Order my Damplifier

[mackin 10+ year member]

Well i went ahead and ordered 80 sq ft of damplifier today so i can get that done before i order my actual equipment.

I'm not sure how much i'll need for the trunk and the front doors. If i have extra, should i just do the back doors for fun? will that help with road noise etc?

edit: the title is supposed to say ORDERED my damplifier lol. its 12:30am give me a break..

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[SRim23 5,000+ posts]

Well i went ahead and ordered 80 sq ft of damplifier today so i can get that done before i order my actual equipment.
I'm not sure how much i'll need for the trunk and the front doors. If i have extra, should i just do the back doors for fun? will that help with road noise etc?

edit: the title is supposed to say ORDERED my damplifier lol. its 12:30am give me a break..

doesnt hurt to double layer. when i had extra i just put more on my trunk lid.

 

[mackin 10+ year member]

doesnt hurt to double layer. when i had extra i just put more on my trunk lid.

word. do you think there would be any benefit from road noise if i hit up the rear doors? or would i benefit more from doubling up?

 

[SRim23 5,000+ posts]

word. do you think there would be any benefit from road noise if i hit up the rear doors? or would i benefit more from doubling up?

depends, what car?

 

[mackin 10+ year member]

Millenia S (sig)

edit: i'm off to bed for the night. i'll check back tomorrow

thanks for input so far keep it up!

 

[bigbangtheory 5,000+ posts]

I am doing my rear doors, just because I have plenty of deadener to use. I need to get off my fat arse and get it going!

Also to give you an idea, I did the rear wells, back part of the trunk, sides, and upper part of trunk and lid with 40sqft of damp. Floors in the trunk with fat mat......all in 1 layer. So 80 will go by fast! This was complete coverage though.

Good luck

 

[mackin 10+ year member]

I am doing my rear doors, just because I have plenty of deadener to use. I need to get off my fat arse and get it going!
Also to give you an idea, I did the rear wells, back part of the trunk, sides, and upper part of trunk and lid with 40sqft of damp. Floors in the trunk with fat mat......all in 1 layer. So 80 will go by fast! This was complete coverage though.

Good luck

yeah my buddy got the bulk pack of dynamat extreme and was able to get the front doors, rear deck, and most of the sides of the trunk lol. i think it was 37 sq ft. thats why i went big lol.

i guess i'll start and see what happens.

 

[FoxPro5 5,000+ posts]

Figure 5sqft per area of the door. If you have speakers in the door, then that's one layer on the outer door skin, one on the driver mounting surface and one on the door trim card.

Total for front doors is about 30 sqft. If speakers in back; 60 sqft total.

I wouldn't expect too much satisfaction of road noise attenuation from any deadening mat. 2 lbs/sqft of mass on your door skins will probably result in about 12-14 dB transmission loss at 125 hz. To get to 2 lbs/sqft you'd need about 4.5 layers of DP. If you figure the cost per sqft to do this, it's not as cost effective as other materials that are more effective for the task at hand (ie blocking noise).

Furthermore, transmission loss can be boosted significantly with a spring-mass system that's decoupled from the surface. Deadening mat is coupled to the surface. It's essentially the wrong tool for the job. Pardon the tech-talk mumbo jumbo but it's the truth. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Megalomaniac 5,000+ posts]

word. do you think there would be any benefit from road noise if i hit up the rear doors? or would i benefit more from doubling up?

if you your goal is to eliminate road noise you will need to do a lot more than doors and trunk. You need to find the cause of the issue, which is usually the floor and wheel wells! Start with some damplifier on the floor, wheel wells(from the inside of the car), and as much of the firewall you can do. Then go over it with some Luxury Liner(vinyl barrier pad, this will be the thing that get rid of the noise(high freq): the damp just stops panel vibration and blocks lower freq noises), then use the aluminum tape and tape the edges of the luxury liner all around down, if you dont do this the noise will leak around, this is a crucial step! Luxury liner is thick so beware with the combo of 2 thick things you are using under the carpet(liner and damp), its going to be a challenge putting stock carpet back.

btw on your doors make sure you put a deflex (speaker tweaker kit) pad or some Overkill(if you have any left over) behind the mid, this will stop standing waves(well some), it makes a ton of difference....I am assuming yours speakers are in doors.

