# How can this possibly work? Sound Deadener



## pionkej (Feb 29, 2008)

Automotive Insulation heat barrier and noise reduction for cars, trucks, classic cars, street rods and much more

I bought some of this stuff a while back to use in my truck, and it worked wonders. Where I used to have a noisy and miserable truck, with engine/transmission/driveshaft/differential/big tire noise, now all I really hear is wind noise (I drive a '89 Nissan p/u which is basically a block).

I would say it cut the noise down by 60-75%.

The reason I ask, how could it work, is because after installing this stuff, all the threads I have read say you need a decoupler and mass. This stuff weighs nothing. I am on the fence about buying some again for my 300zx build but was kind of looking for some input on how this could work based on what I have read here as far as noise barriers go.

And if you say it's physchoacoustics, maybe, but I don't think so, and there is a link on the site that shows the 5db reduction a guy realized. And if you think that is fluff, go to THE H.A.M.B forum and he asked people for honest opinions of the stuff before marketing it as having heat reducing or sound deading properties and they seem to swear by it too.


----------



## 240sxguy (May 28, 2009)

Looks to me like it would soak up road noise nicely, I would love something like this on my firewall and floor to keep some heat out.


----------



## pionkej (Feb 29, 2008)

Yeah, I didn't really notice a difference on ambient heat in my truck, but I don't have much radiating heat on it. I can't say much there, but it definately "soaked up" the noise. I am just confused how, because everything I have read says: decoupler+mass loading=sound blocking.

Also, my bro has a 240sx with the "disco potato". His car and mine are two totally different beasts too. His is: nothing, nothing, nothing.....nothing....snap your neck, where mine behaves much more linear like a N/A car with the two smaller turbos. However, at the end of the line, they are about the same, just two different ways of getting there.


----------



## 240sxguy (May 28, 2009)

Yeah big difference with that increased displacement you have. 

I suspect mass loading would improve the deadning, but that doesn't mean that decoupling isn't helping!


----------



## mda185 (Dec 14, 2006)

The foam core sandwiched between two layers of foil works because the foil is acting as a sound barrier and the foam absorbs sound that gets through the foil layer. Mass loaded barriers would work even better but be thicker and heavier. I do remember reading something about 6 years ago in an SAE paper that said the combination of foam and sound barrier works better than the simple sum of sound transmission loss (STL) ratings for the barrier or the foam alone. I do not remember the science behind it. Your experience would appear to prove the theory.


----------



## Catman (Mar 18, 2008)

That looks like Reflectix ...available at Home Depot / Lowe's. They are just using foam in the middle. I've been using Reflectix for years under the carpet in many vehicles. I have found that one layer of "Dynamat Alternative" and a layer of Reflectix are better than 2 layers of "Dynamat Alternative".

>^..^<


----------



## 89grand (Nov 23, 2006)

I bet you guys would buy it if it said "the right name" on it.


----------



## vellocet (Nov 14, 2008)

I think I'll try that on my 300zx build as well (2+2, a tt was out of my budget) ontop of "popular dynamat alternative" #3. I know most of the road noise will be from the ttop and hatch, but it's not That much area to cover.


----------



## pionkej (Feb 29, 2008)

I was reading some old posts ofrom foxpro5 while I submitted this thread. Turns out that a good ccf and mlv like those found on sounddeadenershowdown.com can reduce noise by 12-18db. This product reduced it by 5db. So while this works, it still does not work as well as other options for a decoupler/barrier. 

I think I may use what I have left from my truck on my roof, hood, firewall, and hatch area since these are all tight area's and some sound reduction is better than none. I will use a 1/4" ccf and then mlv on top of it anywhere else I can (even the places mentioned above if I can get it to fit). Make sure if you do anything like this, you seal all the seams with vinyl glue or some aluminum/butyl tape (aka sound deadener).


----------



## FoxPro5 (Feb 14, 2006)

Looks to be a pretty good thermal product as pretty much everyone knows how well even thin aluminum can do for heat blocking. 

CCF is also a good thermal product. So you put the two together and they both benefit each other.

When you talk about transmission loss/blocking, you're talking about an actual elimination of sound/noise across something (a wall, metal, glass, etc). There is no such thing as a broadband blocker, so you always have to look at the frequency in question. To say foam and aluminum foil is an "excellent sound deadener" without talking about which sound they're referring to is misleading (probably on purpose.) 

When they claim 5 dB loss without a reference, then you have to wonder. You can get a 5 dB loss at 10khz with a piece of paper just due to simple refraction or diffusion of that tiny wave.

