Diamante Build in DC - Page 2

Last I  heard, Ted has been shying away from recommending the soundproofed-shell-with-everything-else-hanging-off-of-it design.  The engineering specs are from another manufacturer's clips.  But I am due for one last call to Ted before finally spec'ing out the soundproofing.  

I think the idea of having beefier firring channels is to increase the apparent mass to allow less flex of the wall/ceiling assembly.

I do appreciate all of the constructive criticism and advice.  Will have more pictures of the space this weekend.

And I definitely agree that there are major questionable design decisions that were made in that room.  I would also point out that the screen-seating distance appears way too short for the first row, and possible even for the second row.  But who knows what kind of distortions could be introduced by whatever lens the photographer used.  I also like how the sound containment consideration (if there was one) ended up in a window curtain assembly in the room partition.  And it's hard for me to actually tell, but it looks like they don't even have a seat in what I would say is probably the best viewing spot which is the middle of the second row.  And finally, if the rear wall is symmetrical to the rear shelves as the front wall is to the front shelves, there is very little room between the second row of seats and the rear wall which would seem to compromise the surround channels.

I was willing to give them the benefit of the doubt with the lighting and assume that the front-facing lighting was a screen wash, comparable to how some people put recessed lights above their screen to light the screen up before a show, and that they would always be off when there was something showing.  But you're probably right in that it was just improperly thought out.

I haven't dug deeply enough to try to find data on exactly comparable wall construction to match product to product.  But the trend shows that the low frequency performance of the Wave Hanger is superior to the more traditional clips.  And since I can't find any impact isolation performance information for either the Whisper Clip or the IsoMax, I can only relate that the manufacturer states that the impact isolation difference between the two types of products is more pronounced than the airborne STC differences.

If I remember the numbers Ted gave me a month ago, the Whisper Clip is significantly less expensive than the Wave Hanger, but the load carrying rating of the Whisper Clip is a bit higher (36# vs. 44#?) which may allow a reduction in the number of clips required?

Hmm.  The way Kinetics seemed to explain it to me was that their products create a leaf spring mechanism for sound isolation.  They do not rely on the flex of the sheathing but rather only the mass of the sheathing.  When asked specifically about Green Glue, he commented that it was sort of a waste of money since they are looking to create one rigid structure that moves (or doesn't move) as one continuous mass.  He did concede, however, that there were other techniques of soundproofing that do rely on the flexing of the drywall and in those circumstances the Green Glue makes sense.  We were talking about his ICW product specifically, but I think he was also including his Wave Hanger product as well by inference.  I believe that the IsoMax product is one that he would say relies on the flex of the drywall since it appears to work on the same principles as Ted's IB1 and Whisper Clip products.

Quote:

Originally Posted by Dennis Erskine 



In the attached photos, both rooms were built according to option 1. (NO PLYWOOD WAS USED!). The entire weight of the millwork (in the millwork heavy room) is supported by clips/channel ... all of that millwork is inside the isolation shell. In the picture of the room with the stacked ceiling ... all the framing and drywall creating the stacked ceiling was installed after the shell and is supported by clips and channel.

Out of curiosity, is any effort made to attach the framing and/or trim inside the soundproofed shell to the firring channels themselves?  Or just glued and screwed into the double drywall shell?

And is it reasonable to assume that any framing/drywall construction inside the soundproofed shell can be very lightweight construction (i.e. 2x2's or 2x4's spaced 24" apart with single layer of 1/2 lightweight drywall)?  

I saw a similar drawing in one of Ted's documents.  I think I talked Ted into being comfortable with just increasing the density of the clips and channels moderately to accommodate the added weight of the ceiling trim details.  I'd guess that Ted is perfectionist enough that he was  uncomfortable putting together a good-enough solution.

I've made a bit of progress in the last month.  Finally got a building permit and started with the demo and reconstruction.

Starting point:

My initial demo efforts:

Taking down the fireplace and the little concrete pillar near the electrical closet:

Rearranging the ductwork.  These ducts supply the theater room.  The ones on the opposite side of the room supply the kitchen upstairs.  They are Y'ed together at the HVAC unit.  So to eliminate a set of direct pipes from the theater room to the kitchen, I took them out and used that trunk to feed other areas of the house:

Finishing up some leftover concrete work from my upstairs renovation:

Now we're ready to do a little framing.

