This all began when Earl A Lirette III started installing car audio at a shop named Apple Audio when he was in 11th grade in February of 1984. The reoccurring problem of grounds coming loose on installations was most certainly evident. Through various trials and remedies evolved a simple solution of overlocking the hardware so it would not loosen just as a carpenter toe nails lumber. After approxi
mately 10 years of trials at the shop now known as Tiger Audio, the patent was filed in November of 2011. Not many people, even real car people, realize that in a low or 12 volt chassis ground vehicle, energy (electrons) actually flow from negative TO positive, not the other way around thus making the negative or ground connection even more important than the power connection. Secondly, in vehicles, all components must be grounded. If there is a weak ground on one unit versus another, there is a voltage difference (potential difference) between the two or more units. When this happens, typically the audio signal can be degraded, or, in many cases, noise can enter the system through what is referred to as a “ground loop”. In extreme cases, when grounds fail catastrophically, the components will attempt to keep themselves grounded by seeking a ground path through the signal cables that connect them to each other, (typically, in car audio applications, these are the RCA style signal wires). When that happens, extreme amounts of current can flow to where it doesn’t belong, destroying the output sections of radios, the input sections and sometimes, the power supply sections of amplifiers. Most recently, with more and more computer based systems in vehicles that rely on data transfer to different electrical components, a ground that’s bad can cause any number of odd results. “data” in the vehicle automotive space is usually just a measurement of voltage to ground, so, if you start off with a weak connection to ground, chances are good that your data won’t transfer correctly and confuse a different component down the line, or, worse yet, wont be received at all. So that explains the main reasons you want, no, NEED a good ground. What usually happens in car audio is that the ground wire of a component is crimped onto a ring terminal. A ring terminal looks like this.:
This type of connector is great for battery posts, but, when it comes to a ground, you want to locate the shortest distance to the electrical component for maximum current flow along with savings on wire costs. In order to accomplish this, usually the technician removes the paint off the nearest piece of sheet metal and applies the ring terminal to the wire, and uses some sort sheet metal screw to affix the ring to the vehicle chassis. Indisputably, this is the way things have been done by installers worldwide. These types of terminals have an inherent design flaw. Since they have one attachment point, they can easily loosen the connections over time, which will lead to ground failure and lost performance in mobile electrical environments. Additionally, automobiles are nominally 12 volt systems, so, when you lose one volt to a bad connection, that’s nearly 10% of the available power that you have. 10% is HUGE. and, as the connection degrades, extra heat will be generated, and the problem will only get worse. Installers, being innovators by nature, have solved this by the following example (in the middle, below) and, in an attempt of overkill, the bottom image. Note the one labeled “best” can still rotate…
You can see that from the two examples above, the screw holes are aligned in the terminals in a very methodical way. When using appropriate screws, the second or third screws overlock the main attachment screw(s), assuring that the securing screw can NEVER come loose. Also, more surface area is allotted to the terminal, since more surface area equals better contact area and better conductivity–much like the contact path of a tire determines how stable the ride of the car is. The more contact area, the more electrons can flow into the wire with less resistance. Furthermore, there are serrations both in the ferrule or barrel area of the terminal guaranteeing the terminal grabs the wire and holds it securely. There’s also serrations around the screw holes that help the screws stay tight. So, in the above picture, you see from left to right, a 22AWG (American Wire Guage) Earl Terminal, a, 16AWG Earl Terminal, a 10AWG conventional ring, and a 10AWG Earl Terminal. From this perspective, it should be obvious that the anti rotational advantages the Earl Terminal has. Also, you can see how the screws overlock each other, meaning the attachment screw cannot come loose. If you were to pull the wires left or right, all of the Earl Terminals would stay firmly seated, but the conventional ring terminal would swivel around the screw. From this perspective, you can see the overlocking screw in action, and see how the camber of the overlocking screw also serves to bind the screws to the sheet metal. The end result is literally the ring terminal re imagined, using 58 years plus of combined experience in the field seeing what problems arise and what the root cause is.
