Dynamat and other sound deadening products - do they work?

[dephilile]

Has anyone ever tried to use that sound deadening stuff (one particular brand that springs to mind is dynamat) that is supposed to improve speaker performance and cut down road noise? I was looking through a catalogue at work today and came across these to cheaper alternatives to dynamat.

http://www1.electusdistribution.com...keywords=3688&SPECIAL=&form=KEYWORD&SUBCATID=

http://www1.electusdistribution.com...keywords=3680&SPECIAL=&form=KEYWORD&SUBCATID=

I guess my question is does this sort of stuff actually work? If it does what sort of performance increase will it yield?

Also, I was talking to a mate today and he said it would be pointless using this sort of stuff in a newer car (ie. My VT) because they spray some sort of sound deadening paint on the inside of the doors. Is this true?

 

[Tasmaniak]

Ok, the stuff from Jaycar and Electus is pretty good. Not quite as good as Brown Bread or Dynamat but not too shabby either. I've found it too be quite reasonable unless using High Performance gear.

Yes, the VT's did have some sound deadening bitumen paint inside the doors...but nowhere near enough! Well worth the effort of putting it in...IF....you use 3mm MDF and cover the holes in the door when the door skin goes over.

 

[Truk22]

hey there, i am about to undergo a major sound deadening project on my car as i am sick to death of not rattles, but panel vibrations.

the whole idea of sound deadening is to make every panel that has the ability of vibrating (boot lid, doors etc) as heavy as possible. when people say to fill it with insulation DOES NOT sound deaded anything, what is does is stop music reflect, ie so as soon as the sound waves hits a wall it is dissapated, however it still vibrates the panels.

the idea of sound deadening is to make the panel heavier so more sound energy is required to move the panel, essentially make it heavy enough that your sub will not be able to push it and bobs your unle, its sound deadened.

i have been doing a fair bit of research on it and my plans are as follows:

- Body shutz (tar based rust preventative thats sprayed on) the inside door skins, and everywhere in the boot, is is mainly for rust prevention, but it is really heavy and you can spray it on up to 3mm thick and because u can spray it makes it really easy to get in those shitty places like door skins.

- tar based sound deadening mat from jaycar. this stuff i am going to use to cover the holes in the front doors essentially making a speaker box out of the door.

- sound deadening matt. this i am also going to use in the boot along with the body shutz. u can also get this from jaycar but u need a contact adhesive to put it on, i can going to put it along the back where the lights are and in the rear quater panels.

i have priced it all up and i should get away with less than $200 for everything, ofcaorse i am doing it myself so i dont have to pay for labour however if u want your car shutzed, go to a local place that does rust preventing and get a quote.

that took ages to write, anyways, hope this helps
Truk22

 

[dephilile]

Thanks guys

I’ll probably stick with sound deadening matt that you use a contact adhesive to put on and cover holes in the door with 3mm MDF.

Concerning the MDF, do I just put it over the top of the plastic that is in the door preventing moisture from getting into the car? And, is there enough room between the door skins and the metal to do that? I pulled them off a week or so ago to have a look and I don’t remember there being all that much room.

Hey Truk22, do you have a digital camera? Would you be able to take some random photo’s as you go with your “sound deadening project” and post them on here?

Thanks

 

[Tasmaniak]

Thanks guys

I’ll probably stick with sound deadening matt that you use a contact adhesive to put on and cover holes in the door with 3mm MDF.

Concerning the MDF, do I just put it over the top of the plastic that is in the door preventing moisture from getting into the car? And, is there enough room between the door skins and the metal to do that? I pulled them off a week or so ago to have a look and I don’t remember there being all that much room.

if you go with the mat, then I would suggest picking up a can of bitumen spray from an autoshop it's about 10-15 a can. Use it to get all the places in the doors that you can't reach with the mat.

Remove the plastic then put th MDF in...grab your ruler and have a look at 3mm. Do you see a problem? With the VT's there is about 8mm where those holes arre...can still be a tight squeeze but it certainly goes in! I would also suggest trying to do as much of the inside skin of the doors as possible with the bitumen spray.

Hope this helps and good luck as it can be a pain in the arse but is definetly worth the effort. People will ask from miles around where the sub is hidden

Remember, that by doing this, you are virtually turning the doors into a sealed wooden enclosure.

 

[dephilile]

just a couple more questions

1. how much bitumen spray should i use. i mean, the more the better but how much to get a good effect? would one can be more than enough for both doors?

2. if i remove the plastic then i should paint it with some kind of waterproof paint? i could just spray it with bitumen spray couldn't i? do i need to worry about putting the plastic back over the top or will the MDF do a good enough job of keeping moisture out of the car.

 

[Tasmaniak]

just a couple more questions

1. how much bitumen spray should i use. i mean, the more the better but how much to get a good effect? would one can be more than enough for both doors?

As much as you like, but if you use any matting inside the door as well then one can will be sufficient for both doors, posibily four if you were so inclined. If you don't use any matting then you will need approx a can a door. You can spray it on upto 3mm think. Do it a two layers though. One layer 3mm thick and it will have a chemical reaction with itself and start to boil

2. if i remove the plastic then i should paint it with some kind of waterproof paint? i could just spray it with bitumen spray couldn't i? do i need to worry about putting the plastic back over the top or will the MDF do a good enough job of keeping moisture out of the car.

Don't spray the plastic with bitumen...once again...chemical reaction and it will boil melting a hole in the plastic. You don't have to put it back in but I would advise you to do so as it keeps moisture out and also can stop small draughts whilstling through.

 

[dephilile]

Grr, I should proof read what I write

When I said “if i remove the plastic then i should paint it with some kind of waterproof paint?” I meant will I need to paint the MDF to protect it from moisture.

I have decided to go with some 3mm ply instead of MDF because it will have better resistance to moisture and it has good stability in one direction which will help stop it from flexing.

 

[Tasmaniak]

Yes, by all means spray the Ply or MDF with bitumen also try to spray the inside skin of the door as much as possible...it's not easy, I won't even try to say it is.

If you spray the wood then I would suggest spraying it with an auto primer first. This will allow the bit. spray to take to it better.

 

[Rmyers]

Sound deadening certainly does work. I put 6 sheets of brown bread on my front doors, covered both inner and outta door skins. I've also put two focal plain chant pads behind my front woofers. This stuff basically absorbs any sound waves emmiting from the back of your speaker, so that it doesn't rebound off a hard surface back into the speaker (this destroys your midbass). Also sealed up the holes in the frame so that the front of the speaker is completely seperated from the rear, and then layed a foam sound deadening over the whole door to cut out as much road noise as possible. It made a MASSIVE difference to the midbass response, and definately worth it IF you do it properly and not just half arsed.

That spray on stuff is useless and in no way compares to a dedicated sound deadener such as dynomat, brown bread, serenity max etc. It does help in keeping some road noise out, but it will do little audible difference to your speakers compared to the proper stuff. As suggested, only use this stuff in places that you canno physically get to.

Where do you plan on using it?? Front doors, bootlid??? Brown bread is about $50 a sheet last time i checked, and I needed 3 sheets to cover both inside frame and outta door skin per door on my EA falcon, so i'm assuming it'd be similar on a VT, so it'd be roughly $250-$300 to do your doors properly with 1 layer. You can put more layers if you wish, but putting on any more than 3 layers can actually have a negative effect on your sound. More expensive stuff such as dynamat is about $90 a sheet but is alot better quality than brown bread, and 1 layer of this stuff would equate to two layers of brown bread while being roughly the same thickness as a single layer. IMO, Definately worth every $ if your after quality sound...