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The information on the Knu products is definitely disappointing. I've had good luck with them in the past. Even if the performance is up to par, the misleading specs going unaddressed is not good business. I'm as much interested now in Knu's response to these findings as I am their test results.

It does have me more curious if this was part of the reason they declined (through lack of follow up response) to be a part of this testing.
 

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Discussion Starter #202
Email has been sent to KnuKonceptz. I will post my email and the response I get if and when they respond.


Also, I have been advised that Alphadamp uses a higher grade foil and higher temper than normal, which is what makes the product harder to bend and cut, but should also make it perform better. This could explain the things I experienced when trying to cut it vs another product that is very similar, yet much easier to cut and manipulate.

I'll be making a video later today, showing the physical measuring of both Knu products, and the GTMat asphalt products. This will include showing how flammable the plastic film on Knu's products is, and testing the aluminum on GTMat's products to either vindicate or silence the critics that do not believe it to be aluminum.
 

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How many of the products contain a film over the aluminum/foil layer? If more than one, are you only testing the Knu because of the amount of product you have?
 

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Discussion Starter #205
I'll be testing all of them for this. I know for sure that there were complaints about GTMat, with people claiming that it wasn't actually aluminum. Whatever the coating on Peel n Seal is, its very similar to GTMat as well. I burned Alphadamp while I was at it, and nothing happened, but I'm curious about Dynamat as well as far as a plastic film. I have enough of each to measure, and test for coatings, so I'll do them all.
 

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TooStubborn - Tell me what accelerometer you would like to have and I will see about getting you one.

Also - I'm dying over here! When are we going to have some preliminary testing? The suspense is killing me.:confused:

It sounds like your plate is full and you are juggling several things at one time. Lots of us can relate.
 

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Discussion Starter #207
Goyop, PM sent. Ya, when I started, things were pretty empty, but some things fell through and that made things much more hectic around here. However, the bulk of things is done, and aside from an interview for a promotion next friday (after testing today), my plate is now empty.


I have everything set up to start tomorrow morning. I will be testing the three asphalt products from GTMat to start with. Everything will be filmed, for ultimate transparency.


KnuKonceptz emailed me back. I'm going to give them a chance to work with me, until everything has run its course. Right now were looking into a few possibilities. I'll know more monday, and it will probably be finalized tuesday.
 

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Discussion Starter #208
Goyop, PM sent. Ya, when I started, things were pretty empty, but some things fell through and that made things much more hectic around here. However, the bulk of things is done, and aside from an interview for a promotion next friday (after testing today), my plate is now empty.


I have everything set up to start tomorrow morning. I will be testing the three asphalt products from GTMat to start with. Everything will be filmed, for ultimate transparency.


KnuKonceptz emailed me back. I'm going to give them a chance to work with me, until everything has run its course. Right now were looking into a few possibilities. I'll know more monday, and it will probably be finalized tuesday.
 

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Discussion Starter #209
Ok, so Knu has emailed me back. Originally, I was told a product that does not meet spec is not a Knu product. I was also told that they double checked 3 samples of each product and all three measured to spec (without saying what that spec was or how they measured). They asked me to send them a sample of the product I have. They told me if there was a problem with their build house, they would correct it (their website claims that they manufacture everything they sell). They also said they were unable to get it to light on fire, and couldn't find a film coating on it either. They asked if I was talking about the backing paper, or the paper separation sheets.

I emailed back explaining how I measured. I also emailed back explaining about the plastic film. I said I would be more than willing to send them a sample of what I have, but I'd like to receive a new sample if possible.

They emailed me back and told me that they measured more samples, and they all measured to spec (again no mention of what they consider spec, or how they measured). They said they did find a coating of some sort on the aluminum, and they are going to ask their build house what it is.

Here are the measurement videos.



We have company tonight so I can't measure, but its set up to knock out a few samples when I get home from work tomorrow, and I'm going to measure the GTMat asphalt products tonight. It'll probably take a couple of hours to load the video (i swear the walls are made of lead here and the wireless sucks), so I'll post them in the morning.
 

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Thanks for all this extra work Chris. As I stated before, this is particularly disappointing for me. I was the one that ordered and supplied the Knu samples as I had every intention of purchasing and using their deadener for my own build. Until this issue is resolved, there is no way that I could in good conscience purchase or endorse the deadener from Knu Konceptz. Unfortunate, because I have had such good luck with the other products that they sell.
 

