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Old 25th July 2010
  #74
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Quote:
Originally Posted by xaMdaM View Post
In "general" or "laymen" terms, (and Ted, Rod, Avare,et al; please correct me if I'm wrong), GG actually does NOT provide the equivalent of an extra layer of gypsum, but more like a layer and a half.
It's actually closer to 2.

2 layers of 5/8" with green glue produce damned near the same isolation as 4 layers of drywall.

Eric Desart, who is one of the leading acoustic engineers in the world (commented in this-thread early on) - and who designed the isolation systems for the quiets recording studio in the world (Galaxy) says that this product works exactly as presented by the green glue company, and worked rather extensively reviewing the test data from the company.

He questioned Brian Ranvass for months on end as to the testing procedures used during testing, etc., etc., etc. and had samples of the material sent to him so he could perform some of his own investigations as to it's properties.

He never once took umbrage with their testing methods.

This is a direct quote from Eric: "Green Glue is indeed strange, very good and special."

Understand that he will be the first to say that there are situations where green glue just would not make sense (like if you could get where you needed to be with a few sheets of drywall) - but (then again) I also say the same thing.

I have never (for instance) used green glue on any of my large commercial projects.

Don't use it for hotels or apartments buildings.....

Wouldn't use it on Power Station or if I built another one of those 15,000 s.f. studios.

In projects of that magnitude there are a lot more cost effective ways of making it from A to B........

Power Station (for example) uses 12" thick masonry walls filled with sand to isolate it from the outside world.........

It uses all 2x8 wall construction for the studio walls (stiffness controls the real low frequencies)....... this also makes for an air spring that is slightly deeper than you would find in a typical small studio build.

With the movie studio we began by investing in testing SPL levels (emenating from the adjacent 4 lanes of highway) all over the property. And then located the studio in a section of the property that had SPL levels 10 dB lower than the next best place we could find. Plus we located the studio section of the building so that the dressing rooms, green room, cafeteria, make up, etc., etc. were directly between it and the highway...... another big plus. Three stories of building 40'+ thick offer a lot of isolation.

This plus a wall assembly which included 28" of air spring, a roof with 4" of concrete on it, all made so that we had no need for any special construction.

BUT - the average Joe in a small build cannot usually afford to build into his model this type of construction or those types of air spaces.

Often times they are building on upper floor assemblies that just can't handle another 10 psf (of wall surface) in weight added to the floor assembly on top of what they are already doing.

There are plenty of situations where green glue makes sense..... the fact that some people choose to bash it notwithstanding.

Of course there is a point where I begin to question the credentials of those posters.......

What exactly is their claim to fame - what are their credentials?

I know Eric's (he's a friend of mine), I am well aware of Ted's, Andre's, bnapes, John Brandt's, and I am pretty certain of mine - but some of these other people posting I have never been able to find anything to indicate that they have any background whatsoever in the field......

Of course - on the Internet I suppose it's easy for everyone to present themselves as an "expert".

Rod