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After talking with Greenglue manufacturer I'm confused. Also carpet on walls maybe?

#1
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3/25/09 at 5:40pm
  • Joined: January 2009
  • Post Count: 68
I called the Greenglue people today and need some clarification from you guys.

My HT will be over my garage. Screen in front, entrance in back. The only wall that is shared with the house is the back wall (entrance). The other walls and ceiling are surrounded by the attic. Basically you go up the stairwell in the house and take a right and go into the theater over the garage.

I had the thought of double drywalling and green gluing every wall but the guy at greenglue said the only wall I should greenglue is the shared wall in back. That way the house won't hear anything and the rest of the sound will disappear into the attic. I thought that greenglue ALSO contributed to the overall acoustics of the HT by keeping the sound inside the HT but he said no, it's only for sound isolation. You tweak the sound with sound treatments (which I assumed anyway) Doing all the walls would be overkill he said. Then I asked what he would do if it were his HT and he said "I'd do them all anyway."

Argh. I am confused. I want an amazingly great sounding HT without having the rest of the house hear it (wife not be annoyed). Do I greenglue all the walls or not?

Also, would short pile carpet halfway up the walls (then a chair rail then paint) make the room too dead? I seem to get differing thoughts from members.
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#2
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3/26/09 at 6:54am
  • Joined: January 2008
  • Location: Colorado
  • Post Count: 129

Re: After talking with Greenglue manufacturer I'm confused. Also carpet on walls maybe?

hanging double drywall is a lot of work. I would use only on back wall. From my knowledge of greenglue, it captures/transforms energy that is passing through it. That means it will help isolate your theater from the outside world. It wont make a lick of difference to the higher frequencies that bounce off the drywall and stay in the room.

I think carpet/fabric on the walls is a good idea.

You can go crazy with a RTA software program and accoustical treatments looking for the perfect room response. However, these days you can achieve better results with Audyssey software. I have an Audyssey Pro box that I use, and also bring with me when I am demoing at trade shows. IMO it is absolutely the way to go. It corrects frequency like you can with accoustical treatments, but more importantly it also corrects in the time domain (which you cant tweak by yourself).
There are several AVR's that can be "unlocked" to run the the Pro version of Audyssey. Denon, for example, is Pro upgradable on models 3808ci and higher. Sure you will have to find an Audyssey registered installer to set it up for you, but the Audyssey Pro version vs. Audyssey MultiQ-XT is barely comparable.
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#3
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3/26/09 at 10:35am
  • Joined: January 2009
  • Post Count: 68

Re: After talking with Greenglue manufacturer I'm confused. Also carpet on walls maybe?

Thanks for the response. Since I'm a relative newb, the RTA and AVR stuff went WAY over my head but it will come in handy when I am more advanced.

Re: GreenGlue. So because my theater is only connected to my house by one wall, I should double sheetrock and greenglue that wall and none else? Essentially greenglue doesn't contribute to room acoustics at all? That's what wall treatments are for? The sound on the other walls will "leak" into the attic and that's OK?
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#4
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3/26/09 at 12:12pm
  • Joined: August 2000
  • Location: Southaven, MS
  • Post Count: 4,539

Re: After talking with Greenglue manufacturer I'm confused. Also carpet on walls maybe?

Quote:
Originally Posted by Rancho5
Re: GreenGlue. So because my theater is only connected to my house by one wall, I should double sheetrock and greenglue that wall and none else?
If you are doing this yourself you can test it. Double drywall the one wall and set up your sound system. Crank it!!!!! Does the sound leak from the other three walls to the rest of the house? Yes - more double drywall.

Quote:
Originally Posted by Rancho5
Essentially greenglue doesn't contribute to room acoustics at all?
None at all. Acoustics are how the sound interacts with the room. You will use carpret on the walls or sound absorption panels (or both) to tame high frequency reflections. You will use placement and a parametric EQ to flatten the response of your sub(s).

