Speaker installation is very critical for performance. Whether you
spent $50 or $1000 on a set of speakers, if they are not properly installed, the sound
will not be up to par.
What makes a good installation? Well, certainly mounting speakers in
most factory locations, such as on the bottom of the doors pointing at your legs, are not
acceptable. In this cases a new mounting location might need to be improvised.
The first thing to consider is distance. If the left speaker is only
a couple feet away from your ears, while the right speaker is several feet away from you,
then the sound will arrive at different times giving you poor sound. The left speaker will
sound louder since it is closer.
The best solution is to figure out a location where the difference
between the distance of the right speaker to your ears and left speaker (also known as
path length difference), are minimal. This is where kick panels shine, making it the
preferred location for many audiophiles and competitors alike.
The other solution, which can get expensive, depending on the gear
you get, is delays. By adding a delay to the left speaker, the sound can be doctored to
arrive from both sides at the same time. This is only a patch, and does not sound as well
as equally spaced speakers, but is the second best alternative.
Multiple Speaker Placement
If you have a system with two or more speakers per side, you need to
carefully try different locations to obtain the best possible sound in your car.
Let's take a 2-way system with a tweeter and woofer per side as an
example. The woofers are mounted in the factory location at the bottom of the door. The
tweeters are mounted high up on the front corner of the door panel. Looking at the
speakers from the driver's seat, you can see that there are 4 speakers all aimed towards
different orientations and all at a different distance to your ears. This interaction of
sound waves at different frequencies arriving at your eras at different times seldom
sounds good. The best thing to do is mount the woofer and tweeter on each side as close as
possible to each other. This is also why kick panels are used so much these days.
Professional installers do use some tricks such as inverting the
tweeters' polarity when mounted for example on top of the dash while the woofers are low.
Achieving good sound with unconventional mounting schemes is very, very hard and is only
achieved after plenty of time has been spent trying different configurations.
Our ears can distinguish the direction of sound more easily at
higher frequencies. This means that aiming the mids, and most importantly, tweeters
towards your ears play a critical role in sound imaging. Midbases are not so
critical, but should be also aimed towards the listener's ears if possible.
To figure out the best aiming angle involves many hours -even days-
of work. To start, try to aim the speakers towards the center of the car. Play
around with different angles until you obtain the best "sweet spot".
Subwoofers should be mounted up front for best sound. Since this is
not possible in most cars, mounting subs in the back is not such a bad thing, since most
people can't distinguish where bass comes from. If you have good midbases going down to 60
Hz or less and subs picking up the signal below 60 Hz, then the bass will seem to come
from the front.
Everyone is aware that subwoofers need a properly designed enclosure
to give top performance. How about midbases and mids? They also do sound much better if
they are installed in enclosures. The best sounding and easier to build enclosure type for
midbases and mids is sealed.
If you are using speakers that fit into a factory location, make
sure there are no gaps or holes. Sometimes building a wood or fiberglass baffle
helps reduce holes and gives you much better sound. Always be careful when using
power tools around speakers. Warranties usually don't cover holes in speakers.
For unconventional speaker locations, sometimes metal has to be cut.
If you have the resources, plasma cutters and pneumatics tools work great.
For most mortals that do not have these tools, a pair of metal snips (left and
right cut) will do the job.