sound proofing materials?

DJ 190

A2OC Donor
I'm about to remove the dash and I want to take the opportunity to add additional sound-proofing whilst the dash is out. I remember some threads just recently regarding this topic (sound insulation), but searching the A2OC hasn't turned them up. I think that what was of interest was the comment that thin materials aren't going to prevent the transmission of noise, but more to stop rattles? Anyway, I need to obtain a suitable material soon, so that I can get my dash back in place? I have seen this :- http://www.ebay.com/itm/Silent-Coat...Proofing-Deadening-Material-Mat-/171282970329 Is this O.K.? Those recent threads regarding this subject .... can you show me where they are? What do you recommend for using between the dash and bulkhead? That is my first priority, so that I can restore the dash .... Oh, a search through the Forum revealed a material called "Max mat" but a Google search doesn't turn up anything? Thanks

David
 

timmus

A2OC Donor
Seemed to recall there were very few (flatish) surfaces where sound proofing materials could be applied
The same thought had been going 'round in my head too, Spike. I'm just not sure where you'd apply any sound deadening, let alone in quantities that would make a discernible difference and not just add weight.

Cheers,

Tom
 

pocoloco

Member
You go with sound races do?Otherwise it's nonsense to do this, too much work and too much money for that little sound that you occasionally hard put.
 

DJ 190

A2OC Donor
You go with sound races do?Otherwise it's nonsense to do this, too much work and too much money for that little sound that you occasionally hard put.
Goedenavond, dank U wel voor U contributie, U kunt zien van de start of mijn post dat ik al mijn dashboord verwijdert heb, zo dat het grootste gedeelte van dat werk is gedaan.Daar ik de A2OC aforum al gestudeert heb daar zijn genoeg positieve gegevens of extra sound insulation(geluid) Maar ik zal het gaan proberen .,Het zal niet zo duur zijn . Ik kon U post niet zo goed begrijpen

David
 

Birchall

Dick Chown Award 2016
Google Translate didn't help much with that one David!

It translated
Goedenavond, dank U wel voor U contributie, U kunt zien van de start of mijn post dat ik al mijn dashboord verwijdert heb, zo dat het grootste gedeelte van dat werk is gedaan.Daar ik de A2OC aforum al gestudeert heb daar zijn genoeg positieve gegevens of extra sound insulation(geluid) Maar ik zal het gaan proberen .,Het zal niet zo duur zijn . Ik kon U post niet zo goed begrijpen

To


Good evening, thank You for You dues, you can see the start of my post that I 've deleted my dash board, so that the majority of that work is gedaan.Daar I A2OC aforum already gestudeert have enough positive data there or extra sound insulation (sound) , but I 'll try to go. , it will not be so expensive. I could not understand you post as well

Steve B
 

DJ 190

A2OC Donor
Ha Ha! Yes, it's rubbish, isn't it?

This is it!

Good evening, thank you for your contribution. You can see from the start of my post that I have already removed my dash, so that the greatest part of the job has been done. Studying the A2OC forum, there are enough positive comments regarding sound insulation. But I will try it anyway. It won't be so expensive. I could not understand your reply


Oh, this is a 100% correct translation!


This is from an earlier post, :- Soundproofing project in Modifications
_______________________________________________________________________________________________________________________________________________________________
Hi David,
after spending many years in a body shop repairing cars this material is the stuff we used when ever replacing pannels, even our A2's have tiny peices under the carpets hear n there, but no where near enough, prob due to the weight it may of added.. youl find all high end cars are covered in this type of material and a heavy spray on sealer type material totally covering the undersides , simular to our own A2s..

I can take some photos over the next week as my A2 is ready to rebuild, put back together as its stripped out at present, not carpets , dash ect, and been that way for a while now, yes you can hear the turbo playing it tunes quite happily and every bit of road noise as the carpets are heavily sound dampened on the undersides...

basically at the front where your feet would go , youv got the curved wheel inner arches, i plan on totally covering these areas as audi only place 1 measly peice plus covering the front floor area up to near the underfloor access pannels, the same at the rear , totally cover the wheel arches.

then theres the doors, you will need to remove the trim and pannel and then the glass surround frame to leave a bare door, then cut a template that fits about and 1in from the sides and cover the inside of the door skin, i would not advise adding any other sound deadening material insides the doors themselfs as water needs to pass through from the top glass seal to the drain holes in the bottoms of the doors..

then depending how far you want to go , you can cover the whole floor from the boot forward, and even the under floor storage , but there i was just planning to fill with some left over foam underlay from a laminate flooring as i can just scrunch it all up and fill up the spaces , then easily removed if need be ..

you could go even further by removing the stone guards and covering the outsides aswell but i think that would be OTT and doing what ive discribed already will make the car totally different and eliminate alot of the droning road noise..

there is also several big voids under the dash when its removed at the tops and lower down behind the glove box and fuse box,,, BUT BE WARNED !!!!! YOUL have to make sure what ever you put in these areas does not have any way to interfear with the stearing or brakes and is fixed securly..

