Cutting down resonance and road noise
Installing Dynamat sound damping in your car
You know the drill. Your car stereo sounds great in the parking lot, but start driving around town and it leaves something to be desired. The overall volume drops, the highs get muddy, and the bass all but disappears. You can turn it up to compensate, but as soon as you merge onto the highway it just gets worse — so you're forced to crank it up some more. By the time you get home your ears are numb from the pounding and your music has lost that crisp edge.
Hustle out to your car the next morning, turn the key in the ignition, and your radio is loud. How loud? Loud enough that you just about jump out of your seat. What gives? Chances are, road noise played a part in that heavy volume knob, sapping performance from your system and unnecessarily abusing your speakers (and your ears).
It can come from all over — tire hum, engine whine, wind, exhaust, and assorted body rattles — but road noise is universally irritating and can make any custom system sound like mush in no time. At its most basic level, road noise is the product of vibration — outside sounds vibrating your door panels and passing the vibration on to your eardrums. In a closed environment like a car, that's a lot of vibration, and a lot of noise to compete with your music.
The good news is that you can cut down that road noise dramatically by installing a sound-damping product like Dynamat. These noise deadeners work by absorbing sound-causing vibration energy, eliminating speaker resonance, and baffling out excessive sound. And since they work as converters rather than simple noise blockades, a little goes a long way, saving you money and installation time.
And given the dramatic effect it can have on your sound system, Dynamat is surprisingly easy to install. Here's a look at how it went adding a complete door kit to a 2002 Nissan Xterra.
Crutchfield carries several different kinds of Dynamat. For this install we chose Original Dynamat. It can cut road noise as much as 6dB and works great in most locations. If you're going to be installing vibration dampening in an especially warm area — under the hood, for example — you'll want to step up to the Xtreme with its heat-resistant aluminum coating. Xtreme is also a tougher sound dampener, with 4x more dampening capability than Original. [Original Dynamat should be molded with a heat gun into your door's tight spaces to ensure proper adhesion.]
Blank canvas: with four large sheets of Dynamat in each box, a door kit can be molded to fit nearly any installation.
Dynamat is sold in kits, packages of precut sheets designed for specific installations. Doors, floorboards, and trunk kits are common. You can also buy it in bulk and wrap the whole car in it, depending on how much sound dampening you need, and how much you have to spend. The door kit that we used came with two 11.5" x 32" sheets of Dynamat and instructions.
Removing the door panel.
The first step was to remove the door panels and prep the interior for the installation. Easy enough; following the instructions in my Crutchfield MasterSheet, the interior panels were popped off and the plastic weather covering peeled back to expose the bare metal. The entire door was wiped down with denatured alcohol to make sure there wasn't any grease or grime sticking around. (Denatured alcohol, available at most hardware stores, is a great choice for this sort of cleaning because it has a lower water content than standard rubbing alcohol and doesn't leave a greasy surface behind.)
Dynamat won't stick to a dirty door. We used denatured alcohol to ensure a grease-free surface.
Once the area was clean, it was time to decide where to apply the material. Dynamat recommends that you install their product on both the metal door shells and the inside of your plastic interior panels, leaving no space for noise to sneak in. If you're prepping your car for a spin through the audio competition lanes, you'd probably take this approach. But as we didn't expect be doing anything more extreme than some highway road trips and off-road driving, we didn't go for overkill, installing a couple of large pieces on each metal panel and a little bit around the speakers for good measure.
The plastic weather-guard was a good template, but be sure to do a reality check with the door before you cut. Dynamat doesn't lay flat on the door, so your holes might be in the wrong place.
That done, it was time to cut the Dynamat sheets to size. Using the plastic door liner as a loose template, holes were cut for the door handle and the speaker. It's OK to cover most of the door with the Dynamat, but be sure that the latch mechanism and window can still move freely, keeping in mind that the sheet is going to change shape as you mold it to match your door.
Cut your Dynamat carefully to ensure the best possible fit.
Reassembling the jigsaw puzzle on the door, the sheets were applied like decals, peeling off the backing as we went. It's crucial to get a good stick when you're applying something like this, so we made sure to hit every inch with the heat gun and use a roller to get it into every crevice. (One note: A co-worker used a hard rubber roller to apply Dynamat to the sheet metal on her 1970 VW Bus and wound up with faint waves rippling across the body panel. So, if you're applying Dynamat to the backside of a older car's sheet metal, don't push too hard!) Original Dynamat gets very pliable when you apply a little heat to it, so it isn't too hard to mold it to the shape of the door. Remember, though, that it will be exposed to heat again in the summer months, so you should make sure every inch is sticking to something before you seal everything up again. Dynamat left loose inside the door can sag in the heat and eventually adhere to moving parts if you're not careful.
Peel and stick, just like a decal.
Checking the fit.
Use a heat gun and mold the sheets for a custom fit.
Once we had everything installed to our satisfaction, it was a simple matter of reinstalling the speaker and returning the door panel. Good as new.
You can't see it, but you can hear the difference: our work is hidden behind the door panel for a clean installation.
So, did the Dynamat make a difference in the Xterra? Overall, yes. While it didn't magically transform the stereo into a 1,000-watt bass machine, it did wonders for road noise problem and definitely tightened up the speaker response. The stereo could be cranked without worrying about body rattle or resonance, and passengers talked normally without having to shout over the din. The drop in overall road hum/wind noise was clearly the biggest benefit. One other nice benefit was the drop in noise at highway speeds.