The Damping Material and Sound Deadener Thread

[s0uljah]

Good stuff sam!!

Re: hair dryer let me tell you about what my friend did with his damping sheets... lol. Laid them out on his black car and left them out in the blazing sun for a while to get them gooey and pliable to work with. Turned out great it seems

[Sam Kapasi]

Originally Posted by Sam Kapasi

For a car like the verna, 3 sheets in minimum for the front 2 doors. It's a bit kanjoos actually. You need about 3.5 sheets.
For a car like a skoda, you would definitely need 4 sheets. But for small and mid sized cars, 3 sheets for the front doors.

Sorry sam, I don't agree with you. Just returned home after finishing the front doors and after damping the doors there was about 30% of the 3rd sheet left over, so I installed it on the upper half of the boot.
2.7 sheets good for a verna, I guess 3 sheets for a slightly larger car. Please don't make erroneous statements in the future. Foolish boy.

[shrivz]

I've self installed cross link foam (recommended by EVO6 as a cheap alternative to other damping materials) on my front doors and it does make a noticable difference. It costed me about Rs. 50 (i think) per 1 x 2 mtr sheet.

Honestly, I havent heard any car with a similar setup with damping, so can't really compare it with other products. But this has made a difference and my JBL components sound better..

@Sam: Thanks for the info about American Dynamic. Have started saving for it. Just hope it doesn't run out of stock by the time I've saved up enough cash.

cheers!
Shrivz..

[navin]

Originally Posted by Sam Kapasi

I guess 3 sheets for a slightly larger car..

For a Skoda one needs 4 sheets for the doors. 4 sheets for under the carpeting, and 4 sheets for the trunk so 12 sheets. A smaller car would require 8-10 sheets.

For 3 cars, Sam I would need about 30 sheets considering I already have some damping.

[Rtech]

What about the sound deadening stuff you get in a can which you just spray on? Anyone try it yet? How are the results?

[Bass&Trouble]

Originally Posted by Bass&Trouble

Sam, I've never heard of American Acoustics.

Originally Posted by Sam Kapasi

Neither had I! But I did see it on my various travels.

American Acoustics nathi, American Dynamics 6.

[Bass&Trouble]

Originally Posted by Rtech

What about the sound deadening stuff you get in a can which you just spray on? Anyone try it yet? How are the results?

There are two types of stuff you get in a can. One is underbody treatment which helps eliminate road noise, and the other is a liquid variety of the semi solid sound deadening mats.

[Rtech]

Is that liquid variety as effective as the sheets? And where is it available?

[navin]

Originally Posted by gunbir

Damping in the car audio context essentially means increasing the weight of plastic and metal panels .

I dont know how one of my earlier posts got lost but what gunbir says above is only PARTIALY accurate.

First lets not call this damping. Our object is to get all panels not to resonate. One can do this via damping, increasing mass or stiffening or all of the above (which is what I prefer).

Increasing mass has it's limitations. Increaseing mass might lower the resonanace frequency of the panel but it also increases the energy the panel can store. This energy is released over time and can lead to smear and other colorations.

Now one needs some mass so what one needs to do is
a) make sure the mass is needed. Mass for the sake of mass is nonsense. mass should be added if it adds stiffness or absrobs the back wave
b) stiffen the panels so that they do not flex and resonate like a drumskin
c) absorb the back wave so that the back panel does not have to deal with this this is what dynamat and it's cousins do.

The easiest (but messy) way to make a panel stiff is to use resin bonded fiberglass mat.

[navin]

Originally Posted by Bass&Trouble

American Acoustics nathi, American Dynamics 6.

American Acoustics used to make some nice rock speakers. Traditional boxes with a 12-15" woofer mated to a 4-6" mid etc...but they sounded nice.

