How important is sound deadening

[CocaColaEatsPie]

I am getting CDT components in my doors, and I was just wondering if sound deadening is a necesity. How does it really work?

Thanks,
Nick

[sr20de4evr]

Yes it's a necessity, completely deadening your doors will easily make your speakers perform like ones that cost twice as much. When a speaker plays you get music coming off the front of the cone and the back of the cone, it's the exact same signal except 180 degrees out of phase. When this rear signal reflects off your door skin, it goes through all those holes in your door, and it interferes with the front signal. Since the signals are basically mirror images of each other, you get huge cancellation. Deadening the doors do 2 things
1) creates a soundproof baffle for the speaker, so the rear wave is isolated and can't interfere with the front wave. This doesn't generate extra midbass like some people think, it just reduces the cancellation, and makes it so that you can actually hear the midbass that your speakers were already producing
2) reinforces the panel that the speakers are mounted to, this isn't as important as #1, but it will decrease vibrations, resonance, and rattling

[CocaColaEatsPie]

What deadener would you recomend keep in mind that I'm 16 and while I have the money, I can't be putting it all in my car. I have college to save for and stuff, and my parents already get on my case for how much I spend on audio stuff. I have been looking at this http://www.raamaudio.com/products.htm on ebay its $79 for for 62.5 sqft that seems really good comapred to dynomat and stuff, I have heard good things about it in other forums.

[sr20de4evr]

I've also heard good things about raammat (sp?)

Other stuff to check out would be secondskin (I have this stuff, I love it although it is a bit more expensive, it's not tar based so it doesn't smell at all, it doesn't gum up your knife, and it's insanely sticky), brownbread, or b-quiet.

You should get about 30sqft for the front doors, that should do 2 layers on the outer door skin and 2 layers on the inner door skin (the part that the speaker is mounted to).

[CocaColaEatsPie]

How much will that crap weigh, Although I'm not racing my car at the drag strip, I'd like it to be quick and I might race someone here and there. Is this stuff really heavy or what? How much to do my trunk, I'll have two pyramid(crap, I know, I deal with what I have for the time being) 10's in there. If i could do it with 30 sqft, that'd be nice because then I could do the doors and trunk for $80. Do you think 30 sqft is enough, to atleast do the trunk lid. Also what's this about carpet padding, alot of people use that. I actually plan on buying some for when I build my sub box, I'll put it behind the vinyl to give it a better apperance. How much is that stuff and I have heard of people using it for deadening, what's that about? Thanks alot for all the help.

[sr20de4evr]

Sure it weighs a bit, but it's not noticeable. 60sqft might weigh 20lbs or so, compared to the weight of the gas in your gas tank, that's nothing. Just putting in an extra quarter of a tank of gas would make more of a difference than that.

30sqft would be enough to do your trunk lid easily, and maybe one layer on your trunk, but I'm not sure about that. Some people do use carpet padding for sound deadening, but it's for a completely different purpose than the mat style deadener. It's to absorb airborne sound, while the mat is to reduce vibrations. To effectively deaden your car you need both. I don't know what you mean by putting the carpet padding behind the vinyl, the way I'm imagining seems pretty odd.

I'm not sure exactly how much it is, I think you can get 50sqft for around $15 or so.

[CocaColaEatsPie]

Well I plan on building a box... and then putting it in the back of the trunk and then having a peice of wood go over the front of it to make it like flush mount with the wheel wells and I was going to just vinyl that peice of wood, but I thought it might be cool to put carpet padding in between the wood and vinyl to give it a 3D type effect kind of thing I guess. If it looks like crap I'll just take the padding out

[Navy I.C.]

Originally Posted by CocaColaEatsPie

How much will that crap weigh, Although I'm not racing my car at the drag strip, I'd like it to be quick and I might race someone here and there. Is this stuff really heavy or what? How much to do my trunk, I'll have two pyramid(crap, I know, I deal with what I have for the time being) 10's in there. If i could do it with 30 sqft, that'd be nice because then I could do the doors and trunk for $80. Do you think 30 sqft is enough, to atleast do the trunk lid. Also what's this about carpet padding, alot of people use that. I actually plan on buying some for when I build my sub box, I'll put it behind the vinyl to give it a better apperance. How much is that stuff and I have heard of people using it for deadening, what's that about? Thanks alot for all the help.

My trunk doesn't have any, (purpose built), deadening. I was mainly worried about having a vibrating trunk. I knew from all of the luxury cars that my friends and I have owned, that it doesn't take an excessive amount of deadening to achieve optimal results, so when my installers told me they just put a couple extra layers of padding and some plush carpeting even though I paid enough for the dynomat, I was still happy because the end results were the same....

bottom line, enough carpet and padding can work as well, (and can cost as much), but it's also more aesthetically pleasing for most applications. Take my trunk lid for example, looks alot better to me than the dynamat logo across the foil sheets...