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Discussion Starter #161
So if "one of each thickness panel" refers to the steel (or aluminum) sheet to which the acoustic material will be affixed, that means you will have to apply (i.e.: glue) each sample material being tested to that metal sheet, then remove it after the test is complete... correct?

If so, what type of adhesive would you be able/willing to use (for anything that isn't peel & stick)? e.g.: 3M 90?

What is the approx. size (width x length) of that sheet?
Based on the size of looks like roughly 14" x 18"?

I have a couple materials (which you probably have not seen before) that I would like you to test, when you have time.

Thanks again for being so determined (aka: 'stubborn') on this project!
For the first new run of tests I'll mostly be focusing on CLD type materials. However, after those are done, I will likely get some more panels to test other materials, such as spray on materials, etc.

The total opening size is 14x17. There will be two test opening sizes, 11x11 and 12x15. This is so there is enough room to solidly clamp the material. It'll be much more clear why once I get the metal cut. I'll be sending the measurements over for that today.

The reason for the smaller 11x11 size is so that all available CLD's can have a fair 25% coverage test using a single, uncut sheet. The larger size will show why its important to use single uncut sheets whenever possible, and will show the disadvantages of some products based on their offered sizing.
 

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can i make a request. maybe go for a piece of metal that has a similar resonant frequency of your typical car door?
This brings up an important point: different sheet metal parts of any given car (or different cars) have different resonant frequencies, and different amplitudes.
Without taking some measurements [edit: of the resonances in the vehicle] before applying any dampeners, it's a shot in the dark.
This assumes the intended goal is more about reducing external noise, as opposed to getting better speaker response.
 

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Without taking some measurements before applying any dampeners, it's a shot in the dark
He does.

Secondly its comparing cld to cld so it doesn't matter what the resonant frequency of the panel is as long as it's in the same realm as automobile metal. Each piece of cld will be asked to dampen in the same exact scenario so you can still compare apples to apples.
 

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...Without taking some measurements [edit: of the resonances in the vehicle] before applying any dampeners, it's a shot in the dark....
He does.

Secondly its comparing cld to cld so it doesn't matter what the resonant frequency of the panel is as long as it's in the same realm as automobile metal. Each piece of cld will be asked to dampen in the same exact scenario so you can still compare apples to apples.
You can compare apples to apples but the point is, every dampener has a dampening curve that peaks at a certain frequency (which varies with temperature), and every piece of sheet metal in a car a peak resonance frequency. As an example, the peak resonance frequency of a typical floorpan is not the same as a door panel.

Any given material is most effective if its peak dampening frequency coincides with the peak resonance frequency of the particular piece of sheet metal to which it is to be applied. Lower frequency resonances are typically more difficult to control, but also aren't a problem if the sheet metal doesn't resonate at those lower frequencies.

Manufacturers spend quite a bit of money conducting controlled acoustic testing to make those determinations, which enables them to apply 'just enough' dampening in the areas where it's needed to achieve the acoustics that the budget for that vehicle will allow.

While end-users can't do that, it is instructive to make test runs with several mics less than an inch away from different parts of a vehicle. Since sound amplitude diminishes greatly with distance, that provides a great deal of isolation and helps create a profile of the areas that need the most treatment, and at which frequencies.

FYI: most compact mics are omni-directional, but it's easy to make them much more directional simply by wrapping them in a tube made of 1/8" mass loaded vinyl.

PS: For more info, check this white paper:
Understanding DampingTechniques for Noise and Vibration Control
 

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When you find anyone outside of OEMs willing to not only go to those lengths with test measurements, and actually apply enough sound treatment material (damping or otherwise) to mitigate the issues, you let us know. :D Even OEMs don't go that far, as they are constantly having to balance so many aspects of vehicle development (cost, comfort, weight, etc.)

