Sound Deadening

Discussion in 'Modifications & DIY how-to' started by Matto357, Dec 29, 2010.

  1. Matto357

    Matto357 Crazyazn likes Naps Staff Member

    Ok, got a few questions.

    Who here has fully sound deadened their car? How much of a difference did it make in daily driving road and engine noise? I'm talking about covering the full car. Trunk, doors, floors etc.

    Second question, for those that have done a WRX. How much square footage do you need to do it?

    Think I've decided on using fatmat btw.
     
  2. AutoxSTi

    AutoxSTi Member

    I'm in the process of doing mine but doing at least 2 layers of it and some spray type inside the door area that I can't reach...I'm a bit retentive when it comes to audio...LOL! I've seen people use dynamat knockoff from lowes...definitely cheaper than dynamat, hushmat. Weight will help deaden the car. Makes a big difference in not only sound inside but keeping some sound from getting into the cabin. They always say you get close to 3db in sound increase.
     
  3. Alex

    Alex Community Founder Staff Member

    Wirelessly posted (Mozilla/5.0 (Linux; U; Android 2.1-update1; en-us; SCH-I500 Build/ECLAIR) AppleWebKit/530.17 (KHTML, like Gecko) Version/4.0 Mobile Safari/530.17)

    A few of us have done this and I'd like to add more but i cannot from the phone. Ill chime back in later.
     
  4. Strayen

    Strayen Active Member

    I am interested in this as well. I need to tighten up some bolts which I think are causing excess noise and then tackle some sound deadening issues with mats and spray stuff.
     
  5. b reel

    b reel Active Member

    Bose noise canceling headset
     
  6. Alex

    Alex Community Founder Staff Member

    I love mine :)

    I used RAAMAT in my car. I don't recall how many sq footage I purchased, just that the box weighed about 21 lbs. It was plenty to do key areas of the floor, both front doors and the rear fenders. I also put three layers on top of the flat portion of the trunk directly above the exhaust. In addition to the RAAMAT I used a layer of peel-and-stick ensolite. There was a substantial improvement inside the cabin; a healthy amount of ambient noise was cut down. Definitely worth a weekend project.

    A great place to gain in general noise reduction is beneath the rear seat and separating the cabin from the trunk via the rear bulkhead.
     
  7. 5spdfrk

    5spdfrk Active Member

    Haven't used this stuff personally, but it seems like a good concept, plus it can get in places where you can't lay mat. It's thinner too.
    http://www.lizardskin.com/
     
  8. slade1274

    slade1274 Member

    Take some time and read this website as Don has great info for those looking to do things right. He started years ago by independently testing various products but got into sourcing his own line sometime in the last couple years.

    http://www.sounddeadenershowdown.com

    Basically, there are two things you need to account for; panel resonance and sound blocking. Each issue has a correct product that is more effective. Large flat metal panels such as doors, fenders, roof can actually resonate and act like a transducer by creating sound. A 25% coverage of a CLD tile (Rammat, Fatmat, Dynamat, SDS, SecondSkin) in the center of said flat panel will eliminate that resonance. From there you can continue to add the costly CLD material to effectively build up mass to "block" the sound or use a product specifically for it; such as Mass Loaded Vinyl. The vinyl works best when decoupled from the surface with a felt liner or closed cell foam. I just did some MLV work under the rear seat, center pass through, and rear deck for member seeingred; maybe he can comment on how effective that treatment alone was to reduce road noise.
     
  9. Alex

    Alex Community Founder Staff Member

    Did you apply the MLV to the OEM sound deadener piece on the rear bulkhead or did you build a new foundation, eg MDF layer -> CCF -> MLV?
     
  10. slade1274

    slade1274 Member

    I did not add to the rear bulkhead MLV, just pulled out the pass through and added a sheet to that area to complete the full rear treatment. I think the most critical aspect of the blocking I did was on the rear deck. I fully covered it to block all the holes that allow sound up from the trunk (wanted to say boot as I've been watching too much TopGear lately) and tucked under the stock bulkhead MLV for full coverage.