The bar and kitchenette area:

The family room:

The mechanical room:

Then I got the plumber involved:

Some more framing.
 

Framing the lobby:

Most of the electrical ground work is getting completed now.  One more day of work tomorrow.  Then it is time for an inspection.  I'm interested to see if managed to cover all the right bases, in the right way.

I'm thinking now of what cables to run to the front of the room from my AV rack closet.  Besides the usual suspects like speaker cables (I'll have balanced and unbalanced line level signals for thee subs as well as speaker level outputs for the front 3 speakers), I'm wondering what else I should put in there while everything is all opened up and easy.

I will pull a couple of Cat 6 cables and a couple of old left over Cat 5 cables that I have laying around from a prior project.  I figure the Cat 5 cables can be used for misc., non-networking purposes.

I have heard that some setups work better with external 3D emitters for the glasses.  What kind of cabling in required for that?  How big are the emitters?  Can they be hidden behind the screen wall fabric or do they have to be "in plain sight"?  How big are they?  Do projectors typically come with them or are they an extra-cost option?  I assume that these connect directly to the projector somehow?  Is it usually just some sort of mini-RCA type plug/jack setup?

I'll also pull a couple of extra speaker level wires up there in case height/width speakers make it into my room at some point in the future.

Anything else I should be thinking about?

Thanks.

The other company, Kinetics Noise Control, does indeed have what seems to be independent lab testing of their products.  I think that their product works on a different principle than the well-described double drywall/green glue method popular here.  Perhaps its akin the the difference between Porsche's AWD system and Audi's AWD system.  Different ways of getting there, but in the end looking for the same destination.  

And I don't think that they "(don't) want to use it simply because they don't sell it".  Rather, they don't sell it because it is not a required component in their system.  Same as you're not going to get see a plumber with a torch when they're installing CPVC in your house.

I guess no thoughts on additional wires that should go in the rough construction before I close it up.  

One other wiring/control issue I thought about.  My ventilation system will be two Fantech FG6XL's in a push-pull configuration.  Is there a way to remote control a fan multi-speed control with IR (I have iRule and a Global Cache IP2IR gateway) on each leg of the system so that I could pull up the fans in iRule and adjust the ventilation system depending on the load in the room?

Close-In Inspection Passed today.  Now on to insulation before my next inspection.  Then on to finishing the framing and drywalling.

I would like to solicit opinions on acoustic treatment of my front wall assembly.  I've enclosed two schematics.  The first one is the top-down view that shows my front wall assembly consisting on a screen wall behind which is a wall to hold the speakers and behind that a couple of feet before getting to the foundation wall.  The "foundation wall" is not the bare concrete but will have 2 layers of 5/8" drywall attached to 2x4" framing (isolated from the ceiling with IB3 clips).

The screen wall will host an acoustically transparent screen and the rest of it will be covered with fabric (presumably as acoustically benign as possible).  Thus, except for the framing members and the frame of the screen, this wall is designed to be as acoustically transparent as possible.

The speaker wall will just host a few studs to screw my in-wall speakers to.  Each of the speaker bays will have OSB or plywood backers and be filled with fluffy pink stuff to a manufacturer's recommendation of 2.0-2.5 cu. ft. volume.  There will be drywall from side to side and from the top of the speaker cavities to the bottom of the speaker cavities.  The tops and bottoms of the wall will be open between the screen wall and the foundation wall.

My understanding is that a good place to start acoustically for reflection control is to put Linacoustic on the "front wall".  And I also believe that there is some consensus that a bunch of loose-fill fiberglass in the "corners" is a good start for bass-trapping.  

My initial thoughts would be to fill the majority of the space between the speaker wall and the foundation wall with a bunch of fluffy pink fiberglass.  It would seem that this would offer a good start to bass trapping in the front corners of the room.  My assumption is that the corners of the foundation wall are the "corners" I should be treating and not the intersection between the screen wall the the side foundation walls?  Since the screen wall is supposed to be acoustically transparent, it would seem that I could just ignore it for acoustic treatment purposes.

