Sound dampening questions

[Krakin]

I used some real cheap sound deadener. its called peel and seal from Lowes, its like $16 for a roll that's 6" by 25'. its not the absolute best but for its price cant beat it.

Or you can keep that horrible stuff on the roof of your house where it belongs.

It takes 5 layers of Peal & Seal to come close to one layer of CLD

This is a response to the thread Is there a big difference from dynomat to something like peel n' seal?.

So I took some time and ran some products through a fairly simple vibration test.

First off how the tests were handled.

The tests took place in my well insulated and heated CNC shack. It was a constant 75°-78° degrees the whole time.

I began with a brand new 12" x 24" sheet of 22 gauge steel.

I then laid out where everything would be applied for the testing.

The sheet is split in half to provide some distance between the vibration source and the equipment that will record/pickup the vibrations.

The bottom half is the testing area.

A 6" square smack dab in the middle is where the CLD product will be placed to simulate 25% coverage.

The Peel & Seal product will be placed over the entire bottom half of the sheet metal to simulate 100% coverage.

Location for the transducer that will provide the vibrations for the test.

A better shot of the "testing area" where the products will be applied.

On the backside of the testing area is where the pickup (in this case a highly sensitive accelerometer) will be placed.

I then mounted the whole shebang to my 8 0/20 built table.

Now onto the testing!

With the transducer mounted to the panel, an audio signal was then fed into it, thus causing the panel to vibrate. I used the 20Hz to 250Hz Sine Sweep from Realm of Excursion. I ran the test a total of three times and took the average of the three and used that as my baseline. Here is the graph for the baseline.

The pink horizontal lines represent the highest peaks.

U-Seal/Peel & Seal

Once the baseline was set, I started off with the U-Seal and covered the whole bottom portion of the panel. I left a little bit of space around the edge for easier removal. With a typical install this would be classified as 100% coverage.

I then repeated the same testing procedure, took the average of the three tests and that became the 100% U-Seal results.

Blue = the bare metal baseline.

Red = the U-Seal run.

The pink line represents the peak while testing 100% U-Seal coverage.

So to make things fair, I also ran U-Seal @ 25% coverage.

And the results of that after three runs and taking the average.

FatMat XXX

After several minutes of scrubbing the panel and getting all of the crap off (the most enjoyable part of testing... : ), I applied some FatMat XXX to the panel, 25% coverage.

Three runs and taking the average.

CLD

Next up was the CLD. Once again the joys of cleaning off this stuff set in...

Once clean, I applied the CLD.

I went with a well known product hovering around the $3-$3.50 price point. I will not disclose which one I used (I don't want to get sued by any company), but it measures around 1.8-2 mm thick and has a foil thicker than 4 mils.

Once again, ran the same three tests and took the average.

I am not going to comment on how each product did but simply post the data I collected and you can make up your own decision.

Also to make comparing everything easier, here are the peaks of all of the products laid over the baseline.

And here is the 100% U-Seal overlaid with the 25% CLD:

So I hope everyone appreciates the time, effort, and money involved with doing this and hopefully this will help put to rest (or at least lessen) the idea of using Peel & Seal as sound deadener.

And as always, if you have any questions about any of this, just ask.

CLICK HERE FOR PART 2 - two layers of U-Seal vs. 25% coverage with a CLD

CLICK HERE FOR PART 3 - 100% coverage with a CLD vs. 100% coverage of U-Seal vs. 25% coverage with a CLD

[BassInMyBLood]

well it worked for me and what's CLD? what does it stand for and how much for how much?

[Agreene]

I don't know what its called I guess your trunk door, but if possible spray the inside of your trunk door then seal it off with deadner and that work very well for me when I fired rear.

[pioneerforlife]

The best option is to fire forward and completely seal off as stated above. Also the reason it doesn't sound as loud is because you don't have all the rattles adding to the noise. The same thing happened to me when I first deadened my car but the quality of the bass was so much better.

[Krakin]

well it worked for me and what's CLD? what does it stand for and how much for how much?

You say it works but it doesn't.. It doesn't do what you think it does..

CLD is Constrain layer Vibration Dampening.

Now let's talk about what it takes to absorb a frequency, it takes a minimum of 1/4th the wavelength of whatever frequency you are targeting to absorb it. That can be extremely hard to do in a car audio environment. Thus was born CLD, CLD is an acoustical dampening material, while adding Peal and Seal is only mass. The idea of dampening is to eliminate the resonance of your car panels, doors, ect.. If you only add mass to them then all your doing is changing what tone it resonates at. You wouldn't go gluing rocks to the inside of your doors now would you? Adding Peal & Seal is doing the exact same thing. There are a few places that an absorbent can be used effectively. Between the roof, the headliner, hollow trim, and empty panels. Don't compress the absorbent though, as it will degrade the effectiveness of the material.

A great acoustical absorbent is 3m Thinsulate, it is an amazing decoupler and very effective thermal insulator.

Next we have the topic of 100% coverage, the automotive aftermarket is the only market that has embraced multiple layers of vibration dampening over a 100% coverage area. Adding too much of anything starts to build a barrier, vibration dampening make a poor barrier. It becomes directly coupled to the substrate and isn't dense enough to add sufficient mass whether it be one layer, two layers, or four layers. When you do excessive coverage of a vehicle it makes body work extremely difficult. If you ever have to remove a barrier of vibration dampening from a vehicle it will be destroyed in doing so. Which it is why that vibration dampening is optimal at 25% coverage.

Let's go back to resonance frequencies, it has been argued that you can add enough mass with roofing materials to drop the resonance of the panels below the audible range. The only thing that is wrong with that is that you can not add enough mass to accomplish that large of a shift in the resonance. To do so you need to QUADRUPLE the mass of an object for every octave you want to drop. Doing this will have you end up with door panels that weigh a couple hundred pounds.

I've even come by tests done to where it takes TEN TIMES as much material, which becomes much more expensive, more work put in, more points to where failure can occur, and once you take in account for the inferior quality of the adhesive.

Using the right amount of the highest quality vibration damper costs less than enough of a poorer quality product to approximate the same result. Why compromise? Put it in and forget about it for the life of the vehicle.

[BassInMyBLood]

ya I guess you have a point. but im happy with what I have done. thanks for the advise in the future though.

[Krakin]

Not saying you are completely wrong for your decision, just that it just physically doesn't "dampen" -or nearly enough- to be considered a useful product for the application.

There is some more info here:

http://www.stevemeadedesigns.com/board/topic/176755-options-for-deadener/

[KillaCam]

You get rid of rattles in one spot and you're going to get rattles in another.

For my trunk I used about 40sq ft of deadener, filled the trunk lid with great stuff, and sealed off. I don't get any rattles from the rear but now there are rattles to be dealt with up front.