Quote:
Originally Posted by Rancho5
The sound on the other walls will "leak" into the attic and that's OK?
Maybe. That's why I suggested a test. I used staggered studs and insulation on my theater room. It keeps out sound (loud cars on the street or people in the next room) but it can't contain my sound system. I don't think adding double drywall would contain the bass. My dual 15's can excite the concrete foundation of my house. You can hear and feel them at the opposite corner of the house. So if you go nuts like I do then you have to use proper control of the volume knob to keep the rest of the house quiet.

-Robert
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#5
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3/26/09 at 3:17pm
  • Joined: August 1999
  • Location: Katy, TX
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Re: After talking with Greenglue manufacturer I'm confused. Also carpet on walls maybe?
Quote:
Originally Posted by Rancho5
My HT will be over my garage. Screen in front, entrance in back. The only wall that is shared with the house is the back wall (entrance). The other walls and ceiling are surrounded by the attic. Basically you go up the stairwell in the house and take a right and go into the theater over the garage.
It’s hard to get a true visual without pictures or a floor plan of some kind. For instance, what’s behind that “only wall?” A bedroom? Attic space? Is the stairwell inside or outside the room? If the latter, then you have a stairwell between the HT room and the adjacent room ( if indeed there is one), which will automatically give better isolation than if the stairwell is inside the HT room.

Just keep in mind that there are some basic requirements for isolation from adjoining rooms. They include walls with staggered stud construction, or even better a separate free-standing wall adjacent to the first, and mass in the form of added sheetrock – double or even triple layered. Also necessary is a heavy solid-core door that’s fully air tight with weather stripping and threshold as an outside door would have. Indeed, a good isolated room should be air tight. Unfortunately, this leads to other concerns, like the air conditioning system, as an air return will be needed in addition to the AC vents (inside the rest of the house, air return is accomplished by leakage under and around loosely-sealed doors).

Any of these requirements that you cut corners on will mean reduced isolation. That said...
Quote:
I want an amazingly great sounding HT without having the rest of the house hear it (wife not be annoyed).
... if you’re expecting 100% isolation, you’re setting yourself up for a big disappointment. Just do as much as you can and hope it’s satisfactory to the wife. You have a big advantage going in that your room appears to be more-or-less separated from the rest of the house, so I’d be surprised if you don’t end up with satisfactory results.
Quote:
I had the thought of double drywalling and green gluing every wall but the guy at greenglue said the only wall I should greenglue is the shared wall in back. That way the house won't hear anything and the rest of the sound will disappear into the attic.
It all depends on whether or not that “attic [that] the other walls and ceiling are surrounded by” is common with the rest of the house or not. If it's a shared attic, I’d staggered-stud those other walls, as well as the ceiling, fully insulating them with double or triple sheetrock on both sides. And greenglue, too.
Quote:
Also, would short pile carpet halfway up the walls (then a chair rail then paint) make the room too dead? I seem to get differing thoughts from members.
In most places I’ve had audio systems set up over the years, the acoustics are fine with wall to wall carpet and normal room furnishings. Adding more carpet on the wall can’t hurt although I think maybe 1/4” height with chair rail will look nicer than having a chair rail four or more feet up the wall...
Quote:
I thought that greenglue ALSO contributed to the overall acoustics of the HT by keeping the sound inside the HT but he said no, it's only for sound isolation. You tweak the sound with sound treatments (which I assumed anyway)

I want an amazingly great sounding HT...
A lot of people confuse acoustics with soundproofing. I think you’ve figured out by now that one has nothing to do with the other. As mentioned, you’ll get plenty of treatment for the highs and a certain amount of the mids with the carpet and room furnishings. You might consider some built-in bass traps if you’re interested in treating the low end (which translates to shortening signal decay times).

Regards,
Wayne A. Pflughaupt
My Equipment List
“A nice mid-fi system,” according to an audiophile acquaintance.

My Tech / DIY Articles and Reviews
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#6
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3/26/09 at 8:35pm
  • Joined: January 2009
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Re: After talking with Greenglue manufacturer I'm confused. Also carpet on walls maybe?

Wayne, much thanks for your help and thanks to everyone else too.

