I've been doing a lot of work, but mostly silent, as I've been trying to get together money to pick up a better accelerometer. But it doesn't look like that's going to happen. Just don't have the budget right now. The problem with the current accelerometer is it doesn't have the signal to noise ratio to pick up the full range from 20-500hz. I was thinking of eq'ing the response to get it to work, with a note in the results that that had been done, but the speakers, amp, and power supply cant handle it. From 90hz to 70hz the response drops 30db. I have about a 20db range the accelerometer will pick up. I would need 20db more head room, but that would put everything I have way past its safe range. At the least, I would need a subwoofer, and a better power supply.
That said, testing has actually begun. I've been dialing in the setup for the last weekend, and actual final results will be coming tomorrow. Unfortunately, the microphone is the only measurement device I have for this at this point. It will be placed as it has been shown in the pictures, however it now has a jig that holds it in the same place every time. I'll be using the Omnimic mic, and REW for results. I'll have both frequency response, and waterfall graphs. REW is soo much easier to overlay graphs than Omnimic is.
I will be starting with the asphalt based products, only because they clean off of the metal the easiest. And with that...........I will now give my SUBJECTIVE opinions on the products, based on cutting them out, handling, etc. Keep in mind, this is only subjective, and not based on results from testing with the mic.
Peel N Seal - One of the thinnest feeling constraining layers. Aluminum seems to be coated, I'll follow up with a polish test. Definitely has a smell to it that butyls don't. My wife knew exactly when I opened the box. Has a good backing paper. Cut relatively easily.
Alphadamp and SDS CLD Tiles - The butyl seems similar in both cases. The aluminum is also thick in both, just a tiny bit thicker on the alphadamp. That said, I expected them to both cut similarly, and especially with alphadamp being 20mil thinner overall. That said, alphadamp was significantly more difficult to cut. I'm going have to ask what grade of aluminum brands are using now, because that's the only thing I can think of that would make it that much harder to cut. Both these products are two of only 3 products that could support themselves while just holding the corner of the sheet.
Dynamat, Stinger Road Kill Expert, and GTMat Onyx - All three are very similar as far as butyl consistency. They all have the most sticky butyl of any of the products, almost oozing. The backing on dynamat and road kill is paper based, and sticks well. The onyx backing is a pretty thick plastic, and sticks well. All cut similarly well.
GTMat 50mil, 80mil, and 110mil - All three had thin constraining layers. There has been some speculation by some that the constraining layer is not actually aluminum. I will be testing this. It seems very similar to the Peel N Seal layer, and it is definately coated in something. The backing paper is not up to par with the others, its a very thin plastic layer, but at least with the samples I received, it doesn't seem to stay in place very well.
Lighting Audio Dead Skin - By far the lightest feeling product in the test. Also seems asphalt based. Also has the worst backing paper, it seems to want to fall right off. Its possible that this sample is old, but I'll test it anyways. Looking around, I couldn't find any specifications for it anywhere.
STP Vizomat - This is an oem type free layer damper. It was very easy to cut. Plastic backing, that sticks well. The website says its a bitumen product, which is a form of asphalt, but there is no smell.
STP Gold and Silver - Both products are an butyl products, gold having both a thicker constraining layer, and butyl layer. It seems very stiff for the constraining layer thickness, and has an embossed pattern in the constraining layer.
STP Bomb - This is the thickest product of the whole group. It is also the third of the products that can support its own weight by holding the corner. It also seems very stiff for the constraining layer thickness. This is also a mastic-bitumen based product, but like vizomat, has no smell.
Knu Konceptz Resonance Control and Kolossus - Both products are butyl based. Both have decent back papers, and seem to cut well. I haven't had much time to play with either, but I have a large amount of both, so I'll post more as I get a better impression of them.