|13th October 2012, 01:23 AM||#11|
Join Date: Nov 2003
Location: Brighton UK
If you have enough dynamat to do the whole vehicle fair enough.
If you have enough foam to do the whole vehicle fair enough also.
Given your going to do that, generally I'll note few possibilities
given when I did the rooms I was making it up somewhat,
but based on sound (sic) physics and acoustic principles.
Covering your doors with rubber backed carpet (floormat)
or bitumen sheeting, (glued to the metalwork) should make
decent lower frequency absorbers, (no hardboard).
The roof of the van look at cars, a non rigid porous headliner
for general absorption, noting it does not really absorb treble
that much (in cars that is done by the floor carpets mainly).
The floor I assume is going to remain carpet. The rest of
shell I can't really see, including the spar arrangements.
I'd suggest bitumen sheeting / rubber backed carpet for
the the lower individual section, and varying the number
of layers 1, 2 and 4 to spread absorption frequencies.
For the top half sections peg board, again open, 1/2 the
holes covered and 3/4 of the holes covered for individual
panels to spread the absorption characteristics.
Everything does not need to be covered in carpet, what you
really want is an approach that addresses different frequency
ranges and no common frequency ranges for more even Rt.
Simple fact is, depending on you ambition, there is no easy
answer to achieving good small space acoustics, and at
best I'm steering you towards something better.
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow
Last edited by sreten; 13th October 2012 at 01:31 AM.
|13th October 2012, 05:11 PM||#12|
Join Date: Jun 2009
If you have enough mat do all the sides and the roof. I also used Scosche AMT-250 on the floor and and as far up the firewall as I could get. The AMT-250 is a barrier as opposed to a deadener. I also used it over the inside of the wheel wells to reduce tire noise (2001 Honda Odyssey). I used AMT-750 between the hood and hood liner and also on the engine side of the firewall.
I used a rubberized spray undercoating on the outside of the wheel wells (after obviously removing the factory coverings etc).
You might check out the Owens Corning website. Some good stuff on sound absorbtion there. I used their "black acoustic blanket" in several areas. Unfortunately the last time I checked it was only available in huge orders. If you use fiberglass of any kind I'd suggest spraying the faces with spray glue and allow to dry so that you don't end up with small loose fiberglass in the van. Not good to inhale that stuff.
|13th October 2012, 06:12 PM||#13|
The other thing to consider in all this is how much mass you are happy hauling around in your van. Mass costs gas and as a previous VW T4 surf-van owner I know the difference in cost between an empty and a treated van with respect to MPG. If you don't intend to put subs in the van you can get away with lower mass damping, EVA foam sheets siliconed to large panels will kill a lot of noise and it weighs a lot less than Dynamat.
Experience tells me that stuffing rockwoll or similar into cavities does very little, you need to damp your panels and pay particular attention to your bulkhead panels under the dash and wheel arches. killing off road noise is key.
best of luck.
hoping to pick up some things.
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