djresonance

I am planning to replace all of the stock 6 1/2 door speakers with new polk db 650s. After much forum reading, it looks like dynamat is definitely needed to help reduce rattles and improve the sound. But how much do I need to do all 4 doors? I don't want to buy too much because it's very expensive. Do I just need it around the speakers or is it supposed to go over the whole door? Any other pointers?

Bass Mechanic

i would say NONE because dynamat doesnt stop rattles unlike people would like you to think.
a rattle is caused when 2 peices of material touch and vibrate together. to prevent this you can either make the peices stick together or put smthing between them to prevent them from touching.
dynamat adds mass to the metal and helps to prevent sound from being transmitted through it. 2 totally different situations.
dont waste your money on it.

djresonance

Wow! That's good news. Thanks for the feedback.

bma

Not exactly like Bass Mechanic said is true. Rattle sound can also come from the vibration of metal. Audio shop charge $800 for the whole car dynamat. The price is high, so it must do something. I had done about 5-6 cars dynamat. They all come with the same result. The dB (bass) is more solid and louder. It does also reduce some vibration, of course it cannot elimate all. But it helps.

Bass Mechanic

actually im going to compleatly disagree with that. metal doesnt rattle unless it has somthing loose attached to it. if it's securly attached (welded) it will vibrate but just because it moves doesnt mean it will rattle.
the reason the price is high is because there are enough people out there that a good sales person can convince it's worth getting but it will NOT stop a rattle. it can however improve bass responce in a few different ways.

1 because your adding mass to the metal the speaker is attached to. it can't stop the metal from moving but will lower the frequency it will resonante at. this can help to improve bass because less of the speakers mechanical energy is absorbed into the metal.

2 if you dynamat a whole door you can cover up some of the larger holes in the metal frame that allow the acustic energy from the rear of the speaker from interacting with the front. in doing this you can limit the amount of cancellation you would get with any infinite baffel speaker setup.

3 by dynamatting a whole car you can also reduce unwanted road noise which will lower the noise level in the car and improve the listening environment.
to be honest Acura has put enough of it into the car from the factory your not likely to improve on it much

bottom line if you have a rattle your better off identifying the source of the rattle and take a countermeasure to stop it from making noise. i had one in my TSX from the factory it was the passenger window switch trim plate. i stopped the rattle by sticking a small peice of double sided foam adhesive strip between the 2 loose parts and stopped it. all the dynamat in the world wouldnt have stopped that.

i have another rattle where the window and the felt strip along the top of the door will rattle when a good bass note hits just the right frequency. this rattle is because the door panel actually moves enough to hit the glass. the only way to prevent it is to stick somthing between the glass and the felt strip or to reinforce the metal of the door so it won't flex so easy.
if i stuck somthing between the 2 areas the window probly wouldnt go up or down anymore. and i cant reweld a support into the door.
again i know for a fact dynamat wouldnt do a thing for this either.

elduderino

You guys are both kinda right. Sound damping products are not intended to stop rattles (regardless of what Dynamat marketing materials have said over the years). They are intended to change the resonant freqency and the mechanical "Q" of the panel they are attached to, and to thus reduce both the vibration of that panel (different from a rattle) and sound passing through the panel (such as road noise traveling into the passnger compartment).

However... it so happens that if you change the resonant frequency of a metal panel (such as the inner door skin) and/ or change the mechanical "Q" of that panel (which in essence means that you've changes how MUCH it vibrates at that resonant frequency, compared to all the other frequencies) you can very definitely have an effect on rattles in that door (an indirect one, but an effect).

Of course, you just spent money on it, made it heavier, and in the case of Dynamat, made your car smell like a hot-mop roofing project on a summer day... but you indirectly affected the rattles.

I concur that sound damping is alousy way to attack rattles. It's not a bad way to approach reducing road noise and improving speaker sound.

Just a foot square of sound-damping material on the inner door skin of a front door with a speaker mounted in it can make an audible difference in the sound quality of that speaker, by making it a more neutral, less "buzzy" transducer as a whole. Because remember, mechanically, when you bolt a speaker to a door, the door becomes the speaker cabinet... or, in effect, part of the speaker. And home speaker makers go to great lengths to make sure that we don't hear the cabinets resonate.

Bass Mechanic

couldnt have said it better myself

TSXTim

I'm using the material that Circuit City sells, more square foot for less $.

It comes in flat square pieces where I was not happy with wrinkles in
the first roll of dynamat that I used.

I put a dynamat gasket under the speaker and pieces on the outer door skin,
and on the inner door metal. I put strips on the inner door panel plastic.

It works, I highly recommend it. I would say a package for two doors, $15 each is
$30 total for 4 doors. I am always putting more in my car as I go. It takes pieces and strips,not full coverage. I just pulled down the engine hood insulation and did the
underside of the hood, 1/2 of one of these packages, about $7.
It is noticeable quieter in the car.

BTW great choice on the DB650's, you will be pleased.