    The stock MLV is probably 1lb/sq ft and the stuff I use is 2lb, so there may have been some additional benefit; but when you account for the mass of the seat back itself it would have been in the realm of diminished returns and not worth the cost and impact on fit/finish to use the thick/semi-rigid aftermarket MLV.
     
  11. seeingred

    seeingred Member

    Wow..

    The stuff works great! I have what most folks think is one of the quieter turboback's but it is still audible from the cabin (Maddad whisper). Before Slade installed the stuff, I would have to turn the music up to about 13-14 on the stock headunit to hear stuff and if the window was open, forget it. Slade installed some of the mass loaded vinyl and you can barely hear the exhaust if the radio is on now (even at a low volume). Since this was just installed a few days ago and I have not driven much, I have not had a chance to test without radio, etc. But will let you all know.
     
  12. Alex

    Alex Community Founder Staff Member

    Definitely. I ran short on my CDL to do the rear-deck but that's one area that people claim to lose the most to. I was going to back and re-visit it but its all a bit moot now that I want to part the car out :)
     
  13. slade1274

    slade1274 Member

    Not CLD on the rear deck... MLV to block the sound from coming up through the holes.
     
  14. BKiller

    BKiller Active Member


    Great reading on that website.
    So where can you get MLV locally?
     
  15. Alex

    Alex Community Founder Staff Member

    I'm not sure if you can. I think Slade has some extra that he'd be happy to sell ya.
     
  16. slade1274

    slade1274 Member

    I don't have a ton left.... maybe enough to do one more sedan.

    I bought a roll of it that shipped in from Charlotte, NC when I overdid my GR.
     
  17. C_wagginz

    C_wagginz Member

    Soo I've been looking at doing this pretty soon. I'm looking to do the doors, floor pans, and rear hatch (primary focus) of the wagon.

    I've read http://www.sounddeadenershowdown.com/ and used his specs/ideas to compare to RAAMmat and Second Skin. I've also read up on other sources what is suggested to do and "who" to use.

    I'm currently stuck between getting the RAAMmat that's on special (89.96/37.5sqft with Ensolite to top it) and Second Skin (Damplifier and Luxury Liner)....I've also been toying with getting some of the materials from the above website, as his specs seem better, and price per sqft is sometimes better (wonder if he'd do a group buy...hmmm...).

    Based on what I've read among all that I've read ideally you would have minimum different 3 layers:

    1. CLD Tile in the center of a panel, covering ~25%.
    2. A layer of CCF covering all the area that you want to block the sound coming through.
    3. MLV over the CCF to cover all the area you want to "sound proof".

    Quoting from slade127:
    So I understand the 25% portion. That makes complete sense. I also mostly understand the "decoupling" with a liner or CCF.

    But I'm still fuzzy on somethings.

    Is it better to do just 25% CLD and cover it with the CCF with MLV...OR just do the whole surfaces in CLD and top it with a CCF.

    Could you do a 25% CLD treatment and top it only with a CCF and still see good results?

    Could you use more CLD on top of the CCF instead of MLV?

    Does the inside of a door panel really allow you to stack up 1/4"-3/8" worth of rubber and foam?

    I'm sure that doing all 3 steps, and (when necessary) multiple layers of these will provide the best sound, but is the practical way to address the problem? Wouldn't a full layer (or 2 or 3), topped with a CCF (the method that Alex went with) provide just a good results?

    Do you have to "float" MLV?

    Are there different "types" of MLV that would be less/more rigid?

    Is there any other product that is easier to use that would work the same as MLV?

    Could I get away with just using 25% CLD?

    I'm curious to do it correctly the best I can and in the most affordable, sensible manner. Any guidance, insight, opinions, stories, experiences, materials, etc. are welcome and wanted.
     
  18. Mad Mallard

    Mad Mallard the mad mallard

    from my understanding, butyl used to suppress mechanical resonance does so by converting vibration energy to heat. Its not blocking or reflecting sound waves at a level that matters in most cases; thats not its job.