As mentioned, these tests are going to provide an apples:apples comparison within the constraints of the test parameters/environment. This is far more than anyone I am aware of in the car audio community has done. Is it going to match ANY specific vehicle condition out there? No. Should it be enough data for most anyone interested in viewing and understanding the results to make a more educated/informed decision when selecting sound treatment products? Absolutely.

Also... DAMPER / DAMPING. ;)

You can compare apples to apples but the point is, every dampener has a dampening curve that peaks at a certain frequency (which varies with temperature), and every piece of sheet metal in a car a peak resonance frequency. As an example, the peak resonance frequency of a typical floorpan is not the same as a door panel.

Any given material is most effective if its peak dampening frequency coincides with the peak resonance frequency of the particular piece of sheet metal to which it is to be applied. Lower frequency resonances are typically more difficult to control, but also aren't a problem if the sheet metal doesn't resonate at those lower frequencies.

Manufacturers spend quite a bit of money conducting controlled acoustic testing to make those determinations, which enables them to apply 'just enough' dampening in the areas where it's needed to achieve the acoustics that the budget for that vehicle will allow.

While end-users can't do that, it is instructive to make test runs with several mics less than an inch away from different parts of a vehicle. Since sound amplitude diminishes greatly with distance, that provides a great deal of isolation and helps create a profile of the areas that need the most treatment, and at which frequencies.

FYI: most compact mics are omni-directional, but it's easy to make them much more directional simply by wrapping them in a tube made of 1/8" mass loaded vinyl.

PS: For more info, check this white paper:
Understanding DampingTechniques for Noise and Vibration Control
 

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When you find anyone outside of OEMs willing to not only go to those lengths with test measurements, and actually apply enough sound treatment material (damping or otherwise) to mitigate the issues, you let us know. :D Even OEMs don't go that far...
Oh, yeah, OEMs absolutely do, and I've seen some of their test rigs.

As you yourself stated...

...they are constantly having to balance so many aspects of vehicle development (cost, comfort, weight, etc.),
...which sounds very similar to what I said:
...which enables them to apply 'just enough' dampening in the areas where it's needed to achieve the acoustics [goal] that the budget for that vehicle will allow.
As mentioned, these tests are going to provide an apples:apples comparison within the constraints of the test parameters/environment. This is far more than anyone I am aware of in the car audio community has done. Is it going to match ANY specific vehicle condition out there? No. Should it be enough data for most anyone interested in viewing and understanding the results to make a more educated/informed decision when selecting sound treatment products? Absolutely.
I'm not criticizing the testing.
Anyone who is interested in this should be very grateful that Chris is devoting so much of his time to this effort.
It's practically the only way end-users will ever get unbiased test results about products like these.

And I also didn't come here to argue, which as it always does, ends up cluttering up a thread with non-helpful gobbly-de-gook.


But I *am* saying that if anyone wants to know how much of what material needs to be applied where, they should measure their vehicle's resonance frequencies & amplitudes at different locations before they start adding a bunch of weight in the form of foil-faced rubber sheets, which may well be the most cost-effective solution for some acoustic problems, but maybe not so cost-effective for others.

BTW:
Also... DAMPER / DAMPING. ;)
"A dampener is someone or something that dampens. So damper and dampener can both refer to one that deadens sound vibrations."
https://grammarist.com/usage/dampen-damper-dampener/
Anyone can use whatever terms they want, but in the most common usage, a "damper" is used to restrict airflow in a duct.
A "dampener" or "deadener" is used to reduce unwanted vibrations.
 

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For the first new run of tests I'll mostly be focusing on CLD type materials. However, after those are done, I will likely get some more panels to test other materials, such as spray on materials, etc....
OK, great.
Let me know when you are ready for that.
I'll send you something to test.

FWIW, what I have in mind is actually a Constrained Layer Dampener, but it will be a lot thicker than those you're familiar with.
 

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I'm about to install a system iny car, without having to wait for the new round of testing what is the current recommendation?

Wish I would have bought more sds, as it is after my last install I only have enough to do like one door. 😔
 

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I'm about to install a system iny car, without having to wait for the new round of testing what is the current recommendation?