The only thing behind that shared wall is the stairwell. The stairwell is a long chute outside the theater. When you climb it and arrive at the top, you either turn left to go into the open gameroom area, or turn right and go into the theater through a solid core door. The theater is all above the garage. It was framed as an attic room truss system. Basically scissor trusses on the edges and a box framed within. (Hopefully the attached picture will help)

Walls C & D go to nothing, just attic. The front is the screen and the back is the stairwell.

HVAC guy, doing a side job, is coming Saturday to put in two vents and two 12" air returns. Floor is two layers, one 3/4 floor OSB tongue and groove glued and screwed and a second opposing 1/2 OSB layer also glued and screwed.

Solid core door with a 1/3 inch space at bottom because of the thick floor.

Carpet will be interlocking carpet pieces that can be removed and replaced when stainied. We NEVER eat over carpet in the house but with this HT, we're going to enjoy popcorn and coke, dadgummit! (no food over carper is my idea, not my wife's. Kids were stunned when I told them we were going to eat "up there".

1/4 way up the wall with carpet would be good considering the walls are 7 feet high. Thanks.

I will do those triangular corner bass traps, ceiling to floor.

SVS speakers came today and even though we aren't finished, I could not resist hooking them up to the older Onkyo 5.1 in the "theater" we have now. (read hugely open area with crappy acoustics) HOLY CRAP, nothing will contain that bass! IT shakes the house and I love it. The fronts I had to put way too high because of the short wire but even then they sounded decent. Can't wait to put them on stands and get them at the correct heights. Rush's Snakes and Arrows concert DVD sounded awesome though as did Roger Water's concert.

Wahoo! and thanks for all the help. Keep it coming!
525x525px-LL-vbattach1368.jpg
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#7
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3/27/09 at 7:48am
  • Joined: August 1999
  • Location: Katy, TX
  • Post Count: 5,823

Re: After talking with Greenglue manufacturer I'm confused. Also carpet on walls maybe?
Quote:
The only thing behind that shared wall is the stairwell. The stairwell is a long chute outside the theater. When you climb it and arrive at the top, you either turn left to go into the open gameroom area, or turn right and go into the theater through a solid core door. The theater is all above the garage.
Still not clear on whether or not the theater and gameroom share attic space, but if you have a door in place that tells me that construction is basically finished. So actually it’s a bit late to be addressing soundproofing needs, which should have been planned for before construction began. The wall (where the HT door is) should have been staggered stud at the very least, or even better, doubled (i.e. both free standing, non-coupled), with double solid airtight doors. Maybe you can still double or triple sheetrock on both sides of the wall – that’s about all you have left at this point.

Another late option would be to wall off the gameroom, so that you have to go through a door to get into it. With your existing HT wall double sheetrocked on both sides, and a wall for the gameroom done the same way, with its own solid-core airtight door, you’d be looking pretty good. Depending on that attic situation, of course…

Regards,
Wayne A. Pflughaupt
My Equipment List
“A nice mid-fi system,” according to an audiophile acquaintance.

My Tech / DIY Articles and Reviews
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#8
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3/27/09 at 4:25pm
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Re: After talking with Greenglue manufacturer I'm confused. Also carpet on walls maybe?

Theater and game room do not share attic space. The theater is basically an above garage rumpus room that we had framed for a live load to use as a theater after we moved in. Therefore the wall between the two is built and in place. I think triple sheetrocking that back wall with green glue is the best way to keep the noise from spilling out.

You have mentioned in previous posts about EQ's. If I purchase the Onkyo SRS606 it has an auto calibration feature. Do I still need a radio shack sound meter and Avia DVD? If so, how do you adjust w/o an EQ?
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#9
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3/27/09 at 6:05pm
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  • Location: Southaven, MS
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Re: After talking with Greenglue manufacturer I'm confused. Also carpet on walls maybe?

I used my SPL meter and Video Essentials to check the the levels of my Pioneer's MCACC auto calibration system. It was close enough that I didn't adjust the levels. I just changed the speakers from Large to Small and started watching.

I do use my SPL meter for sub equalization. I'm using a Behringer Feedback Destroyer to flatten my sub's response from 80hz to 17hz. I've also used the SPL meter and VE to adjust friend's and family's systems that don't have an auto calibration reciever.

-Robert
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