[shrivz]

I recently visited my tyre-wallah to get a puncture fixed and spotted something interesting..
It was double side adhesive rubber sheet (no, its not a patch) the sheet was about 4mm thick and seemed similar to feel like the butyl rubber suspension on speakers. I've placed an order for 5kgs (yes, thats how they sell it).. It should be approximately a 9" x 300" roll and it costs Rs. 1050/-
I will be getting it on monday..

I also went on a hunt for Crosslink foam, as I realised that the foam I used in the door was poly foam and wasnt that effective.. I finally managed to track down one seller who all other shops recommended. F Gulam Ali in Bhoriali. He had just 5 sheets of one side adhesive crosslink foam 3mm thick, bargained a bit and picked up all five for Rs. 1000/-

Now I have 2 questions:

1. Should I use the rubber sheet below the foam, or foam below the rubber sheet?

2. How do I DIM (Do It Myself)? any inputs on this will be highly appreciated. Should I install it inside the whole doorframe and cover the side impact beams too, or just put it on the outer frame, thats where the door panel is mounted.

I will post pictures on monday evening, you guys would probably have a better idea with pics.

cheers!

[low_bass_makker]

Originally Posted by shrivz

I recently visited my tyre-wallah to get a puncture fixed and spotted something interesting..
It was double side adhesive rubber sheet (no, its not a patch) the sheet was about 4mm thick and seemed similar to feel like the butyl rubber suspension on speakers. I've placed an order for 5kgs (yes, thats how they sell it).. It should be approximately a 9" x 300" roll and it costs Rs. 1050/-
I will be getting it on monday..

I also went on a hunt for Crosslink foam, as I realised that the foam I used in the door was poly foam and wasnt that effective.. I finally managed to track down one seller who all other shops recommended. F Gulam Ali in Bhoriali. He had just 5 sheets of one side adhesive crosslink foam 3mm thick, bargained a bit and picked up all five for Rs. 1000/-

Now I have 2 questions:

1. Should I use the rubber sheet below the foam, or foam below the rubber sheet?

2. How do I DIM (Do It Myself)? any inputs on this will be highly appreciated. Should I install it inside the whole doorframe and cover the side impact beams too, or just put it on the outer frame, thats where the door panel is mounted.

I will post pictures on monday evening, you guys would probably have a better idea with pics.

cheers!

Shrivz the idea you thought is very good but some thing is missing here.....you have a rubber sheet that is good....but why do you need foam...........I would suggest this......take the rubber sheet as it is quite thin make it a two layer of it as it will give it some strength.....now put something on it so as it will get a bit heavy......like washer.....and then put another two layer of the sheet on to it....all this because the damping sheet has weight on it ....this is its purpose to increase weight of the panel which is vibrating.....the rubber (butyl) is used as it will get the shape of the panel easily......and the common stuff to increase the weight is lead, bitumens......are used......

[Bass&Trouble]

Originally Posted by shrivz

the sheet was about 4mm thick

4mm thick damping?

Originally Posted by low_bass_makker

take the rubber sheet as it is quite thin make it a two layer of it as it will give it some strength

8mm thick damping??

[shrivz]

@LBM: what is the disadvantage of using crosslink foam?

just to clear out any confusion:

I have two products.
1. Crosslink foam ~3-4mm thick (single side adhesive)


2. Rubber sheets 4mm thick (double side adesive)



I'm looking at pasting one on top of each other and insulating the front doors and boot.

My question: What would be the best option?

1. Use the rubber sheet as the bottom layer and paste the crosslink foam over it.

2. Use the crosslink foam as the bottom later and paste the rubber sheet over it.

The way I look at it, the rubber can give stiffness to the door, and crosslink foam is a sort of minor sound absorbant. Please correct me if i'm wrong.

@B&T: the total thickness of the damping used would be about 7-8mm.

[zenx]

Ok, probably totally OT, but can this/similar damping material be used for making the passenger section more soundproof wrt road and engine noise ? My OHCs 6 years old - just trying to get to 'current generation' NVH