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Discussion Starter · #1 ·
Hey, I read your webpage about your 855R. Can you hear the engine/exhaust note coming from the back? If you can, that means the things you put in the tailgate doesn't work. What they sold is is probably sound "damping", which is to stop the metal vibrating thus generating noise. However the noise that comes from the back is mostly road noise and exhaust note. You need sound absorbing/reflecting materials there for that.<p>ahh where is your topic for the IPD strut brace, I wanna read it again <IMG NAME="icon" SRC="http://********************/smile/emsmile.gif" BORDER="0">
 

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Re: sound proofing #2 to KaiZai (xtremepsionic)

I think it helped with road noise a little, but it is still going to be coming from right below that area (spare tire) and on the sides. I have not done these areas...yet... <IMG NAME="icon" SRC="http://********************/smile/emsmile.gif" BORDER="0"><p>I had a topic for a strut brace?
 

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Re: sound proofing #2 to KaiZai (Kaizai)

I remember you talked about it when you just got your 855 R <IMG NAME="icon" SRC="http://********************/smile/emsmile.gif" BORDER="0"><p>hehe<p>I think most of the road noise is coming from near the wheel wells and also from the weather seals, dunno what I can do about those...
 

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Re: sound proofing #2 to KaiZai (xtremepsionic)

sorry to butt in guys, but I have quite a bit of experience in this area. My main thing is really car audio, car mechanics and performance come a distant second. Sound dampening material will help a little with road noise and exhaust noise, but you are right, it cant eliminate it. What it will do is stop the panels from resonating at the frequencies of the exhaust and road noise and thus increasing the noise in the car. It does this by adding mass and then lowering the resonant frequency to an inaudible level. Materials that make good isolators are often refered to as either mass loaded Vinyl-not great but cheap, or Lead-the best. If you see any dampening sheets that have a lead isolation level, that will do the most to isolate to distinct areas, such as the outside and inside of the car. In my car I have sticky backed lead sheets on the sheetmetal of the car around most of the floor, the firewall, and the transmission tunnel. Yes that will add a lot of weight, I think I have added around 50 pounds total in dampening material alone in my car, and that may very well be a major underestimate. I then followed this with a spongy acoustic foam. This is really the only way to absorb sound, through a spongy acoustic foam. The carpet pad in the car basicly does the same thing, but I have not found it to be nearly as effective. I actually removed the carpet pad and replaced it with two layers of acoustic foam. Measurements taken before and after the aplication of the dampening material showed a 25 decible drop in roadnoise. Now my biggest problem is trim pieces ratteling, the glass of the car, and tire noise. I am yet to be able to completely remedy these problems, though I have some ideas to try out.
 

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Re: sound proofing #2 to KaiZai (pj's 850)

WHAT?<br>25 DB?<p>nooo way...<p>are you kidding me... how did you measure it?<p>a lexus 430 isn't 25 DB quieter than my car at 70mph...
 

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Re: sound proofing #2 to KaiZai (xtremepsionic)

don't mean to accuse you or anything, maybe your finger just slipped <IMG NAME="icon" SRC="http://********************/smile/emsmile.gif" BORDER="0"><p>2 DB would be good by my standard, according to C&D a BMW 540 @ 70mph does like 67 db, a ford mustang Mach 1 or whatever goes at 73db.<p>its only 6 db but each 10 DB is 10 times louder. so 6 db thats quite a bit louder..<p>if you said 25 db thats like a few hundred times quieter <IMG NAME="icon" SRC="http://********************/smile/emsmile.gif" BORDER="0"><p>I would be really happy if I got like 2-3db quieter... I think my car got 1db quieter (guess, I'm too cheap to buy a sound meter) after my sound "mods"
 

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Re: sound proofing #2 to KaiZai (xtremepsionic)

