Currently i am sound deadening my doors and i have 1 layer of dynamat extreme on the outer skin of my doors, and i was wondering if it would be benificial to put on another layer before i seal up the inner skin and cover that in sound deadening. the install is going into a holden commodore ute and i am trying to make it a super SQ install. any opions?

also what other sound deadening could i do to the doors besides focal plain chant, for a sq oriented car? maybe some foam between the door trim to cancel out any vibrations and stuff like any suggestions would be great.

ohh by inner skin i mean the part where the speaker pod mounts onto the outerskin is dynamatted in this picture the inner skin has no dynamat on it...

Click to view attachment

Cheers, Grant

P.S. Not sure if this is in the right section but it is for a sound quality install so i thought it had some relavance, mods feel free to move it if you don't think it is in the right section.

as many as you can afford, would be my simple answer
anything more than 3 layers, inner and outer, is probably not going to yeild you any significant benefits, but i think 2 layers definitely if u can afford it, and 3 if u really want to do it REALLY well.
also remember you have to be able to fit the door trims back on, can get a bit hard with some cars even with 2layers of SD

it might be worth just doing 2-3 layers around the speaker mount, and behind the speaker, with other areas having just 1-2 layers?

Id also line the inside of the door with a closed cell foam

+1 on 2/3 layers.
+1 on closed cell foam.
Also plenty of SD on the actual speaker baffle itself. Which is often forgoten. I also suggest if the door card allows, cavity size etc, the biggest possibel baffle you can get in there. I've read up on a few cars that with a large baffle; returning some very credible/improved results. That is the piece of MDF that the actual speaker mounts to. The bigger, the better. Its not directly related to sound-deadning however it will need to get done more or less at the same time.
Also dont forget about similar treatments to the rest of the car; floor, roof, boot, behind the dash, firewall, inside the wheel weels etc.

Ever wondered why PA bins use such large front baffles gains to be had my freind gains to be had


Wheel arches and transmission tunnels allow heaps of noise in. Also using rubber over synthetic bushes is always better for sound quality.
treating the firewall with foam is better than dynamat.

allready done the floor and back wall, don't have a boot as its a ute. , will look into the wheel arches seems like a good idea. have plans to do the roof aswell with dynamat and some foam to block some heat. also put a little bit of SD on the firewall

2 layers sounds good for the inner skin and one maybe two if it fits on the outer skin. with the baffle i have some pods i am going to modify and make the baffle go all the way to the inner skin, so it makes the door pretty much an enclosure for the mid basses.

i will start up a install thread soon in the next couple of weeks, it should have some cool looking inovative parts to the install with some great gear. just hope its going to end up sounding great aswell.

would some dynamet extremeliner work well on the fire wall - its a lead sheet with neoprene on one side and some dense foam on the other? here is alink for some information

http://www.dynamat.com/products_car_audio_extremeliner.html

Cheers, Grant

1 layer done correctly is plenty.

3 layers is a waste of money and time.

yeah i doubt you would need a hell of alot on a VZ.....maybe a 2nd layer on the outer skin but as Fudd said 1 layer should be enough

on the inner skin i think you main goal would be to make an encloseure out of the door - ie sealing it up

if you really want to go all out......look into the hood (bonnet) liner and the stuff they use for firewalls for that too to keep out and unwanted engine noise

then maybe even look into some of the spray on/paint on deadener for under the car

Do you want it to be quite while driving or mainly for comps and such where the car is off, and not moving?

In my VT commodore (not sure if the door skins/trims are still the same in the VZ) I put two layers on the outer skin behind the speakers, all the way across the skin and right up to the intrusion bars. Above the intrusion bars I just put one layer. If you can get some sort of blocker in there too (i.e. thick but malleable ally insulation, similar to the aluminium backing on the dynamat but way thicker) you'd stop some more noise getting in/music getting out of your doors.

edit: those speaker postions are very different to the VT's, do two layers ABOVE the intrusion bars in your case, since the speaker is up high (WAY better sq position by the way).

Check all of your seals too. I know it's not an old car, but if any of them have cracked or started to go hard, you'll need to replace them.

I would l like to get the car quiet for driving i know it won't be perfect but hopefully i will kill a bit of sound.

For the doors i put 2 layers on the outerskin and 1 layer on the inner skin after sealing up all the service holes, and put some focal plain chant behind the speakers, there has been a fairly big difference in the music and the sound of the actual door(no tinny sound when you knock on the door) even know i'm still running stock at the minute.

now the doors are dead ill move on and get back onto my a-pillar and dash pods. ill continue deadening a few more places like putting some extreme liner on the firewall and doing the wheel arches later on after ive done the pods.



The speakers arn't up high??? they are at the bottom of the door...

Cheers, Grant

the real question is "how long is a piece of string?"

if i may humbly request that someone explain the theory behind this please?

A piece of string is twice as long as halfway....

and this topic hasn't got any thing to do with the length of string because i gave the question substance and a senario so if you gave a piece of string a senario and substance like i need a piece of string that will reach around the circumference of a circle that has a diameter of 5cm how long will the piece of string need to be? The answer is quite clear, the string will need to be pie X the diameter which is 3.14 x 5 which = 15.7cm thats how long the peice of string is.

nuff said, please keep to constructive advice in this thread please...


Cheers, Grant

Joe Peeps,

i would like to learn about this aswell. would be a handy thing to know.


Cheers, Grant

Acoustic loading.

Baffles that are suitably 'large' in comparison to the wavelength being emitted get the benefits of firing into a 2pi steradian space, and therefore the 'spherical' disturbance folds over onto itself and is emitted (in phase) as a half sphere.

Good baffle loading also prevents the rear wave from 'leaking' through, and therefore causing phase cancellation with the front wave.

You'll tend to find Bins have such large baffles to prevent a baffle load drop, where the volume of the acoustic wave drops because the baffle isnt big enough to support 2pi steradian loading (half space) and the disturbance equates more to a 4pi steradian load (full space). This will happen when the frequency drops (and wavelength increases). The result? a 3 to 6dB drop in the volume as the frequency moves below a certain level.