To block large, high energy sound waves you need mass. That is a fact. As it has been stated on this forum many times, "road noise" is typically centered within an octave or two of about 125 hz....so that's like 75 to 500 hz. Study any STC data on any materials that make good blockers (MLV, lead, rubber) and you'll see something interesting happen at around 500 hz on all of them. 

Anything that weighs 1 lb/sqft is good for ~12 dB transmission loss at about 500 hz. Bricks or feathers, doesn't matter. Mass Law right there for you. How much does this stuff weigh? Nothing? Big clue #1.

Also, CCF makes a good decoupler as it's typically not very compressible and is almost all air. You don't want your barrier to vibrate, that would be very bad. Think about what you're doing when you pull your interior and add a decoupler and put it back in. Are you not creating a decoupled barrier by floating your carpet? Carpet has mass and somewhat of an absorptive matrix to snag some of that sound. Bottom line: don't get fooled by junk science and anecdote.


----------



## pionkej (Feb 29, 2008)

FoxPro5 said:


> Looks to be a pretty good thermal product as pretty much everyone knows how well even thin aluminum can do for heat blocking.
> 
> CCF is also a good thermal product. So you put the two together and they both benefit each other.
> 
> ...


Thanks for the info. That was basically what I gathered from reading your other posts after posting this one. I had one question though. As far as the ccf being a decoupler between the cld and the mlv. Does it matter if it is an 1/8" or a 1/4" since it is just helping absorb the refracted sound from the mlv? Is an 1/8" junk? Is 1/8" fine but 1/4" better? Does it really matter? Will 1/8" be fine since I already have a layer of ensolite down? 

Thanks for any light you can shed on this!


----------



## ANT (Oct 15, 2005)

We have a roll of this product in the warehouse. A customer brought some in to compare against our line of sound deadening. When he left, he bought a bunch of material and told us to keep the lobucrod.
The closed cell foam the speak of is actually bubble wrap.
They sell the same exact material in my local Ace hardware store as a water heater insulation.
TIFWIW


ANT


----------



## vactor (Oct 27, 2005)

89grand said:


> I bet you guys would buy it if it said "the right name" on it.


"Richard Clark"???










:mickey::rimshot:


----------



## Oliver (Jun 25, 2007)

DIYMA said:


> We have a roll of this product in the warehouse. A customer brought some in to compare against our line of sound deadening. When he left, he bought a bunch of material and told us to keep the lobucrod.
> The closed cell foam the speak of is actually bubble wrap.
> They sell the same exact material in my local Ace hardware store as a water heater insulation.
> TIFWIW
> ...


**** . . i just put ss pro on my hot water heater


----------



## Rudeboy (Oct 16, 2005)

pionkej said:


> Thanks for the info. That was basically what I gathered from reading your other posts after posting this one. I had one question though. As far as the ccf being a decoupler between the cld and the mlv. Does it matter if it is an 1/8" or a 1/4" since it is just helping absorb the refracted sound from the mlv? Is an 1/8" junk? Is 1/8" fine but 1/4" better? Does it really matter? Will 1/8" be fine since I already have a layer of ensolite down?
> 
> Thanks for any light you can shed on this!


You're getting to the complexity of configuring a barrier for use in the tight spaces available in a car. If the whole decoupling thing was just a question of getting some air space between the substrate and the barrier we'd be screwed because there just isn't enough room to get the barrier far enough away. 

Still, every test I've done shows better results with CCF than without. There are several reasons for this. When the substrate is well damped, I can't tell the difference between substrate/CCF/MLV and substrate/MLV/CCF. The CCF is contributing some high frequency attenuation no matter what else is going on. With an undamped or poorly damped substrate, particularly on a horizontal surface, substrate/CCF/MLV helps damp the substrate and the CCF gets rid of resonance transmission at the substrate/MLV boundary eliminating the problem Fox was addressing. Unless there are good reasons for doing otherwise, substrate/CCF/MLV has the best change of getting the best results.

One of the factors that comes into play is the number and variety of boundaries sound encounters on its way to pissing us off. The greater the number of and the greater the density difference between adjacent layers the better, but the thicker the layers the lower the frequency of the sound that will be affected. Looking at it this way, 1/8" CCF can't do much in the audible range. 1/4" moves us into the top end of the audible range. 1/8" WILL still help with panel damping and barrier decoupling. These thicknesses are cumulative - if you stack up 3 different 1/8" mostly air layers they will behave pretty much like 1 3/8" mostly air layer. Since the are pretty much homogeneous (mostly air) you aren't really introducing any meaningful boundary complexity between the layers.

