The Head Unit

The Head Unit
Without a doubt, this is the main unit in a car audio system, and your most important investment. It is better to go in for a good quality main unit which has all the essential features and conveniences, rather than one with glowing lights all over. The display should be easy to use with quick access to all the basic

A coaxial speaker driver unit

features. Detachable head units are better for theft prevention.

The Speakers
These are equally important since they are the orators and you'd be hearing them. There are different types of speakers.

1. Coaxials: Coaxial speakers are two-way or three-way speakers built-in the same frame. They are relatively cheaper than separate woofers and tweeters and are also easy to install. The tweeters deliver the high frequencies, the woofers the lows. Coaxials are usually fitted as rear speakers.

2. Separates: These consist of a tweeter and woofer and most of the times come with an external crossover. The woofer is usually mounted in the kick panel (eg. door mounted) and the tweeters can be mounted in different places.

3. Horns: Horns are very good at directing the sound and are very efficient. These are usually mounted under the dashboard. Installation is a skilled job.

4. Mid-bases: They are usually of 5, 6 or 8 inches. Designed specially to go lower down in the frequency spectrum, they are a part of a three way system with a mid and tweeter.

5. Subwoofers: These add lower frequencies. They have to be mounted in enclosures. Matching subwoofers an speakers to amplifiers is an important aspect of system planning often overlooked. The subwoofer should be matched with the correct box size and type.

The Amplifier
Amplifiers are meant not only to make a system sound louder, they are also meant ot make it sound better. The greater power the amp can supply to the speakers, the cleaner the speakers sound. It is good to get an amp with built-in crossover. Look out for a low THD (total harmonic distortion) rating while deciding on the ramp.

The crossover unit

The Crossover
A crossover splits frequencies so that each speaker receives a certain range of frequencies. This done to avoid speaker damage an also maintan overall balance in the system. There are three types of crossover:
a) High pass- This blocks the low frequencies and allows the highs to pass.
b) Low pass-This blocks the higher frequencies and allows the lows to pass.
c) Band pass- This will block low and high frequencies below and above crossover points.

Active crossovers need external power to operate while the passive crossovers work after the amplifiers.

The Equalizers
Equalizers are used to fine-tune a system. They are valuable instruments to flatten a system's frequency respons. If you have the money or are an ardent audiophile then equalizers are a useful value addition.

Auxiliary Input Devices
Componens such as CD changers and equalizers, not to mention cell phones, navigation systems, MP3 players and many of the newer technologies, interface with the head unit for amplification and signal processing.

The Tuner
This delivers AM and FM radio signals to the head unit. The tuner section includes the presets and all the receptors for the radio signals. The tuner section is typically attached to the antenna.

The Cassette player
Most head units have a built-in cassette player. Although the cassette is considered passé in audiophile circles these days, the format has been around for 30-plus years and is a very cost-effective way to transmit information and / or entertainment. Cassette players are more prone to breakage and wear-and-tear because they have many more moving parts.

The CD player
Some head units have a CD player build in. Discerning music buffs prefer the clarity delivered by a CD over a cassette. The CD player is subject to wear and service issues; but itcan be repaired or replaced without trashing the whole head unit. Many vehicles also incorporate a six- or 10-disc DC changer into the sound system, located somewhere else within the car.