 

[FoxPro5 5,000+ posts]

Overkill behind the mid, this will stop standing waves

Not a chance in hell, sorry. Please don't do this, people.

 

[Megalomaniac 5,000+ posts]

Not a chance in hell, sorry. Please don't do this, people.

it made a dif to me, before the mid wolud kind of bounce back like a clank every time it played with midbass heavy tracks. I put some foam behind it and it went away. I have seen other installs with the same experience.

edit: but i understand what you are saying, with the deflex pad it redirects the wave and the overkill wont, however the overkill did soften the blow..

 

[audioholic 5,000+ posts]

Im a big believer in getting a full single layer throughout the vehicle before I start double layering. Ive always believed in creating a sonic barrier. I dont even like leaving small gaps between pieces of mat. I see people double or even triple up sound deadener mat, with bare sheetmetal all around it, and I just shake my head.

 

[FoxPro5 5,000+ posts]

it made a dif to me, before the mid wolud kind of bounce back like a clank every time it played with midbass heavy tracks. I put some foam behind it and it went away. I have seen other installs with the same experience.

Ok, sweet. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif Not saying what you did didn't work. But, 1/8" close cell foam cannot absorb anything at all really. Depending on it's porosity and the angle at which the sound waves hit it, it MIGHT be able to diffuse higher octave frequencies (like 10k + due to their wave lengths) and therefore eliminate them.

If you're talking absorption, you're talking about changing sound energy to heat. If there's no matrix for the sound to try to "fight" through, then this is not what's happening. Absorption is particle-velocity dependent. That means, the higher the particle velocity, the greater the phenomenon. Since the foam is basically right next to the driver (where particle velocity is low) absorption is very limited.

If you're talking diffusion, then that's what Deflex Pads do. Close cell foam is also a diffuser in some cases, but it's main benefit in a car is for thermal applications (blocking cold/heat) and/or acting as a mechanical isolator/decoupler. This is why closed cell foam is the material of choice for something like Luxery Liner Pro.

If you're talking blocking, you main concern is mass. Search: Mass Law

If you're taking damping, you're taking change in elastic modulus: Search: hysteresis or hysteretic damping

 

[Megalomaniac 5,000+ posts]

Ok, sweet. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif Not saying what you did didn't work. But, 1/8" close cell foam cannot absorb anything at all really. Depending on it's porosity and the angle at which the sound waves hit it, it MIGHT be able to diffuse higher octave frequencies (like 10k + due to their wave lengths) and therefore eliminate them.
If you're talking absorption, you're talking about changing sound energy to heat. If there's no matrix for the sound to try to "fight" through, then this is not what's happening. Absorption is particle-velocity specific. That means, the higher the particle velocity, the greater the phenomenon. Since the foam is basically right next to the driver (where particle velocity is low) absorption is very limited.

If you're talking diffusion, then that's what Deflex Pads do. Close cell foam is also a diffuser in some cases, but it's main benefit in a car is for thermal applications (blocking cold/heat) and/or acting as a mechanical isolator/decoupler. This is why closed cell foam is the material of choice for something like Luxery Liner Pro.

ok I threw the term out "standing waves" too loosely, my apologies. I still recommend he put some sort of absorption material behind the mid if he doesnt have that deflex pad.

thanks for the tidbit fox!

 

[FoxPro5 5,000+ posts]

ok I threw the term out "standing waves" too loosely, my apologies. I still recommend he put some sort of absorption material behind the mid if he doesnt have that deflex pad.

thanks for the tidbit fox!

The term "standing wave" gets thown around very loosely. It's not my job to tell you that you're wrong and that you're an idiot, it's to demonstrate that it's not possible in that case. A simple wave length calculator will tell you all you need to know. And the laws of physics don't change for car audio, which is unfortunate for a lot of manufacturers of "sound deadening" products.

Only thing I'd recommend in my experience is to make the most rock-solid "proper" baffle he can to completely separate the front and back waves.

Once done it should do the trick, but possibly something like a Deflex Pad (Cascade Audio product which is often used like "Windex" or "Kleenex") for insurance purposes, I guess. In a blinded experiment, I'm not so sure he'd be able beat chance whether a diffuser pad was there or not. Just my $.02, don't read all into that and stuff. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif