Audio


Wired for sound...

You don't have to be an audiophile to appreciate good sound quality, and you don't have to spend much time listening to the average car stereo system to realise there is considerable room for improvement.

The first upgrade is inevitably the headunit, but this is only half the system, the most important part - the speakers that actually generate the sound waves, are often left untouched.

Check out the guides section here for a full step by step guide to upgrading the speaker system.

The first step is to upgrade the speakers all round.

A Component system with separate woofer and tweeter provide a superior sound and allows better staging over the cheaper coaxial systems. Most speakers are a standard depth and will not fit into the 600 door without modification to avoid fouling the window mechanism. Creating MDF rings gives the speakers a solid mount and improves sound quality as well as providing the spacing to allow standard depth speaker fitment in the shallow door.

Standard speaker wire is quite thin and can be upgraded to thicker oxygen free audio grade wire which has a lower resistance and is capable of carrying more power. To ensure the wiring is kept as neat as possible the wires can be run through the existing door connectors.

The original dashboard tweeter grills can be modified to take the new tweeter units which can then be fitted in the stock location and all the cabling can be run to the crossovers, here located behind the glovebox.

The rear speakers are generally not as important as the front speakers, and if they are too loud can overpower the fronts and spoil the sound stage. Although often omitted from an installation altogether, here a set of coaxial 6x9 are run direct from the headunit to provide a slight rear fill without interfering with the front setup.

If a sub woofer is to be fitted the rear speakers must be physically isolated from the subwoofer to avoid the sound waves generated from the subwoofer conflicting with those generated by the rear speakers and causing damage to the speakers - or detracting from the sound quality. In this case a sealed box for each 6x9 is sufficient.

Now the speakers have been upgraded the wiring for the crossovers and RCA cables to the headunit can be run. To make a neat job it was necessary to remove the interior.

Here there are several RCA leads as well as additional cabling for the carPC and video feeds.

Do you like bass?...

The biggest problem with subwoofer installations is down to lack of understanding - the relationship between the subwoofer, the box and the amplifier are crucial, and often ignored.

The specification of the subwoofer determines the size of the box needed to house it - and the power output of the amplified to drive it. In this case the OZ audio Matrix Elite which requires 700Watts RMS and an optimum enclosure of around 1.7 cubic foot.

A single subwoofer provides sufficient bass while allowing enough boot space to still remain practical - to further save space the box shape and size was calculated to allow enough room to incorporate the battery which provides extra space under the bonnet for engine modifications.

Once the sub box had been constructed, strengthened and sealed it was used as a template to make a MDF base which would be used for mounting the rest of the build.

One of the main criteria of the boot build was the retention of practical space for luggage and the spare wheel. With the extra increase in height of the boot floor it was actually possible to accommodate a standard 17" Alloy Wheel which became the basis for the design.

A "false" floor could then be created which would sit a couple of inches above the base board, covering the spare wheel and providing enough space to mount the amplifiers for the subwoofer and front speakers and the other various components.

The "false" floor would actually consist of three parts, two fixed "wings" and a removable centre section, making installation simple and providing a solution for access to the spare wheel

The Amplifier and wiring would be hidden under one "wing", and the car PC mounted inside the space provided by the other.

The car PC links to an indash touchscreen at the front of the car and provides satnav, mp3 playback and other entertainment features.

The PC comprises of a miniITX board with M1-ATX DC to DC power supply which is designed to work in automotive environments.

The PC mounts inside the flash floor "wing" with all components secured and additional cooling fans and USB hub.

Once the fitment had been tested, the wiring was then installed. 0 gauge was used for the distribution from the battery to a circuit breaker and bass amplifier, with a 4 gauge spur to the door speaker amplifier and 2 gauge feed to the engine bay.

A good earth is essential when fitting any electrical item, most problems with audio installs relate to poor quality ground connections. A solid point on the bodywork was chosen and cleaned of any paint to become the earth point for the amplifiers.

Once the wiring had been installed the remaining boot trim was amended to suit the new design and refitted.

The finished sub box was covered with automotive grade carpet to closely match the colour of the boot trim. PVA adhesive was used to stick the carpet to the primed and sealed MDF box.

With the sub box fitted the amplifiers were installed and connected to the wiring.

Here an Alpine MRD800 (class D) is used to drive the subwoofer and a JL Audio E2150 is used for the front components. A circuit breaker is also fitted to protect the long cable run form the battery to the engine.

An electronic volt/ammeter is also fitted so battery condition can be monitored when under heavy load from the audio system. It is flush mounted under the "false floor" to minimise the chance of any damage.

The finished installation with all the trim in place - the colour difference in materials is exaggerated by the camera flash.

The removeable board is slotted into place and the boot build is complete.