Given the extremes of hot and cold, constant vibration and shocks, dust and dirt, and fluctuating power, the car is a harsh environment for any type of electronic component. Amplifiers have it particularly rough because they give off heat as a byproduct and they are usually stuffed in out-of-the-way places, sometimes with poor ventilation. And they are often asked to perform at the extremes of their design limitations. That’s why manufacturers build in a variety of protections to keep an amp running smoothly and safely — and not ending up as an expensive paperweight.
Not all protection circuits work in the same way. Some shut an amplifier completely down, whereas others simply lower the operating parameters of the amp until the dangerous situation passes.
Thermal protection
see Gearing Up with Accessories Car Audio Systems
Protection from heat is one of the most essential forms of protection an amplifier can have. Because heat is a major source of failure in amps, manufacturers build in circuitry that senses when heat rises to a dangerous level and shuts down the amp. After the temperature returns to a safe level, the amplifier fires up again.Cooling fans
In addition to thermal-protection circuitry, some amplifiers also have cooling fans built in. The fans will either run continuously (which can be a source of unwanted noise), or they’ll kick on when the temperature inside the amp reaches a certain threshold. Installers and DIYers will also often add fans to an amp rack to blow air across amplifiers’ heatsinks (the part of the amp, usually with fins, that dissipates heat away from the circuitry).
Short-circuit protection
When positive and negative power wires touch or a power wire is pinched and is grounded to a car’s metal chassis, a short circuit can occur, which can damage an amplifier. To prevent this, many car audio manufacturers build in a circuit that detects a short-circuit situation and shuts the amplifier down before any damage can occur.
Impedance protection
A drop in impedance can damage an amplifier by placing too heavy of a load on it and making it work too hard. Some amps have circuitry that senses an impedance drop and shuts down the amp or lowers its output to prevent damage.
Connection shroud
Some amplifiers come with a shroud that covers the connections to the amps to protect them from, say, spare change that falls under the seat that could touch the controls and cause a short circuit.
Low-Voltage protection
If the supply voltage drops below a certain threshold, rather than the amp working harder to compensate and potentially damaging its circuitry, low- voltage protection kicks in and dials the amp back or shuts it down entirely.
Keeping It Pretty: Cosmetic Considerations
Part of having a car audio system is being able to show it off to your friends.
If that wasn’t the case, all car audio amplifiers would probably be plain, utilitarian black boxes. Instead, you’ll find amplifiers in all manner of shapes, colors, and finishes. Some are large and flashy (see Figure 12-8), whereas others are compact and subtle (see Figure 12-9).
Of course, the cosmetic style you choose in an amp depends on your taste and budget, but you’ll generally want to follow the aesthetics of your car and system. For example, if you drive an understated European vehicle, you’ll prob¬ably want a more elegant-looking amplifier. But if you drive a chrome-dripping sports compact or tricked-out pickup, you’ll want to go with something more showy.
looking for Level matching starts with the head : Audio Car
In a system with multiple amplifiers, an installer will often build a custom rack to create a show of power. A popular option is to mount amplifiers on a subwoofer box, although the vibrations from the subwoofers can cause damage to an amplifier’s circuitry.If multiple amps are mounted together, as on a rack, some manufacturers offer cosmetic links that join multiple amplifiers together to make them appear as one. Many manufacturers also have end caps on their amplifiers to hide the connections for a cleaner look.
