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Topic ClosedDynamat in yer Doors?

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PaulG View Drop Down
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Direct Link To This Post Posted: 12 Feb 08 at 09:58

Morning!  I'm still digesting the overnight discussion guys, phew, what a post!!

Bearing in mind that I have a camper, with thermal insulation in its cavities, carpets, a bed, a mattress over the engine cover, cupboards full of stuff, sleeping bags etc. etc. I'm not sure I could add a whole lot more general damping/ sound insulation.  Engine is in good nick, and exhaust is brand new.  But I will review your ideas Mr. Bric.

Alloy wheels with new properly load-rated tyres are imminenet as well. (I had already noticed the tyre noise was fairly dominant from the factory spec van wheels and tyres)  also I reckon the plastic wheel trims resonate as well! (Might give it a go without them?)

Globbits' Speaker points...need to mull that over for a while.  I'm not sure about the sub route though yet.  I'm an acoustic folkie in his 50's don't you know!  (But I do sometimes rock as well  )

I'll get back to this later.  In the meantime, how do you wire in a sub innit?  (I haven't looked into this with the Blaupunkt info BTW)

PaulG

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Direct Link To This Post Posted: 12 Feb 08 at 12:31
:D Don't worry about the wheel trims. Mr Bricolage is right though - the majority of what noise you hear from outside is essentially the noise of the rubber smacking on the tarmac, then the sound bouncing back up into the wheel wells and the like. Properly load-rated tyres are likely to be quite hard and will be noisy. But as long as you're ready for this and know what you're looking to do to resolve it, it won't matter. Just be aware of what's making your bus noisy and deal with it one area at a time.

As for a sub, they really aren't just about going thud. A badly setup sub will go thud - a well setup sub can barely be heard and will just make your main speakers sound much stronger. Of course, your typical dance fan will argue against this and that comes down to musical taste (and I enjoy an Underworld track as much as anyone) but they don't have to be the boomy things that we all assume them to be.

As for how to wire them up, they are an amplified speaker. They will either have their own amp or will need an external one. They therefore require a signal from the head unit (ideally a line-level signal if your h/u has pre-out cables, but not necessarily a requirement) and power from your battery. The sort of thing you'd be looking for would neither break the bank nor your battery/charging system.

If you're ever down the Portsmouth way, feel free to look me up and we'll discuss

Richard
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Direct Link To This Post Posted: 12 Feb 08 at 12:44
Brilliant thread chaps.

Have several sheets of sound deadening ready for the Westy and ScoobyVelle. Will follow advice re wheels out. Am expecting the Westy to be more civilized as anything with an aggressive pattern on the Syncro negates the effort, esp with the howling beast in the back.

Quick Question - when ripping apart a more modern car there was a lot of polystyrene foam cut into the doors - would this act as damping without the moisture retention drawback of foam?
T3 Westy, T3 Syncro (the ScoobyVelle), New Beetle Cab, 2 x Polos - I have too many projects
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Direct Link To This Post Posted: 12 Feb 08 at 13:28
i found that putting my porsche rims with load rated car tyres on reduced the road noise as the commercial spec tyres the stock vans run generate far more noise
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Direct Link To This Post Posted: 12 Feb 08 at 13:36
Jason k - me too. I'm using Toyo's on my Caravelle and find them much quieter than van tyres. The down-side is they're more expensive and aren't load-rated up to a fully-loaded camper. But I'm not driving one of those 

Rogerthecat. If the foam in question is closed-cell foam (eg expanding foam from a squirty-tube) then it would have minimal effect on moisture retention. BUT I still wouldn't use it. I can't help thinking that anything which bonds to the surface of the metal could retain water underneath. Closed cell foam is fully sealed, so any moisture trapped underneath will stay there and rot like a goodun.

