Anyone have experience with Acoustiblok?

[AudiocRaver]

Have any of you had any experience with this stuff? It is a super heavy (1 or 2 lb per sq ft, depending on version selected). Effectiveness? Ease/difficulty of application? I am looking at it as a possible material for my room.

Acoustiblok

 

[Matthew J Poes]

Have any of you had any experience with this stuff? It is a super heavy (1 or 2 lb per sq ft, depending on version selected). Effectiveness? Ease/difficulty of application? I am looking at it as a possible material for my room.

Acoustiblok

Hey Wayne, I obtained a sample of it. It seems to be a form of mass loaded vinyl. It is different from standard MLV, but I see no evidence that its better.

I am not against MLV, but I will say that the best direct research testing of MLV vs other methods that I have found suggest that MLV is less effective and more expensive than products like Green Glue. My suggestion is to use Green glue instead of Acoustiblok with two or three layers of drywall. You will likely find it to be cheaper with greater noise blocking.

I have also considered MLV in addition to Green Glue in the past, I suspect that MLV may have some benefits in blocking lower frequencies that when used in addition to CLD (drywall plus Green Glue) may be better.

The main issue with drywall and MLV is that Drywall is rigid and not well damped. It has two regions, the wall resonance region and the material coincidence frequency in which a huge dip in transmission loss takes place (It's fairly deep and wide). This is not improved by more mass. At these two frequencies you lose all benefit of the wall mass and only the MLV is stopping sound. It doesn't stop all that much sound. If you damp the drywall with CLD methods you not only gain the mass of two layers of drywall but get significant damping and so there is little to no dip in the transmission loss at these two critical frequencies.

If you are looking at sound isolation also look seriously at decoupling methods as that seems to be the single biggest improvement.

If you really want to get into exploring different transmission loss values for different approaches, let me know. I did a lot of research and saved a lot of the test documents for this. I tried to stick with only products that were tested by an NVLAP lab and where the method was reasonable for comparison. For example I found one company that claimed their spray foam insulation provided 45db's of transmission loss (STC45) but it turns out that was with steel studs, two layers of 5/8" drywall on both sides, and filled with this insulation. That wall with no insulation would have had similar transmission loss values. Simply adding green glue between the drywall layers would have improved that STC value well into the 50's.

 

[AudiocRaver]

Thanks for the info, Matt. My searches have led to the same conclusion:

1. Green Glue works.
2. It is not cheap, but it is cost effective.
3. You can spend more on an alternative and not get as effective a result.

Looks like time to order some Green Glue.

 

[Matthew J Poes]

Thanks for the info, Matt. My searches have led to the same conclusion:

1. Green Glue works.
2. It is not cheap, but it is cost effective.
3. You can spend more on an alternative and not get as effective a result.

Looks like time to order some Green Glue.

That is where I landed too. I wish I had the bandwidth and budget to test all the different options. The biggest problem I found was that most products were not tested using real home theater wall construction techniques making comparison difficult. CLD walls with resilient wall mounting was something Earl Geddes was really big on, even before Green Glue came around. He mixed his own damping compound, but it was based on a soft urethane casting compound and is hard to use (and expensive as sin). However Green glue is proven, I've now used it, and in the big picture its expense isn't so great.

Acoustiblok advertises their greatness with a wall STC of over 80, but...what they don't mention is that this is a commercial wall construction technique that is well over 12" thick. This identical wall technique was simulated using MLV and included as a case example for the mathematics of transmission loss in one of my engineering books and they came to similar conclusions. I don't think Acoustiblok demonstrated anything spectacular. I think they just showed that MLV with a 12" thick wall using a block core will block a ton of sound. I looked into adding cinderblocks to the common wall in my theater (which is 14" thick) and found you need to dig out the concrete slab and reinforce it to support the weight. On top of that, and Green glue has shown that with a double stud wall you get results well into the 70's, without the cinderblock core (which makes a huge difference given its mass and stiffness).
http://www.soundproofingcompany.com/wp-content/uploads/2015/12/sw-wood-double-stud-gg-bothsides.jpg

My own opinion after having chased the dragon on this one is that it is a fools errand to try and achieve STC values in excess of about 60 or so in a domestic space without a huge budget and a lot of know how. Once you reach STC 50 or so you get to a point where everything is a weak point. Your outlets, hvac, doors, even the wall seams to the floor and the floor itself. Fixing those problems are not trivial. A door that has an STC rating that would equal that of a STC60 wall is about $6000 plus installation. HVAC that can provide transmission loss from breakout sound and transverse sound that is on par with the 60+db's of loss for the walls is easily that expensive. The floor is about $10,000 to resolve to the same degree, and there aren't a lot of products available to provide that level of isolation. You need a resilient decoupled floor. What is the point.

I have a wall in my theater that alone would likely (based on calculations) reach an STC rating in excess of 70, and I guarantee it was a complete waste to build the wall the way I did. I have dual communicating door assembly using the highest STC rated domestic doors I could get from a Masonite company (I think Mohawk, but I forget now) and the door is still clearly the weak link.

 

[AudiocRaver]

Well said. The way I see it with my room planning and research so far is that treatments in a home theater can help accomplish two possible goals.

1. Make the room sound good.
2. Keep the sound from bothering other people.

Item #1 is relatively easy and inexpensive - relatively, not necessarily "piece of cake" easy, but compared to item #2, not so bad. Item #2, soundproofing, is very much like getting Swiss cheese to act like an inflatable balloon. Every seam, crack, coupling point, hole, or weakness must be understood and dealt with completely to get even close to the end goal. Not gonna happen in a typical home basement turned Home Theater.

I have determined that my current room construction project will simply never get to goal #2, too many of the types of factors you mentioned to be dealt with.