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Thanks SO much for doing all this testing.

Not only will this benefit everyone here with in depth test. This ALSO benefits the companies. It's my hope, and I'm sure yours as well, companies will take this information and further their own products. Even bring to light potential build house shortcuts, etc. In which you found with Knu. As to why its like it is we can speculate all we want. That's not the point of the thread.

I look forward to see your testing. Keep it up the good work
 

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I just found the thread. And I'm not going to read through it to see what products you do/don't have, but I have some AudioTechnix 60mil I'm willing to donate.
 

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Discussion Starter #215 (Edited)
KnuKonceptz KnoKnoise Resonance Control

Butyl rubber viscoelastic layer

80mil total thickness

7mil aluminum constraining layer thickness

0.71 lbs per square foot

-50 to 350F temp range

10 to 130F operating temp range

Meets FMVSS 302 standards for flammability

ACTUAL TESTING

Total thickness - 80mil

Constraining layer thickness - 3mil

Approximately 0.74 lbs per square foot

Notes - The constraining layer on the sample I received directly from KnuKonceptz is less than half as thick as they claim it to be. There is also a very flammable plastic coating on the top of the aluminum constraining layer.

Test samples are about 29% coverage.

Bare Metal Frequency Response


Damped Metal Frequency Response


Overlay of Undamped Metal Vs Damped Metal Frequency Response



Bare Metal Waterfall


Damped Metal Waterfall
 

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Great job! Very interesting to see those plots. According to the graphs the CLD's seems to remove ringing in the midbass area but increases it slightly in the lower frequencies. The immediate resonance is lowered in amplitude and the Fs seems to move down in frequency with a lower/wider Q. I assume all CLD's behave more or less in this fashion?

May I suggest you start another thread when the testing is complete? It's much easier to find the first post of the actual testing than searching through 10 pages ;)
 

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Great job! Very interesting to see those plots. According to the graphs the CLD's seems to remove ringing in the midbass area but increases it slightly in the lower frequencies. The immediate resonance is lowered in amplitude and the Fs seems to move down in frequency with a lower/wider Q. I assume all CLD's behave more or less in this fashion?

May I suggest you start another thread when the testing is complete? It's much easier to find the first post of the actual testing than searching through 10 pages ;)
It's lead to believe that's the exact function of CLD. Will be interesting the differences between the products. Even the difference between what the findings were now and the correct product IF its found the samples of KNU are incorrect.


It would be really interesting to see if there is any difference in using just aluminum duct foil tape. Granted there is no butyl layer.


I've used the foil tape on my trunk lid to hide the nasty 25% coverage of CLD tile I have back there. To me it seemed to help but could be negligible.

But it wasn't the function I meant it to be. It was to hide only. Not dampen
 

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Just caught on to this now. What an excellent project, stubborn, kudos for all your hard work.

I wonder, have you considered using a hall effect transistor for measuring your panel vibrations? Rather than attaching several magnets and a large-ish accelerometer-and-cable assembly, you would simply attach a small magnet to the resonant surface and place the hall-effect transistor close to it. This approach has proven to be very effective:
Magnetic Levitation (Hall Effect) - YouTube

The fact that you are using steel as your resonant surface could be an issue with this idea, however, as the coupled magnetic field may introduce non-linearities or harmonics in the measurement. But, it's worth considering.

Accelerometers are very noisy. Replacing the caps to increase bandwidth will cause the undesired effect of introducing time-based noise into your measurements. Even with multi-sample smoothing, I'm not sure there will be enough resolution in your measurement data to confidently arrive at a conclusion.
 

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Awesome to see we (Chris) has gotten to the point where we can get some real data! And the initial evidence presented here is coinciding with what many of us, including Hanatsu in his observations of the test results, have posited all along. While the dampener may reduce the amplitude of the initial resonance to some degree, what it is doing just as much is changing the resonant frequency of the material you are attaching it t. Hence, the peak shift from ~93 Hz to ~80 Hz in the Knu test.

I personally appreciate the waterfall graphs as it really helps tell a more complete story. We can see the reduction of amplitude in resonance over time when comparing the dampened sample from the non-dampened sample. We also see the resonant frequency shift become apparent in these graphs as well. The amplitude actually appears to have less decay at the extreme low end of the spectrum with the dampened material than when not dampened.

Chris, please say that you're going to do a color coded waterfall overlay of every single sample taken! ;)
 
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