In my opinion, you could safely attach foam to the back of the door-card, but make sure that you can attach the door card back onto the door

Final point though, bear in mind that most of the work you do on the doors is about improving speaker response. Yes, you have a small effect on the amount of noise coming and going, but since the majority of the external noise is from the wheels and then from where the wind hits the van (ie the front) the noise "produced" by the doors is minimal. Sure, pay a bit of attention to the doors, but you'll get better results in ambient sound reduction elsewhere

Richard
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Direct Link To This Post Posted: 12 Feb 08 at 13:39
Currently running 16" Merc Alloys on the Westy with Continental 225/50 ZR 16 tyres - which are not bad, but MG has suggested a slightly taller profile might help too.
T3 Westy, T3 Syncro (the ScoobyVelle), New Beetle Cab, 2 x Polos - I have too many projects
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Direct Link To This Post Posted: 12 Feb 08 at 14:43
OK chaps as this is turning into a highly useful thread. Here are some links to important info which gives reasons why you should not use bitumen based products in your car /van

http://www.thesamba.com/vw/forum/viewtopic.php?t=140472

and a very interesting thread with some scientific measurements as whether it is all worth it

http://www.thesamba.com/vw/forum/viewtopic.php?t=254839
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Direct Link To This Post Posted: 12 Feb 08 at 17:02

Wow!  Just read the TheSamba threads and watched/listened to the video clips.  Are these guys thorough or what?

I'm taking what's been said here and on TheSamba into account, but I feel like I'm losing the plot a bit!  The original plan was to get a stereo, sounding half-decent, into the van some time soon.  Starting with speakers in the front, and then a second set above the R'n'R bed for 'filling up the sound' on the move and listening to when I'm parked up.

So... The plan as at now is... get some 5 x 7 or 6 x 9 Blaupunkt's for over the bed, and replace the 5.25's in the front doors with the next model up that have seperate tweeters (which I should have bought in the first place!).  Think about a sub after that (innit!)

Then, (well straight away actually) stuff out the cavities under the front seats with pillows or whatever.  See how it goes from there.

I'm still a little concerned about moisture hold-up in the Dynamat that's in the doors, so I think I'll monitor that.  Likewise the Rockwool in the tailgate, slider and rear quarter behind the slider.  The latter has been in there for 1 year now, time for an inspection perhaps?  I think the difference between cab doors - in this respect - and the Rockwool-ed places is that water routinely gets into the cab doors through the wind-down window 'seals', but the other places have fixed windows which do not leak to my knowledge (so only condensation is an issue there I guess)

Globbits/Richard and Mr. Bric - any more thoughts in addition to what's been said?  You clearly know this subject well.

Until tomorrow...

PaulG

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Direct Link To This Post Posted: 12 Feb 08 at 20:45
At the end of the day you could spend thousands. Personally I reckon if you spend your money in the right places, you'll get really good results.
Sound proof in the right places. Get some decent speakers with good frequency response curves, put them in the right place. Don't use string for speaker cables and try to keep your cable runs as short as possible.
Finally make sure you have a decent head unit and you'll have something way out does most factory installs.
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Direct Link To This Post Posted: 13 Feb 08 at 08:46

Mr. Bric - I think that sums it up about right!  BTW my speaker cable is 2.5mm oxygen free nonsense from Bluespot, so miles better than the 'string' they give you in the speaker kits.  It's a pig to solder though!  Especially when the outside temperature including windchill is -7°C!

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Direct Link To This Post Posted: 09 Sep 08 at 01:40

A spot on topic.

We have just had our van done up and am about to fit the door cards to the cab doors.
Before I do that I would like to reduce the road noise. Does the flashband go on the inside of the outer skin panel - or do I lay it across the inner panel instead of the plastic sheeting that is cut out for the speakers and inner door handle?
 
If i goes on the door outerskin, I assume I still put the plastic sheet on the inner skin panel. Will the flash band not trap moisture against the outer skin panel?
 
Very confused - looking for clarity (as ever)
 
BM
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Direct Link To This Post Posted: 09 Sep 08 at 08:28
The flash band (or whatever) is inert and does not hold water - I sprayed waxoil over the entire door interior after I had applied the sound deadening material just to make sure, then a plastic membrane to cover the door card. 
My van is better known in these parts than I am
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Direct Link To This Post Posted: 09 Sep 08 at 11:34
Cheers JohnB
 Flashband on the inside of the outer skin, followed by plastic on the inner skin.
Thanks for the that
BM
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Direct Link To This Post Posted: 10 Oct 08 at 18:29
 just done the rear doors areas in my crew cab and the area behind the back seat and back of rear seat box area. used screwfix flashing tape. difference is noticable already and have not even done the front doors yet.
   Will eventually take the dash off and do all the back of front panel.
Is it worth putting two layers on or just overkill?
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Direct Link To This Post Posted: 10 Oct 08 at 18:53
damping that front panel makes a huge difference to the overall noise levels in the van, might well be worth putting a couple of layers over the whole lot.  I would be can't be arsed taking the dash out!
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Direct Link To This Post Posted: 10 Oct 08 at 19:15
Good shout. Got some flash banding left from curing leaks in the summerhouse - will apply it to the ScoobyVelle when get if back.Thumbs%20Up
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Direct Link To This Post Posted: 13 Oct 08 at 09:17
This post lives still on then!
 
