Of course, this setup is going to require some custom fabrication since very few vehicles come with factory kick panel speaker locations. You can't just throw a board in the panel and screw a speaker into it if you want it to work, however. With mid and high frequency speakers, the angle of the driver in relation to the listener is very critical. In my BMW, we spent over a month just experimenting with speaker angling and position until we found the combination that worked the best. The trick is to get accurate imaging and staging from both seats, so you have to try different angles until you get the best possible results. Sometimes, it's necessary to angle the left and right sides differently to compensate for differences in each side of the car (like a steering wheel or a gauge cluster, for example). The best way to do is this is to make temporary kick panels out of wood, and secure them to the floor with tape so that they can be moved easily. When you get the angles right, you can build some permanent panels out of wood or fiberglass
There are a few other tricks to remember if you are considering a kick panel system. Many successful competition cars put the midrange in the kick panel, and place the tweeter in the a-pillar (the panels on each side of the windshield). This can work very well, since the high position of the tweeter usually gives the soundstage good height. Again, angle and position are very important, so experiment. Velcro works very well for this since it allows you to move the tweeter very easily until you find the right set-up. If you still can't seem to get the sound right, try changing the phase on one of your midrange speakers (simply switch the positive and negative leads on the speaker). This often works very well with kick panels, so try reversing the phase on each side and see what works best.
One final tip: keep it simple. Most of the successful cars on the IASCA and USAC circuits use a very simple system layout, consisting of a pair of midranges, a pair of tweeters, and a subwoofer. This makes tuning much easier, and it also minimizes phase errors in the compact interior of a car. You will be amazed how good your system can sound if you spend some time setting it up right. When you can close your eyes and imagine that you are really at the live performance instead of inside your car, it's time to hit the sound-off lanes and start collecting some trophies.
Our question of the month comes from Chuck, who has a bad trunk rattle problem in his Beretta and wants to know how to solve it. The first thing you need to do is determine the source of the rattling. Most of the time it's the trunklid. Try putting some pressure on it with the bass playing to see if that stops it. If it does, you need to readjust your lid to close tighter, and also add mass in the form of sound deadening material. If it still rattles, have a friend get in the trunk while the bass is playing (a small friend is best) and look for it. Check under the car as well, since many things like exhaust shields and bumper covers can make a lot of racket.
As always, send your questions to sbrown@alpine-usa.com, and I'll see you in the lanes.