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Sound Deadening (CLD) Testing

780K views 2K replies 210 participants last post by  TOOSTUBBORN2FAIL 
#1 · (Edited by Moderator)
So like many other people, I'm tired of wondering what CLD ACTUALLY works best. So I've decided to test a whole spectrum of them, using an accelerometer, so this can be put to rest. This will take between 1-2 months to start, but may be drawn out over time if people want continuing results from new products, etc. Once I have the test rig set up, it wont be that hard to test.

As of right now, I plan to build a box out of baltic birch. It will have two removable baffles, both secured with 10-32 screws, and hurricane nuts. The front baffle will hold two speakers, which will remain unchanged throughout the testing. This will be HAT L6SE's. There will be two front baffles, one completely sealed, aside from speaker mounting holes, and one with two 2" vent holes. The reason for this, is that a sealed box will cause different levels of vibration than one that is just measuring structural vibration, and I want both measurements.

The back baffle will be 22ga 12" squares of mild steel. There will be a new piece of steel for each different CLD. The reason is, removing this stuff could result in bends, and that could change resonant frequency of the baffle. So each CLD test will get its own piece of metal, and each will have before and after measurements, so that deadener effectiveness can be seen as a percentage. I will also post the frequency response of each test, if possible (I need to check one what kind of output I can get from my O-Scope, more on that by friday). Each panel will be bolted on at a set torque with a calibrated torque wrench, to keep that from being an issue. The piece will have a 1/2" perimeter to be bolted down to.

Each CLD piece will be weighed, measured, and photographed multiple times pre and post installation. I may also take video of each test. Samples will all be 6x6" squares, just a tad bit over 25% coverage. Testing will be done indoors, and will be temperature controlled.

I'm open to durability testing, but using the oven is out. New house, and not quite ours yet, means thats not going to happen. I have a torch, but thats a little inconsistent. It does get ridiculously hot here in the summer, I could save all the pieces, then leave them out when its 110 degrees for a week or so.


Once I've gone through the testing to "rank" the deadeners, I will move on to some intall technique tests/alternative deadening techniques tests. Things such as seeing what kind of differences to expect going from 25% coverage to 50% coverage, etc. I'd also like to test using small pieces vs on large equal area sheet. I've seen it suggested that small pieces randomly spaced works just as well, I'd like to prove or disprove that. Then I'd like to test bracing, and bracing+deadening, etc.


If anyone has an input, feel free to let me know. I'd like to get this issue settled.

If anyone wants to donate products, they are more than welcome, I'll post in the first post what I have, and whats been donated, and by who, unless they wish to remain anonymous. All I ask is that pieces donated are 6x6" squares or larger.

I've updated what people might be able to send so far. I want to make sure no one feels any pressure or rush, the soonest I forsee being able to start actually testing is the beginning of May. When I get products in, I'll move them to the corresponding area. I will also start to build the test enclosure this weekend.


Dynamat xtreme - 1 12"x12"
GTMat Pro 50 Mil - 1 12"x12"
GTMat Ultimate 80 Mil - 1 12"x12"
GTMat 110 Mil - 1 12"x12"
GTMat Onyx - 1 12"x12"
Alphadamp - 1 10"x14"
SDS CLD - 1 6"x10"
Stinger Road Kill Pro - 2 6"x6"
Lightning Audio Deadskin - 1 8"x8"
StP Bomb - 1 sheet
StP Gold - 1 sheet
StP Silver - 1 sheet
StP Vizomat - 1 sheet
Peel N Seal - 1/3 Roll

Things that are on the way or have might soon be on the way

Fatmat
second skin damp pro
edead
possibly some cascade V-2
possibly some knu concepts stuff

That leaves me wanting for the test

cascade vmax
maybe some raamat
 
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#369 ·
Absolutely, there will be a results thread, where everything is put together. I've been working on it as I go, it should be in PDF format. Right now, were looking at close to 75 pages for the full in depth results of all products, that said there will be a simple speadsheet at the beginning with a simplified version.
 
