llebcire

Thanks for your reply! I believe what he was going for is cost and effectiveness. The fiberglass is ceiling tiles from your big box home store (Lowes, Menards , Home Depot) with the white pebble surface removed then sealed in thin plastic. If I remember I was about $10 total for all materials. I also want to add some deadening to the doors (peel/stick) and work on a few rattles from the door panels (felt). I remember the outside noise reduction significant enough in my Accord Coupe that I may also do the rear doors on this sedan. Seems like my noise comes through the door skins and the rear door quarter glass which this won't solve.

-Eric

Here's some of the other engineer's explanation:

"Ensolite is CCF. it is used for decoupling and mitigating rattles. it is not used for sound absorption and the website is misleading (it doesn't "break up" sound either). i don't use it for sound absorption. i use it to decouple the MLV from the metal, and i use it to prevent the plastic door panel from rattling against the door. it doesn't compress like open cell foam, nor does it absorb moisture.

it's a common misconception that if you put an absorber in plastic it becomes inert. the thickness of the plastic plays a role but the product still absorbs sound - and is much more effective than OCF.

fiberglass batt/ceiling tiles wrapped in plastic is what we use for sound absorption in commercial applications. the plastic reduces some high frequency absorption but boosts midbass absorption (membrane properties). i use a 1mil PVC sheet, so it's pretty thin. thicker PVC sheeting would shift absorption ranges even lower. we don't care about high frequency absorption so it's a win. it's stupid effective and in my opinion is a requirement in any car door. without effective sound absorption - a door is a reverberant chamber. we hear the reverberating rear wave some time later as it comes back out through the speaker cone later. this is why simple music can sound good but complex music sounds worse over time. the PVC sheeting keeps the fiberglass dry, which is important. i'm the only one preaching this method (besides those who have also done it and had the benefit). the comparison is that if you do just one door and listen to the untreated door in comparison - the untreated door becomes unlistenable.

i got the idea while comparing acoustical absorption samples from CMA and realizing we've been looking for a PVC encased fiberglass product. We use PVC encased fiberglass in areas subject to humidity/moisture and we use it above ceilings and acoustical clouds.
http://www.cmainc.net/ProductDetails...productID=1161
http://www.cmainc.net/ProductDetails...productID=1163
Then i came up with an affordable alternative suitable for doors (less than 2" thick). ceiling tiles work better since they are compressed and thinner. compressed fiberglass panels are what we use for sound absorption in all commercial applications. we don't use open cell foam. in professional recording studios we use fiberglass absorption and diffusion and design the room correctly.

if you look at absorption coefficients for faced fiberglass batt insulation (normal stuff used in walls with the paper facing) - when you put the paper facing out, high frequency absorption drops but midbass absorption increases.
if you look at bass traps, they use a membrane. low frequencies lose energy by transferring energy into the membrane - you can think of it as moving it while high frequencies mostly reflect. similar to how panel flex is lost energy.

the denim is a nice alternative to fiberglass and 10x more effective than polyfil. since i can touch it without itching, it's perfect in cavities and i use it in every cavity i can find. it's comparable to fiberglass batt (maybe better, depends on the density of the fiberglass batt).

what my door is missing is diffusion, but i have enough absorption it's more anechoic than anything."

llebcire

I did that in my Accord using Morel separates in the doors, adding a Zapco 5 channel and Audio Control LCQ-1 along with an Alpine 12" Type R in a sealed enclosure. I actually enjoy the sound of the Bose, have never been a Bose hater, and will add a sub, treat the doors, and add a 4.5 Khz 12 db lowpass to the door midrange drivers based on an extensive review of the drivers done on this site. While the Morels may sound better I'd be hard pressed to get the same bass from a pair of 6.75s that I'm getting from the 10s and they're already installed. I'm contemplating using 4 channels of the Zapco to drive the doors but I'm not sure of the ROI. The LCQ-1 could flatten things out a little but its actually not bad.

-Eric

llebcire