When we listen to a home stereo, we have ideal conditions: A quiet
environment, speakers pointing to the "sweet spot" on the same axis, etc.
By properly aligning the speakers, and designing a good crossover, a sweet spot can
be achieved on a car with as good quality sound, staging and imaging as a high-end home
There is still one thing that is different between a car and a home
stereo listening room: The background noise. There are all kinds of exterior (road noise,
rain hitting the windshield, etc.) and interior (rattles) noises that draw attention away
from the music in a car. To make up for the road noise, we simply turn the stereo up
Even though it is impossible to eliminate the noise completely in a
car. There are products that will decrease the noise floor a great deal, particularly on
non-luxury cars. Reducing the noise in a car will make a big difference in the audio
system's performance and overall ride comfort.
Tar mats and similar products such as Dynamat are used to reduce
resonances in metal panels. A car lined with a mat will have a much lower road noise. To
add a mat liner to a car, seats, carpet, door panels, etc. have to be removed. With the
help of a heat gun, and a small wallpaper roller, the material can be laid over door
panels, floors, wheel wells, etc. A cheaper alternative to Dynamat, as mentioned in the
rec.audio.car FAQ is a product used by roofing contractors called Ice Guard,
which has an adhesive backing and works the same way.
There are products such as Rockford Fosgates Noise Killer Blue
which are sprayed to the panels. They are used in places where a liner cant be
applied such as inside doors, trunks, etc. Most of those products are applied in the same
way as paint: Either sprayed or with a brush. There are two types of sprays: Some need an
air compressor and a spray nozzle and the others already come in a spray bottle such as
An alternative is rubberized undercoating which can be obtained at
any major car parts store. It comes in a spray can and is easy to apply. The only drawback
is that it is very sticky and messy. Could be used for the inside of the doors or places
where it won't come in contact with carpet or fabric.
Expandable insulation spray foam is used in homes to seal around
pipes and fill up holes in basements. In a car, it can be used in irregular surfaces where
tar mats cant be applied, such as the trunk, trunk lid, etc. To apply, clear the
area from fabric, panels, etc. Once the foam dries (about four hours), cut excess off with
a long knife.
Used for home door insulation. A strip of foam with an adhesive
material on one side, used to seal between the door and the door jamb to keep air from
escaping the house. Apply between panels, behind license plates, etc. Quick, inexpensive
and easy way to get rid of annoying rattles.
Another product that can be placed between panels to cover larger
areas is carpet padding, available at any carpet store.
Damping a Door: Step by Step Instructions
A combination of three products will be used in this case: A spray
noise damping material, spray rubberized undercoating, and a tar mat. This allows for
maximum noise isolation.