#370 ·
Great! I had to read a few pages back to catch up with some of the brands tested.

Sorry but Im not so great at reading the graphs and figuring out the fast decay I just need to get used to it and now I just look at the specs read the conclusion since most grraphs are similar. Will it be possible maybe in the final summary also nominate the better performer not just on the numbers and sonic difference but maybe on better Performance based on lighter weight assuming any of them is worth mentioning or a case applies.
thanks.
 
#371 ·
This weekend I worked through the data to come up with a way to rank the products based on vibration damping performance. Lots and lots and lots of zooming in, zooming back out, windowing things differently, etc. I'll work on getting those online by mid week. Also tested Damp Pro, Memphis Mojo Mat, and STP Silver. Some surprising results, I'll get them up after work.
 
#373 ·
Second Skin Damplifier Pro

ACTUAL MEASUREMENTS

Total Thickness - 75mil

Constraining Layer Thickness - 6.25mil

0.55 lbs per square foot

Notes - Seems a little under on total thickness. 75mil is the thickest measurement I made, some measurements were around 70mil. I'm going to cut more pieces from around the sheet and measure them as well. Constraining layer was just barely under. Weight was under as well.

Bare Metal Frequency Response


Damped Metal Frequency Response


Bare Metal vs Damped Metal Frequency Response


Bare Metal Waterfall


Damped Metal Waterfall
 
#374 ·
Memphis Audio Mojo Mat

ACTUAL MEASUREMENTS

Total Thickness - 80mil

Constraining Layer Thickness - 4mil

0.67 lbs per square foot

Notes - Stick butyl, not as gummy as Onyx or Stinger. Feels relatively stiff.

Bare Metal Frequency Response


Damped Metal Frequency Response


Bare Metal vs Damped Metal Frequency Response


Bare Metal Waterfall


Damped Metal Waterfall
 
#375 ·
STP-Atlantic Silver

ACTUAL MEASUREMENTS

Total Thickness - 80mil

Constraining Layer Thickness - 3mil

0.74 lbs per square foot

Notes - Again, all STP has the cleanest removing butyl. Thin aluminum layer.

Bare Metal Frequency Response


Damped Metal Frequency Response


Bare Metal vs Damped Metal Frequency Response


Bare Metal Waterfall


Damped Metal Waterfall
 
#380 ·
There's a few things going on here. If you just look at the the frequency response graphs, it doesn't appear that Damp Pro is a very good damper, but that would be misleading, as the difference between frequency response graphs is not what tells how good a damper a product is. The Damped Waterfall plot is what shows that. I know its hard to read them, but those are what needs to be looked at first.

The frequency response plot shows something else. For instance, one product puts up a good number when you compare frequency response plots, but performs poorly when looking at the waterfall plot. This means that over time, the product does a poor job at damping vibration. The big number between frequency response plots represents the instant amplitude reduction between undamped metal and damped metal. This can be caused by a product acting more as bracing, increasing rigidity, while not damping vibration as well as other products that don't increase the rigidity as much.


Give me a few minutes and I'll expand, I'm putting the numbers together now.
 
#381 ·
Have you thought about expanding this into other deadening measures? Such as adding CCF and MLV


I'm not talking about testing that right now but in the future maybe. Would be nice to see the results.
 
#382 ·
Ok, so I have two ways I can list the order of product performance. I will not at any time list it based on the reduction in frequency response between bare metal and damped metal. I will also not list a final, comprehensive order of performance, as it would require me to subjectively pick and choose which measurements carry the most importance.

The comparative frequency response graphs are showing the reduction in impulse amplitude between the bare metal and damped metal. This is not a measure of damping, but other things going on, like bracing the panel.