My question now becomes what is the "front wall" that is typically treated with Linacoustic?  I'm actually off to the supplier to pick up some 1" and 2" Linacoustic right now.  I would assume that the Linacoustic would be attached to the drywall of the speaker wall.  Is there a need to put any Linacoustic along the foundation wall - either at the tops or bottoms to cover the areas not protected by the speaker wall drywall and its Linacoustic covering, or the whole foundation walll?

Any other thoughts for acoustic treatments would be appreciated.

I guess I must start with what I assume a baffle wall to be.  And that is essentially a structure designed to house speakers behind an AT screen.  I guess I should add that there should be some thought or engineering behind the construction of this wall so that it adds to, instead of detracts from, the acoustics of the room and speakers.  

What I seem to see many people doing with these baffle walls is putting some 1" Linacoustic lining the "front" (screen side) of the wall presumably to absorb a) reflections off the back side of the screen and b) reflections coming back to the baffle wall after reflecting off of the rear or side walls.  

As far as appropriateness of the speakers for a baffle wall, I assume that you are speaking to a speaker's radiation pattern.  An assumption I would make is that the baffle wall also serves to block or attenuate any sound reflected off the "back side" of the driver.  I believe that this "back wave" typically travels to the rear wall and reflects off of it into the audience.  This seems to be a "feature" in many stereo/music-only setups and in fact many speakers utilize a "bi-polar" or "omnipolar" design -- sometimes going to the extreme of having a second set of active drivers directed 180 degrees from the forward/audience facing drivers.  This reflected sound presumably defines the "spaciousness" or "ambiance" of the soundfield.

But in HT/multichannel applications, it seems that there is much effort taken to abolish this "back wave" with absorptive materials placed all along the "front wall" (see my previous post with questions as to what really constitutes the "front wall" acoustically in situations such as mine where there are multiple surfaces that could be construed as walls).  These setups now rely on multiple speakers and discrete soundfields encoded in the soundtrack to define the "ambience" of the soundspace.  So presumably any bi-polar speaker design (i.e. Definitive Technologies which I used to own) would be a poor choice of speakers in a dedicated HT environment.  Baffle walls would seem to enhance this separation of the "back wave" from the "front wave" and I  understand that some speakers are designed to be used in such a baffle wall (Procella comes to mind as they are discussed in these forums with regularity).

As to my BG Radias not being appropriate for a baffle wall setup, my question is why ALL in-wall designed speakers would not be perfect candidates for such an installation arrangement?  In fact, I'd argue that in-wall speakers require such a baffle wall setup.  By definition, in-wall speakers are designed to operate with a large plane (wall) in line with the speaker drivers.  This is in contrast to traditional box speakers that are designed to sit inside of a room with a large plane (wall) at some point behind the plane of the drivers.  In addition, in-wall speakers by necessity have to be designed to assume that the "rear wave" will be blocked by something before it gets back to the audience.  So I guess I'm curious what might be different about the BG Radias that make them inappropriate for use with a baffle wall?  I hope that I can get this figured out as this setup is fundamental to the design of my sound system.  

Thanks for your input.  As my mother used to tell me, you're never too old to learn something new!

Thanks for the reference.  It seems that most of my impressions are correct.  Things I hadn't thought about were isolation of the speakers from the baffle wall and the constrained damping construction (do I need another bucket of Green Glue???).  They don't demonstrate in those pictures how they isolated the speakers from the baffle wall?

My thoughts on in-wall speakers essentially requiring a baffle wall type construction still remains.  The difference here would be the fact that I essentially need to build the enclosure of the speaker into the baffle wall framing versus having the back of the baffle wall speaker enclosure open to the back.  But it appears that with all the fluffy pink stuff behind their baffle wall, they are absorbing as much of the "rear" wave as possible which is also what I'm proposing doing by filling the space between my baffle wall and foundation wall with pink fluffy stuff.

I appreciate how it is mentioned that the tops and bottoms of the baffle wall can be left open to allow the area behind the baffle wall to act as a bass trap.

In looking at how much Linacoustic I have available to use, is there any advantage to using 2" Linacoustic vs. 1" Linacoustic?