Basic sound deadening for the Riviera

I just need some thoughts on what I can do to help keep things from rattling in my car. I got one 12 sub wired at 4ohms at 300w rms and it has good clear deep bass but the problem is when I roll up the windows it rattles everything in the whole car. I've read about a certain vibration proff sheet that helps reduce vibration but I don't know what I should do.

drive into a pool. dat will definitely make it vibration proff

Here's what I did. Requires a little patience, but it works.

Buy a CD or MP3 album with bass test tones (sine wave tracks), optimally from 10 Hz up to 100 Hz in 1 Hz increments. Bass Mekanik - Quad Maximus is my personal choice. If you are resourceful, a sine wave general will also work well.

First, take everything out of your car.

Start low at 25 Hz - NOT TOO LOUD, BE CAREFUL NOT TO DAMAGE YOUR SUB! - listen for vibrations in the car. With the tones on repeat, you can hunt the rattles down. Advance the tracks in 1 Hz steps up to 100 Hz, or until the rattles stop. Different trim panels and accessories in the car will rattle at different frequencies. Fix them one at a time by tightening screws, adding mass behind panels (Dynamat), inserting insulation (felt or thin foam) - there are lots of ways to stop the rattles. I used a small rubber washer from a dart to stop the rattling button on the rearview mirror, and poster putty inside the speaker grills. Dynamat is available at most stereo shops and online. It's pricey, but will keep thin sheet metal from rattling - good for doors, roof, and trunk lids - lots of work to install, though!

Good luck! It takes a while, but this method does work!

This thread is for us to share information about basic sound deadening for our cars. Things that I post will rely on my experience with the 1995-1999 Riviera. And maybe a little from other cars I have owned.

Please contribute your experiences, too.

Albertj

Safety aspects

Sound deadening in a car is a little tricky. On the one hand, if you are well rested a quiet environment will let you stay calmer and alert because hums, buzzes and such tend to be at worst annoying and at best hypnotic. On the other hand, if you are somewhat fatigued a bit of noise might well help you stay alert if only because it's annoying.

I think the ambient noise level to shoot for in a car is a matter of preference. There are practical limits, too. An interesting table of ambient noise measured by an amateur with a Radio Shcak sound meter is here:

http://www.rpsoft2000.com/decibels.htm

Point is that in order to drive safely we need to keep self-noise in a vehicle below a certain range. And it looks like that range might be 70-90 dBA as measured with one of those cheapie Radio Shack sound meters. Point is to be BELOW this range - 90dB is the noise level of a good loud alarm clock.

I don't know what your noise control goals will be. MY objective is to minimize self-noise from the car, to a point, so I can hear components (pullies) that make noise when they are failing and hear commotion (horns, yells, collisions, and such) that are outside the car while I am driving. Also since I live in a rural area, I want the car to make a degree of noise so as to discurage animals from crossing its path. Over the years I have found that deer whistles don't work, really, but turbocharger whine (think leaky donut gasket) and exhaust sounds on acceleration seem to warn them away. I think.

FUN Aspects

Since I was not planning to get a new car anytime soon I thought it'd be fun, when my mufflers wore out, to install a custom stainless exhaust such that teh car woudl be quiet at cruise but growl a bit while accelerating. What I learned is you can't really do this on a Riv. On a car witha smaller six or four cylinder engine, the engine is turning pretty fast when the car is cruising. Not so the Riv. Think of it this way. When accelerating in a RIv, the tach band in use will be 500-3000 RPM. You can design an exhaust to sound off in part of that band. But it turns out that the Riv cruises at pretty low RPMs - right in the band where if you're accelerating you might want to make a little noise.

So when I got a 'fun' tuned exhaust I soon discovered that it made noise at cruise - kind of fun on a cruise night but lousy, lousy, lousy on a highway trip of any significant duration. So another objective of my noise control is to reduce exhaust drone to tolerable levels, pending my saving up the cash to make further changes in my exhaust.

Albertj

The '95 - '99 Riviera actually lets a good bit of road and mechanical noise into the cabin via the rear seats and trunk. The bloomin' trunk is kind of like a huge drum especially the spare tire well and the sheet metal under the rear seat.

