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Discussion Starter · #1 · (Edited)
Very interesting discovery in my WRX: started to deaden today... had to temp. stop...

Well the basic install is in & playing, sounds very good for 5 speakers total (6.5 components & sub)... so I had a nice day, figured I would get the roof deadened use the day productively.

Anyway... I Head out to pull the head liner & decided I would take the Coustic RTA 33 & hook it up take some baseline SPL readings & do a real comparison.

77db : idle in my driveway 900rpm. Stereo off, windows up, a/c fan on 1
88db : 35 mph in 3rd gear, stereo off, fan on 1 :surprised:
97db : 70 mph in 5th gear, stereo off, fan on 1 :eek:

HOLY road noise batman... I knew the car was noisy, but that's insane.. with stock exhaust no less!

I had to run to town for a couple thing for the Mrs.. I had the hatch area, JUST the floor & spare tire are cover removed 70mph went to 102db!!! that hatch floor is like a vibrating drum....

So... new plan... I am going to this in stages. Roof first... take new measures. Then the rear hatch area, more measuring, then the rear doors, finally the front doors.

Once my new carpet arrives the final measure will be with the whole car 1 layer of peel-n-stick.

Then... when my materials for the headliner arrive, I will drop the Headliner again (luckily its very easy to do) I will add some barrier layer to that... & then eventually I might do a barrier on the floor too...

The goal is to get the car closer to premium car standards . aka mid to low 50's @ idle & 65-70db @ 70mph.

Right now, the sub & midbass are GONE on the highway... I mean GONE...

So the challenge is on... can I shave 20db with logical deadening choices? How far will I have to go to get there?

Should prove interesting...

Rob
 

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The plan for my hatch. In the spare tire one layer of damp and one layer of VB3.5. I just used this stuff on a friends car/ rear wheel well, trany tunnel love it. I knew 60% or so of my road noise came from the rear of my hatchback. Lots of glass, no trunk bad combo.
Wayne
 

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Im not sure about 20 db, but with the extensive deadening in my car i use to have to have my bluetooth on full volume and it would be difficult to hear while driving 80 mph on the highway.
Now that im done full volume is over powering, i now have it it 1/2 volume and dont have any difficulties hearing.
 

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Yeah. My car is at 90db at 70mph on a low-noise stretch of road on the freeway. Hence, why I want to do the whole car. I'm tired of my system competing with external noise.
 

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Discussion Starter · #5 ·
Yeah... I don't know where I will end up with final db levels...

I don't have $500+ to spend on deadening & its STUPIDLY expensive across the board...I spent all day yesterday comparing every product out there & no matter what its $200+ minimum to join JUST the Peel-n-Stick club... THEN another $200 or so minimum, with the good-guy hook up for a Mass Loaded Vnyl Barrier of some type or a foil/cotton barrier, either one.

I was telling Genxx yesterday, that the WRX has, literally, carpet that is like the green fake grass you put on your patio. No backing, no jute, NOTHING under it except steel & about 5 randomly placed sound pads... that's it... nothing on the [email protected] the firewall, & a minimal firewall blanket/barrier.. So I am confident I can make som SERIOUS improvements with minimal materials...

The car is so structurally solid.. No squeaks, groans, or flexing at all.. Solid car. So... the fight is ambient noise.

Wish me luck... should take about 3 weekends... assuming everything arrives as its supposed too.

Rob
 

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Discussion Starter · #7 ·
I'm going to try & use this as an experiment in just how "little" product can be used to get the max benefit.

Expanding foam is a very dangerous game... lol... I will use it where needed... I plan on using some spray-type deadener in areas where I cannot reach...

I will give a full product-by-product list... & the results after each section... etc...

Just kind of a modified Build-Log/product test thing....

First pics & first update will be likely on Weds or Thurs.

Rob
 

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"Peel-n-stick"? Please GOD don't tell me you're going to put asphalt peal n seal (roofing repair tape) in your car. :eek:

Example scenario.....

To get: 20 dB transmission loss at 125 hz....

Then you need: 22 kg/m^2 worth of mass which is ~4.5 lbs/sqft worth of barrier.

