JohnVroom

rev I am not picking on you, in fact I am not fault finding on this. And frankly it is not all that important

This is a UNIVERSAL issue (everyone uses the term) to the point where the term which is essentially slang will become an accepted word, it will mean different things to different people though and that WILL screw the consumer eventually.

I use Dynamat but I dont see a single reason another product couldn't match performance for less money. I like that Dynamat uses testing and does try to use engineering to promote their product. I think the superior product will be the one that doesn't cut your hands to shreds like Dynamat does.

MTT

iTrader: (17)

Was not questioning your knowledge, I know it to be vastly superior to mine in the audio and acoustics world.

JohnVroom

BWAAAA good one

MTT

iTrader: (17)

wasn't "one"...wasn't being sarcastic, I have read many of your posts and have a lot of respect for what you know and what you say. my comment earlier in this thread was that although you and I both know there is a difference in deadening and damping, the o/p specifically asked about "deadening". is he going in the wrong direction?...I think so, but he did ask about specific products, to which I submitted a link that he could further his knowledge on the subject......all is well, lemme buy ya a beer?

JohnVroom

I was making a funny, I really dont have an ego over this stuff. Car audio is a hobby and as such it is there to entertain and provide enjoyment. I enjoy all my conversations on here (except for those with that ***** Dukk)

I was just shoving my 2 cents in on the deadening (non) issue... probably unneeded but I sometimes wonder what people are really asking.

For the record I think damping is a wonderful tool and is essential for good sound in many/ most SQ vehicles and it has little to no bad affects on SQ no matter how much you use. Sound treatments in general are skimped on by manufacturers so an upgraded sound system results in a NEED for upgraded sound treatment, wire, power delivery, better batteries etc. Every SQ and SPL competitor is always wondering "what is the next step to improving my score?" and every discussion like this is making someone somewhere go "ah-ha!". So hopefully they will learn the terms transmission loss, damping, attenuation, absorption, diffraction, and reflection when it comes to how they deal with their cars acoustics.

And man am I ready for a beer...

Manfish

So is it damping or deadening only joking I’ve used both terms and not even thought about it, but when your right your right.

I think the material which ever you chose has to convert the in coming sound energy into another form of energy, heat.

In order to measure the energy exchange you measure the vibration of the panel before and after and this gives you the loss factor.

This is from memory, we had visit from the man who started dynamat, so since then I’ve used there products.

If I made any errors I apologize in advance.

JohnVroom

hehehe I am done with my soap box routine!
if the product needs to keep sound out of the car then I would recommend a multi-constrained layer approach. That will address the various frequencies noise comes in a little better than dynamat alone. But the asphalt/ rubber,/ spray on or roll on damping material is best at stopping the all important frequencies below 1000 Hz. The effectiveness can be incidentally shown by measuring vibration but the proof is in the reduced noise level in the vehicle.

The trash can demo Dynamat uses is still affective (though long in the tooth) as to its benefit to sounds generated in the car.

Also treating the car properly is a good way to keep the sound in the car from being peaky or accentuating certain notes and masking others through cancellation.

I have hear SPLers swear by damping materials and others swear at it... so I certainly have no SPL comment though it should smooth out the response

MTT

iTrader: (17)

so, I've got my car completely covered in butyl mat, and am aware of its benefits and deficiencies, whats can I add in the back half to quiet down the muffler ?????(A new muffler is not the answer)

JohnVroom

when I use the term dynamat please substitute the name of your preferred damping product

the dynamat is part of it but it is not complete at stopping the intrusion of noise. the damping material will minimize the radiation of noise produced by the sheet metal of the car and do a fair job of stopping noise at certain frequencies. Actually in the case of a muffler the dynamat will be one of the most effective solutions due to its low frequency performance (everything else commercial works best at frequencies over 500 Hz and engine/ road noise is all over the 50 to 3000 Hz range)...Damping ASTM 756

Mass loading is a tried and true method, it is a way to increase the transmission loss of sound entering the cabin. You can pour concrete (SPL cars do this for several reasons) into the offending area, you can put down a second or third layer of dynamat, basically anything that can out and add mass. if you use a rigid material it will stiffen the area and raise the resonant frequency, which might help quite a bit OR it could be a problem when the frequency is hit, so a soft compliant material is generally used like vinyl or asphalt to lower the resonant freq. Adding mass means for the material to get excited by the incoming sound wave more energy will be required.... Transmission loss ASTM 90

To lower the level of reverberant noise that still enters is the area of absorbent materials (ASTM 423). This is the stuff we are most familiar with; fiberglass insulation, rugs, foams drapes are all absorbent (the stuff you see in a theater). They generally work best at frequencies over 1000 Hz but by adding a greater thickness it increases the lower end of the functional range. Using expanding foam in hard to get at places is a good trick (while only fairly absorbent it fills air gaps and increases attenuation while adding rigidity. you can use Thinsulate, urethane foams and any one of a number of commercially available products. For the exhaust issue I recommend jute (typically sheets of recycled blue jeans) since it works very well in the automotive environment (low frequencies) and it is cheep. I also use 3M marine sheet thinsulate for the 2000 Hz and up region. Filling ALL the air gaps is fairly important here so be meticulous

As you tear apart your car to make these additions or to run 0 gauge wire you will find damping materials and foams and jute, it is not a coincidence since inexpensive products that work well are in the manufacturers best interest too.

MTT

iTrader: (17)

Thanks for the info, the mat worked well on the lower frequencies of the exhaust, but it's still a little louder than I'd like, I have about an inch thickness to work with, I'll look into your other recommendations, thank you.

crap, just realized that this isn't my thread, I'd like to apologize to the original poster oopsie