?Sound deadening doors - do one or two surfaces?

I have Damplifier on both the outer skin and the inner skin of my doors, so I can't tell you the difference between applying one layer vs two. My guess is that the difference is subtle but exists, especially since the woofer is attached to the inner skin and can create a lot of vibration just by itself.

If you're going to only do the outer skin you'll still need to remove the plastic cover anyway, and that's another reason why I went ahead and did both skins while I was at it.

I didn't use Overkill and would like to know if it reduces airborne noise as advertised. (Testing this would require you to apply only one layer at a time, do some measurement then proceed with the next layer, which can be quite an exercise in patience and restraint.)

I haven't had any problems with water, and we've had an extraordinary amount of rain in Texas this past summer.

 

<div class='quotetop'>QUOTE(dstrevel @ Oct 10 2007, 11:03 PM) [snapback]524009[/snapback]</div>

Here are some pics from my install:

http://picasaweb.google.com/MagGreyPrius/2ndSkinDriverDoor

You can also take a look at the other albums that show the other parts of the car that I also damplified.

For the doors, I pretty much covered everything on the inner skin. As for the wirings, I first popped off the clips holding them to the metal skin, put Damplifier over everything, then cut little holes to snap the clips back on when done. I did have to cut two small slits to run some wirings through, but because the material is pretty thick and sticky, it didn't really create much of an opening.

As for effectiveness, I used a sound meter to measure, driving on the same route at 65mph at night with the audio off. The average noise level was reduced from roughly 82dB to 72dB. Still, it's very hard to quantify the difference because there are so many factors involved. But for sure the car is much quieter over rough or bumpy roads, or over those dots dividing the lanes. It's definitely noticeable when you close the door and hear a solid "thud". (Last week we rented a Highlander for a long trip, and I immediately noticed how much noisier and louder that car is compared to my Prius, especially over bad roads.) A really good test, in my experience, is to try having a normal conversation with someone in the back seat. A quieter car will not require anyone to raise their voice or strain their ears.

Because I've also replaced the stock speakers with JL components and added a subwoofer, it's hard for me to tell how much adding just the SD helps the sound of the stock speakers. My guess is that it can only improve the sound, although I wouldn't be able to say by how much.

What I do know is that now when I have the stereo cranked up I can hardly hear any outside noise at all. If I had to do it over again, I might even go for the Damp Pro and some Overkill. But right now I'm quite pleased with the results as they are.

 

[attachmentid=11947][attachmentid=11945][attachmentid=11946]<div class='quotetop'>QUOTE(zenMachine @ Oct 10 2007, 11:41 PM) [snapback]524033[/snapback]</div>

Nice job on the sound deadener application. Very clean. I am surprised you didn't use some type of sound absorber, like ensolite, as well. Especially on the outer door panel where the speakers will be creating cancelling waves from reverberating between the outer/inner door panel.
Attached are my subaru doors. Outer door skin is like two layers of raamat and one layer of ensolite. then I sealed off the inner door panel and did one layer of raamat and one layer of ensolite. As you can see, I went all the way and covered ALL the wiring. This is to minimize any chance of rattles in the future, and yes, it would suck if I needed to access all that wiring. Makes a huge difference in noise and sound quality. the only problem now is I can really hear the noise through the floor. I'll do that next summer when I do the prius doors!

Jonas.

 

Zen, You got a 10dB reduction in sound? Wow, that is half as quiet. That is amazing! Did you only do the doors, or did you do the floor too? Did you do all four doors?

 

I used B-Quiet Ultimate to do my doors and the road noise went down. The sound system got louder with "richer" or "fuller" sound. I tested with a friend's Prius without any mod. We played the same CD and noted the differences.

BTW, I still have extra if anyone is interested... PM me. I ordered 50 sq-ft and used maybe 30 sq-ft?

 

<div class='quotetop'>QUOTE(Winston @ Oct 11 2007, 01:34 PM) [snapback]524189[/snapback]</div>

I've done the front doors, the floor, the rear seat, the trunk, the roof, and the hood. But I'm not done yet.
I'll do the rear doors when I get new speakers for them. I'd like to do the wheel wells too at some point.
Then maybe add some noise absorber under the carpet and in all the door panels. Keep in mind that SD mats only reduce unwanted vibrations but have very little effect on blocking airborne sound waves.