Wish I would have bought more sds, as it is after my last install I only have enough to do like one door. 😔
https://resonixsoundsolutions.com(shilling for Sk LOL. I have small doubt his stuff will be up in the top 3 at the least)

Kno Knoise - Kolossus Edition Sound Deadener

This was... 2nd or 3rd in the first round of testing.
Sounds good. I may give Resonix a try.
 

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...
But I *am* saying that if anyone wants to know how much of what material needs to be applied where, they should measure ...
...
^I have to agree^, but then the question is how to measure it?
 

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And I'm still saying that it doesn't matter for this type of test. It's not "How cld reacts on certain panels, with certain stimulus, in certain circumstances. It's just simply how cld reacts in the exact same situation compared to another piece of cld.

I do think pointing it out for those that want to further their unwanted sound mitigation abilities is a good thing.
 

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^I have to agree^, but then the question is how to measure it?
The way I do it is described in post 164

I will mention again that the closer the mic to any given source of noise, the more it isolates that noise source. The mic mounts must isolate them from structure-borne interference. Memory foam works pretty well. Fortunately, most of small USB mics don't have much mass. I use USB mics because it makes it easier to make simultaneous measurements (8 at a time).

The other thing I left out of that post is that once you've mic'd up your vehicle, you need to make test runs over different road surfaces at different speeds. Once you do that, you'll have a pretty good characterization of the noise problem.

Also read the white paper referenced in that post. It's only 6 pages of content. It's helps most people understand how a constrained layer damper actually works (which is really the same as any other composite material, i.e.: two hard "skins" separated by a lower density core... same as a piece of ordinary foam-core poster board).

Once you do that, it becomes obvious why thicker materials have a large "leverage" advantage compared to ~2mm thick butyl, especially at lower frequencies.

And I'm still saying that it doesn't matter for this type of test. It's not "How cld reacts on certain panels, with certain stimulus, in certain circumstances. It's just simply how cld reacts in the exact same situation compared to another piece of cld.
Strictly speaking, that is true. It's also true that I have not been disagreeing with that, either. I've have not been suggesting that the new test won't be apples-to-apples. The new test will be an apples-to-apples test yielding data over a certain frequency range (20Hz - 1,100 Hz in the previous test).

But the *applicability* of that data to control a noise problem depends on how much of what to use and where.

Not all noise control problems are solved most cost-effectively by Constrained Layer Damping. And even if structural damping is required, the choice of the "best" one to use is not just which one is most effective (in absolute terms), but which one is most effective relative to cost and weight.

Given the orientation of this forum, I want to point out that my focus (and that of my advice) is overall vehicle noise reduction, rather than making powerful speakers sound better.
 

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The way I do it is described in post 164

I will mention again that the closer the mic to any given source of noise, the more it isolates that noise source. The mic mounts must isolate them from structure-borne interference. Memory foam works pretty well. Fortunately, most of small USB mics don't have much mass. I use USB mics because it makes it easier to make simultaneous measurements (8 at a time).

The other thing I left out of that post is that once you've mic'd up your vehicle, you need to make test runs over different road surfaces at different speeds. Once you do that, you'll have a pretty good characterization of the noise problem.

Also read the white paper referenced in that post. It's only 6 pages of content. It's helps most people understand how a constrained layer damper actually works (which is really the same as any other composite material, i.e.: two hard "skins" separated by a lower density core... same as a piece of ordinary foam-core poster board).

Once you do that, it becomes obvious why thicker materials have a large "leverage" advantage compared to ~2mm thick butyl, especially at lower frequencies.

While all of this is good, it is beyond the scope of most people in car audio. I would like to know how many extreme competitors actually go through this process. If you do not have the equipment up front for this, as most only have one microphone, this quickly does not become cost/time effective compared to just placing CLD that seems to be one of the top performers in a controlled test. I know if I were to do this with my one microphone, it would take me a few days longer, is that time spent really beneficial than just spending another $100 on extra CLD/MLV/CCF/Thinsulate? If I purchased 7 more microphones, now I am out $700 plus time. I could nearly double layer all of the CLD/MLV/CCF in my truck for $700.


The way I do it is described in post 164

Strictly speaking, that is true. It's also true that I have not been disagreeing with that, either. I've have not been suggesting that the new test won't be apples-to-apples. The new test will be an apples-to-apples test yielding data over a certain frequency range (20Hz - 1,100 Hz in the previous test).

But the *applicability* of that data to control a noise problem depends on how much of what to use and where.

Not all noise control problems are solved most cost-effectively by Constrained Layer Damping. And even if structural damping is required, the choice of the "best" one to use is not just which one is most effective (in absolute terms), but which one is most effective relative to cost and weight.

Given the orientation of this forum, I want to point out that my focus (and that of my advice) is overall vehicle noise reduction, rather than making powerful speakers sound better.

I, as well as most on here, also think that this CLD test is just one part to many sound deadening steps. To achieve overall noise reduction we need to follow the CLD/MLV/CCF/Thinsulate approaches that have been established. From my understanding, CLD isn't really being used to "quiet" the vehicle, just stop panel vibrations. To quiet the vehicle we need to do the 100% MLV/Thinsulate step as well.
 

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...From my understanding, CLD isn't really being used to "quiet" the vehicle, just stop panel vibrations. To quiet the vehicle we need to do the 100% MLV/Thinsulate step as well...
What do you think vibrations propagating through the air are?

Thinsulate is not even close to being one of the most cost-effective acoustic insulations, especially not in applications where having a lot of thermal insulation is also desirable. I won't bother mentioning examples because (based on past experience) I doubt you're really interested in them anyway, because you already believe you "know" what works and what doesn't.

I use USB Clip-on Omnidirectional Condenser Microphones, which cost about $14-$15 each. It really only takes five or six, although more is better.
I guess your next complaint will be that this type of mic isn't "good enough" but in fact, the only real drawback is they are omnidirectional, which is easily changed using the method I mentioned in a previous post. The consistency is excellent because the exact same mic is used in the exact same location & orientation before & after treatment.

As I mentioned before, it always seems to turn into an argument between people like *you* who presume to know what will work best without actually having tested much, if anything, yourself, and those like me who have done that (along with more product research than you would believe). I guess that's the difference between amateur and professional. So, I'll let you get back to your previously established presumptions.
 

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What do you think vibrations propagating through the air are?

Thinsulate is not even close to being one of the most cost-effective acoustic insulations, especially not in applications where having a lot of thermal insulation is also desirable. I won't bother mentioning examples because (based on past experience) I doubt you're really interested in them anyway, because you already believe you "know" what works and what doesn't.

I use USB Clip-on Omnidirectional Condenser Microphones, which cost about $14-$15 each. It really only takes five or six, although more is better.
I guess your next complaint will be that this type of mic isn't "good enough" but in fact, the only real drawback is they are omnidirectional, which is easily changed using the method I mentioned in a previous post. The consistency is excellent because the exact same mic is used in the exact same location & orientation before & after treatment.

As I mentioned before, it always seems to turn into an argument between people like *you* who presume to know what will work best without actually having tested much, if anything, yourself, and those like me who have done that (along with more product research than you would believe). I guess that's the difference between amateur and professional. So, I'll let you get back to your previously established presumptions.
did you not get the part where he said from his understanding?no need to come off so harsh
 

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Dude, you’re welcome to volunteer and put forth a testing methodology and see if people will donate to help you test some products.

TOOSTUBBORN2FAIL did CLD testing several years ago that were valuable and did provide valuable consumer information. Based on that testing and the different products now, he offered to test some more products using an improved testing methodology. He has taken his valuable time and money to do some testing that will benefit the DIYMA community. Will it answer every question we want/need, no, but it will definitely help with which are the better CLD materials on the market.

