Car audio and video systems have become increasingly popular in recent years and there are a massive number of products available in the market today.  There are products for every budget and gadgets for almost anything you can imagine. Most OEM audio/video systems are extremely expensive, especially when compared to the aftermarket standards of quality and performance for your dollar, so it is usually the aftermarket that a wise consumer turns to if they want high performance at a lower price.

Car Audio Basics

Basic car audio systems usually include several components: A head unit, speakers, amplifier, crossovers, wires, and power source. Additional products that can more fully round off a system would be subwoofers, component speakers, molded speaker boxes, capacitors, signal cleaners/digital tuners and sound/vibration dampening. Often systems are designed from the ground up by people that have a lot of cash to spend; if however they don't have the money all at once it is also possible to build a great system in stages. Depending upon what the consumer already has it is usually possible to work with existing equipment by incorporating in until money is available to replace each product to the desired capability. Head units (Or receivers) are the most common component in today's vehicles that are often the last to be exchanged. Head unit capabilities have come a long way in the OEM world and now that they are usually mp3 and gps capable it has become less important to change them right away.  Head units are often technically difficult to remove from a vehicle, by this I mean not that the removal is difficult; instead I mean that preserving the car's function without the OEM stereo is difficult.  Often OEM steering wheel controls, alarms, and occasionally air bag operation may be affected! So make sure you have done your research and are listening to good advice from your sales person or installer!

Car Audio Components:

Head Unit

The Head Unit (Receiver or Deck) is the part of the audio system which creates the sound signals. It is created from the CD, DVD, MP3 player, Phone, Radio or any other source that can be plugged into it. Most units will have simple crossovers and or equalizer options. As a general rule higher end decks have pre-outs for amplifiers and considerable better cross-overs so if you’re looking to build a higher end system make sure that your head unit has all the required features.  Realistically expect to pay $200+ for a decent product and $500+ for something truly high end if your shopping at a retailer. Car Decks come in 2 main universal sizes, DIN or Double DIN (Could be with 2 N's). DIN is the standard size for 90% of all vehicles, Double DIN are for the newer vehicles with GPS and Video capabilities. You can get DIN decks with GPS and Video but because of the small size they are almost useless for that purpose. Installation is usually straight forward in older cars but can become tricky in newer cars. I recommend only attempting installation of a Deck if you know what you’re doing because there are lots of wires back there and on new cars those wiring harnesses sometimes require some serious modifications in order to work properly. In older cars you will probably only find power, acc, 8 speaker leads, ground, dimmer, FM and a power antenna wire. That’s a manageable amount. New cars can be a different story!

Wires

Often overlooked these are actually quite important to the safe operation of your stereo. Make sure to have properly shielded wires that will not be damaged easily. Also make sure your wires are of an appropriate gauge. Power supply wires are super thick and only high quality wire will still be easy to bend. (Quick way of testing the quality of your 4 or 0ga is to see it will bend back and forth easily). Speaker wire should also be of reasonable quality. I wouldn't bother with time corrected wire, but for god’s sake don't use household wire or worse! I am not lying when I say that an improperly wired audio system has set more than one car on fire! Wires are fairly inexpensive if you know were to look.

Amplifiers

Amps are the backbone of all stereos and this is where I personally spend the bulk of my budget. The amplifier takes the signal from your deck and amplifies it so that it will be able to power speakers cleanly. Most decks have amplifiers built into them but true enthusiasts always go for external amps. Not only do they provide the power needed for clean signal but they also do not conk out as often from heat buildup. Amplifiers come in many different shapes, sizes and types. Commonalities are that they all have channels (1 or 2 or 3 or 4 or 5 or more). Each channel is a distinct speaker port. I.e. Front Left port on the amp will play the music that the receiver tells it is Front Left. Music is usually stereo (2 channel) but you can also fade Left/Right and Back/Front (now 4 channel). The fifth channel is designed as either a center front, (like a 5.1 surround sounds system) or as a subwoofer driver. Most people use more than one amp so it is actually rare to see a 5 channel. (They are also really expensive). Standard Amp doctrine usually breaks down like this:  Cheap system: 4 speakers off Deck, 1 sub on small amp. Medium system: 1 sub + 2 speakers amplified = 4 channel amp.  Basic Comprehensive system: 4 speakers and 1 or more subs = 2 amps or more. Amps range in price and capabilities, id recommend buying the best you can afford.

Speakers/Subs

Speakers come in many different sizes, materials, power ratings etc. High end speakers will last you a lifetime and never fail. Poor quality speakers are made of paper and will die within a year. "I don't even like to eat off paper, much less listen to it". Component speakers are the best. These are either 2, 3, or 4 way; each component of a component speaker is actually a separate speaker. In basic terms you will have a speaker for highs (tweeter) and at least 1 speaker for mid/low (woofer). Low frequency sound will come from a sub woofer. Woofers are non directional so you usually find them in the trunk. Personally i don't put to much stock in buying crazy good speakers, my philosophy of high end amp makes even modest quality speakers sounds good. Also, because i tend to switch cars quite a bit it makes more sense to put money in an amp that will more with me into my next car instead of speakers which will probably stay with the car. Because of the size issue i usually write off the speakers i leave behind in an old car.

Installation

Installing Car Audio is great fun. Make sure you have time, beer, and more than a bit of knowledge. Take your time taking panels, seats, wires and everything else out. Don't loose any pieces and try not to break any clips that hold your panels together. If you break them the panel will start rattling! Be careful to disconnect the battery before you begin and take care to install wires in such a way that they cannot wear through and short circuit. If your doing fancy stuff with fiberglass etc make sure you don't mess up your seats and such. Invest in sound/vibration dampening material, it keeps your car from rattling. This can be bought online for super cheap!