Have a Few Sound Proofing Questions (sorry) - Page 2 - AVS Forum | Home Theater Discussions And Reviews
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post #31 of 41 Old 10-01-2019, 02:13 PM
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Originally Posted by htpc-geek View Post
...I don't think there is really any "debate" on the effectiveness of GG. I just don't see that. Only people that don't know and are thus skeptical (especially when they see the price), and people that answer their questions.

I see most of the convincing evidence in these 3 forms:

1. The testing and technical data that the GG company shares, with comparisons across different ceiling/wall structures (example: GG vs Extra Drywall)
2. The many professional theater builders and designers on this forum that can speak to the differences across the vast number of theaters they've done
3. The overwhelming number of theaters built using it with anecdotal evidence

The measurable and proven performance gain may not be worth the price tag to you, and that's certainly understandable. That doesn't mean it's not's as effective as it's clams.
Yes I'm firmly in the ignorant and skeptical category, in case that wasn't apparent, but I'm looking to be educated. I'm just not sensitive to the "I've always done it this way and it works for me" argument, or the other one that goes "lots of people are doing it, how could they all be wrong?"; points 2 and 3 that you made more or less. We are talking about something that is eminently measurable are we not? Why would anecdotal evidence or the number of people participating in the practice carry any weight in the face of hard numbers?

As for the technical data then, what do you make of what Acoustic Fields has to say about the numbers in their video? "It's glue with a fancy name" they claim.

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post #32 of 41 Old 10-01-2019, 02:55 PM
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post #33 of 41 Old 10-01-2019, 03:30 PM
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For some reason I was imagining that Green Glue was also utilized as an adhesive, but of course as you say screws are still required. Thanks for the clarification.
It should have been called Green Goo, but that probably would not sell as well.
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post #34 of 41 Old 10-01-2019, 05:14 PM
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Quote:
Originally Posted by The OH View Post
As for the technical data then, what do you make of what Acoustic Fields has to say about the numbers in their video? "It's glue with a fancy name" they claim.

Green Glue Nonsense
I think that video shows a drastic misunderstanding on what green glue is, and also his data is pulled literally out of thin air and sensationalised.

The fact is there is HARD data to show that green glue is insanely effective especially so when used together with clip and channel systems. Its been compared in just about every scenario possible with data for all of it, his extremely low numbers he chose to share for green glue efficacy are literally fictitious. They are not from any documentation of testing I have ever seen.

Its a shame, some of his videos are very good, but he clearly does not know what he is talking about here.

Compare the dark green to the red here, all they did was add green glue.

At 63hz its about 6db, 100hz its nearly a 20db reduction, 125hz about 10db, and stays at 10-15db reduction almost through the whole range. Just with the green glue product. There are numerous other tests showing the same phenomenon.



Here is another:



Another:



Another:


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post #35 of 41 Old 10-02-2019, 12:28 AM
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Ah I'm getting data thrown at me. Now we're talking! I must admit I need to become more adept at interpreting data sheets on STC but the fact that there is data says something to me already. I've been looking at the comparisons too and I'm (slowly) coming around to this green magic...

I think what bugs me and turns me off is hearing others gush about a product in senseless ways. For many it's is all they need to be sold, but for some reason it has the opposite effect on me. (I'm often accused of being too rational!). There's another in-depth discussion on Gearslutz on this topic. Here too you find many proponents of GG, also among the experts/respected contributors, though unfortunately it's also peppered with the kind of non-sequitur comments that I recoil from. Here are some of my favorites just for fun:

Post 3, concluding GG works despite having used a different product:

"the stuff works good. I actually just completed my build with QuietGlue, which is very similar. it was actually a little cheaper, and there was no nasty smell. I didn't use it between all joints, but i did use it between all layers, and I'm pretty dang pleased - from everything i can tell, it's helped greatly."

Or the commentator in post 55 that admits (in the very same sentence too) that it's impossible to conclude anything, but happy that he used it anyway.