I think that if the dash etc. ever has to be stripped out of mine, I will flashband the inside of the front panel with a couple of layers.  That panel really is a 'drum-skin'!  You only have to hear rain hitting it as you drive along to tell how resonant it is!
 
Audio gear wise, I think the next step for me will have to be an amp.  I have to have the head unit at nearly full volume to hear it on the motorway, especially if it is anything like windy!
 
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Direct Link To This Post Posted: 13 Oct 08 at 10:28
Sorry guys - I haven't forgotten about this thread. Just had a string of bad luck with engines so Myrtle's been off the road for a few months now Cry She should be back and running shortly, so will get some pictures then. But, my findings so far are:
  • Flashing tape over the engine bay is nigh-on pointless. It makes things smoother and easier to keep clean, but makes almost no difference to the interior noise
    NOTE - This is based on a standard WBX engine with a single Pierburg carb and air intake. If you use twin carbs, particularly with metal air-cleaners, then you will be experiencing engine noise due to the more direct path from the cylinder heads to the engine lid. If this is the case, consider putting a mattress over your engine lid Wink
  • Flashing tape in front of the engine bay (on the diagonal behind the seat) does make a difference, but only if you haven't got anything in front of that panel. It vibrates like a wotsit from the engine vibrations, but if you have a rock 'n roll bed with boards below it, then you won't get any significant benefit from reducing the vibrations in that panel
  • Carpet/something padded on the floor between the back seats and the front seats makes a fair difference to road noise levels. If you just have the metal floor at the moment, seriously consider doing something about it
  • Deadening underneath the front seats makes a huge difference! The horizontal surfaces that make up the "roof" of the wheel arch are flat sheet and ring like a bell! Anything you can do to stop them resonating the road noise through will significantly affect the volume in the bus
    I started off putting pillows in there, which make a big difference. I've now taken them out and covered them in a layer of Second skin Spectrum (liquid form of Dynamat). That improved things a little, but not much. I then cut MDF board to the size and shape of the tub, covered it in car-audio carpet (more for presentation than anything else) and bolted it to the panel (on the inside of the bus, obviously Wink). This has made an incredible difference - the panel doesn't ring at all and I can reduce the volume on the stereo by 9dB (equivalent to 1/8th the previous volume)
  • Deadening the doors makes a difference to where you can hear wind-rush at speed, but not overall volumes. It does, however, improve the sound of your stereo no-end! Wink
    Again, I used Second skin Spectrum for this, because you can just paint it on so it's much easier to get into all the crooks and nannies. Oh, and my doors now go "clunk" when you shut them, instead of "ting".
  • The front panel is next on my list. As Monsho says, the wind-rush and rain noise against it is phenomenal, so I see no reason why a layer or two of flashing or Spectrum won't make a massive difference to the noise
As soon as I get Myrtle back, I'll take some photos of what's been done, but to summarise:
Wheel arches are the enemy - concentrate on them!!!!!!

Richard
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Direct Link To This Post Posted: 21 Oct 08 at 21:45
finished doors now . done all 4 doors of crewie with double thickness of screwfix finest flashing tape. doors are SOLID now .(and as above - stereo sounds so much niecerer!)
   gonna do front panel this week when i take dash off (hell - might even do dash as well seeing as its metal)
   also gonna do under seats with double thickness/carpet n stuff as above!
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Direct Link To This Post Posted: 21 Oct 08 at 22:15
Looking forward to hearing how you get on Elvis - I'm planning on attacking Myrtle's front panel when she comes back from Elite. So please let us know!

Richard
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