Building a successful IASCA compliant car in six easy to follow steps

After reading about a good setup and which brands to choose it is time to install. Blow is a description as to how to build a good audio system in a car. It is based on my own experience, my mistakes and my strong points. I only have knowledge of pure hifi systems. If you're building a boom car just use this article as a rough guide line.

The final result of your installation depends on installation. Good equipment and bad installation make a poor result. "A chain is as strong as its weakest link". The speakers depend on the enclosure and the amplifier, the amplifier depends on current and the current depends on wires and the alternator. Make a mistake in any step and the final result will be disappointing.

Step 1 - Where to put it?

Speaker location determines your entire sound image. The problem with cars is that fact that the listener isn't in the middle of two speakers but in a corner making one speaker sound louder than the other. The distance between the left speaker and the left ear isn't the same as the distance between the right speaker and right ear. Try to make the difference between the distance on the left and right as little as possible. Placing the speakers near the ground does the job but creates a risk of sound coming from below. Placing an extra speaker on the dashboard doesn't help because that will rip the sound in two.

To find the perfect location in your car temporarily install the front speakers in card board boxes. This test is only to find a location, so poor sound due to the minimal enclosure of the card board boxes is no problem. Play at a low volume, the speakers may even be driven by a home audio system, and move the speakers around the car to find the perfect location. Listen, don't look. Some very unlikely places may proof to be good for audio.

Subwoofer location cannot be found using this method. Location of amplifiers and other equipment is a cosmetical case only. Just keep in mind that some devices may interfere with each other.

Bare metal door

Step 2 - Cables and Dynamat

Now you know where to put the speakers and other devices. Time for the first layer: Dynamat. Dynamat (and similar materials) are used to stop the car from vibrating and to prevent metal panels from carrying noise like a tuning fork. Dynamat is not sound isolation! I only used Dynamat on my doors to be sure the metal wouldn't be part of the enclosure of the speaker (affecting the sound severely). Some use Dynamat on the entire car, I think that's over done.

Next to the metal is cabling. Cables are the first essential link in your audio chain. Screw this part up and your entire system won't perform. Some people run huge amplifiers but don't get the expected performance. They visit a store for an even more powerful amplifier. Again the amplifier doesn't deliver. In fact they only needed a good cable. It is like a sports car with a super thin petrol hose. An engine needs sufficient fuel to perform. An amplifier needs sufficient current. Use this table for cables to the amplifier(s):

Current Draw Length (in meters)
Ampères upto 1 2 to 3 3 to 4 4 to 5 5 to 6 6 to 7 7 to 8
0 - 20 A 2.5 mm2 4 mm2 4 mm2 6 mm2 8 mm2 8 mm2 8 mm2
20 - 35 A 4 mm2 6 mm2 6 mm2 8 mm2 12 mm2 12 mm2 20 mm2
35 - 50 A 6 mm2 8 mm2 8 mm2 12 mm2 20 mm2 20 mm2 20 mm2
50 - 65 A 8 mm2 8 mm2 12 mm2 16 mm2 20 mm2 20 mm2 35 mm2
65 - 85 A 12 mm2 12 mm2 20 mm2 20 mm2 35 mm2 35 mm2 53 mm2
85 - 105 A 12 mm2 12 mm2 20 mm2 35 mm2 35 mm2 35 mm2 53 mm2
105 - 125 A 20 mm2 20 mm2 20 mm2 35 mm2 53 mm2 53 mm2 53 mm2
125 - 150 A 35 mm2 35 mm2 35 mm2 35 mm2 53 mm2 53 mm2 60 mm2

This table is for pure copper wire, taking a loss of half a volt tolerable. Resistance for connections and clamps has been accounted for.

The cables should run from the battery to a fuse within 30 cm of the battery (IASCA rule) to a fuse box near the amplifier(s). The power cable to the amplifier(s) goes on the side of your car where the battery is located. The signal from the head unit to the amplifiers goes trough the middle of the car (expected the head unit is in the middle). The speaker cables go trough the remaining side. For a full example, take a look at the schematic car at the practice part of the setup page.

Now would be a good time to install an alarm since most panels are removed and you're busy doing cables anyway.

