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The truth about MLV Dynamics Plugins
Old 7th August 2008
  #1
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The truth about MLV

Naethoven sent me the following query

Quote:
You had mentioned on a few of your posts that MLV is unnecessary or overpriced or not as good as another layer of drywall/wood etc. I am building my studio and doing a lot of research and you are the first source I've seen say anything bad about MLV. Just hoping for an explanation. I've seen several sites that sell MLV claim "6 dB more TL than lead" or something like that. I realize it is frequency dependant, but it would make me think MLV has got to be good for something. ???? However, it is only 1 (or 2) lbs/sqft, which doesn't seem that dense to me.
Working indirectly at your questions, MLV is a very good barrier material for industrial applications where the noise is at higher frequencies and the noise sources have to remain readily accessible for maintenance or other reasons. In other it provides sound attenuation and access.

I have never seen any tests data on MLV showing a significant difference than using cheaper materials for mass in walls. As you implied referring to the weight, physics rules. The comparison to lead is misleading at best. Have you priced lead per pound? A similar comparison might be to say lead is not as effective as gold or depleted uranium, both of which are denser.

You may be wondering why MLV is sold so much. The best explanation I am aware of is unknowing people going to "sound specialists", and asking what they can do for sound isolation. The "sound specialist" can either send the customer to a construction supply company, not making any money, or sell a fancy named product and make money.

Andre
Old 8th August 2008
  #2
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Lightbulb

STICKY! STICKY! STICKY! STICKY!

heh
Old 8th August 2008
  #3
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might a good post for your new area Jay.
Old 8th August 2008
  #4
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MLV must be tested like any other product in an independent lab and still you have to see how it behaves in the real world. Most tests I've seen regarding MLV have been for industrial or building application so I'm not even aware how it performs against other products
Old 10th August 2008
  #6
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For those wondering, MLV = Mass Loaded Vinyl
Old 10th August 2008
  #7
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You are trying to compare apples and oranges with that site. MLV is related to sound insulation and that product is used for absorption


Old 10th August 2008
  #8
NLP
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Yes, but also some absorbers use MLV.
Old 10th August 2008
  #9
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Another part of the equation in my experience (having built with MLV a few times) is whether it is used as a complete envelope around a space or not. This involves overlapping all seams and using an adhesive. Also using it for the floor and ceiling. It's much trickier (and ferociously heavy...) to create this envelope layer but I guess more effective(?)

I'm curious what more experienced minds think.

-Silas
Old 11th August 2008
  #10
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Quote:
Originally Posted by Legacy View Post
Another part of the equation in my experience (having built with MLV a few times) is whether it is used as a complete envelope around a space or not. This involves overlapping all seams and using an adhesive. Also using it for the floor and ceiling. It's much trickier (and ferociously heavy...) to create this envelope layer but I guess more effective(?)

I'm curious what more experienced minds think.
Silas,

as someone with a somewhat experienced mind ( ) I will comment on this.

MLV is a typically over priced method of acheiving less isolation than one can acheive with less expense using just more mass.

Drywall is relatively cheap - and each doubling of mass (if done correctly) can acheive 8 to 9 dB of additional isolation - weighted averages (with "normal" drywall contractors this number is probably more realistic around 5 to 6dB)

Of course the more mass you add the more you attenuate low frequencies.

High freuencies are pretty well in shape early on in this process.

The actual reported values for MLV values (as far as isolation goes) are for the material itself - and not for tested assemblies - everything beyond that is calculated - which may or may not have any value in real life.

I have yet to see any of the manufacturers provide (as does Green Glue for example) actual test data on a specific wall assembly.

I do studio design around the world - and do not hesitate to specify Green Glue for added isolation - and have never specified MLV.



Now - for the poster who listed Primacoustic - Acoustical Solutions - that is a joke.

I was amazed at the bulls**t being spread at that site - AND how stupidly they even went about spreading it.

Quote:
membrane is made of barium impregnated vinyl and weighs in at 1-lb. per square foot (the same weight as lead!). [/B]
Also the same weight as a pound per s.f. of feathers - eggs, steel, rocks, woman's undergarments ......... etc., etc., etc.

BTW - that is some pretty thin lead they are comparing themselves to not a whole lot thicker than tin foil. A 1psf piece of sheet lead is only a wee bit more than 1/64 of an inch thick. Standard masons lead flashing (which is 1/16" think) weighs in around 4 psf. I like to use 1/8" thick (8psf) sheet lead in my super door designs.

The fact that they have never been tested is just icing on the cake from my perspective.

The entire presentation seems to me like amateurs trying to imitate professionals, for example - they give the "ABSORPTION CHARACTERISTICS" of the product (which we know is pretty much useless - what they give us that is - not Absorption Coefficients in general) as individual frequencies defined as (NRC values)"........

As we well know, NRC values are an average of a series of absorption measurements - and not the individual measurements themselves [they never even give an NRC value for the product - not that I would care - or would desire to see one (the individual values are all that really matter here) except for the fact that they use the term - which would suggest that you would probably see it somewhere, on their site - at some point in time].

They haven't impressed me much......


Sincerely,

Rod
Old 11th August 2008
  #11
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Thanks for the insights, Rod. Makes a lot of sense having handled the stuff and also having dealt with multi-layer sheetrock.

I certainly wish that a friend who I helped had not just swallowed all the PR about MLV. Hanging that stuff from 14 foot ceilings was more trouble than another layer of sheetrock and Green Glue for sure!