As for the measurements, I only did a few test runs and didn't have time to do a more thorough experiment with more data points. So I would only describe my results as suggestive rather than definitive. Nevertheless, the improvements are definitely worth the effort as far as my ears are concerned. And I actually had a lot of fun doing it. Learned a lot about the innards of the car along the way.

I'm new at this SD stuff so I'm still learning as I go. But it's become an obsession of sort. Now my ears start picking out all kinds of sounds and noises that I'd never noticed before. Drives me crazy sometimes. Drives my wife crazy too, now that her ears have been similarly conditioned. But that's a good problem to have, IMO.

 

Thanks for the feedback, I am excited to install some deadening too. While it is mainly to improve stereo performance and reduce road noise, I would also like to reduce the engine noise. The whiny noise from the little ICE is not a very pleasant sound. Some engines sound nice when they rev up, but the Prius just sounds annoying. Thanks for all of the info.

BTW what material did you use for the hood?

 

<div class='quotetop'>QUOTE(Winston @ Oct 11 2007, 05:29 PM) [snapback]524265[/snapback]</div>

Engine noise is a tough one. But I think damping the hood does help reduce some of the vibrations coming from the engine. Damping the firewall is what I'm really interested in, but that's just way too difficult for now.

The hood actually has two layers, and it's impossible to damp the outer skin, so I all I could do is damp the inner skin. You'd have to first remove the liner to do this. I just used a few sheets of leftover Damplifier on the hood since I didn't have enough to do the rear doors with them.

I started out w/ 80sqft. I plan to get another 20sqft to finish out the rear doors. Or 40sqft even, to do the whell wells too. Then if I have leftover after that I'll just double up in some areas.

The reason I didn't use any sound absorber (like Overkill) is because I was totally new to this SD business so I really didn't know any better and had no clue what to do. I just wanted to start with the basic, see how well it works then go from there.

I may add some absorber in the future, but first I'll need to finish the rest of the doors. Then think about getting rid of the tire/engine noise. That is a much more challenging problem.

BTW, Secondskin also sells the pads to dissipate the cancelling waves from the speakers. I don't know how well they work, but it's definitely a possibility.

 

<div class='quotetop'>QUOTE(zenMachine @ Oct 12 2007, 09:55 AM) [snapback]524607[/snapback]</div>

I have heard good things about the sound deadening "disks" they make. I have also read that puting an extra layer of whatever foam you are using behind the speaker does pretty much the same thing. The goal is do dissapate the rear wave of the speaker so it doesn't cancel itself. I put like 3 layers of ensolite behind my speakers in the subaru. I have spent MANY hours on caraudioforum researching this stuff.

Also, I have a hard time imagining that deadener on the inside of the hood is going to help with engine noise. in fact I would almost argue that it would prevent noise from excaping! I also think it will hamper heat dispersion, which is why the hood is made from such lightweight material. I think doing the firewall will reduce engine noise than anything.

Jonas.

 

<div class='quotetop'>QUOTE(JonasB @ Oct 12 2007, 06:29 PM) [snapback]524892[/snapback]</div>

Thanks for the tip on the disks. I'll definitely look into that. They're pretty cheap and simple to install anyway.

As for the hood, all the SD does is reduce vibrations. If you tap the hood of your Prius you'll notice that it's VERY hollow sounding. After applying the SD to the inner skin, my tap test showed a much subdued sound which, theoretically, should translate into a reduced kettle-drum effect when the car is rumbling along.

Secondskin also has a product called Motormats that probably are more appropriate for the engine compartment and firewall. But I don't know how to get to the firewall.

 

<div class='quotetop'>QUOTE(zenMachine @ Oct 13 2007, 11:03 AM) [snapback]525128[/snapback]</div>

Yea, I think the firewall will be a tough one. I haven't actually poked my head under the dash yet but its my understanding that people who deaden the firewall do it from the inside. I think the idea is to remove the front carpets and as much other "stuff" (vent pipes etc..) as you can w/o having to take the dash out. Then, Reach up as high as you can (hopefully, all the way to the top of the firewall) and lay mats of deadening material, and hopefully a layer of foam.

I never thought about the "kettle drum" effect the hood can have, especially on a prius. That's an easy fix so I'll look into it!