noise better than ever before, but we still run into problems sometimes.
Secondly: We now have two additional connections in the flow of electrons between the battery and the amp. At least, that's what most people think. In reality, modern cars are made up of several smaller panels, spot welded together to make up the unibody chassis. This means that, assuming you car is indeed all metal, and more and more aren't, you have got something like four or five additional connections between the ground location in the back of the car, and your battery and alternator. Each connection is a potential location for noise to enter the system, and for there to be a source of resistance. As your vehicle ages, corrosion can build up at these joints and further degrade the connection reliability.
Third: With the advent of extremely high strength and high-quality adhesives, a great many cars aren't even welded together any longer. The unibody sections are connected to each other with the use of adhesives, or in common terms, glue. These can provide mechanical connections that are as strong as, or stronger than welding can offer, and does not cause any distortion in metal due to heat (from the welding process). the down side, glue isn't conductive. AT ALL! In fact, most glues and adhesives make great insulators. Can you imaging a system with a big amp in the trunk, trying to draw 150 Amps of current, and it's only connected through the edges and sharp points of panels that are glued together?
The solution is very very simple. Run a ground cable from the battery to a block in the rear of the car, just like you did for the power connection. You will reduce the chances of picking up noise, and will help to ensure that the system remains reliable for a long time. It doesn't cost all that much more, and is well worth the investment if you are using multiple large amplifiers.