After shopping around a bit I decided to buy EDead. I bought a couple rolls off EBay. About $1 per sq ft and the vendor threw in a roller. look at the price VERY CAREFULLY as more than one vendor is selling it and the price varies somewhat. You also need to pay attention to the thickness. They sell it in 45, 80 and 120 mil thicknesses. I got the 45, which was OK but consider getting a roll of the 45 and a roll of the 80. Use the 80 in the spare tire well (it is really drummy and it took me 2 layers in the center to fix it) and under the rear seat (you would not believe what a difference that makes) and use the 45 elsewhere.

There was a comparison showing how different sound insulation stood up to heat. And another showing how much deadening was achieved (using a radio shack sound meter). EDead was not the best but by far was the least expensive of the ones that were acceptable, The only ones better were Dynamat and Damplifier Pro, both more expensive if I recall.

Damplifier and Dynamat both probably work better than EDead - however, EDead is the probably the best of the inexpensive lines of sound damping materials. Basically, eDead is wider rolls of roofing/weatherproofing material similar to what's sold in narrow rolls at Home Depot for sealing around door and widows between the rough openings and the window/door frames. The point is that it passes automotive flammability tests and has a 'mass loader' mixed in to the butyl. Think of it as a thin sheet of butyl windshield adhesive with aluminum foil on one side.

See this site (Damplifier fans) for amusing "comparisons":

http://www.talkaudio.co.uk/vbb/showthread.php?t=208026

Bottom line for me was I was able to cut ambient noise in my Riv at cruise from 91 dB to 69 dB using eDead sheeting on the 'drummy' areas ('drummy' means areas tapped with screwdriver handle that did not make a dead thump but rather resonated like a drum) in the trunk and under the rear seat. It's around 50 dB at idle. Measurements taken with an electronic Radio Shack sound meter using "A" weighting. Nice explanation here:

http://www.jimprice.com/prosound/db.htm

When I earn enough surplus cash and if I am keeping this car, I am still putting on a quieter exhaust. Noisy pipes are OK for short runs but not for 2+ hour drives, I don't care what Turtle thinks.

Albertj

Thank you Albert for compiling and sharing this information.
It is very helpful to me and I'm sure others who are thinking of adding some sound dampening material to their cars.
I had considered Dynamat and other well known products in the past but was put off by the price. This is a more cost effective way of doing the same thing for the average joe.

Quote :

Bottom line for me was I was able to cut ambient noise in my Riv at cruise from 91 dB to 69 dB using eDead sheeting on the 'drummy' areas ('drummy' means areas tapped with screwdriver handle that did not make a dead thump but rather resonated like a drum) in the trunk and under the rear seat.

That's a dramatic decrease! It's on the order of decreasing perceived sound levels by more than 200%. For reference, 79 dB would be half as loud as 89 dB, and 69 dB would half as loud as 79 dB.

85 dB is designated as the point above which hearing loss can occur. From an online source:

"Any sound above 85 dB can cause hearing loss, and the loss is related both to the power of the sound as well as the length of exposure. You know that you are listening to an 85-dB sound if you have to raise your voice to be heard by somebody else. Eight hours of 90-dB sound can cause damage to your ears."

I own a Radio Shack sound meter as well. I'll make a test drive and report back my findings.

Yeah, that 85-90 dB at cruise had to go.

90+ dB is not legal in some jurisdictions.

Albertj

How much $$$ are the Radio Shack dB meter's.?

Never mind. Found it on-line @ Radio Shack for $50.00.
Cheap enough to do reference measuring. Think I'll get one when the time comes.

Reducing resonance

Dynamat, eDead, and other mastic/foil or butyl/foil combinations reduce noise by stopping panels from resonating. Think of it this way - if you take a drumstick and tap on say a neoprene mousepad, it makes a little noise but the noise is dull. That is because the motion ends up being converted to heat in the mousepad. If you then drum the stick on a desktop it's louder. Instead of the motion energy being converted to heat as it is absorbed, it gets radiated back out.

