CAR AMPLIFIERS INFORMATION:

mplifiers take a signal from a source and produce a larger one. This process makes the sound powerful. The main challenge of any amp is to amplify the signal without producing any distortions. Amplifiers must maintain sufficient power and that’s why they have a powerful power supply. Many car owners add amplifiers to maximize their sound performance and quality.

How do car amplifiers work?
A cassette radio or CD player produces a maximum of about nine real watts into four speakers given the power it gets from the car's electrical system. So what if you want more than nine real watts to power each of the speakers? You obviously need an amplifier. Amplifiers give more power allowing you to play your music more loudly. Amplifiers also improve the sound quality of music at all volume levels.

Features of Car Amplifiers:

Are you looking for the right amplifier for your car? There is no doubt that choosing the right amp can be a challenging and complicated. Below are some things you need to look for before you buy any car amplifier.

Bridging (Bridgeable Amplifiers):
To understand amplifier bridging, we need to know what it means. Amplifier bridging is basically using 2 channels of an amp to drive a common load. Bridgeable amps have a huge advantage of being able to use them in different system configurations. 4 channel amplifiers, for example, can be used to power four, three or even one speaker if you decide to change it.
Why do I need to bride an amplifier?
Sometimes you need to bridge your car amplifier to maximize power to your speakers and enhance sound performance.

Speaker-level inputs:
Since most factory stereos don’t have amplifier outputs, then the only way to wire your amp is through your radio’s speaker wires. The main advantage of Speaker-level inputs is being able to hook up an amplifier to your factory stereo system.

Remote bass control:
It’s useful to have a remote bass control because gives you the flexibility to change the output level (power) of the amp from anywhere in the car. The remote bass control knob can be placed anywhere to easily adjust power (or bass) to your subwoofers.

High-pass filter/low-pass filter/crossover:
Filters let you adjust the frequencies you send to the speakers or subs. High-pass filters eliminates can be used to prevent speaker damage caused by low frequencies. The low-pass filters however, eliminate high frequencies the sub can’t handle.

Bass boost:
Bass boost is a circuit in your amplifier that improves the bass even if you don’t have a subwoofer. This can be useful if you need more bass in your system.

Buying the right amplifier is not an easy task due to the technical issues involve. Make sure to understand what you exactly need the amplifier for. This can help you buy the right amp for the budget you can afford.

Amplifiers classes:

Car Amplifiers are clasified by 5 main classes:

Class A Amplifiers:
Although class A amps provide clear sound, they are considered to be inefficient because they get heated very fast. Class A amplifiers also don’t provide enough power for the effort they consume. Class A amplifiers are ideally used for car tweeters.

Class A/B
Unlike class A amps, class A/B amps are considered to be more efficient but produce more distortion. A class A/B car amplifier is formed when a class B style output stage is biased so that around the crossover point both transistors are conducting. This yields more distortion than either a proper class A or class B amplifier, however the bias point is much less critical.

Class B amps consist of two transistors, one for each supply rail. In properly-biased class B, only one conducts at a given time, but there is always one conducting. Much of the bad name class B has is due to amplifiers actually being underbiased into class C where there's a portion of the cycle around the crossover point where neither is conducting.
Furthermore, Class B proper biasing may be made very difficult to achieve due to thermal stability issues (especially proper thermal coupling and tracking between the biasing circuit and the output power devices). Class C amplifiers are useless for audio. They are used in RF applications where the harmonics can be filtered out. Nonetheless, the so called "Class G" is just the plain combining of a normal Class AB car amplifier output stage with a Class C "booster" enabled to operate only if high power peak are required by the load. If properly designed they performances are equivalent to that obtained by normal class AB amplifiers.

Class D amplifiers are a rather new phenomenon in the hifi world. They are extremely efficient (80%) and can give a very good result. They use pulse width modulation to amplify the signal; this lets them use the output transistors in switch mode where they're most efficient and dissipate the least power. Originally only for subwoofers, newer designs have since surfaced making this technology capable of sounding very good as a full-range amplifier.

A class D amplifier is one in which the output transistors are operated as switches. When a transistor is off, the current through it is zero. When it is on, the voltage across it is small, ideally zero. In each case, the power dissipation is very low. This increases the efficiency, thus requiring less power from the power supply and smaller heat sinks for the amplifier. These are important advantages in portable battery-powered equipment. The “D” in class-D is sometimes said to stand for “digital.” This is not correct because the operation of the class-D amplifier is based on analog principles. There is no digital coding of the signal. Before the advent of the class-D amplifier, the standard classes were class-A, class-AB, class-B, and class-C. The “D” is simply the next letter in the alphabet after “C.” Indeed, the earliest work on class-D amplifiers involved vacuum tubes and can be traced to the early 1950s.

The high switching frequency used in class-D amplifiers is a potential source of rf interference with other electronic equipment. The amplifiers must be properly shielded and grounded to prevent radiation of the switching harmonics. In addition, low-pass filters must be used on all input and output leads, including the power supply leads.

Amplifier Classes Comparison: