There helps then also the most mad plant nothing. This does not have to be. Already with simple means the worst noisemakers can be silenced. With the right damping not only unwanted background noise disappears, with a few simple, inexpensive tricks you can advance with your system into whole new worlds of sound.
Basically, a distinction must be made between two types of insulation. Pure material deadening quiets unwanted noisemakers. Large sheet metal surfaces in particular, such as the doors or the trunk, are systems susceptible to vibration. Strong basses stimulate them to resonate, sometimes very loud, disturbing background noises are generated. Today's usually thin car panels have a very low weight per square centimeter. Therefore, only little energy is needed to make them vibrate. In addition, the resonant frequency, at which the excitation is particularly effective, lies disturbingly in the frequency range of the music. The inherent damping of bare sheet metal is low, even with short music impulses it resonates for a long time.
Mass does it
Remedy for noise reduction. Whether liquid insulation or bitumen mat, the principle is the same. By applying additional mass, resonances are softened and their frequency range shifted. In addition, the self-damping of the plate is strengthened. The swaying is minimized. It is seldom necessary to dampen the sheet metal over its entire surface. In most cases, it is sufficient to apply the insulating material to only part of the resonating surface Insulating materials should therefore be as heavy as possible for optimum results. Not for nothing there are high-end enthusiasts who cast their home speakers from concrete. Even in the car, real freaks use additional ground rings (AIV, Heilbronn) to acoustically stabilize the speaker basket. Otherwise, additional weight in the vehicle tends to be a disadvantage, as fuel consumption increases and payload and performance are reduced. This may seem unimportant when only small parts of the doors are insulated. However, if the entire car is to be immobilized, one must be aware that quite a few kilos can accumulate here. The manufacturers of damping materials are therefore endeavoring to develop lightweight materials with the greatest possible effect.
Airborne sound insulation
The second type of insulation is airborne sound insulation. Here it is a question of preventing unwanted air turbulence and reflections on walls. For this purpose z.B. Nap foam mats, as you might know them from the recording studio, and insulation wadding, as it is used in the construction of loudspeakers. The functional principle is clear. Dimpled foam mats absorb the sound or. Bring it to extinction by multiple reflections between the knobs, (polyester) wadding extends the transit time of sound by many small detours and partially absorbs it. Materials for airborne sound insulation are mainly used in subwoofer boxes or when subwoofers are used in the spare wheel wells. Waterproof sealed nap foam can also be used in the doors.
If you want to acoustically immobilize the whole car, it takes a lot of time and money, depending on the car type. If you don't listen permanently to extreme levels and don't have audiophile high-end demands, you are well advised to limit yourself to some neuralgic spots of the bodywork. These are all large-area sheet-metal parts that are not profiled or reinforced Indispensable, as a rule, is the insulation of the doors. Already the sticking of ca. Third of the surface with insulation material usually works wonders. Lets not only the kick bass range become clearly more precise. This work should be done directly during the installation of the door loudspeakers. Subsequent disassembly of the door panels only creates unnecessary extra work and here insulation is really mandatory. The floor panel can be immobilized after removing the carpets. It makes sense to insulate the roof, but dismantling the headliner is difficult and requires considerable effort.
The standard bass solution is the subwoofer in the trunk. Therefore, insulation is also useful here. Trunk lid, rear sill, side panels and, depending on the shape of the body, the partition wall to the passenger compartment are notorious troublemakers. It is also advisable to insulate the parcel shelf, especially if loudspeakers are used here. In addition, there are weak points in every car model that expose themselves in the form of annoying droning noises. So: when installing the system, if the vehicle is disassembled anyway, insulate the obvious places directly. If something is still annoying, open your ears, locate the noise culprit and silence it.
The range of insulation materials available on the market is long. Classic are bitumen mats, which are available in self-adhesive version or for application with spray adhesive. They insulate effectively, but are relatively heavy. As alternatives, there are now numerous high-tech materials that weigh less but are generally more expensive. In addition to such mats for special applications, such as dashboard insulation, the following applies to all of them: they are suitable for use on flat, accessible surfaces. If it is necessary to keep corners quiet, liquid insulating materials can be used. These are available for brushing on or in spray cans for all conceivable materials. In the case of large areas, compressor application is the cheapest and most environmentally friendly method. As long as they are still wet, particularly environmentally compatible materials can be easily processed and removed with water if something goes wrong. Once dry, only a hammer and chisel will help. The insulating effect is in no way inferior to that of mats. Before applying the insulating materials, the surfaces must be cleaned. Cavity sealant can be removed with a hot air gun and then reapplied.
An important prerequisite for all insulation materials is resistance to heat, cold and chemical influences. To avoid fires the ignition temperature must be as high as possible. Especially when used in the doors, resistance to moisture is indispensable! Stuffing the doors with household absorbent cotton inevitably results in mold, rot and ultimately rusted-through doors. Polyester wadding and dimpled foam are usually waterproof, but should only be used in dry places or at least wrapped in plastic film, as they retain water and thus open the door to rust. All materials must be free of vapors. If you care about your health, beware of alleged "DIY store bargains" warned.
Short and sweet
Careful insulation reduces annoying background noise, makes bass more precise and improves the overall sound image. With a little skill and good planning, the necessary work can be done in a short time and at a reasonable cost.