In the Riv, sound waves hitting large flat surfaces (fenders, trunk floor, cabin floor) tend to 'drum' and radiate. So the first thing to do is put the resonant frequency out of the audible range or get rid of the resonances. Dynamat, eDead are great ways to do that. So that sound from the exhaust and drive train are not in effect amplified by the cabin of the car. Unfortunately this adds a little weight - the Buick engineers seem to have tried to keep the car from generating much self-noise (can't resonate if there is not a noise in the first place) so they did not have to add sound deadening padding (which ads weight and cuts mileage) but there is still some noise and this is a way to get rid of it.

As for the noise transmitted into the car from outside, the only way to stop that is absorb it with mass. In the 'old' days this was done with a layer of lead sheeting placed between two layers of jute carpet padding. Now people use mass-loaded vinyl or a mastic with fine sand (think spray-on rustproofing or roll-type linoleum) sandwiched in. If you remove your trunk liner you will see some such padding, rag pads with a layer of sticky stuff in the middle like cream cheese in a tea sandwich. You can make such a padding yourself using flame-retardant carpet padding (get a remnant) and some spray on rustproofing. Use scissors to cut the pad pieces to fit where you want to place them, then spray on a rustproofing layer, then sandwich them together so the clean pad side is out and the sticky rustproofing is in the middle. . Leave them out of the car a day or so to cure in order that the smell dissipates. Then install. To absorb sound even better, while the rustproofing is still wet put a layer of fine white play sand on, then shake off the excess, spray on rustproofing again (so it's sticky) then make the sandwich. The downside of these mass loaded structures for sound control is they weigh something and weight costs money in terms of gas mileage - you have to determine if the trade off makes sense for you. You may want to make a test piece or 2 to determine if they will even fit where you want them to go. Also bear in mind that the Riv is already heavily padded under the carpet - it may be that a layer of eDead or Dynamat under the carpet won't add much weight and will get rid of 80% of the problem . I am not sure, only did the trunk an under rear seat so far.



Albertj

Rickw wrote:

How much $$$ are the Radio Shack dB meter's.?

Never mind. Found it on-line @ Radio Shack for $50.00.
Cheap enough to do reference measuring. Think I'll get one when the time comes.

I was going to buy the analog RS meter, walked into the store and found the digital one was on sale at the analog price so I bought that instead.

Point is if your travels take you past a store you might want to stop in - or phone them and ask if they are going on 'managers special' anytime soon. One Thursday some months ago the one that's often on my travels had the Magellan GPS navigators for US and Canada, 2 for price of 1 ($150).

Albertj

The price i posted was for the Digital one. Analog was only a few dollars cheaper. But I will check the store and buy from there.

AA wrote:

Buy a CD or MP3 album with bass test tones (sine wave tracks), optimally from 10 Hz up to 100 Hz in 1 Hz increments. Bass Mekanik - Quad Maximus is my personal choice. If you are resourceful, a sine wave general will also work well.

Aaron,
Where does one buy this disk.???? And how much should I expect to pay.?
I need to do the same thing and I don't even have my Amps or Sub installed yet, but i have noise and vibration coming from the front grills and door panels from the MBQuart's that were installed. I know I can find and solve this problem without the disk but I want to be prepared for when I get around to doing the rest of the upgrades.

I bought mine from Amazon.com many years ago. But have since converted to MP3. I could send a copy of the test tracks on CD if you want!

Yes, that would be great. I don't have an MP3 player. But CD's I do have.
Who knows maybe one of these days I'll jump into the 21st century, just not in any hurry I guess.
I'll PM my Address if you don't already have it on file.

PM sent

The roof is also a large untreated surface that is very noisy. As far as deadeners go I have used several in the past, but I have been the most impressed with "second skin".

Just my 2 cents.

Rickw wrote:

The price i posted was for the Digital one. Analog was only a few dollars cheaper. But I will check the store and buy from there.

Unless the store is on your way someplace, might just want to phone. If manager is not too busy he just might tell you when the one you want will go on sale.

Albertj

AA wrote:

I bought mine from Amazon.com many years ago. But have since converted to MP3. I could send a copy of the test tracks on CD if you want!

see

http://www.gvengineeringstore.com/servlet/the-5/tone-generator-CD-1Kz/Detail

Albertj

I know we discussed sources and prices for these materials back when you were installing all this.
I've re-read this thread and it's not here.
Did we have that info in another thread by chance.????

