Hi all, quite new to all of this really.

I'm not looking to improve the quality of the music with speacilist sheets that sit around the speakers, but more block out road and tyre noise.

In between the door cards and the cars shell, there's about 5 inches of empty space, with a tiny block of foam going from the shell to the door cards by the speakers (presumably to stop vibrations). I was wondering, if I used something like loft insulation (normally cheaper than car stuff) to fill the gaps, would that make much of a difference to the sound levels, or would it be worth spending to extra money in order to buy something speacilist.

Thanks,

Joe.

Dynamat and similar products are thermoacoustic. In other words, they absorb sound and turn it into heat. However, they are most effective at low frequencies and by helping to "mass load" the panel they are attached to. This lowers the resonant frequency of sad surface and prevents it from continuing to vibrate when sound waves of certain frequencies hit it.

For example:

Let's say that a doors normal resonant frequency is 100hz (totally making it up, I have no idea). The mid driver in your door produces a bass sound at 100hz, so a kick drum or bass guitar or something. That 100hz wave hits your door and the whole panel resonates. I.e. the door continues to vibrate at that frequency (like a piano tuning fork). This makes for rattly and vibrational noises which aren't the music you're trying to listen to, it ruins your mid-bass sound and in the case of door cards, creates that awful farting sound which people often mistake for distortion.

So, in short, foam may absorb some road and tyre noise, depending on how it's used. A lot of professional installers use foam to fill cavities in certain places. I've experimented with it in the past. However, mass loading panels which come into contact with the most noise will be far more effective as a starting point. Always start with the panels which have the speakers in them. Then work on from there. If you do a bit at a time, the beauty of Dynamat will be revealed. The more you do, the more you can hear the next problem area and whether it's enough to be worth doing for you.

Hope that makes sense...

Thanks for that, lot of useful stuff there.

So in sort, Dynamat etc lower the resonant frequency to a point where it's lower than the speakers range. So if the speaker can go to 95hz, the matting takes the panel to around 50hz (or whatever)?

Hypotheticly, could you use something like bendy MDF to do the same thing, help change the frequency and stop the vibration? (Don't intend on doing this! Just trying to gain an understanding.)

So if I line the innermost parts of the car, rather than the gaps, I should see the most benefit?

Thanks again.

Yeah, that's basically it. It stops the door (in that example) from resonating with every single bass note or kick drum! Which is obviously gonna improve your sound a lot! You'll get the most bang for your buck by covering the majority of thin, prone to vibration panels. Don't worry too much about 100% coverage, just a nice big single slab for most of the panel will make a significant difference. When starting out, the main things to do are the door skins and door cards. Like I said, you can always listen for rattles/vibrations and add more as you go.

Fantasic, thanks.

Will see what I can get my hands on, and have a go.

It's not only keep away noise but also increase the power of your speakers.

Check StP & Dynamat products as both companies have sound laboratories.

There is plenty imitators on the market.

Don't buy products based on the bitumen (asphalt) basis. It may cause headeaches are not easy to install and may slide in hot days

I've got a feeler for a group buy in the group buy section of the forum if you're interested.

Thanks to both of you.

I've put a provisional reply in the Group but topic - cheers.