Go up an octave (or double the frequency to 250 hz) with the same mass and you can add another 6 dB of blocking getting you to 26 dB.

Doubling the mass (9 lbs/sqft) at the same frequency (125 hz) gets you another 6 dB transmission loss (26 dB).

Mass law for ya in a nutshell. Good luck with your project, noise is a horrible horrible thing.....:(
 

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Discussion Starter · #9 ·
I hoped you would chime in John.... LOL

No I mean Vb/BXT/Damp-Butyl/foil backed deadener... the basic first layer.

I'm just trying to make LOGICAL choices & keep costs under a tight control.

I want to do it right. But I don't want to overdo it either or do the wrong things in the wrong order.

Rob
 

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This makes me appreciate just how quiet my Prelude was when it was new. One of the car magazines tested it at 67dB at 70 mph. That's pretty incredible for a nimble 2,900 lbs coupe. The track tires I have on there now don't help much, but I would expect low 60s when these wear out and I get some quieter tires.

I don't know how realistic your goals are. Sound control is a helluva lot of work for very limited rewards. If you've seen my build log you'd know I've spent probably close to 120 hours over the years working on sound control. It can be done, but you might as well do it right the first time. The problem is weight. If you don't care about the weight, do it right the first time and use a lead barrier on top of your dampening mat, decoupled with foam. Go one step further and put some cotton batting on top of that.
 

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Hey TX, very interesting post. I'm not sure if I'm really surprised or not though. Road noise sure is a bee-otch !

On the one hand, my truck (even with true dual Magnaflows) seems pretty quiet inside, as long as I'm not getting on the throttle. But on the other hand, I really do have to use a LARGE percentage of my systems potential, to hear every sound at 65mph.

My buddy and I actually went for a ride / stereo demo a couple days ago, and between songs I mentioned my mufflers, to which he replied, "Dude, this is nice and quiet"..... But then again, he's comparing my 08' F150, to his 90' Bronco, with mud-terrain tires !

I wish I could test my trucks DB's like you are... right now, before I have any sound deadening done yet, to see how much quieter I can make mine too....

Peace,
Fish
 

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Discussion Starter · #13 ·
Fish... heck Ratt-Shack (radio Shack) has a handheld SPL meter for like $30... will do I think 130db... easy really...

I was spoiled by my Harley F150 & my 2001 Mercury Mountaineer... which were very quiet... My wife's 2004 Mountaineer is like a Mercedes compared to the Subaru! (yeah the Subie is the ONLY non-Ford product in my family LOL)

Mooble... link to your build? My intention is to dampen, then MLVB (mass loaded vinyl barrier) then the the cotton batting.. I'm lucky, the carpet in the WRX is NOTHING... literally. a single, near cardboard material. Even my new carpet will be the same. So some depth/density under the carpet is not an issue like many cars.. Thank Zeus...

I bought the Blue STi carpet out of an '05 off a local guy... got it for $100... my greyish/black carpet is trashed... the previous owner was NOT a detail freak like me... LOL

I have yet to find anyone making aftermarket carpet for the Subaru's... Depending on what kind of car you have, www.accmats.com is the hands down BEST carpet producer out there... Both my Mazda 323's, & all 3 of my Mustangs have Acc Mats carpet kits in them...

But I promise, no matter what final route I take.. I will measure after each & every layer... Meaning I will remove the interior, do a product, reinstall the entire interior.. then report... then do it again... This is the first car where I can actually get 90% of the interior out in under 20 minutes... 30 minutes if I take out the headliner!.. Seriously... it comes apart that easily... yet its solid.

I just ordered all new clips, plugs, fasteners for the interior today, just to have back ups... LOL.. So its a combo-deal... deadening test-bed, redoing/updating the interior, & final stereo install... it will be a BIG build log... I will link here to the build log & vise versa.. Although I will only post deadening pics here.

Rob
 

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I like your chances :)

To do this according to your requirements, you will have to be very clear about what needs vibration damper and what needs a barrier. The aftermarket way has been to lay on as much CLD as possible and when that hasn't been sufficient, put a barrier over that.

