Why Not Asphalt?

[j-roadtatts 1,129]

Thanks again for the Info Don. I learned ALOT from your original test website.

[siccostyle 0]

Great read very informative and answered all my questions. Thanks for breaking it down like that Don.

[RWatts 0]

Ok so I'm new here...is Don part of a company that sells deadening products? If so will someone tell me who it is because I know I can trust that product.

[NB50 206]

Ok so I'm new here...is Don part of a company that sells deadening products? If so will someone tell me who it is because I know I can trust that product.

He owns SDS. Very helpful guy, Just tell him what you want to do, give him some measurements and he'll sell you only what you need.

http://www.sounddeadenershowdown.com/cgi-bin/index.cgi

[Dictator 39]

Great read tis true.

[slim2fattycake 85]

Show me someone from any other brand that has that knowledge and can explain it well to customers.

Not AT.

[GAMEOVERCCA 3]

wow..

[Aaron Clinton 2,372]

Show me someone from any other brand that has that knowledge and can explain it well to customers.

Not AT.

Yeah, I agree, but will refrain from commenting right now.

[A nabil 0]

Since this is the only sticky post here, and since don is involved. Its a good place to ask this quesrion.  

Don, you say that butyl reaches the dampening critical mass at a well placed 25% surface coverage.

You also say that it loses some dampening ability if it gets too hot or too cold for being too fluid and too stiff respectively.

Could covering a bit more surface than 25% make up for the partial loss of dampening characteristics? To keep it above the dampening threshold when it would be otherwise below it? 

This is critical for me since I live in an extemely hot and humid .

Thank you 

Input from other experts is highly appreciated. ///M5?

[///M5 2,833]

25% is probably overkill, but an amount that Don uses to show the ridiculousness of other companies recommendations.  Let me rephrase that, 25% is way overkill but when you don't have intrinsic knowledge of the actual car panels you need to overkill to compensate for the lack of knowledge you have about the vehicle dynamics.

You should also be aware what CLD does.  It fundamentally changes the damping of the panel it is applied to.  For instance, if you take look at the curve below you can see there is a time response of a device under test that had a mode excited and is ringing.  One of the major things we would see when applying damping is that the time axis would shrink.

So what does this mean for your question?  You are applying damping to reduce and structure "created" noise (I used quotes as the forcing function is not in the structure so it is really a response function, but the noise is created at the panel) from that structure.  The goal being to limit this as much as possible, but they are far from the major source of noise in your car.  Airborne transmitted noise is dominant and needs to be muffled as much as possible.  For this, CLD is pointless as fundamentally to block airborne noise you need mass.  CLD is a crappy way of adding mass.  Reducing the modal panel contribution however dampening can help. The source of energy in the panels is primarily driven from the vibration response of your car interact with itself and the road.  Since it is only the structural side of the noise going buck wild and crazy to stop it gets well into the law of diminishing returns quickly.

One other story on this.  We optimized an dampening package for an OE a few weeks ago.  They computer optimized their placement, but we analytically measured the whole body in white.  The net result was that we pulled out more than 50% of their optimized package and reduced the structure created noise by more than 10dB at simulated highway driveway conditions.

So now the simple answer.  Yes adding more will compensate for the change in response due to temperature, but whether or not that makes your car any quieter is dubious at best.  Focus the overkill on killing the acoustic noise instead of the structural and you will be better off.

One other caveat of course is that a monstrous sub setup creates all sorts of other energy that needs to be dissipated or stopped from happening.  CLD is also bad for this as it is a structural problem, not a resonance problem to resolve.

If you want to know more about the panels and their response, google Modal Analysis.  Feel free to then add a thread to post questions on it  

[Rudeboy 152]

Couldn't agree more. Even at 25% coverage with CLD we are just "slapping it on". That's the best we can do working on one vehicle at a time. It can't be said enough that for all of the attention paid to vibration dampers in the aftermarket, they are a small part of any noise reduction solution. Blocking airborne sound is where it's at and barriers are the key tool there. When I'm treating a vehicle, I look at applying vibration damper as a warm up for the real work to come. Absorbers are the icing on the cake and can make a very nice reduction in the high middle to high frequency range. All comes down to the right tool for the job. 

[A nabil 0]

Thank you guys for the answers.

M5, that is a truly great lesson. I'm planning to focus the overkill on acoustic block, I am. But this was a vibration dampers specific post and I made my question topic specific. I'v already asked Don many questions to wich I got the best of anwers on his fb page. I have many more questions which I'll be asking once I finish reading the sound deadening posts as I  hate to be the guy who asks a question that's been answered one thread back.

Now I understand that 25% is already taking into account slight misplacement and temp change.

Thank you.