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tock speakers with stock electronics have enough power to vibrate your car doors, creating buzzes and rattles. Better quality speakers and aftermarket amplifiers have more output capability, causing

even more vibrations and rattles. But the untold story about speakers mounted in doors is lost performance. The untreated thin sheet metal on stock doors is flimsy. When the speaker moves, the vibration of the metal is lost acoustical output from the speaker. Also, the outer door skin is extremely close to the back of the speaker. The reflection and reverberation created from the back-wave noise and distortion negatively affects the sound quality of the speaker. Don’t believe me? Take some aluminum foil, put it close to your mouth and speak. Hear the difference? Not only do you hear the vibration of the foil, you hear the sound of your voice change. Not good. And don’t forget the access holes. With so many holes on the inner door skin, you can’t expect any real mid-bass response.

Sound conTrol SoluTionAn optimal speaker enclosure is made of a solid, non-resonant material that

minimizes internal reflections (back-wave noise and distortion). As you can see from the picture, a non-treated door is far from ideal. With the right materials and techniques, you can restore the lost sound quality of your door speakers and lower the overall road noise inside your vehicle. When your vehicle is quieter, you no longer need to turn up your stereo to overcome the road noise. A 3dB increase in dynamic range is equivalent to doubling your stereo system’s amplifier power. (For more information on this, read the article titled Sound Control – The Ultimate Invisible Upgrade at www.pasmag.com/article.asp?ID=404.)

In your car door, you are dealing with three types of noise: vibrational, airborne and reflective. The vibrational part is obvious. The midbass output from your door speakers causes buzzes and rattles of the door sheet metal and the door panel itself. Airborne noise comes from two sources. The outside road noise and the back-wave speaker output come through the holes in the inner door skin. The speaker’s back-wave noise is particularly bad because it not only colours the sound, but also cancels the bass output. The final problem is reflective: sound bouncing around where it shouldn’t. This happens in two locations. First, the back-wave sound from the speaker reflects (bounces) off the outer door skin. This sound interferes with the speaker and makes the speaker sound like it is playing through a tube. The second area is between the inner door skin and the decorative door panel. Sound bounces between them and gives it a reverb type of sound. The guys at Dynamat have developed a Good, Better, and Best solution to deal with these problems.

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Text and Photos by Paul Sonoda

1. Stock door with no sound control. Look at all those holes and flimsy plastic!

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Let’s face it. Doors are terribLe speaker encLosures. if you have ever taken off a Door paneL, you know what i mean. we’re taLking thin sheet metaL with Lots of hoLes. worse yet, the Doors have pLastic moisture barriers that fLap aLong to the beat of the music. however, if you are upgraDing your speakers or just want better sounD, reaD on.

2. Installing Dynamat on outer door skin

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The door Speaker upgrade

Sound conTrol

SummaryYour stereo’s sound quality will be dramatically

improved by creating a neutral acoustic environ-ment. These techniques and high-quality materials allow you to achieve this. It’s all about the installa-tion. You have stopped door panel buzzes, reduced road noise and eliminated back-wave noise and distortion. You’ve also improved midbass impact, clarity of sound and increased dynamic range. It will make good speakers great and great speak-ers awesome. Without sound control, you are only getting half of the sound quality potential of your new speaker. With sound control you will get all the sound you paid for.

Tech TalkproducT recommendaTionS

good Apply DynAmAt Xtreme to the inner Door skin

Apply a Dynamat Xtreme Door Kit to the inner door skins. The inner door skin is the metal panel directly behind the decorative door panel. This is not only the mounting baffle for the speaker, but also the most important area to treat. Covering the holes eliminates midbass cancellation, resulting in better dynamics and more punch in your system. Not only do you eliminate speaker panel distortion with this application, you also reduce outside road noise. A Dynamat Xtreme Door Kit reduces road noise up to 5dB in actual vehicle testing. A 3dB gain is similar to doubling your effective amplifier power. The result is a very good bang-for-your-buck solution that improves sound quality and lowers road noise.

BeTTer Apply DynAmAt Xtreme to the outer Door skin

For a better treatment, apply Dynamat to the outer door skin in addition to the Dynamat Xtreme Door Kit applied to the inner door skin. For good results, we recommend at least 50% coverage. More coverage is better. Treating the outer door skin creates a complete solid enclosure for your door speaker. The “back panel” of your speaker enclosure is now as solid as the front baffle. Your midbass performance is now optimized. This solution completes the sonic barrier that blocks road noise from entering your vehicle.

BeSTADD DynAliner to the inner AnD outer Door skin

In addition to the other two steps, add a layer of Dynaliner to the outer door skin directly behind the speaker. This reduces the speaker back-wave noise and distortion and dramatically improves the speaker’s sound quality. You have now eliminated the hollow sound created by the speaker’s back-wave. Adding a layer of Dynaliner to the inner door skin eliminates the reflections (bouncing sound) between the inner door skin and the door panel. (We were able to fit 1/4-inch thick Dynaliner here. However, some vehicles can only accommodate 1/8-inch Dynaliner.) Dynaliner between the inner door skin and the door panel also decouples the door panel from the door, eliminating door panel buzzes.

Go to www.dynamat.com/tech for a detailed in-stallation of Dynamat and Dynaliner on these doors.

3. Installing Dynaliner on outer door skin

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Dynaliner on the inner door skin. Door is finished, ready for the panel to go back on.6

$49.95CODE 7 • CARB Listed

Sound conTrol

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4. Dynamat Xtreme Door Kit on inner door skin

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5. Cutting speaker hole out on Dynaliner

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here’S how To geT The BeST SoluTion from your dynamaT inSTall: 1. Stock door with no sound control. Look at all those holes and flimsy plastic! 2. Installing Dynamat on outer door skin. 3. Installing Dynaliner on outer door skin. 4. Dynamat Xtreme Door Kit on inner door skin. 5. Cutting speaker hole out of Dynaliner. 6. Dynaliner on the inner door skin all finished, ready for the trim panel to go back on.

recap!