Dynamat and my sealed box

[merlinski]

I'm building a sealed box to house 2 IDQ12D4V.2's. The normal sealed box volume for these subs of the IDQ site is .85 cu. ft., which is the volume I'm looking for. I'm building a trapezoidal box with these dimensions:

slanted wall: 15" tall
top: 4.818"
bottom: 8.798"
rear wall: 14.489"
depth: 14.836" per sub
angle of tilt: 75 degrees (15 off vertical)

I know these figures are insanely precise but I want to be as precise as possible. I have a few questions. First, would it be better to seperate the two subwoofer chambers, with each having a volume of .85 cu ft, or to make one large chamber for both subs with a volume of 1.7 cu ft?

My other question is regarding the material. I know I'm going to build it out of MDF, but I'm thinking of going with two sheets of 3/8 inch MDF with a layer of dynamat sandwiched in the middle. I'm only going to have my current car for 2 more months, so I don't think it's worth dynamatting the interior. The interior SA of the box is 10.95 sq. ft.

Is it a good idea to use the 2 sheet and dynamat construction, or will this just be a waste of dynamat?

Also, for this project, would it be better to use ordinary dynamat or dynamat xtreme, or something more obscure like dynaliner or extremeliner?

[negativezeroz]

y would u put dynamat inside the box? to get vibration down?

[jujumantb]

Two chambers is always better, though not necessary, dont use dynamat like that. Dynamat is a vibration dampener, it adds mass to the panels you put it on to stop vibration, it can also insulate the sound from escaping through it the same way. There is no reason to use it in any way in the construction of a box.

[merlinski]

Two chambers is always better, though not necessary, dont use dynamat like that. Dynamat is a vibration dampener, it adds mass to the panels you put it on to stop vibration, it can also insulate the sound from escaping through it the same way. There is no reason to use it in any way in the construction of a box.

That's the reason I want to use it in the box - to stop resonance from interfering with my sub and to stop the vibration of the box.

[jujumantb]

Your box wont vibrate if build correctly and you dont have to worry about resonance with subs. Standing waves is one thing it could help with but that is only if your box is a perfect cube and even then its been argued by extremely intelligent people that standing waves have no affect on bass.