The only places you need vibration damper is where panel resonance excited by your sound system is introducing noise or panel resonance is transmitting noise into the passenger compartment. 25% coverage at the centers of resonant panels should be all you need. Since you need so little, it only makes sense to use high quality materials.

Now you're on to blocking. Here you need full coverage between yourself and the noise sources. I'd expect the roof to be the least productive target - floor and vertical sections should yield the best returns. The further from the ground the noise source, the more your glass is going to define your ability to attenuate it. Vibration damper will help with air/panel noise transmission through the roof. Beyond that, installing a barrier in the roof is only going to help significantly with noise originating directly overhead.

Getting at least one layer of barrier over the firewall is going to help. I've had good luck applying CLD to the HVAC ducts to reduce air flow and transmitted fan noise. I've also stuffed the voids in the dash with thick slabs of CCF.
 

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Are you going to try to localize the noise first and do that, such as if the hatch is the most noise then start there?

I wonder about spraying the wheel wells (outside) with some kind of rubber coating. I saw that on a lot on European cars like Porsche. They would coat the whole bottom of the car, and it also protects the car of course (and we have winter here). I sprayed many of my cars and it seemed to help tire noise, but at the time I didn't really care enough to make a note of the results. Newer cars I have to pull the plastic liner to find the steel, and I only do the wells and behind/between tires for stuff hitting the car. I prefer not to spray moving parts/wires/lines/etc under there just the rocker areas.
 

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Discussion Starter · #16 ·
Don... thanks to you as well for chiming in.... I am already ahead of you... LOL

the butyl "peel-n-stick" will go everywhere... just cause the car has already proven its a vibrating tin can...

the barrier(s) are the trick & I understand are the key... If Cascade or anyone else offered a REAL Lead based MLB I would be ordering tonight... alas.. a LEAD based barrier product I cannot find... so a Vinyl mass loaded barrier is the next, obvious choice... followed by the cotton/batting style final layer...

Contrary to my perceived "arrogance"... I have been trying to get this figured out for better part of a year... lol on here & EMSQ & other forums... trying to get a clear, logical path...

I am completely open minded & willing to listen... I just need someone with experience to let me know when my thinking is flawed.

So, with that said... peel-n-stick dampen everything in one good, solid layer.. then a Mass Loaded Barrier is the next thing... as you are suggesting, floor/doors/firewall... from there... is there something more I should be considering?

I am your & Fox's student... guide the lowly grasshopper to the Epiphany... lol

Rob
 

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Discussion Starter · #17 ·
String... you bastard... you pulled my final fury out!.. LOL

YES I will be spary coating the wheel wells, but only at the every end... In every car I have built, the wheel houses seem to be a MAJOR issue... will I use spray deadener or good old fashioned undercoat? only time will tell... I have had interesting results using both products...

we will see what Fox & Rude have to say... maybe Ant will jump in as well...

Rob
 

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I know your car can't hold a candle to the noise generated in my Tercel wagon. When I'm not carrying my usual couple hundred pounds of random layered crap in the cargo area, the noise from there is truly amazing. I also get to enjoy an exhaust system that's falling apart by the minute, and I don't have a single audio component installed in the old car at the moment.

I'm going to go ahead and work out the mounting for my front mids, and install everything within the next couple of months. By then the weather will be warm enough to attack the deadener all at once. Since I'm usually the only one who drives the Tercel, I can drive it for a few days (or weeks) with the interior gutted if need be. This should also be the year to have the windows tinted and the A/C fixed.

I picked up most of the parts to do a proper quiet exhaust on ebay, along with a set of Greenstuff brake pads (for $12!), and I'll be doing some maintenance/repairs to prepare the Tercel for the next few hundred thousand miles.
 

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Why do you say Cascade does not offer a real lead barrier? I have some ,it sure tasted like lead to me? VB3.5.
Wayne
 

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Discussion Starter · #20 ·
is the VB3.5 actually AVAILABLE TO SHIP? I didn't say that companies didn't "offer" the product... or at least I didn't mean to say it wasn't out there... no one has it available to SHIP... lol

Rob
 
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