Regards Gary
_____________________________________________________________________________________________________________________________________________________________

Wasn't this really helpful and useful information from Gary? It was just what I was trying to remember! He sure seems to know his stuff? Well, I certainly believe what he has said! What do you think, Tom?

David
 
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bretti_kivi

Member
I understand pocoloco's comment extremely well and he has a point: the effort to sound insulate the car is significant in comparison to the return.
If you don't isolate 100% the source of a noise, it will still travel through the space. There's a diagram somewhere on the web where 90% isolation only insulates 70+% of the existing noise and 99% coverage only hits 90% of it.

If you want to stop vibration, then butyl is a good material to start with. To really kill the noise down, though, you're going to have to use mass, and even on the wheelarches, this is *not* easy to do. Butyl on the rear footwells and under the seat, the rear arches and the boot can help but the noise will still come through. The Dash is open at the bottom, so any effect that can be had from insulating the underside is going to be noticeable but not necessarily significant.
Even taking the inner arches out on the outside and damping behind those won't help much unless it's massively heavy, and even then, the shell does an excellent job of moving vibration around to the last place it can be let out - it is a very stiff piece of aluminium, after all. So you end up having to damp essentially *everything* or drop some MLV onto it, preferably decoupled, and then the fun starts because nothing fits again. I already have tried 1-2mm of spectrum on the outside of the floor pan and was underwhelmed with the effect, even with Butyl on the inside. It's better, but not as good as I'd hoped. MLV on the inside of the plastic at the bottom of the A pillars has made a significant difference for me, as has the butyl in the boot. The boot is now the source of 90% of the road noise in the car and when it's full, the car is really quite quiet.

The carpets are heavily foamed to reduce road noise. If you've driven a car with or without the OSS net, you should have heard the volume difference because it's significant. Any hifi will sound different too, because of the reflections; there's a lot more treble without the net in. With my reindeer in place, it's very much deadened in comparison.

Essentially, I'm in agreement with pocoloco here: If you're not into Hifi, I wouldn't put too much effort in, because even if you do, without a perfect re-fit, you will not get that significant an improvement. The doors help to a certain extent, but there's not *that* much noise that comes through; original door cards are actually treated to limit noise intrusion. I've got a source for that, somewhere, too. Can't remember where.

Tyres will see more improvement. And I'm prepared to back that one up with some empirical measurements at some point; I'm pretty sure all teh damping in my car has resulted in around 3dB positive difference as opposed to a new A2. But that's on a smooth road. And tyres give around 6dB difference; on snow my car is extremely quiet but on rough asphalt it's significantly louder. When I've finally done the front doors I might get another 2-3dB improvement added to that. Considering the time, effort and money, that's minimal. The noise level is currently similar to the Fiesta. Both wear 195/50R15s.

- Bret
 

JIGSAW

Banned
Thanks for all that information Bret as really great to have first hand knowledge, my myself aint after a dead quiet A2 but hearing your results does help me decide on just covering the floor pan and doors as planned, its motorway miles where ive the only problem with road noise and thats a very rare event for me, i even enjoyed having no dash or carpets in for 8weeks as you could hear the turbo singing away quite contently all the time which i liked, And ile agree 100% on tyres as my 15in winter tyres are SO loud compaired to my 16s, did you try filling the voids behind the stone guards around the wheels as may be a better area to fill up with material and not impose on interior refitment.

Gary
 

DJ 190

A2OC Donor
Thanks for all the information, Bret and Gary! All this post was about was taking the opportunity to add further sound insulation behind the dash, whilst that area was accessible. (you don't take the dash out very often, do you?) In the past, I have left out the small, spring-out tray in the centre of the dash and really noticed an increase in noise. This led me to believe that the bulk-head would benefit from additional sound-deadening? It can't do any harm, can it? When I have removed my dash, I will take it from there and see what can be done. I'll have the material to hand and apply as appropriate. Then, back in with the dash!

