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artto's Klipschorn Room


artto

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Green Glue applied to the back of the OSB. It's a good idea to leave a couple inches around the sides free of Green Glue to make handling easier. I applied Green Glue directly to the wall where the edges of the OSB are to make sure I have complete coverage.

 

Green Glue is applied in a completely random manner but evenly distributed. There is a video on their web site  that shows two different application methods. Supposedly the method that uses larger amounts applied in a sort of sweeping curved manner produces slightly better performance. On second and third layers I started using the second method.

 

Two tubes of Green Glue are used per each 4'x8' sheet of OSB/Sheetrock.

 

http://www.greengluecompany.com/videos/applying-green-glue-noiseproofing-compound

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The Green Glue applied directly on the wall where it's not applied on the OSB for easier and less messy handling. Green Glue is somewhat "loose" as compared to caulking. It doesn't "run" or flow much but it can get a little sloppy applying it to vertical wall surfaces if you're not careful.

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4" course thread drywall screws were used to secure the first layer of OSB to exterior wall studs. A 1/8" full 4" depth pilot hole was drilled for screw installation.

 

As I mentioned earlier, the middle of the wall was acting as sort of a huge woofer passive radiator. I realized it was just as important to reinforce the entire will to stop its movement as it was to increase its mass to lower the resonant frequency. I figured by the time I had at three layers, and possibly as many as 7 or more layers of OSB the wall would be pretty stiff and stop acting like a passive radiator outside.

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Just a reference for the size of the screws used to get through the first layer of OSB and all the other layers of sheetrock, 1x2 lath and Celotex to reach the exterior wall studs. Its important that the whole wall work together as a system and the Green Glue Compound/sheetrock/OSB layers are tightly constrained together to achieve maximum performance.

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Edited by artto
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I intend to do the same thing to the west (side) wall (which used to be the front wall with the Klipschorns) so I had to begin some OSB installation on the west wall at the corners. I didn't the entire layers OSB to simply butt up against the west wall and then have the OSB on the west wall butt the front wall. I wanted each layer to overlap to get the structurally strongest and leak-free joint.

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With the first layer of OSB installed all joints/seams had more Green Glue Sealant applied over them immediately prior to installation of each additional OSB section. The Green Glue "squiggles" you see are where the edge of the next layer section of OSB will be installed.

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Edited by artto
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All screws were filled with Green Glue Sealant not so much to plug-up any potential air leakage but to to prevent a loss of Green Glue Compound getting squeezed into the screw holes. Some screws go in deeper than others and leave a substantial hole depth allowing for a lose of Green Glue Compound being constrained. Yes, it's overkill. But why cut any corners at this point?  :)

 

Notice the spacing of the screw holes. They are about 4" to 6" apart, vertically and horizontally. Green Glue Company recommends following your local building codes for screw spacing.

 

Here I decided more screws is better and the architect at Green Glue agreed that it would improve constraining the Green Glue as well as contributing to increasing structural stiffness of the wall.

 

The second layer of OSB was secured to the first layer of OSB with 1-5/8" drywall screws. And the third layer of OSB was secured all the way through all three layers of OSB and into the wall lath spacers with 2-1/2" fine thread drywall screws.

 

As I went along securing each layer to the previous it was apparent that using more, tightly spaced screws contributed greatly to making the wall less resonant when pounding on the wall with my fist.

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Edited by artto
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The whole wall with all three layers of OSB/Green Glue.

 

When I finished the first layer I was kind of disappointed in the improved performance. As mentioned previously, Green Glue Compound is kind of "loose". I noticed that after it began drying it (like next day - squeezed out material) became much more sticky. I suspected there might be a curing time and that in fact turns out to be the case. Green Glue does not reach peak performance for at least 30 days. So I won't be performing any additional sound transmission loss tests until then.

 

But I can tell you that so far I'm getting a pretty substantial reduction in low frequency sound transmission. Last night for instance, my wife was kind of surprised how loud I was playing the music but when she went outside she was surprised again that she didn't hear anything.

 

And this looks like it will be a win for my neighbors and a win - win for me. Why two wins for me? Apparently I was getting a lot of energy loss through the wall. Now a lot more bass energy is being reflected back into the room with the result that I don't have to turn the system up quite as much to get the same or higher SPL, and most certainly don't need as much or any low bass boost on certain recordings. The "signal present" meter lights on the subwoofer processor hardly ever even light up now!

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Here are the measurement results of the wall sound transmission loss performance BEFORE OSB and Green Glue installation.

 

Just be clear, the lower the number, means the SPL is higher. These are relative values.

 

I used a matched pair of calibrated Dayton EMM-6 microphones, one inside the room and the outside, about 1 foot from the outside wall. The mics used a Focusrite Scarlet 18i/20 digital USB audio interface. The USB signal went to the laptop PC and I used Sony Acid Pro 7 to record the sound. The Acid Pro & file was rendered to a .WAV file where I processed it in Sony Sound Forge Pro 10 using the spectrum analyzer isolate frequency peaks and amplitude.

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And this looks like it will be a win for my neighbors and a win - win for me. Why two wins for me? Apparently I was getting a lot of energy loss through the wall. Now a lot more bass energy is being reflected back into the room with the result that I don't have to turn the system up quite as much to get the same or higher SPL, and most certainly don't need as much or any low bass boost on certain recordings. The "signal present" meter lights on the subwoofer processor hardly ever even light up now!   DSC01239OSB_WholeWall_25%.jpg

 

I also see that you found the solution to your low ceiling issue - 50 degrees by 50 degrees coverage - at least down to 200 Hz.

 

What are those objects on top of the SH-50s?

 

Chris

Edited by Chris A
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It's a standard 8' ceiling, except maybe for the additional layer of Celotex and 5/8" sheetrock.

 

Those are Auralex MegaLENRD on their side on top of the SH50. Sometimes (if I want to) I can slide them forward to overhang the top front edge of the SH50 to reduce sound reflection off the ceiling. They work really well just for some additional bass trapping in a different part of the room other than just the four corners as well as some additional broadband absorption. I've removed much of the wall absorption materials from the room since the SH50 are putting the majority of the sound where it belongs - at the listening position. Regardless, the sound stage depth, definition and resolution are improved with the MegaLENRD on top of the SH50. I think it has more to do with killing some of the remaining reflections in the room rather than doing anything for the SH50 per se'.

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Almost forgot to mention that eventually, since I know I have ceiling reflection issue (with the SH50 it's not a big deal, but I know from experience with the MegaLENRD on top of them it can be improved), is I plan on installing RPG Diffsorber/Broadsorber panels or Auralex Q'Fusor arrays on the ceiling over & around the seating area. The Q'Fusor seems like a more cost effective solution for my needs. The RPG Diffsorber are interesting in that they provide the required diffusion but act like bass traps at lower frequencies. Both Q'Fusor & Diffsorber are relatively low profile of 2-3/4" and 4" respectively. This will have to wait until I get the outside wall(s) sound transmission loss improvements in place.

Edited by artto
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Please post some recent photos of your HO layout.  I have been limited to Trainz12.  Please!

Here you go jacksonbart.............

 

The Santa Fe Super Chief tuggin' along up Edelstein Hill.

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Thanks for posting the photos.  JB would probably enjoy some more.  I know I would.

 

I can almost smell my late father's musty collection of Model Railroader magazines.  I wish I had the space and the time to set up some of his trains.

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Actually the whole train layout is getting renovated, upgraded and expanded. I guess maybe I'll start a post in the Lounge section.

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