25 replies to this topic

[abmolech]

foil is a LOT easier to work with.

[~thematt~]

What about straight out Lead Sheets? Say, 1/64 or 1/16 thick lead sheeting??

Its malleable, so you can contour it quite well. Wear gloves and dont sand it, and you dont need to worry about contacting Lead vapours. Plus according to Abmo's above statement, it is 4x better then Al sheeting.

[Music Pirate]

Lead sheeting is heavy as hell, and last time I checked pretty expensive


Why do people continue to substitue for inferior/not as practicle solutions as road kill/dynamat?

[Captn_Awesome]

Lead sheeting I cant get for nothing matt

Music_Pirate if you READ the above posts we are discussing things to use in conjunction with DYNAMAT for a more EFFECTIVE sound deadening.

[mac_man_luke]

because according to abmolech, lead and aluminium sheeting does a far better job of noise reduction (dynamat is a deadener, not so much an insulator)

[zion187reigneth]

Theres nothing extreme about dynamat extreme .............cors

[austin-towers]

Music Pirate, on Oct 4 2007, 03:43 PM, said:

Why do people continue to substitue for inferior/not as practicle solutions as road kill/dynamat?

Yeah, why approach things scientifically when you can just layer up a thousand dollars worth of dynamat?

[Brycestro]

Music Pirate, on Oct 4 2007, 03:43 PM, said:

Lead sheeting is heavy as hell, and last time I checked pretty expensive
Why do people continue to substitue for inferior/not as practicle solutions as road kill/dynamat?

Why do you not drive a Ferrari instead of your current vehicle? I'm guessing cost plays a pretty significant part.


A number of sound deadening articles I've read have gone on about the importance of applying it on the surface as flat as possible and try not to have too many wrinkles in it. Is this purely an aesthetics/adhesion thing (even though in most cases people will never see it) or is there actually some benefit gained in how affectively it attenuates sound? Please nobody answer with a "well my mate Barry did it real flat and his car goes off" style reply

Edited by Brycestro, 05 October 2007 - 06:23 PM.

[~thematt~]

Its not about getting it as flat as possible, but ensuring the adhesive layers have the most contact with the skin its contacting. The more contact, the closer the dynamat can emulate the skin with added mass, the more effective the added mass will become, and the more effective the dynamat in general.

[Music Pirate]

Yes we all know Dynamat/Road Kill is expensive, but I was just stating that lead sheeting is expensive and heavy!


The science behind lead and aluminum being more superior for noise reduction is fair game, but how much would you have to spend to get similar results as insulators like dynamat, roadkill and other materials that have a greater surface contact then that of lead and aluminum sheets?

[abmolech]

Quote

The science behind lead and aluminium being more superior for noise reduction is fair game, but how much would you have to spend to get similar results as insulators like dynamat, roadkill and other materials that have a greater surface contact then that of lead and aluminum sheets?

The only reason for "surface contact" is for a decoupler. If the panel is flat and large enough (read resonance within 250 -50 Hz) then these decouplers will work well. A panel resonance of 400 Hz plus, these will be a complete waste of money and time. (On a strictly decoupling perspective)

What they can do is act as a blocker.
Yep that aluminium backing.
A blocker does not require adhesion to work.

I am getting old (OK I am already old) and too lazy to retype this...

Quote

Lets step back a bit and use our brain rather than trying endless "solutions".
There are various ways sound can inhabit our space.
1/Through the air
2/ Vibrate an object and then through the air.
3/Bone conjunction.

To reduce the sound through the air we require a blocker and or an absorber.
To reduce vibration we need to change it into heat, and or change its resonant frequency outside our bass band. De-couplers and either raising the resonant frequency through bracing, or lowering it through additional mass.
Bone conjunction is best dealt with use of decoupler.

The first variable normally considered in predicting sound transmission through a panel is its mass per unit area. An increase in transmission loss is expected with increasing mass, because the heavier the panel, the less it vibrates in response to sound waves, hence the less sound energy it radiates on the other side.

TL = 20 log (m*f) - 48

where:

TL is transmission loss (dB),
m is surface mass (kg/m2),
f is frequency (Hz).

Surface Mass
kg/m2 per mm thickness

Aluminium 2.7
Concrete, dense poured 2.3
Hollow concrete block 1.1
Fir timber 0.55
Glass 2.5
Lead 11.0
Plexiglas or Lucite 1.15
Steel 7.7
Plywood 0.6
Dynamatt extreme 1.3


At higher frequencies, each exhibits an appreciable dip, called the coincidence dip. This dip is centred at the coincidence frequency, which depends on the material's stiffness and its thickness.

Which category does liquid deadening fall into?

Increasing mass?
Well if used on a convoluted and or braced surface (floor inner guards etc) then it is possibly detrimental, although actual mass increase is probably low.


Blocker?
Possibly, but at 1 mm thick it has a coefficient mass of 1.2

To equal lead it would have to be 9 mm thick, but since we only need 12 dB attenuation when applied to steel, 4.5 mm thick will do the job. Good luck ....