Any thoughts about best materials for smaller applications such as good ways to acoustically reinforce existing doors or inserts for existing windows etc when trying to minimize noise while maintaining a 'relatively' thin footprint?

Thanks,
Silas
Old 11th August 2008
  #12
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Rod,

The only situation where I see any use on using NRC is for building acoustics. In such a specific situation like studio construction NRC like STC means nothing.
Old 12th August 2008
  #13
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Quote:
Originally Posted by andrebrito View Post
Rod,

The only situation where I see any use on using NRC is for building acoustics. In such a specific situation like studio construction NRC like STC means nothing.
Andre,

What you said is worded a little funny - so I don't get the whole gist of the first sentence - But - they did not give an NRC value for the product - they presented the individual absorbsion coefficiencies as NRC values - which speaks a lack of knowledge on their part as to what they are really talking about.

But that doesn't surprise me seeing as they just took the numbers from elsewhere and added a bit to them because of the MLV - they never had anything tested.

Sincerely,

Rod
Old 12th August 2008
  #14
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Rod,

Sorry for my writing, maybe I was not clear enough. I was talking about a generic product and not this particular product (MLV).

What I meant to say was that several products in the market still only give the NRC value and that NRC does have some use for acoustical building regulations, at least where I live. Places such as offices or gymnasiums have a maximum allowed reverberation time, defined by law, in the octave bands from 500-2000 Hz.
Old 14th August 2008
  #15
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Quote:
Originally Posted by andrebrito View Post
Rod,

Sorry for my writing, maybe I was not clear enough. I was talking about a generic product and not this particular product (MLV).

What I meant to say was that several products in the market still only give the NRC value and that NRC does have some use for acoustical building regulations, at least where I live. Places such as offices or gymnasiums have a maximum allowed reverberation time, defined by law, in the octave bands from 500-2000 Hz.
Andre,

I understand and agree - there is a time and a place for NRC values - HOWEVER - individual absorption coefficients are NEVER presented as NRC values - Just as individual TL values are NEVER presented as STC values - they are simply presented as they are - and then the final calculation (Be it NRC or STC) is presented as a calculated weighted total.

To present this as it is done on that website - where the individual values are shown as NRC values - and THE WEIGHTED CALCULATION IS NEVER PRESENTED AT ALL - is just indicitive of ignorance on the part of the company.

When you take that into account- along with the fact that the numbers they present for values are not even tested numbers (they said they couldn't be calculated - therefore they used other tests perfomed by a testing lab - and extrapolated the values with the MLV) it makes everything on the site relating to those "traps" virtually useless.

So it is their data I was specifically questioning - not NRC values in general.

Sincerely,

Rod
Old 15th August 2008
  #16
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Would you guys share your opinions on this? Acoustiblok Inc., Soundproofing, Soundproofing Materials, Sound Deadening It's similar stuff, but the STC ratings seem quite high (when combined with particular wall construction). Just wondering if this is any better than regular MLV, or any different at all.

I attached some info one of the reps sent me.

Nathan Webb
Attached Files
Old 15th August 2008
  #17
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Quote:
Originally Posted by naethoven View Post
Would you guys share your opinions on this? Acoustiblok Inc., Soundproofing, Soundproofing Materials, Sound Deadening It's similar stuff, but the STC ratings seem quite high (when combined with particular wall construction). Just wondering if this is any better than regular MLV, or any different at all.

I attached some info one of the reps sent me.

Nathan Webb
Nathan,

it is the same stuff for all intent and purpose - 1 psf - MLV.......

And the numbers are not impressive at all (those are not high numbers)when compared with other options for a LOT LESS MONEY......

You keep asking the same questions - and for some reason don't seem to get the answers........

so I'll try this differently......

this stuff runs you 389.00 for the equivilent of coverage you can get with less than 4 - 4x8 sheets of drywall (1 to 5 rolls) 30’ x 4.5’ (135 sq ft) $389.00 ea. cost is $2.88 per s.f.)

Even if you paid 30 dollars a sheet for the drywall installed (which would be high) that's only 120 for the coverage of more area (remember that in 8' lengths this will only cover 3 sheets of 8' - the added width is for required lap purposes) leaving 4' of material left over).

If you then add resilient channel for the same 4sheet (16' of wall ) @ 2' on center horizonatally) which will require 7 pieces (they are available in 12' lengths) and sell for about 2.50 (again the high side) and even if you spent 10 each to install then (an absurd number) that would still only add 87.5 to the cost of the wall.

OK - so now you have one layer of drywall one side -with resilient channel - and 2 layers of 5/8 on the other side fastened to the studs...... for an absurd estimate of 207.50 and you have a wall with an STC rating of 55 (versus their 53), for a cost savings of almost $200 FOR JUST THEIR MATERIAL. And you have a wall completely finished.

Now - this is the last time I will bother to comment on this - MLV is MLV is MLV - I don't care who manufacturers it - I don't care what name they call it and I don't care what color it is -

It does not make sense in normal wall construction to use this material.

There are places in industrial situations where this material might make sense - but not for general construction - and especially not in any sort of studio construction.

And now there is nothing more for you to ask about this material - because you should certainly understand now why it doesn't make sense.

It's all about the money.........

Sincerely,

Rod
Old 15th August 2008
  #18
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Quote:
Originally Posted by Ethan Winer View Post
STICKY! STICKY! STICKY! STICKY!

heh

thumbsupthumbsupthumbsupthumbsup

Thanks for the low-down on MLV Andre and Rod.

Frank
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