Definitions
Amplifier: A component that increases the gain or level of an audio signal.
Bass: Low frequencies; those below approximately 200 Hz.
Bridging: Combining two channels of an amplifier to make one channel that’s more powerful. One channel amplifies the positive portion of an audio signal and the other channel amplifies the negative portion, which are then combined at the output.
Channel: In components and systems, a channel is a separate signal path. A four-channel amplifier has at least four separate inputs and four separate outputs.
Crossover: A component that divides an audio signal into two or more ranges by frequency, sending, for example, low frequencies to one output and high frequencies to another. An active crossover is powered and divides the line-level audio signal prior to amplification. A passive crossover uses no external power supply and may be used either at line level or, more commonly, at speaker level to divide the signal after amplification and send the low frequencies to the woofer and the high frequencies to the tweeter.
Midbass: The middle of the bass part of the frequency range, from approximately 50 to 100 Hz (upper bass would be from 100 to 200 Hz).
Midrange: The middle of the audio frequency range. Also used as a term for loudspeaker drivers designed to reproduce this range.
RMS: Root Mean Square or the square root of the arithmetic mean (average) of the square’s set of values. A reasonably accurate method of describing an amplifier’s power output.
Subwoofer: A speaker designed to reproduce very low bass frequencies, usually those below about 80 Hz.
Tweeter: A speaker driver designed to reproduce high frequencies; usually those over approximately 5,000 to 10,000 Hz.
Alarm: Makes noise, flashes lights and possibly sends you a text or pager message when someone tries to steal your car! Some can be made to alert a tracker system ( see below) The remote control used to operate the alarm can be made to operate your cars central locking and maybe even wind your windows up! There are different alarms with many features, I believe the most important thing an alarm has to do is be reliable and work when a real attempt to break into your car happens.
Immobiliser: Ok so they got in your car because you did not have an alarm, it was unreliable or the thieves were very very clever and then they try to pull out the ignition switch and hot start your car but if you have an immobiliser it will not start! An immobiliser prevents the car from starting by breaking into two or more of the following circuits starter, ignition and fuel.