Back to the original question - How can this stuff work? No question it will help with thermal insulation. By itself it will probably help a little bit with noise, but there is almost always something else going on with these before and after evaluations. I just read an article where a guy claimed that roofing felt was very effective as a low cost alternative to MLV in walls in building construction. First he hung drywall and evaluated the sound transmission through the structure. Then he stapled roofing felt between the studs AND heavily caulked every gap in the wall. After was better than before. I'd be willing to bet that after with the caulking and without the felt would be 90% or more as good as after with the felt. Applying a bubble wrap/foil composite (or just about anything like it) is going to at least partially close off many of the previously existing openings through which diffraction will occur.


----------



## 89grand (Nov 23, 2006)

vactor said:


> "Richard Clark"???
> 
> 
> 
> ...


Oh yeah, that name too.:laugh:


----------



## pionkej (Feb 29, 2008)

Rudeboy said:


> One of the factors that comes into play is the number and variety of boundaries sound encounters on its way to pissing us off. The greater the number of and the greater the density difference between adjacent layers the better, but the thicker the layers the lower the frequency of the sound that will be affected. Looking at it this way, 1/8" CCF can't do much in the audible range. 1/4" moves us into the top end of the audible range. 1/8" WILL still help with panel damping and barrier decoupling. These thicknesses are cumulative - if you stack up 3 different 1/8" mostly air layers they will behave pretty much like 1 3/8" mostly air layer. Since the are pretty much homogeneous (mostly air) you aren't really introducing any meaningful boundary complexity between the layers.


I get what you are saying here. The cff is both a decoupler, and depending on the thickness, a sound barrier as well. The problem with the latter is that 1/8" thick is only good for frequencies outside the audible range and the 1/4" is only good for the higher frequencies which are not what usually plague us inside the car (70-500hz). From everything I have read, you are getting into foam several inches thick before it begins to touch this frequency range, which is where the mlv comes in handy above the layer of ccf.

Regardless, it is like you said that the thicker you can get it, the better, so I plan to check and get 1/4" where I can and 1/8" everywhere else with some (most likely mlv) 1lb. per cu/ft material on top.

Also, is there any merit to putting foam everywhere I can behind the dash and behind panels. From what I have read, it is actually better to use ocf instead of ccf in this situation. I plan to just put it on top of these layers mentioned above to help cut down on resonances (panel to panel, wires behind the dash, etc.). Is this step worth the time and money?


----------



## Rudeboy (Oct 16, 2005)

OCF absorbs better and that goes for sound, moisture and odors.


----------



## pionkej (Feb 29, 2008)

Rudeboy said:


> OCF absorbs better and that goes for sound, moisture and odors.


Yeah, I would put ccf and mlv around everything. I was just talking about stuffing it in open panel areas that are not that hard to get to should it start to go south on me. My rear hatch area has large openings that could have it stuffed and removed fairly easily. I may go with something like memory foam or a ccf behind the dash, thought it won't absorb sound as well, it won't absorb the other stuff either, and it is a pain to remove.

Any comments on using two component foam to fill the chassis? I know it reduces resonance that can carry through hollow areas in the sandwich panels and chassis, but is it worth the effort and money ($$$) if I plan to do ccf and mlv over the entire floor area from the firewall to the hatch? It is expensive to buy the stuff that will work properly (i.e. not Great Stuff foam). 

Here is the cheapest I have found it: Acoustical Foam > Products (look at P10650 and I would need 2-3 bottles)


----------



## Rudeboy (Oct 16, 2005)

I can't really say how much benefit there is to any sort of expanding form. I've used them in a variety of applications but the more I do this the more I prefer irreversible alterations.


----------



## FoxPro5 (Feb 14, 2006)

pionkej said:


> but is it worth the effort and money ($$$) if I plan to do ccf and mlv over the entire floor area from the firewall to the hatch?


Nope


----------



## pionkej (Feb 29, 2008)

Rudeboy said:


> I can't really say how much benefit there is to any sort of expanding form. I've used them in a variety of applications but the more I do this the more I prefer irreversible alterations.





FoxPro5 said:


> Nope


Thanks, saves me $100-$150 and allows me to spend more money on ccf & mlv. I appreciate both of your help as it seems you give honest/unbiased opinions, even though you could be (or could have in the past in fox's case) trying to sell me everything under the sun. I mean, I haven't seen one prop yet from Don for his products, just what does or doesn't work. In return, I know where I WILL be spending my money in the next couple weeks. Thanks again guys!