I am grateful for the time and effort TOOSTUBBORN2FAIL has put into the CLD testing he has proposed.

If you have a different set of criteria to test, by all means start a new thread as the more information people have, the better. As you said, the study of acoustics is very complex and no one test will answer the myriad of questions we have or some we don’t even know need asking.
 

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What do you think vibrations propagating through the air are?

Thinsulate is not even close to being one of the most cost-effective acoustic insulations, especially not in applications where having a lot of thermal insulation is also desirable. I won't bother mentioning examples because (based on past experience) I doubt you're really interested in them anyway, because you already believe you "know" what works and what doesn't.

I use USB Clip-on Omnidirectional Condenser Microphones, which cost about $14-$15 each. It really only takes five or six, although more is better.
I guess your next complaint will be that this type of mic isn't "good enough" but in fact, the only real drawback is they are omnidirectional, which is easily changed using the method I mentioned in a previous post. The consistency is excellent because the exact same mic is used in the exact same location & orientation before & after treatment.

As I mentioned before, it always seems to turn into an argument between people like *you* who presume to know what will work best without actually having tested much, if anything, yourself, and those like me who have done that (along with more product research than you would believe). I guess that's the difference between amateur and professional. So, I'll let you get back to your previously established presumptions.

This felt personal and it is my first interaction with you....:confused: Maybe you didn't mean it to be personal but you used the word "you" a lot which definitely portrays the original writer, or me in this instance.

I wasn't disagreeing that your method would *probably* yield better results, which is why I said it is good. But your method is still beyond what most people are willing to do and for how much of an improvement over the standard 25%+ coverage of CLD (less than 6db compared to 100% coverage according to the paper you linked)? Will your method of measuring first result in 0db difference compared to 100%? or 5db difference? I also say probably because to actually figure that out, we would need to have a very controlled test, using the same exact car and applying the CLD with the "standard" method and measuring results compared to applying with your methods results. We would have to use the same car, as you stated, all vehicles are different. This would be very hard in reality so we go to tests like TS2F's CLD test and Justin Zazzi's MLV test.

You have to admit that if you just use one microphone this is going to take some time to do all of the tests. If you were to buy more microphones, even at $15 a piece that is $100. Is that $100 and less time invested better spent on other sound deadening materials? A $100 buys ~15sqft more of Resonix Squares and minimal additional time when you are already applying it.

Also, while panel vibrations do contribute to vehicle noise, there have been quite a few tests with data (which I am sure you are aware based on your writings in this thread, so I won't bother linking them) that CLD alone does very little for sound reduction in vehicles when compared to other products.

Even the "white paper" that you linked states that CLD isn't that effective at normal car temperatures of up to 40 degrees celsius. Also, that white paper does not go into any testing methodologies to achieve that data, so definitely is not a paper that I would be able to quote if I was writing a paper on dampening. It also says estimated noise reduction so those two things make me lean to these are theoretical values and never actually tested.

I'm a scientist by nature and career. Therefore I am always open to new data and my mind being changed. But there is definitely an amount of diminishing returns that is happening with your microphone method. Which was my whole point.

If you are Jennifer Renninger of E-A-R (a 3m company), then the facilities/materials are already there for you to do this type of testing and I am sure you would do it just because that is what you like to do. So it is time well spent.
 

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Just gonna throw out a thank you for doing all these tests. It's extremely helpful to see these tests done in a close to real life situation. I get so sick of reading amazon reviews where everything is supposedly perfect. I'm about to do my first real audio build and you have definitely put me in the right direction for the first step of the build.
 

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So, how's the Amazon-sold Vibro Solution product?


Vibro-Black is 10 sq ft for $80, and 200mil, and its endorsed by the baddest (semi-famous) builder crew I know, Arclight.



Honestly I've been burned a lot on brands I don't know for deadening, but it looks GREAT.
 
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