would adding spectrum sludge/similar...

[MidnightCE]

significantly help road noise in this location?

I've run out of places under my carpet to apply shit.

pic stolen from another site... The area I'm referring to is the flat light grey panels. These are the other side of the floor.

http://images.vetteweb.com/tech/vemp_0710_20_z+c6_chevrolet_corvette+exhaust_syste m_install.jpg


Getting under the car to paint them with sludge will be a total bitch,

so do you think it will make an appreciable cut in road noise?

and for appearances sake, spectrum, or spectrum sludge? I'm not sure why I'd need the activator.

What would be the appropriate amount to order to cover something like this 3-4mm thick? I'm thinking 1 gallon.

[Rudeboy]

Are those panels highly resonant? If not, the only advantage would be reducing the sound from pebbles and the like bouncing off of them. If you are looking to block noise from penetrating, I'd expect virtually no improvement ater applying liquid to those areas.

[60ndown]

id do some research and see exactly which product will stay attached when getting wet under there, then borrow / rent a good jack, and do everything i could see under the vehicle that resonated or made any noise when tapped with the handle of a screwdriver. it will only take you a couple hours and $120 in product and might reduce road noise A LOT.

[MidnightCE]

Are those panels highly resonant? If not, the only advantage would be reducing the sound from pebbles and the like bouncing off of them. If you are looking to block noise from penetrating, I'd expect virtually no improvement ater applying liquid to those areas.


Not really. It's a 'balsa sandwich' floor. Though doubling mass supposedly is -5db.

[FoxPro5]

Mass law states that for every 2x in barrier mass, you get about 6 dB in attenuation. Road and exhaust noise is the job for transmission loss products, not so much structural damping. You need mass, my friend.

Spectrum is .047 lbs/sqft at 1 mm thickness and will cover 40 sqft. Say that area you need to cover is 20 sqft, which will come out to be 2 mm or .094 lbs/sqft. You put down two gallons for good measure, so now you're at 4 mm and .188 lbs/sqft.

At roughly .2 lbs/sq ft you'll probably hear 10 dB drop (which sounds like half as loud) starting at 800 hz and up. At 125 hz the noise will just refract right around it. If you wanted to halve the sound at 125 hz, you'd need about 25 coatings of Spectrum at 1mm thick (1"; 1.22 lbs/sqft). That's some thick Sludge, dude. :)

At this point in your battle with this car, you either need to sell it for a quieter car or buy bigger amps IMHO. :)

[MidnightCE]

Mass law states that for every 2x in barrier mass, you get about 6 dB in attenuation. Road and exhaust noise is the job for transmission loss products, not so much structural damping. You need mass, my friend.

Spectrum is .047 lbs/sqft at 1 mm thickness and will cover 40 sqft. Say that area you need to cover is 20 sqft, which will come out to be 2 mm or .094 lbs/sqft. You put down two gallons for good measure, so now you're at 4 mm and .188 lbs/sqft.

At roughly .2 lbs/sq ft you'll probably hear 10 dB drop (which sounds like half as loud) starting at 800 hz and up. At 125 hz the noise will just refract right around it. If you wanted to halve the sound at 125 hz, you'd need about 25 coatings of Spectrum at 1mm thick (1"; 1.22 lbs/sqft). That's some thick Sludge, dude. :)

At this point in your battle with this car, you either need to sell it for a quieter car or buy bigger amps IMHO. :)

Well I can 100% overpower the road noise at about 80% volume. But I like listening to my stereo at 50-70% since it doesn't hurt my ears at all.

[60ndown]

ive used spectrum sludge, its like peanut butter consitency, easy to apply 15-20 mm in 1 go, takes a while to dry, but super easy to apply.

[FoxPro5]

Well I hope my post didn't seem anti-Spectrum. I just don't think it's the right product for the job. Just my personal opinion after using both Spectrum and Sludge in my car with great results (see Review sub-forum.)

[kimokalihi]

What would be the right product for the job? Wouldn't some vertex barrier padding work better inside under the carpet?

[Turbosixpiston]

I would think lead plates would work for what you're wanting, no?

[Second Skin Rep]

Depends on the guage of the metal, but adding a layer of Spectrum certainly will help.

If you already have a vibration damper inside the car, followed by a barrier product, and you are still not happy with the results, go for it.
Sandwhiching the floor pan with 2 products that have different elastomeric values (weight, viscosity, gravity, elongation, tensile strength or whatever else) is a great way to reduce more frequencies on that vibrating sheet metal. All depends on the car though.

Idealy you would use a heavy barrier type product in and outside the car, but, that is not really all that possible with most cars. Aftermarket noise barriers on the outside is a rare application, so an acoustical undercaoting then becomes the most logical way approach the project once you have fully treated the interior.
Spectrum will do the job as advertised, it just might take a decent amount of product to achieve your own personal goals. 3mm at least I say..

ANT