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Sorry I never got with you on Friday about the metal work. Ended up being a crazy day for me. Let me know if this Friday might work for you.
 

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Discussion Starter #102
No worries at all. I actually didn't end up doing anything this whole weekend, my mom ended up in the ER friday afternoon. Shes gotta get more tests done this week.

This friday should be good, I should actually be able to hook up everything and test it out by then, after that its just figuring out documentation, and getting the pieces cut and ready.
 

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TOOSTUBBORN -

Way to go. It's about time we got some objective numbers on this stuff. I won't list all the things in the audio world that prey on people's gullibility because it is a long list and would divert this thread into more stories of "I bought a $200 cable to connect my subwoofer and it sounds so much better now", etc. (Sorry - don't mean to sound negative. This is a very positive project.)

I want to help out so once you have some data tell me where I can send a couple dollars. It is great to see all the support you are getting here.

A couple things to consider (you may have already thought of it or perhaps your dad who sounds like a great guy). I doubt you will take a set of measurements and then burn your test gear but you may find it useful to conduct a variety of tests. Certainly what you have in mind sounds solid but there may be much more needed once the initial tests come in. You mention different frequencies which is a must. I don't know that it matters how you generate the sound. You can dial up an online sound generator on the internet for pure sine waves if needed.

I think as long as you conduct your work using baselines and reference levels, etc. then it will be all about the results. Are there any acoustical engineers on this forum? If not I am sure I can find one to see what else you might consider as a test.

Anyway this is all to say way to go and I want to help.

GPM
 

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Also I have a pristinely recorded pro pink noise disc. It covers 33 bands and has one test file at the highest level that can be cleanly recorded. It also has sweeps, etc. Recorded by two of the best audio engineers in the world. Let me know.

GPM
 

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Wave Shepherd
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Also I have a pristinely recorded pro pink noise disc. It covers 33 bands and has one test file at the highest level that can be cleanly recorded. It also has sweeps, etc. Recorded by two of the best audio engineers in the world. Let me know.

GPM
I've heard of recordings being made by great engineers, and how choice of microphones, placement, etc can contribute to a great recording.

I could understand differences between stand-alone signal generators that sit on your workbench. But I've never heard of how some pink noise is better than other pink noise, or that there is any significant variation between digitally generated test tones put onto a CD, or how an engineer can affect that process.

Please explain.
 

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Just a quick update on this. My brother and I met with TOOSTUBBORN2FAIL on Friday evening and picked up the steel. My brother will be doing the work to turn the plate and strap into a 5 1/2" x 5 1/2" punch to cut consistent pieces of CLV from each of the products being tested.

I was able to check out the test equipment and "stash" of product, and I must say I am even more excited to see the results of the testing now. 'Stubborn' is going to great lengths to eliminate variables and provide non-biased information to the good people here at DIYMA and elsewhere. If anyone out there has a product that hasn't already been provided for the test and can afford to send out a piece larger than 6" x 6", please get in contact with 'Stubborn.' I think the more products we have for testing, the better!
 

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Discussion Starter #107
Thanks Dustin, I just got your text. Any time in the afternoon is good, I'm usually asleep by 7pm, but sometimes that doesn't work out so well. I got the power supply, amp, and head unit setup for sending signal to the speakers. I'll be using test tones, at 1/12th octave, from 20h-640hz. So 60 individual measurements for each sample. Ordering the neo magnets for attachment, and omnimic for further experimentation tomorrow.

So at this point, its simply waiting for the magnets and omnimic. In the meantime, I'll sharpen the dies for cutting the material, and harden them, so I can get the samples cut out. Once those things are done, I'll start testing immediately.
 

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Subscribed and look forward to the testing


Heard anything on when your expecting some Audiotechnix CLD. I have a good bit of the 60 mil and could spare sending you 1 sheet. Let me know
 

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To Jazzi - you are correct in most of your assumptions and understanding. The purpose of having what I call a high quality recorded CD (which now could be a thumb drive) is that the best quality pink noise generator created the original signal meaning it is clean of distortion and has an accurate drop off toward the higher frequencies. This is more important when setting up a listening environment than a test like the one being done here.

The reason the CD/drive is a good thing is that not everyone has a high quality pink noise generator on hand. There are tones available over the internet but no doubt if you stream them they will fluctuate. You can download them as MP3 which should work in most cases but still there could be distortion and inconsistent wave forms. This brings up another reason to secure a reputable source of pink noise because no doubt if these tests show what we think they will, then for sure manufacturers will attack the results as flawed for any and all reasons. The idea then is to have the experiment designed to be easily replicated and with as few questionable pieces as possible. Not "I used bobsaudio.com pink noise from the internet".

As far as your question of recording it versus simply generating it, it goes back to having a reliable source if you don't have a quality audio generator and it is highly portable. So if you are going to record it you would want a high quality source, and then a quality recording job. This means careful attention to levels. A good engineer will take into account the headroom needed to ensure all the frequencies and possible harmonics will have room so they don't get squashed/distorted. For example when recording a cymbal or any high pitched percussion, it is common practice to get a level from the meter then drop it down 10 db from there. Otherwise it will come out distorted.

I have no idea if I answered your question or not. Sorry for the rambling. If you would like more confusion let me know and I will try my best.

Cheers
 

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Wave Shepherd
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To Jazzi - you are correct in most of your assumptions and understanding. The purpose of having what I call a high quality recorded CD...............
As I understood it pink noise was something that could be generated from a mathematical function with a random variable responsible for frequency. My assumption was any computer should be able to generate the same "quality" of pink noise as any other, but I do not know much about the details or what could contribute to errors.