As the measure of damping is the measure of how quickly a material reduces vibration over time, the Damped Waterfall graphs most clearly show how well a product works as a damper. Oberst Beam testing is very good at showing this number, but with a few catches. It is almost always done with 100% coverage. Since the numbers released from such testing are damping coefficients, its difficult to know what other effects are going on, such as panel bracing. Lastly, its always done on narrow strips of metal, to limit complex shapes from affecting the results. As you can imagine, this doesn't apply very well to what we are doing.

So, in a car, I can imagine the most wanted number as far as performance, is the reduction in vibration combined with the instant reduction in impulse amplitude.

This weekend I windowed the damped waterfall graphs down to 150ms. I picked that number, as past that, the top performing product decays to the level of background noise. To get the combined vibration damping reduction, along with the impulse reduction, I added the impulse amplitude reduction in db (taken from the comparative frequency response graphs), and the reduction in vibration in db from the initial damped impulse, to 150ms later. When I post the final results, the waterfall graphs will be windowed to 150ms as well.


The second way I can rank the products, is strictly by damping performance. This ignores the impulse amplitude reduction, and only uses the reduction in amplitude from the damped impulse, to 150ms later.



The top three, and bottom four products so far do not change no matter which method I use. Sixth place doesn't change either. Fourth and fifth exchange places depending on which method I use. Seventh and eighth exchange places, and ninth and tenth also exchange places.



I have 7 more products on hand to test. I'm supposed to have 2 more on the way currently. At this point, I have all major products, aside from Cascade and Focal products, which I'd love to test, am not able to procure myself. I'm going to email Orca tomorrow, and see if they are willing to donate, but I'm not holding my breath. I may also email Cascade, but I really don't see them donating for this, as they already do their own testing (oberst beam testing).
 
#386 ·
Raamat BXT2

ACTUAL MEASUREMENTS

Total Thickness - 60mil

Constraining Layer Thickness - 4mil

0.57 lbs per square foot

Bare Metal Frequency Response


Damped Metal Frequency Response


Bare Metal vs Damped Metal Frequency Response


Bare Metal Waterfall


Damped Metal Waterfall
 
#387 ·
I'm going to pull off my Neon's door this winter and test some things in car. Not so much vibration damping, but after seeing how many people still put thin closed cell foam behind speakers and claim there's a difference, I feel it needs to be tested. Since any difference heard would be the result of either frequency response, distortion, or decay (likely the first or last of those), and the microphone is better at picking out differences in those things than the human ear, I plan to test it. Closed cell foam, deflex pads, and fiberglass.
 
#391 ·
I would like to test it, especially after seeing the claims on the site. I just dont have the budget for it after some things fell through, and housing costs went up (another part of the reason the neon is parked, I dropped insurance on it). Focal and cascade are also on my short list, but I dont know if its fair to drag out the final results, as it will likely be 2 months before I can personally pick anything up.
 
#393 ·
Im talking more about people that glue things like ensolite on the outer skin behind the speakers hoping that it "absorbs or breaks up the backwave". Thats what ill be testing, mostly since I already have ccf, deflex pads, and fiberglass.
 
#397 ·
Regarding the peel and seal, the weakest of all. The graph or chart looks like it did nothing to the sound frequency. But I can't tell by it if it reduced vibration and no info was provided other than it will be tested again. Not worth it I know I'm just wondering if it did anything as far as reducing vibration since vibration causes rattles and apparently on you tube many use peel and seal and claim some benefit from it. :)
 
#398 ·
At the resonant frequency it did almost nothing. At 150ms out from the impulse, its reduced vibration by 6.75db iirc. But, at the resonant frequency, it showed no change in amplitude at 0ms. Ill be testing it again, if for anything else, to see the tolerances of this testing. I have 1/3 a roll of it.

I can see how people use it and think it works however, as it does seem to work better the higher the frequency. Since people are more sensitive there, they hear an improvement, and if they havent used anything else, that may lead them to believe it works well. Peel n seal does work better than nothing at all. But everything else ive tested so far works better than peel n seal.
 
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