I also figure I get some "good student" points for asking questions, listening, and moving forward right? None of that, "thanks for the help...but I'm going to do my idea anyway even though you said it won't work because reasons x-y-z."


----------



## Oppenheimer (Jun 22, 2009)

Hey guys, I don't want to hijack the thread but its somewhat on topic and if pionkej is going to be installing MLV in the near future he may have the same issues as I am.

I'm currently installing CCF + MLV in my car... I had a HELL of a time with the spare tire area / wheel wells (hatchback). CCF is pretty easy because its stretchy and moldable, MLV is... well, the opposite. Obviously the hatch area is a major source of noise in my car, so I really did my best back there but before I seal everything back up I figured I ought to make sure I didn't miss something technique-wise. I definitely underestimated how tricky it would be to cover the weird angles on the floor.

Basically I had the best success cutting the MLV into strips of varying width, cutting them to whatever length I needed, and overlapped the sections by a little bit (maybe 1/4 inch or so) and taping the seams with foil tape. I'm sure it would be better to glue or epoxy the sections together (maybe put something down over the seams after everything is laid?), but I don't really know HOW much better. Over the wheel wells the MLV is 3 layers thick, so strips or not I think it should at least help. I hope so anyway as it was a TON of work (I was in the garage literally all weekend, my back KILLS haha). I used the largest pieces of MLV possible, depending on location, and as these things seem to work (this is my first install) I'm much better now at laying the stuff now than I was at the beginning.

Basically what I'm asking is, is my experience typical or did I just completely miss something? Thanks...


----------



## Rudeboy (Oct 16, 2005)

I've never found it too difficult to do. slitting and overlapping are your friends. For a wheel well I cut out a piece to fully cover the half moon shaped perpendicular surface then cut one for the top of the arch that is an inch or so wider than the arch itself. Cut slits in the overlap, fold them down and bond in place. I prefer vinyl cement for this work, but tape can work too. A hate to ask at this late stage, but did you test the bond strength of the tape you used on the vinyl? Hope it was an acrylic adhesive. Vinyl is tricky stuff when it comes to adhesives.


----------



## Oppenheimer (Jun 22, 2009)

Hey Don, thanks for the response... the tape is just the foil tape that SecondSkin sells, its very thin but surprisingly strong. It seems to bond to the vinyl well enough, though I didn't perform any specific tests. Really I had more trouble with the tape tearing than anything else, and that really only happened when I was trying to make the MLV do something it didn't want to.

The wheel wells gave me specific trouble because there are seatbelt assemblies on top of them. I suppose I could go back and remove them / install another layer / reinstall them but the assembly takes up most of the top of the wheel well anyway (for it to reinstall properly its going to have to sit flush with the metal in a relatively large area). As it is I tried to be meticulous and get vinyl in everywhere I could... I guess we'll see how it goes. The method you describe actually sounds sort of similar to what I did, half moon / over the top, then I followed up with a layer of vertical strips, then a layer of horizontal strips (wrapping the well). It'd be interesting to do a test on each wheel well because the second one definitely went better than the first (practice).

I tried to minimize the number of seams as much as possible, thinking it probably doesn't take a very large opening to let through a lot of sound. I just wanted to make sure that I wasn't doing something that really wasn't going to work... its reassuring to hear that I'm probably ok. Looking back, I probably should have started in the front and worked backward, as the under-seat / rear seat area was much easier than the trunk (was able to use bigger pieces of vinyl).

Thanks again, hope to post a build thread in a week or two


----------



## Rudeboy (Oct 16, 2005)

I'm sure that tape is fine. I tested a bunch of hardware store duct and foil tapes and was pretty discouraged when most of them just slid off the vinyl after a few hours.

As long as you have overlaps that are taped down, you should be more than fine.


----------



## Oppenheimer (Jun 22, 2009)

Sweet, thank you. BTW your website was a HUGE help, so thanks for that as well... a few weeks ago I didn't know anything about any of this and now I feel like I have a decent understanding of the basics of sound control.


----------



## Rudeboy (Oct 16, 2005)

Oppenheimer said:


> Sweet, thank you. BTW your website was a HUGE help, so thanks for that as well... a few weeks ago I didn't know anything about any of this and now I feel like I have a decent understanding of the basics of sound control.


:thumbsup:


----------