    And afaik, closed cell foam by itself isn't nearly as effective as using it as a de-coupler and then covering it with a vinyl tile. The CCF acts as a dispersant (which is important as it scatters the sound wave and lowers how loud its perceived even if there's still the same sonic energy), and the soundwaves are dampened by the mass in the vinyl tile.

    The reason to decouple and not just use the mass tile is the tile is not as good at dealing with mechanical resonance from other things its touching.

    ----

    if you're trying to do a minimal job, I'd first drive around in various places and identify actual noise sources getting into the car; where road & tire noise gets in, where wind noise gets in, ambient sounds get in, etc.

    then I'd go with identifying the most potentially resonant surfaces; roof, wheel wells floor, outer door body, trunk & lid, hood, spare well, firewall. Decide which ones you're willing to uncover completely to apply butyl sheet to first.

    compare the 2 lists of locations, and focus your attentions on places that show up in both lists.
    --------

    (imo, when doors are concerned, I would use more than 25% coverage and focus it around the speakers. The speaker is the transducer making the noise/music you want to hear, so you want to kill as much resonance around it as you can.)
     
  19. slade1274

    slade1274 Member

    ^ Great advice.

    CCF does nothing for sound insulation/blocking; it is merely to float the blocking layer. It is also used to cushion two surfaces that can vibrate against each other.

    In order to block sound you need MASS... and the loaded vinyl at 1-2lb per sq foot is an effective way. It takes many layers of CLD to achieve that density; and it gets costly. The other product I recommend is Cascade VB3; but it is costly as well.

    http://www.cascadeaudio.com/car_noise_control/car_barriers.htm

    you can make your own with some spray adhesive, two sheets of CCF and a sheet of lead.
    http://www.rotometals.com/Lead-Sheet-s/31.htm?gclid=CK7b9KSf9KQCFRBl7AodyX6xZg
     
  20. WRboXer

    WRboXer Active Member

    Great reading.

    Question:
    -If you wanted the best bang for buck, what single material would you use and in what specific locations?

    I am trying to isolate the biggest problem areas, and try to avoid to much weight.

    For anyone who sits in my rear seat, they cant hear a damn thing you are saying up front. My catback is also funky, its more quiet then my Borla Hush outside the car, yet is louder inside the cabin then the Borla.
     
  21. slade1274

    slade1274 Member

    Bang for buck.... depends on the problem. It sounds like your current exhaust is hitting the right note to find the natural frequency of something on the car causing it to resonate- or the right note is at the right wavelength to bounce off and back into the cabin with the largest amplitude. Each situation has it's correct solution.... if something is resonating you need to find what is and kill it with a CLD tile. If it is sound reflecting into the cabin at a given wavelength- you could try moving the source, finding and changing the reflecting surface, or block said sound with MLV decoupled from the structure with CCF. Most likely treatment under the rear deck trim piece with some CCF/MLV will do wonders.

    The all in one products are:
    http://www.cascadeaudio.com/automotive_audio_enhancement/car_noise_control_barriers.htm
    http://www.secondskinaudio.com/noise-barrier/Luxury-Liner-Pro.php?category=122
     
  22. Mad Mallard

    Mad Mallard the mad mallard

    ^^^ specifically, if its mechanical resonance, I'd pull out the seats and rear carpet, and then find the closets "mounting points" of the exhaust where they meet with the floor. Apply mat to that area and check results.

    (i know the exaust doesn't directly connect to the floor, but if its mechanical resonance, then you should play a game of 'knee-bone connected to the thigh-bone' to figure out how the mechanical resonance is travelling.)

    If it makes no difference, then its probably the sound waves making the panel resonate thru the air pressure.
     
  23. WRboXer

    WRboXer Active Member

    Panel resonating through air pressure sounds like it may be the most accurate. Kind of sounds like when one window is down and its making the buffeting effect. I think i am going to start with CLD on the trunk floor, rear deck, rear seat bottom, rear footwells, and doors(if anything to help keep some noise out and make the speakers sound alittle better.
     

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