David
 

bretti_kivi

Member
If the ashtray's not there, the noise is coming from the centre of the car, so above the exhaust. Dampen that by all means, but remember it gets *hot*.

- Bret
 
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dj_efk

A2OC Donor
Bumping this thread, as noise forms part of one of the two key aims for Merlin as a long distance express: Namely leaves you feeling fresh and relaxed after a long journey and gets you there with excellent high-speed economy.

@DJ 190, where did you get to on sound-proofing - what did you end up doing and can you give us an assessment of the results? What items would be at the top of your order of preference, knowing what you now know?

I note the comment that tyre noise is a large part of the issue, so I’m glad I have / chosen 185/60/15 summers and 175/60 winters rather than wider sizes - Also, like you I have a six speed gearbox so that should be engine noise considerably reduced also, I wondered what else would be subjectively worth the effort?

Thanks!
 

Kleynie

A2OC Donor
Three years ago I was upgrading the HiFi in my old BMW 535d GT, I had to remove the door cards to change, and add speakers, at the same time I added Dynamat inside every door, every wheel arch and the boot floor. The main reason was to stop road noise from the massive 285/35/21 rear tyres, I used 12 sheets of Dynamat. The difference was not night and day but was noticeable, however, it was a lot of effort for a small gain.
The 535d was a quiet car anyway, so I was never going to get massive gains, but I suspect doing something similar to an A2 may see better results. You could even place Dynamat on the backs of the aluminium door cards as well as inside the actual door skin. I think that would be easier, cheaper and better than trying to line beneath the dash.

I hope that helps.

Ian
 

bretti_kivi

Member
inner liners won't help with Dynamat / Butyl as they're already very stiffly held in place and can't vibrate much. Outer door skins make a difference as does the rear footwells. Roof would be one place I'd definitely do if it's not got OSS.

- Bret
 

DJ 190

A2OC Donor
@DJ 190, where did you get to on sound-proofing - what did you end up doing and can you give us an assessment of the results? What items would be at the top of your order of preference, knowing what you now know?I
I can't remember where I got it from ..... Ebay? ..... but it was similar to the material I've highlighted in this thread. It's sticky butyl with a shiny aluminium skin. I'd converted my Mercedes SLK to run on liquid LPG. This meant that the tank in the boot had an internal pump to circulate the liquid LPG. It was noisy so I wrapped the tank in the sound-deadening material. It would work anywhere, though, and is easy to apply. Door skins, under dash, floor? Hope this helps

David
 

timmus

A2OC Donor
A good few years ago, Tony (of A2 Cars in Milton Keynes) removed the entire interior from his A2 and lined every single panel with heavy butyl/aluminium sheet, just cutting out little squares such that the clips and bolts could still go into the rightful places. Kilo after kilo of the stuff went into the car. The result was that the doors felt reassuringly heavy, but the whole process achieved next to nothing in terms of acoustic isolation. His car gained the weight of an extra person and suffered the corresponding penalty in fuel economy for little discernible gain. Acoustic waves show great determination. You can almost entirely enclose a source of noise and barely notice a reduction in volume; a majority of the acoustic wave will still find its way through the tiny gaps that remain.

When designing recording studio architecture, proper acoustic isolation is one of the first things to be considered. If it's done right, you can turn the volume up to 11 in one room and not hear it at all in an adjacent room. However, when building studio audio systems in existing 'standard' rooms, secondary acoustic treatment is needed. This 'retrofit' approach is hopelessly inadequate when compared to proper 'floating rooms'.
The same is true of car interiors. Large luxury cars like the A8 are designed from the ground up to be really quiet. It's a consideration throughout the development of the car. The A2 was designed to be a lightweight eco machine. Adding vast amounts of weighty material not only goes against the philosophy of the vehicle, but is a fundamentally flawed approach that achieves precious little. Heavy sticky stuff works well to reduce panel vibration, which is why Audi fitted it at factory in (almost) all the appropriate places, but it is not a transmission barrier. Trying to retrofit silence in this manner just doesn't work.

By far the better approach is to try to reduce the amount of noise created in the first place. The addition of a 6th gear reduces cabin noise at motorway speeds much more effectively. A dash of 2-stroke oil in the fuel tank helps to keep the engine smooth and quiet. My own A2 whizzes along the motorway in 6th gear doing circa 1950rpm. The predominant noise comes from the wind and the tyres, not the engine. I set cruise control, relax in my seat (with or without music) and enjoy getting 75mpg. I never arrive at my destination feeling fatigued by the environment of my car.

Cheers,

Tom
 
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