So the "quality" you refer to is all about the generator I think, and that seems to make sense. So question answered, I think! Thank you for the help.

-=-=-=-

I'm happy to see this project coming along and not fizzling out!

Have you decided on a method to use your accelerometer? The last I remember reading, you were going to use speakers to excite each of your samples, is that still the plan? How do you plan to interpret the data? I've been thinking about this a bunch and have a few more ideas. I'm curious what you have come up with!

-J
 

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Jazzi - I believe you are thinking of white noise based upon your description. Pink noise falls off at 3db per octave and is logarithmic. This is how the human ear hears and this is why it is used in audio for testing and tuning rooms.
 

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Discussion Starter #113
As I understood it pink noise was something that could be generated from a mathematical function with a random variable responsible for frequency. My assumption was any computer should be able to generate the same "quality" of pink noise as any other, but I do not know much about the details or what could contribute to errors.

So the "quality" you refer to is all about the generator I think, and that seems to make sense. So question answered, I think! Thank you for the help.

-=-=-=-

I'm happy to see this project coming along and not fizzling out!

Have you decided on a method to use your accelerometer? The last I remember reading, you were going to use speakers to excite each of your samples, is that still the plan? How do you plan to interpret the data? I've been thinking about this a bunch and have a few more ideas. I'm curious what you have come up with!

-J
I have some neo magnets on the way, should be strong and light enough not to screw with the results too much. As of now, the plan is still to use the L6SE's to excite the metal. As soon as the magnets arrive, I'll start testing things to see where we stand. I may need more speaker to get good results, I might not. I'm hoping to get the stamp that rton20s and his brother worked up sharpened tomorrow, and start cutting out both the vibration test samples, and the heat/removal/measurement samples.

Same goes for how I'm going to interpret the results. My dad is coming up this sat and I plan to talk about it some more with him. I think definitely there will be graphs showing before and after in DB. I'd love to show damping ratio, but I can't find a method that seems to work reliably, especially at multiple frequencies. The most reliable so far might be a simple impulse, and recording the decay with the accelerometer. But, I'll have to experiment to see how that works. In the end, I think that all of the samples will be under damped. I have yet to see a test where a deadener approached critical damping, let alone over damped. Most (cascade, stp-atlantic, dynamat xtreme, second skin damp pro) all reside in the .3-.5 range according to ASTM-756.
 

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Discussion Starter #116
This is the list as of right now.

Dynamat xtreme - 1 12"x12"
GTMat Pro 50 Mil - 2 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 - 2 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
Audio Tecknix


I'm at the limits of my budget right now, but there will be more things tested. I just need to wait for funds to catch up. Things on the wish list are Second Skins products, Cascade's products, Blackhole products, and Knu's products. I also want to try a spray on. Of course, if my motocross bike sells, this stuff will all be added to the list immediately.
 

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Discussion Starter #118
I would be VERY interested in that. I remember that thread, and had some super secret plans to try something similar lol. But, definitely, if you want to see how it does, we can get that tested. I'm headed to bed, work at 4am, I'll pm you though.
 

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toostubborn - I found an interesting study from back in 1983 made by a Master's candidate in the Navy. It is called

THE DESIGN OF A TEST PROCEDURE FOR MEASUREMENT OF ACOUSTIC DAMPING MATERIALS AT LOW STRESS

You can see it at http://ia701202.us.archive.org/3/items/designoftestproc00heid/designoftestproc00heid.pdf

He did a very similar procedure to what you are planning and you might gain some insights. Especially in the analysis area. I have no idea what your background is and I don't want to insult you in any way. But it is definitely an interesting read. And the laws of physics haven't changed since 1983 no matter what people say.:)
 

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Discussion Starter #120
I will absolutely take a look at that this weekend. And nope, physics hasn't changed a bit since 83 (although my physique has, but I was born in 83 and that's a different story).

No worries at all about insulting, I'm here to learn as much as possible. Just for those wondering, my background is basically what my dad has taught me, and research I do on my own. I've been interested in flight and aircraft design since I was a kid. I won an invite to NASA's Space Camp program in 6th grade for a Space Craft design program, but was unable to go due to money. Initial intentions in junior high and high school were to go through the UC Davis Aeronautical Engineering program, but I generally had problems focusing in school as it was usually too easy, and bored me. I usually aced tests, but didn't do homework or class work. Then I also started slacking off when I started getting paid to jump motocross bikes my senior year.

My dad's background is a masters in physics, and 30+ years designing power supplies for everyone from NASA and the military, to Honeywell home thermostats. I can't say (and don't know everything hes built), but I know the F-16 gyroscopes used power supplies he's designed. He also is a hobby engineer, building a robotic vacuum 20 years ago that relied on radar to map out the house. He's also been working on a voice recognition/simulation program. His goal is realistic sounding human voice, and is using FEA and Navier Stokes equations to do it instead of the common Fourier transform equations (which result in the metallic sounding "Steven Hawking" voice. I have a file that I'll ask him about sharing, that simulates air blowing through a tube, and it actually sounds real. He said it took 500 billion calculations per file, and there are 3 different tube length/diameters. His goal is to as accurately as possible model an average human lung set, voice box, throat, mouth, etc, to attempt to make the simulation indistinguishable from real human voice.

He actually recently left the company he was with for 30 years to start his own project, although I can't yet divulge what his new project is, it is something that most people would assume is straight out of a movie.
 
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