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Discussion Starter #1
Figured I'd post here since I just installed a new system
(Massive audio CK6X, Eclipse 3640, Stinger Roadkill sound deadener).

Quick version, TlDR: put sound deadener in through the speaker holes.

Long version:

Most of my info comes from the wonderful Sound Deadener Showdown | Your Source for Sound Deadening Products and Information

He mentions four ways to deaden sound in a car




  1. Control vehicle component - mostly panel - vibration and resonance.
  2. Block air borne sound.
  3. Decouple objects that would otherwise transmit vibration or make noise themselves by making intermittent contact (rattles).
  4. Absorb.
Theory: It turns out that you only need about 25% coverage with sound deadener to get the results you need for #1 , and the most resonant areas are the metal parts of the door. Sound deadener isn't actually very good at blocking the other 3, though our Mazdas are designed very well to block airborne sound (#2), and that turns out to be the problem.

Our cars are very resonant, tap on the outside door panels and you'll hear them sound tinny.

Almost every how to I've seen has involved removing the inner door skin (the plastic part that's underneath the main door trim that actually blocks a lot of road noise).

However, it turns out that when you take the speakers out, there's enough access through the speaker holes to get the required 25% coverage and then some. I mostly applied mine along the bottom of the door panel, though I managed to get a few pieces on the top (there's actually a very small piece of what appears to be factory sound deadener near the top). I also put some sound deadener along the reinforcement bars on the inside of the door.

Results: When the bass hits (I don't have a sub but the massive's have some pretty intense excursion) the doors no longer rattle or sound "off", and it only took about a quarter of the material most people use, with (IMO) better results because I targeted the resonating metal, not the mostly benign plastic.

Of course, it would be better replace the inner doorskins with mass loaded vinyl, and I still have yet to address the back doors or the rear deck or the headliner (which all have their own unique rattles and could probably benefit from closed-cell foam in addition to sound deadener). I'll make sure to take some pictures when I do the rest.
 

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Where'd you get the sound deadener? And what's closed cell foam and how is it different?


Sent from AutoGuide.com App
 

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Discussion Starter #3
I used Stinger RoadKill sound deadener, which is a butyl based vibration damper, like dynamat (much better than asphalt based peel-n-seal/fatmat) but much cheaper. The main purpose of it is to stop metal surfaces from "ringing" or resonating. Closed cell foam is actually the stuff they make yoga mats out of (considering cutting one up for some deadening), it's mostly useful to stop things from rattling against each other (plastic or metal)
 

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I did this today. I had recently installed infinity 6.5 splits in front doors of 6 gen1.
The bass was horrible, alot of reverb. Tracked down door panel as being the culprit.
Ripped the door skins off, the glass out and got to work, silicone and rubber matting.
Worked a treat, 1 tube of silicone per door, 3/4 on ribs, 1/4 on sheeting.
Bass is some much cleaner and deeper, plus less road noise when you have audio off.
I will attach pictures and vid of the sound difference between non deadened area.
The difference is virtually replicated in speaker sound, use to be tinny, now solid.
20191114_093742.jpg
20191114_102151.jpg
20191114_105907.jpg
 

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