Have A Question?

A volt is a unit of voltage, which is the difference in electrical potential between two points. An amp (short for ampere), on the other hand, is the measure of electrical current. While the true technical definitions can get pretty intense, volts and amps can be explained with a simple comparison to water. If all of the wires and metal chassis of a vehicle were considered a network of tubes that were completely filled with water, an ampere would be the measure of water flowing through a pipe. A volt would be the measurement of pressure difference between two points. With this analogy, the alternator is a water pump that creates pressure and the battery would be the tank reservoir that holds the pressurized water. The higher the difference in pressure between two points, the faster the water will travel within the pipe between them. Larger pipes can move more water and have the capacity to handle more water flow, just as thicker gauge wires can handle more current.

RFI, or Radio Frequency Interference (also referred to as EMI or electromagnetic interference) is a disturbance caused by something that emits electromagnetic radiation, such as electric power lines and electric motors. Most people have experienced RFI when listening to AM radio and passing by a major power line. Within the car audio world, RFI/EMI usually refers to audible noise that is caused “through the air” versus “through the wires,” even if it’s not technically in the radio frequency spectrum. Depending on the vehicle (some are electrically noisier than others) EMI can be caused by the alternator, ignition system, and relays. Keeping audio signal wires (RCA and DIN cables) and passive crossover networks away from factory high current wires and relays is one way to avoid induced noise. RFI was more common in the days of aftermarket cassette decks because the tape head would pick up interference from noisy wires surrounding it, but I think it’s safe to say those days have passed.