The penang one is it A**x auto? They quote 2k plus for wheel arch coating only.

1.5 days labour X 2 person? With this amount of time , your labour cost is going to be high.

50% or -6 db is achievable for this class as there isn't much soundproofing in the first place.

You think shop owner will charge RM90 a day for his labour + shop rental.
He takes the risk dismantling all your car stuff for RM90, be realistic nobody is going to do such business.




This post has been edited by Drian: Nov 29 2016, 12:11 AM

I've been doing soundproofing on my cars since 15 years ago, and I myself do trial and error on what reduces road noise and what doesn't. I've also gone through letting those audio shops do the soundproofing.

Firstly the labour cost will roughly dominate the soundproofing cost, not the material. For this eg, I expect maybe 1.5K to 2k worth of materials and the rest are all labour cost.

Secondly looking at the pictures some of the soundproofing installers, they just follow a standard operating procedure of pasting tonnes of sound deadening and putting some close cell foam that doesn't anything. That's actually an outdated and inefficient way of doing soundproofing. You don't need that much to deadened the panels and if you use too much you join all the panels together to create one huge resonant frequency instead of multiple ones which increases road noise.

I'm also just doing this out of curiosity and for my own knowledge. I frequent those audio forums and see how they do it . The real pros are those acoustic and chassis engineers working on BMW, Mercedes, Lexus. They not only need to soundproof the vehicles, they also need to know what sounds pleasing to the ears which means knowing which frequency to suppress at the "lowest" amount of soundproofing weight.

This site is good, he really knows what he is talking about. He even mention about the cabin pressure feeling (which is actually exhaust drone) that you're talking about.

https://www.sounddeadenershowdown.com/





So some things I found out through out the years:-

1.) You only need 30% coverage to deadened most panels. Going beyond that is point of diminishing returns.


2.)Those shiny sound deadening sheet does not block sound efficiently. It's meant to dampen vibration. Most installers assume it blocks sound and therefore put tonnes of them.

3.) Road noise is a combination of airborne and structural noise . Chassis/bushing/subframe/tyres design plays an important role on how far you can go on soundproofing this. People don't often understand road noise and assume it comes from noise radiating from the tyres. It's not entirely true. You have to imagine how a speaker work. The speaker cone vibrates and pushes the air back and forth. Now imagine the whole chassis vibrate , the chassis itself acts like a speaker and you get that surround road noise. It only takes a tiny little bit of vibration to generate a lot of noise because the chassis surface area is so big compared to a 6 inch speaker. Take note that this noise does not come from the tyre, it comes from the chassis which vibrates(structural noise) due to the tyre rolling on the road. This is where bushing design, soft tyres(isolate the chassis more), and chassis design works. This is also why changing to softer tyres is the most effective method of reducing road noise. Preventing the chassis from vibrating in the first place is way easier than soundproofing all the noise that come from the whole chassis.

4.) Road noise is predominantly in the 500-1kHz region. It is very hard to filter these frequencies out.

5.) Close cell foam(superlon , insulflex) offers very little soundproofing qualities, usually only in the high frequency region which is useless. However it is good as a decoupler, (prevents things from rattling) and it is use to decouple MLV.

6.)Open cell foam/fibre/jute is better and useful for mid to high frequency. Helps a bit for road noise but not entirely as most of the road noise energy is in the 1khz region. Thinsulate is one of the better open cell fibre in terms of soundproofing performance but even it can't attenuate the 1kHz region very well. Notice from below, a 3M thinsulate spec for 10mm I think from one of the forummers selling in garage sale. The 1kHz is only suppressed 10% compared to 90% at 6kHz.

https://forum.lowyat.net/index.php?act=Atta...post&id=5098597

7.) If you put in too much thinsulate in the wheel arch, you might get more drone for some reason. Also Thinsulate doesn't discriminate road noise or your stereo, so it'll improve or degrade your sound stage audio system as well depending on where you put it. This is through trial and error. I once placed 20mm type thinsulate in the external wheel arch and it made my sound system muddy but putting it at the A pillar improved the sound quality.

8.) If you imagine filling the whole car with thinsulate, you'll filter out all the frequencies above 2-3kHz and leave behind the 1kHz frequency noise. Then your ears only only hear all the noise from 1kHz and below which may sound irritating. You probably need those psychoacoustics experts to know how to deal with this. The way our ears work is that the more prominent sound gets amplified. Hearing someone talking in the mall for eg doesn't sound as irritating than hearing someone talk in a ultra quiet library. Same amount of noise but one feels more irritating. Same goes for soundproofing in the car. I feel thinsulate should be used as targeted areas rather than cover the whole car 100%.

9.) Best way to deal with road noise is to put MLV, doesn't absorb so the only way is to block it from reaching the cabin. And to block it you need a floating mass like MLV. It needs to be decoupled from the metal so that it doesn't vibrate along with the panel so a close cell foam is needed. This is somewhat similar to double pane windows where two glasses are separated by air. The term MLV stands for Mass Loaded Vinyl which means it needs mass/weight to be effective uaually at 1lb/ft2 .This method is heavy and require 100% coverage but it is the most effective method. If you have opening the effectiveness is reduced as noise can escape through the opening. You can see an example how effective it is if you have 100% closure in the youtube below. Some brands of MLV includes Dynamat Dynapad, CAE VB4, and Luxury Liner Pro.



This post has been edited by Drian: Nov 29 2016, 11:39 AM

What is BBK?

You should leave it untreated because that is where it is closest to the exhaust and you need to take the spare wheel into account. The spare wheel itself is part of the soundproofing. If you put in too much sound deadening you change the resonant frequency of that panel and if so happen you make it close to the exhaust resonant , and then it will drone even more.
You should still soundproof the boot. That is where the rear suspension is bolted to so all the road noise will be in the boot and couple to the passenger cabin. Your car seats won't be able to block most of the lower frequency noise. That's why subwoofer are still placed in the trunk. The wavelengths are long enough to penetrate the car seats easily. As for whether it is the most important to treat first depends on how isolated the trunk is to the passenger cabin and how much soundproofing that is there in the first place. Luxury cars designs so that the passenger cabin and the trunk are isolated acoustically.