Originally appeared in the March/April 1990 issue of Car Stereo Review magazine.
Would you go to a concert and listen with your back towards the stage? Of course not, it just wouldn't sound natural. Yet many people settle for this same un-natural sound when listening to their auto sound system. This doesn't have to be the case. In my experience, the best sounding, most realistic systems, always have a spatial ambiance about them that is created by good frontal imaging and just a touch of rear fill.
When listening to these systems, you can close your eyes and almost imagine that you're at a live concert with the stage stretching out before you. The trick to creating this illusion is to locate the sound stage in front of the listener. Master installers accomplish this by positioning the speakers in such a fashion as to provide good frontal imaging.
This can sometimes be difficult to achieve in a vehicle. Space is generally very restricted in the front of a car. For the most part, dash mounted speakers are limited to only 4 inches in diameter or less. And even if the speakers are Mondo Kamikaze 1000's, it will take more than a miracle to get a couple of 4 inch speakers to produce the acoustic illusion we are searching for.
So what is the technique the professional's use to create this illusion? Generally, they install tweeters in the dash, and midrange and/or mid-bass drivers in the doors to augment the speakers in the rear of the vehicle. Since most tweeters are pretty small, they can be mounted quite easily in the dash. Installing speakers in the door is another matter.
The Right Stuff
Installing door mounted speakers takes the right stuff. Motivation, creativity, determination, ingenuity, and patience are all required to produce satisfactory results. Don't be fooled, door mounted speakers are a lot of work. In addition, since almost every door is different, a certain amount of creativity and ingenuity will be required. If you feel that you don't have enough of the right stuff, I would recommend hiring a professional installer to do the job for you.
Selecting a Suitable Speaker
It may seem strange to wait until this point in the installation process to select a speaker. However, when you think about it, you can see that this is really the safest way to proceed. Why? Because until you actually see the interior of your door, you really have no idea what type of speaker will fit. After examining the door, you will be able to select a driver based on the space available and the requirements of your stereo system.
Another equally important matter to consider is the durability of the speaker itself. Car doors will almost invariably leak when it rains or whenever you wash the car. The question you should ask is, "Will the speaker be ruined if it gets wet"? Even if the driver you select is water resistant (such as a poly or aluminum cone), I would still highly recommend the use of a speaker shield (speaker umbrella?) over the back of each driver. These devices, which are commonly made of plastic or foam, can usually be purchased from your local auto sound dealer for a couple of bucks apiece.
If you want your speakers to work, they'll need to be connected to your system. The best time to run the speaker wire is before you physically mount the speakers. In some vehicles, this will involve little more than snaking a speaker cable through an existing rubber boot between the door jam and the door.
If there aren't boots in your vehicle, you will have to make your own. Start by removing the kick panels next to the hinges of each door. This will provide you with an access point on the back side of the door jam. Select a location towards the center of the door jam and away from the courtesy light switch (the push-button that turns on the interior lights whenever you open the door). Next, drill a 3/8 inch hole in the door jam and another one in a matching location on the door.
After drilling, install a rubber grommet into each hole. This will prevent the wire from being damaged on the sharp metal edges of the holes. Plastic wire-loom tubing or rubber hose will also work equally well.
To snake the wire, insert it into the grommet (or tubing) from the back side of the door jam. Slowly pull about five feet or so of cable through the hole. Next, thread the same wire into the facing grommet on the door and carefully pull the cable out of the speaker hole until the slack is just taken up between the door jam and the door.
To protect the speaker against possible damage in the event that something were ever to pull on the wire, I always install some form of strain relief inside the door. The easiest way to do this is to tie a knot in the wire immediately after it comes into the door. Other methods include tie-wrapping the wire to the sheet metal or using special strain relief plugs that snap into a hole.
Modifying the Door Panel
Before modifying the door panels, you will need to select the type of cosmetic option you desire. There are basically only two choices here; perfed door panels or surface mounted speakers with grills.
For a really professional looking installation, you can perforate the door panel. This involves punching holes in the door panel with a special tool called a Perf Tool. In this type of installation, the speakers are hidden from view. Other benefits include a more securely mounted driver; no speaker grill; and retention of the auto's resale value.
Perf tools are expensive, though. Unless you install auto sound systems on a regular basis, you probably won't be able to justify the cost. Fortunately, most auto sound installation shops are willing to perf your door panels for a modest fee.
Your other option is to use a surface mounted speaker and grill. This method is easier, and if done carefully, can also produce satisfactory results. In this type of installation, the speaker is mounted on the outside of the door panel and then a speaker grill is placed over the top of it.
In both cases, you will need to mark the exact location where the speaker is to be mounted. If the panel is to be perforated, use the perf tool to perf this area. If the speaker is going to use a speaker grill, cut this area out. Remember, only cut a hole big enough for the magnet structure and basket to fit through. DON'T CUT THE HOLE THE SIZE OF THE SPEAKER FLANGE! If you cut the hole the same size as the diameter of the speaker, the speaker will fall right through the hole. Bummer!
Replacing the Door Panel
To replace the door panel, proceed in exactly the same fashion you did when removing it, only backwards. Align the plastic anchors and snap them into place. Replace all the screws, arm rests, and door lock buttons. Finally, replace the door and window crank handles in the same orientation as they were when you removed them.
Mounting the Driver
Mounting the driver securely is imperative. It's a real pain when your speakers fall out on the floor every time you shut the door. Even if the speakers you have chosen are light, they still need to be secured to the metal of the door, not just the door panel itself. This is necessary even if the speakers are being used in a surface mount installation.
Don't over-tighten the mounting screws. Unless the mounting surface is true (flat), this will distort the speaker's frame and could, quite possibly, ruin it. Also, remember to connect the speaker wires to the speaker before mounting it. Be certain that the speaker's terminals aren't going to short out by touching the sheet metal of the door. This is a very common problem in door-speaker installations.
Check for Interference
After everything is assembled, check for interference. Roll the window up and down to make sure that nothing strikes the speaker. Shut the door to verify that the speaker isn't an obstruction. Does the door handle and window crank work? What about the door lock? Keep your eye on the speaker wire between the door jam and door as well. Does the wire fold neatly when you open and close the door? Take care of any problems now or they most certainly will become a headache later.
To finish up the installation, install the speaker grills. These usually just press onto the top of the driver, but in some cases, will require mounting screws as well. If you really want to get creative, you can fabricate your own speaker grills using a fabric that matches the interior of your vehicle.
If you've completed the installation successfully, you can consider yourself a member of an elite group of auto sound enthusiast. Not only will your system sound more realistic because of the frontal imaging, it will sound even better because you did the work yourself.