Recommendations on sound proofing?
 

Looking to add some sound deadening.

Anyone have recommendations? All the stuff on Amazon is rigged with fake reviews and spam brands. Can't even tell what's what.

Thanks in advance

it's all really the same-- the differences are going to be brand recognition, and possibly deading material thickness. it's all butyl rubber with an aluminum foil skin that works by mass loading panels to lower their resonate frequency.

the main thing is to understand the fundamental aspect of how it works, and you can save a significant amount of money over the 'standard' way of lathering it everywhere.

i posted this before, but it perfectly sums up the wrong and right way to use sound deadening:

https://www.ft86club.com/forums/show...=143757&page=2
out of those 2 pictures, they're going to really work the same, but the first picture cost at least twice as much, and took twice as long, and added much more weight, for the same end result.

Soundman is right. It's been my experience that all of that dynamat related stuff all works the same but if you buy the generic versions you're going to save a fortune.

It's been a decade since I've really messed with car audio but coming from the home theater side of things I know about acoustics materials. If you wanted to be as quiet as possible do a rear seat delete and in the seat wells fender wells and spare tire area cut and pack it full of Rockwool safe N sound in conjunction with the *dynamat*. Like soundman said It's going to add a lot of weight to your vehicle but if you're trying to lower the decibels that's how you do it.

If you really wanted to go next level with it you could get 2-in thick panels of Owens Corning 703 and lay across the top of the safe n sound and use those panels as your seat deletes and trunk floor.

I used Noico (a Dynamat clone) in the trunk applied selectively to the floor, tirewell, the wheel arches and the body I could get to and a mass loaded vinyl/closed cell foam composite between the body and the side trim panels in the trunk compartment, and a large MLV/CCF sheet under the trunk carpet panel.

Hey, that second photo is me! :) Nice to be used as a positive example for once. Mom would be so proud.

Anyway another thing to consider is what sound you're trying to reduce, and what's the source. Several types of mods will increase noise more than you expect (like a transmission mount collar, say). But you can also decrease exhaust noise with some JDM rubber bits.

I'm trying to decrease tire/road noise, but I don't care about exhaust/drivetrain noise, and I don't want to add a boatload of weight. So that means strategic dynamat on the floor/side panels, and maybe some Thinsulate Acoustic (if I can ever find a good place to buy the stuff) in the doors and rear quarters. Staying away from MLV because it's so heavy.

this stuff?

https://www.amazon.com/Thinsulate-Ac...074XGMJ47?th=1

Honestly I'm not sure. There are so many different specs of the stuff, I'm a little lost as to which to get. I've been looking at this: https://www.ebay.com/itm/281788282480

my primary experience with thinsulate is winter wear. it works awesome at keeping heat in. but it doesn't do well at rejecting heat.

and in that aspect, even just the thin stuff i linked is more than enough.

Gotcha. I'm less concerned about heat management, more about sound deadening for road noise. 3M's website is not much help at all, since they're mostly concerned with selling to OEMs.

the old adage is "there's no replacement for displacement"

thicker is always going to be better-- i know fiberglass insulation works on the concept of the fibers rubbing together from the noise and converting that movement to low level heat.

with that knowledge, usually the jute/felt/bitumen stuff that oem's use works quite well while also maintaining a suitable fire/thermal rating for automotive use.

Exactly. That's why I recommended the mineral wool. Recycled denim works equally as good. I mean if you really wanted to go nuts you could pull down the headliner, trunk, and door panels to install half an inch of open celled foam under all those surfaces.

Same as an acoustical panel an air gap usually works best so the waves can be reflected back into the material but when you're dealing with these type of constraints you deal with what you've got.

My understanding is that the recycled denim stuff doesn't do well with moisture/condensation, so maybe not as good for an automotive application as a synthetic material.

With your experience, what's the best compromise for sound absorption material, in terms of weight:deadening potential?

Edit: This stuff looks interesting. https://www.summitracing.com/parts/dei-050110

For road noise the the butyl mat/MLV/CCF combo seems to have made a noticeable difference. I applied the butyl to the underside of the trunk lid as well. I don't think it made a huge difference, but it did make the lid sound less tinny when I close it.

Next, I'm going to slip some leftover MLV panels under the rear fabric covering of the rear seats.

My experience with this in a automotive sense is limited to not so much "sound deadening" but the desire to eliminate rattle for the purposes of bass. I just know the fundamentals of treatment for home audio reasons.

Now like someone mentioned earlier, I would say the best course of action is to try an address the root cause if it's something like a vibration or resonance. That is if it's a sound the car is making and not road noise you're addressing.

For this car you would really need to go nuts and do everything. Not worth it IMO, put music louder or get a nice exhaust to listen too, you will not make this car a Lexus. But go for it.

I disagree that you have to go nuts. I've only done the trunk and back seat area with a minimal application of Dynamat so far, and there's been a nice difference. Sure it'll never be a Lexus, but if I can take the edge off the road noise, with a minimal weight gain (<30lb total) that'll be satisfactory.

the only thing i've sound dampened was the trunk lid and rear parcel shelf. and only because i could hear both of them rattling all the time. the rest of the car i haven't touched and don't see a significant need to.

For rattles I totally agree. I have some dynamat in key places that seemed to make noise. But this car is light and tinny.

sry, asking the same question here (https://www.ft86club.com/forums/show...2&postcount=48) since this thread is specifically on sound proofing:

Does this approach work just as well for general sound deadening? or is it just for killing resonance for better audio quality. I'm trying to make my car quieter from road/wind/tire noise

EDIT UPDATE since I may as well update both comments:

Edit: I ended up doing it like #2. Out of lazyness more than anything else. I'm gonna measure it now

Edit with update "measurements" on a Samsung S20 FE with some app. 76db going 70mph with the seats up became 73db going 70mph with the seats up. Seats down measurements were basically the same, and 80mph the measurements were basically the same. I am very wary of "placebo-ing" myself, but listening to afunkydiabetic on youtube (a talker) I find myself setting the volume in the 30s now instead of the 50s. This is true months later. I used to always have volume in the 50s with my phone volume all the way up. Subjectively it seems quite a bit quieter.

I've done it exclusively to make the car quieter, actually. Any improvement in audio quality is just icing on the cake.

yes.

the idea to sound deadening is to reduce external noise. in audio, the idea is to reduce unwanted noise from intruding on the wanted noise. in your case, you're just skipping the 'audio' portion.

Ironically, after I added some cheap Peel and Seal to these places I got into audio. Probably not going to go all out in my car but I wish I had just added foam and vinyl while i was in there. I'm gonna upgrade the resonator on my TRD catback and see if i can at least hear the bass in my music at reasonable volume and go from there before I spend 20+ hours tearing my interior out again.

EDIT: resonator barely did anything. There is a measureable difference using a phone app, but its not nearly enough. https://www.ft86club.com/forums/show...6&postcount=35 for more detailed updates