Yeah, sorry, I dont know were I got 25 decibles from, that was way off. I was like, maybe I read it wrong or forgot the decimal. Anyway, I got the sheet back out, I did get a major drop, it depended on the area. Oh wait, hehe, I reading while I write, now I see, I got a 25 decible drop at 15-20khz. For the most part, you can much more easily antentuate high frequencies over low frequencies. The averaged A-weighted drop was 6 decibles from 20hz-20khz. Thats not bad really, I havent heard of many able to do much more than that. from 20-50hz there really is only about a 2 decible drop, there is a few resonant spikes from things like I assume the exhaust and transmission that I noticed, along with a few7-10 decible drops in the midrange area. Actually, when I had window tint applied to all my windows I realized a consistant averaged 1.2 decible drop-again averaged. Oh, as for how I know the exact frequencies, I used an RTA for my tests, I basicly was just recomending an SPL meter to others. I do recomend you get a radioshack spl meter. I think they start at 30 oe 40 dollars, and are very needed for proper stereo setup. No shop can install and setup a system properly all in the time of one appointment. I have been involved in Tuning Iasca cars for a couple of years, and when we go about it, we usually spend about a week or so with the car. What Im saying is that you will get much better performance by spending time tuning the system as it breaks in, you get used to its qualties, etc. An Spl meter and a multimeter are essential tools in any tuners tool box, er whatever we are called. I hope that clarifies things, and It hink I know what I was thinking when I wrote 25 decibles. Oh, I must say, the aftermarket deadening materials I mentioned using are far superior to anything used in a car OEM, and will reduce the SPL levels more intensly than any OEM setup will.
 

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Discussion Starter · #8 ·
Re: sound proofing #2 to KaiZai (pj's 850)

>decibles from 20hz-20khz. from 20-50hz there really is only about a 2 >decible drop <p>I see, yeah low frequencies are hard to block out.. So you redid the entire floor with the "lead" sheet and 2 layers of foam? I might look into that, kinda expensive to get that much tho. Did you cover the trunk also?<p>What about wind noise? I can't think of anything to add to the weather strips...<p>Did you sound proof the doors also? I think most of the road noise in my car is coming from the doors more than the floor.<p>>Actually, when I had window tint applied to all my windows I realized a >consistant averaged 1.2 decible drop-again averaged. <p>ReallY??? Gotta get my windows tinted! I wonder why.. is the window tint absorbing some vibration from the window? Or blocking out something there?
 

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Re: sound proofing #2 to KaiZai (xtremepsionic)

Ok first, Window tint, or atleast mine, I think all, is made with a metal substrate to get the color. The tint is actually pretty dense and heavy given what it is. By adding it to the windows it is sort of making a constrained layer on the window. So basicly its like adding dampening to the windows, not very good dampening, but dampening. <p>As for the doors, I did the doors also. I guess I should have mentioned that, or clarified that. I did the whole car. Floor, doors, roof, as much as I could get. I didnt use two layers of foam everywhere, infact only under foot. I used different kinds of foams and materials in different areas also, but that was basicly how it was done. For isntance, there is no lead on the roof and not really any foam, just a aluminum backed dampening material with the stock absorption put back over it. As for the rubber seals, I treated them all with a rubber rejuvinator once, but basicly I didnt touch them. I dont know what you could do there either, you think they are a problem too. I really havent given them much thought, they seemed pretty robust, so I always assumed that everything I had left was basicly not going away or was from the windows, and still likely not going away. <p>They should make audio grade windows as an aftermarket option for cars, they could be like double payned or something, made specificly with car audio in mind. although of course they wouldnt make them for volvo, they never make that stuff for volvo's. Maybe an audio grade window tint with enhanced dampening properties. <p>Oh yeah, one thing to watch out for, get your priorities straight. Dampening adds wieght, lead is very heavy. I used it as sparengly as possible, but still needed to cover a good 85% or so of the floor of the car. Adding lots of dampening material could easily add a few hundred pounds in weight, and that will hinder performance.
 
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