Car Audio Systems:
The standard audio on a lot of cars is fine for most purposes, but if you want better sound quality you will have to upgrade. In most cases the first upgrade will be the headunit (the unit in the dash) and this will be connected to the existing speakers. The difference will be noticable, but alongside this, chances are there will be some clipping occurring.
This is because the OEM speakers are not capable of handling the power from the new headunit
or the internal amplification of the headunit is being driven too hard (read: loud).

To reduce the strain on the internal amplifier, an external, more powerful amp can be connected to the system, which in turn will provide much better sound quality. The speakers should also be changed when fitting an amp.

Generally speaking, audio can be divided into three frequency bands: highs (treble), mids, and lows (bass). To get the best sound reproduction, you need to have some form of output for all three ranges. The best way of doing this (imo) is by using a good set of components in the front of the car (handles mids and trebles), and a good quality sub in an enclosure of sorts (thats a different article altogether…) in the rear.

For those who aren’t familiar, component speakers come as a set containing a mid-range woofer and a tweeter to handle the mids and highs respectively. The set also contains a device known as a crossover which separates the incoming signal and routes it to the appropiate component. See image below – the mid woofers are mounted in the door, the tweeters up closer to head level to drag the sound stage upwards, and the crossovers are fixed inside the door itself:

Unless you really need or want speakers in the rear, my advice would be to avoid them (particularly 6x9s on a parcel shelf) as they will drag the sound-stage behind you (you dont go to a concert and stand with your back to the stage!). Additionally, having 6x9s and a sub in close proximity will undoubtedly cause some damage to the 6x9s and will have no worthwhile benefit.

Amplifiers:
You can get a variety of amplifiers for car audio purposes. The main differences are the number of channels and the output rating. In general, stick to good quality, well known makes. Cheap amps sound like garbage in comparison.

If we stick to the example above of using front components and a sub, there are two feasable options:

• Use a 4-channel amp. Use one channel per set of components in the front, and ‘bridge’ the remaining two for a higher output for the sub. This is the method I will go through.
• Use a 2-channel amp for the front components and a mono-block for the sub. This is the more powerful method but requires extra cabling and other considerations.

Cabling:
The amplifier is generally secured in the boot as it allows easy dissapation of heat (they can get quite warm) and is quite accesable. The problem is…it needs power from the battery…which unfortunately is in the front of the car…There are five items you need to deal with:

• Live cable from the battery positive terminal with an inline fuse to amplifier
• Earth cable from amplifier to unpainted section of car chassis
• Shielded RCA cables from headunit to amplifier. For sending audio signal from headunit to amp.
• Remote control cable. For allowing volume control, auto switch on/off etc from the headunit.
• Sheilded speaker cables from the amplifier to the front components and the sub.

The power cable you use is very important, more so in high power installations. If the cable you use is not capable of handling the current draw, it will melt and short on the car chassis potentially causing a fire. You can go through the calculations to determine the max current draw etc, but in general, choose the thickest cable you can. 4AWG is fine for most cases, but do your own research! You can buy amplifier wiring kits from many places and these are fine – just make sure you check the lengths and gauges.

Before beginning any electrical work, disconnect the negative terminal from the battery.

If you are lucky enough to have a pre drilled hole through the firewall then use that for routing the power cable into the car from the engine compartment. If not, you will have to do this youself (make sure you don’t drill into anything important!) and seal the hole using a rubber grommit or other method. When feeding the cable through, make sure the in-line fuse is at the end of the cable closest to the battery.

In the above image, the red cable is the power, and you can clearly see the fuse beside the battery. Ignore the other cables I have going through the hole…

Don’t connect the cable to the battery just yet.

You now need to route the cable down the side of the car – its fairly simple to prise away the trim and stick the cable underneath (see image below). Do this until the other end of the cable is in the boot. You may have to be inventive during this step – it depends on your cars design.

While you are at this stage, route the RCA and remote leads down the OTHER side of the car in the same way as you did with the power. Putting them down the opposite side will help eliminate inteference and alternator whine. Also, route the cable for your front speakers in the same manner.

You should now have a selection of cable ends in your boot: power, RCA x2, remote and speaker.

Before any of these are connected, secure the amp in place (I screwed mine into the rear of the back seat), and connect the GND terminal to an UNPAINTED point on the car chassis as close to the amp as possible. Remember, the ground cable should be the same gauge as the power cable.

Now you can connect the remaining cables to the appropiate tabs on the amp. The image below shows how I connected them up:

RCA’s in for channels 1,2,3 and 4.

From left to right:

• Channels 1 and 2 connected by the white cables to the front component speakers (double check you get the positive and negative the right way round)
• Channels 3 and 4 are ‘bridged’ and connected to the subwoofer. Again, check positive and negative.
• Thick red power cable (connect this last)
• Thin red remote lead connection
• Ground

There should be nothing left loose in the boot.

You can now connect the live end of the power cable to the battery positive terminal. It may be wise to use a distribution block for ease of use, but it is not essential.

Double check all connections and reconnect the negative terminal block to the battery. Test out the amp, make sure everything works correctly, and fine tune the settings using the crossovers, high pass and low pass filters etc on the amp to suit your music.

Final Words:
There are many different ways of connecting and configuring your system, this guide shows just one of them. Feel free to leave a comment here about anything contained in this guide, or if you have any specific questions or problems with your installation, post up in the forum and I can try to help.

Leonard.

Note that this is only intended to be a guide, and as such, I can’t be responsible for any problems you come across by following it. Use your common sense – if you aren’t sure, ask someone for advice or get someone who knows what they’re doing to help you or do it for you.