I don't know where the info went and don't see it in the Search. Hopefully AA will point to it.

Albertj

Albert,
I'm looking at a 50 sq/ft Roll of EDead Ultra Butyl w/roller, 80mils thick for $139.00 with free shipping. Does that sound about right price wise or should i keep looking.?
Also, I remember you mentioning to get some 40 mil and some 80 mil, do you really think it is necessary to have both thicknesses, and if so, why?
Also, If I need both 40 and 80 mil, how many sq/ft of each do you recommend.? I plan on doing the Trunk, Rear Seat area, and Doors for now.
Then in the spring I'd like to pull the seats and carpeting for full stereo install and do the floors.
Thanks for your input,
Rick

P.S. There is another product called Fatmat Xtreme that comes in 50 mil and 80 mil which is a Foil Damper, light weight composite consisting of a viscoelastic damping compound on alum foil.
They also sell a 70 mil butyl product for less than the EDead.

Just get the 80mil, you will be fine with that. I would also stay away from the fat mat products. I have used it in the past. sometimes it sticks great and sometimes it falls off. I have heard good things about e-dead. My favorite brand is "second skin" I have had better results with this brand than any other I have used. How much of your car are you planning on deadning? Just as an example I am using about 400sq/ft in my car, but I am covering everything with some places getting two or three layers. I would say to do an entire car with one layer you will probably need at least 100 sq/ft.

Thanks, I'll go with the 80 mil butyl and look at both brands, the Second Skin and the EDead.
Probably just order a 50 sq/ft roll for now and do the trunk and under and behind the back seat.
In the spring when I remove the complete interior, for the sound system install, I'll get another 50 sq/ft or whatever it takes to do the doors and the floor.
I also need to replace the door seals to eliminate some road noise from leaking seals.(air leaks)

For a $1.99 I ordered a sample kit of a product called B-Quite. Another sound deadening material that i wanted to get a look at and for 2 bucks shipped i thought it would be worth looking at it for comparison to some of the other products out there.
I have a sheet of DynaMat to compare to.

Rickw wrote:

Albert,
I'm looking at a 50 sq/ft Roll of EDead Ultra Butyl w/roller, 80mils thick for $139.00 with free shipping. Does that sound about right price wise or should i keep looking.?

Not sure. I used the 40mil eDead.

Rickw wrote:

Also, I remember you mentioning to get some 40 mil and some 80 mil, do you really think it is necessary to have both thicknesses, and if so, why?

Not necessary but desirable, depending on the damping problem. IMHO the 40 mil will damp resonances, the 80 will be a better sound barrier due to mass loading of the surfaces. However, I'd like to see a test of some sort.

Rickw wrote:

Also, If I need both 40 and 80 mil, how many sq/ft of each do you recommend.? I plan on doing the Trunk, Rear Seat area, and Doors for now.

I used one roll of the 40 mil for the trunk and under rear seat including the reinforcement beam that runs across the passenger compartment under the front of the rear seat. HOWEVER, the way I did it was by thumping with a screwdriver and covering only the areas that sounded drummy. I did not do the areas that sounded dull.

Rickw wrote:

Then in the spring I'd like to pull the seats and carpeting for full stereo install and do the floors.
Thanks for your input,
Rick

P.S. There is another product called Fatmat Xtreme that comes in 50 mil and 80 mil which is a Foil Damper, light weight composite consisting of a viscoelastic damping compound on alum foil.

I am not so sure about this at all, if only because typical viscoelaastics used in sound damping applications have a nasty characteristic - as temperature goes above or below 60 deg. F the attenuation is less and less. For more see

http://www.kineticsnoise.com/kdce162.html

Granted the example is a paint, but they are measuring attenuation assusming a uniform film thickness--which is what you'd have with the visco on foil implementation.

Rickw wrote:

They also sell a 70 mil butyl product for less than the EDead.

If you are shopping around you might find this site useful:

http://www.full-line-audio.com/sound_deadening/liquids/