"I spec'ed GG into my room build. Obviously, I can't compare to NOT using GG - but I certainly got the results I was shooting for."


Similar sentiment with this post:

"I used GG in my wall construction as well, and the results have been fantastic! I have nothing to compare it to however, so I cannot say for sure that I would not have been as happy without it. I think that the entire process adds up to sound transmission reduction, and I am very glad that I did not cut any corners as my room sounds fantastic (and quiet!!!)"

I think this last one encapsulates well the intuition that kicks in when you think about applying a flexible goo between layers. It just intuitively seems like it will work. It's easy to apply and once you do you feel good about your efforts. If the overall result is pleasing, it's natural to attribute all the success to the special sauce, without which it's, well... just a regular sandwich! Such a great product. As I said earlier, I wish I'd invented it.

Alright done ranting... no wait, just one more...

https://www.youtube.com/watch?time_c...&v=LiUBxjFG53o

The presenter shows how two layers of wood stuck together with GG can still twist and move. But in real life that won't happen with all those screws (that you need since it's not actually an adhesive) preventing the layers from moving even a millimeter!

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post #36 of 41 Old 10-02-2019, 06:59 AM
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A couple of items, constrained dampening layer building methods didn't start with Home Theaters. There was research done decades ago on how to reduce vibration of steel plates on attack submarines to avoid detection. Some of that research is unclassified and you can find it on the net.



Then there is this video.
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post #37 of 41 Old 10-02-2019, 10:09 AM
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What about that video? It sounds different when he taps it with a hard object... but I don't imagine I'll be tapping a hammer against my new wall too often. I'm worried about airborne sound transmission loss, not impact. Plus I wasn't considering ceramic tile instead of drywall, but of course ceramic tile makes for a better marketing video. BIGmouthinDC, you must be trying to wind me up because I find it unlikely a man of your experience is so easily convinced! :-)

Anyway, as I said, I'm slowly coming around, but not because of videos like that!
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post #38 of 41 Old 10-02-2019, 11:25 AM
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I used that video to try to convince a rookie. The general principles are the same tile versus drywall . I've directly installed about 300 gallons of GG and wrapped my knuckles on the resulting walls. You should buy a tub and do an A/B comparison with drywall yourself.
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post #39 of 41 Old 10-02-2019, 02:45 PM
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I used that video to try to convince a rookie. The general principles are the same tile versus drywall . I've directly installed about 300 gallons of GG and wrapped my knuckles on the resulting walls. You should buy a tub and do an A/B comparison with drywall yourself.
I trust you have and that there is a difference. I'm just not sure what that proves when it comes to airborne sound transmission. You'd have to educate this rookie on that one.
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post #40 of 41 Old 10-02-2019, 03:32 PM
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Airborne sound hits the wall/ceiling and causes the inside drywall to vibrate, that vibration is transferred to the studs and on to the outside drywall/or floor sturcture above. That large outside surface area vibrating excites the sound waves and you hear it outside the room. A small percentage of the sound is actually transmitted via the air cavity in the wall and ceilings. That is why when you want to hear a conversation in the room next door you put your ear on the wall to hear the vibrations in the structure more directly. It is a more efficient pathway. How to you mitigate that propagation? Mass, Isolation, Dampening and Absorption. You use multiple layers of Drywall (mass) with Green Goo dampening compound between layers hung on a clip and channel isolation system. The insulation is to prevent cavity resonances which can amplify any sound energy that makes it through the double drywall layer.

In essence the airborne sound transmission through a wall is impact noise. You have alternating air pressure waves slapping against a very large surface area, causing it to vibrate. Think about the fact that sound can escape from an air tight room. If air can't get out how does airborne sound get out? It is through the structure, the outside surface area structure converts the vibration back to airborne sound.
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post #41 of 41 Old 10-02-2019, 09:05 PM
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Nothing special about Green Glue vs the other appropriately tested CLD compounds IMO.


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