Install a head unit

Step 3 - Head unit and amplifier(s)

There's cables and there's current. Time to hook up the head unit and amplifiers. First install the head unit and optional CD changer and they turn on the amplifier(s). Some choose to feed the head unit using factory wires, other make a separate circuit for the head unit. This depends on the quality of the factory audio preparation. The amplifiers must each have their own fuse. Use good cable, don't skip on quality of power distribution blocks and clamps. Filters (as described in the setup page) should also be installed now.

Connect a speaker to an amplifier to see if it works, but play at very low volume since the speakers don't have an enclosure yet.

Step 3.1 - Installing amplifiers

When competing with a system installation is more important. Just slapping an amplifier on a piece of MDF wood or on some factory panel won't do. Also try to be original. Amplifiers under a carpet in the boot are not original. Find hidden panels, try the roof, the back door or anything new. I choose to install the amplifiers in the back seat, spray painted the remaining visible metal "iceland blue" and finished the install with plexi glass. The amplifiers are cooled using a mechanism of vans and air vents (so those are not tweeters in the upper left and right corner!).

Amplifier install
Bare wooden door

Step 4 - Building a speaker enclosure

There's no such thing as the best enclosure for a certain speaker. That is why the manufacturer doesn't describe what box to build for a speaker. In fact any box will do, but each type of box will give a different result. Long, short, high, low, ported or sealed each will give a different result and most will work with the same speaker. The manufacturer doesn't know what kind of sound you want the speaker to make, so it is up to you to make an enclosure that suits your needs. This is why the manufacturer gives is a set of so called "Thiele Small" paramaters (consult the owner's manual). Feed these parameters to a computer program (to be found at the usenet archive or the software archive) and the program will tell you what sound to expect for each kind of box. You can change the box size and type on the screen and the software will show what the speaker will do. One type of box will play very low while the other might play very loud. Most programs will also allow working the other way around and show what box to built when the user defines the desired result from the speaker.

The enclosure is the most important part for the speaker. Good speaker, bad enclosure, poor result. A good car audio store may also be able to do the calculations for you. In case of a subwoofer you can also choose to buy a ready made box and speaker, in which case you can be sure the manufacturer make the perfect enclosure for you.

Step 4.1 - Custom door panels

After finding the best location using a temporary enclose as explained in step 1 I decided my car doors are the best place to install front speakers.

My door panel is made out of MDF (medium density fiberboard) because it is easy to work on and the sound is good. This door panel is an entire new panel, and not built upon the old Suzuki panel. Then a second, third and fourth layer were added to fit the speakers. The pocket is divided into two parts, the one near the speakers hold exactly three CD cases (2 doors times 3 CDs = one filled CD player). The door handle comes from a Fiat Uno. The little lights come from a Mazda 626, just because they looked good at the junk yard.

I actually drove around with bare wooden panels for three months. In this time one can still adjust little things, like the angle of the speakers and the location of the tweeters. Tweeters on the dash gave a sharper more clear sound, but it was audible that midrange came from the door and high notes from the dash. The tweeters on top on the door panel sounded very natural and blended in with mid and midbass. By reflecting in the front window the sound stage is still high up in the car and appears to be on the dash or even on the bonnet of the car.

Door panel before installation Door panel after installation
before after (downloadable as 665x457x24)
At the upholsterer

Step 5 - Upholstery

A bare door panel doesn't look that good, so it is time to apply some clothing. A nice opportunity to write an article about upholstery and have my doors finished at the same time.

The upholsterer found a material that matched the colour of the rest of the interior. It turned out to be from a Renault 5. I wanted an inlay using the same material as found on the seats. As Suzuki does not sell the separate material I had to visit the junk yard once again to get a back seat. This material was used for the inlay. The Suzuki logo (very subtle in a far corner, same colour as the clothing) was copied from an advertisement.

At IASCA competitions one needs a photobook to prove that one really did all the work, and that the car really did not have these features before. With a car as basic and primitive like mine a photobook is more important. For example there were no wires from the chassis to the door, so the doors had to be removed to fit wires. 99% of all other cars already have such things and one has to prove this is not standard to get the points.

The upholsterer

Step 6 - All done?

The final result, with a picture of the upholsterer as used in the magazine. For him it's all done. But a good looking system that makes sound is not done yet. Next step is fine tuning. Tweeter may need some final aligning, filters may need to be adjusted and amplifiers need their gain set. Just follow the little car on the bottom right for the next step: fine tuning.

StereoDrive article If you're planning on competing be sure to make pictures like this because the jury only believes you actually did the work if you can proof it by showing photographs.

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