Sound Deadening

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Sound Deadening

Post by Drift_Instructor on Sun 22 Apr 2007, 3:23 am

Hey guys,

Sound deadening the front doors improves the mid bass from your speakers by a lot. And i mean..a lot. It's definetly worth doing. People buy $300 + speakers and think they're getting they're moneys worth just putting them in and amplifying them...theyre not. IMO if I had a $300 budget, i'd be spending it on $150 speakers and $150 on sound deadening and installation in proper pods, which will sound MUCH better than just whacking some speakers in.

You'll be amazed at how much bass is coming from your front splits and not your sub.

Sound deadening adds weight to the panels..When something reaches its natural frequency, it starts to vibrate. Making it heavier, reduces its natural frequency...that way it can go lower without vibrating, thats what we're trying to do.

Sound deadening is not hard, if you screw up, it doesnt matter, you cant go wrong in other words. Unless u apply the deadener to the window or something, your still making the panels heavier. If you do it properly however, it will be worth its rewards in the end.

Thanks to Chef_32 who helped me with all this.

Materials I used:

- Sound deadener (I used Gspot serentiy Max + 1L tub of Gspot sound deadener paint)
- Defusers (I used Gspot fleximax ones also called wave breakers. see pic.)
- Grease cleaner (Prepsol, or Amonia based cleaner, or engine degreaser)
- 3mm sheet of MDF (or 6mm)
- Duct tape
- Electrical tape
- Stanley knife
- Scissors
- Paper (or cardboard)
- Jigsaw (or handsaw)
- Paintbrush (cos i used gspot paint, if you dont, u dont need it)
- Spray paint can ($2 stuff, or some sort of paint)
- A hot day (or a heat gun..i dont have one)
- Patience!


Step 1 :
Before you start, ensure your window is FULLY up.

Leave the sound deadener in the sun for a while (including wave breakers). It helps soften it and makes it flexible for you later on..(use heatgun otherwise)

Place sticky side up so it absorbs most of the heat.

Remove your door trim. Few screws and clips, shouldn't be that hard.

Step 2 :
Remove your speaker pod from door.

Step 3:

Undo all brackets and clips, making a mental or physical note of where these screws and clips go. You will have to put them back later on..I took a picture before hand so i can double check.

There is a plastic sheet over most doors, it is a vapour sheet/sheild and is there to stop the mouisture from getting to your door handles and electrics and such. Because you will be sound deadening the door, the deadeners provide some resistance from the water moisture, so you can completely get rid of this sheet.

Just peel it off, the glue is a bit messy in some cars (not in mine however).

Step 4:

The door lock rods are a source of rattle. These thin bits of metal can be deadened simply by wrapping electrical tape around them. Wind it nicely and you'll have a heavier rod. (Sorry I forgot to take pics, ill take them when i do part 2)

Step 5:

Clean the inner door skin. You have to put your arm fully through the service holes to do this. Its hard to do, but do as much as you can. The inner door skin is the source of many rattles, it is very thin and we want to deaden it. It needs to be cleaned thoroughly of grease (as theres quite a bit of dirt there usually). Use some prepsol or degreaser and spray it on, and wipe it off. Get to as many of the areas as you can. Give a wipe over the side intrusion bars aswell.

Step 6:

Now you can start applying the deadening to the inner skin. First start off with the wave breaker. You need to put this directly behind where the speaker will sit. Squeeze it behind the electric window rail, and wrap it around the side intrusion bar. The bar position there is not ideal but what can you do....the breakers will still be very efficent there despite this. Wrap it around and make sure its stuck as best it can be. Positioning this breaker nicely will give good results.

Now apply the rest of the deadening to the inner skin. I cut up the sheets into more managable quaters (stanley knife). With the quaters, put your arm through the service holes and try and cover as much of the inner skin as you can as possible. (I went behind the side intrusion bars (cos i would use the paint deadener on the bars). see pic). Its very hard to get the whole skin covered, but try to get as much coverage as you can. The more the better. If you have ample deadening, do another layer. Firstly clean the already applied layer the same method as before, and repeat.

Next I used the paint deadener for those harder to reach areas aswell as to overlap the matting and any bare spots missed. I also did the intrusion bar with the paint deadener. The paint deadener solidifies into a harder material which has acoustical properties. It is to be noted that the products im using have acoustical properties and simply do not add weight to the panels unlike some others sold at shops for cheaper prices.

You have finished deadening the inner skin.

Step 7:

Those holes you used before were left there as service holes to service the electric windows and other mechanisms if needed. These holes aren't very good for our use as we want to keep the sound waves trapped behind the speaker as much as possible. It is this volume of air that is pushed by the speaker to create sound. We wish to block this gap as much as possible (particularly near the speaker) but still be able to remove it if needed.

Take a bit of paper or cardboard, and put one arm into another service hole, and hold the peice of paper behind another hole and trace it with a marker. The trace need not be precise at all. This is a stencil so cut it out and trace the paper or cardboard cut out onto the MDF. The final result is as shown.

Cut it out with a jigsaw or a handsaw, remember it can be rough, it doesnt matter too much. I didn't even bother using a bench or clamps..just cut.

Next use your spray can to paint the MDF peices (both sides). The MDF needs to be painted as it will go over the service holes but the paint gives it moisture protection. MDF alone will absorb the water. (There isnt that much water going there its mainly moisture...if there is lots of need new seals).

Step 8:

This isnt necessary...but it helps.
This can be done last, but I did it as I wanted to finish my paint off and throw it away as it was hardening up. Start deadening your door skins. The door skin is a flimsy bit of plastic. It helps putting more weight on it, but its not as necessary as the outer and the inner skin. Thoe other 2 should be a priority...this I'd leave if you dont care about it. I just had left over paint so gave it a layer or 2. Once i buy some more deadening sheets, i will go over it again. (Probably not, i'll forget...)

Step 9:

Now that the mdf peices are cut, use the duct tape to secure the mdf peices of wood to the holes. If you put quite a bit on it should be secure enough for u to push lightly with your hands and it wont budge. Do this as shown in the pic:

Do this for all the large holes you have cut mdf out for.

Step 10:

Now we can start to sound deaden the outer skin.
Again i have used smaller manageable quaters and basically all you do is apply it on as before. But now there are so many holes etc, just use a stanley knife and roughly cut the required holes for bolts and ur clips. Remember there are heaps of holes and u just need the small ones for your clips to show through.

To save time, you can flip the quater over, and cut the same stencil on another quater for the other door. It will be the same just mirror image.

Step 11:

Clean as before and now stick the peices on the door. Remember the door skin is very curved, leaving it out in the sun or heating it up will make it more flexible. Start from one side and rub it in deep so it sticks. It will stick very well. If you've used a heat gun, use some sort of tool otherwise it'll prolly burn your hands .

Try to get as much around the speaker as possible, this is where the most rattling will be.

If you have thin pods or rattling pods, take the speaker out and attach it to door first, then sound deaden that too. I haven't done it for mine.

Again, if you have more deadener go for more layers.

Step 12:

Remeber those doorlock rods you covered in tape? well now when you attach your locking mechanism most likely it wont work. Its designed to be a tight fit (see pic) so you will have to get your stanley knife and cut away some of the tape in the fitting region. See pic.

Step 13:

Finish up, make sure everything else is put on and works, ie. door locks. Put the trim back on, and go admire how much more bassier your speakers are! Go back to your amp and retune it as im sure it will go much more without distortion.

Thanks to NAV2K
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