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post #121 of 410 Old 07-17-2016, 10:45 AM - Thread Starter
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I don't recall if I mentioned this in my past posts or not, but I decided to build a concealed storage area into the wall that is shared with the bedroom. The purpose of this storage space is 3-fold: 1) WAF (always wants more storage); 2) someplace to put my DVDs; and 3) another buffer between HT and bedroom.

The space is only going to be about 7 1/2" deep, but it's deep enough to store and hide (when desired) all my DVDs and a few other things. Since I'm planning on fabric panel wall coverings, the fabric panels will be placed over the storage areas (thus concealing it). I plan to build shelves between the 3 columns along that wall.



Here you can see the result after framing the inside portion of the supports for the storage area. The columns will ultimately be attached to these posts. The front of the posts is missing atm. I still need to decide on the final configuration plan for the concealed storage area. I'm thinking of drywalling over it and then cutting out holes for the shelving. The shelves will either be cabinetry veneer on the sides, or more likely stained wood. I'll drill some peg holes to allow the use of shelves.
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post #122 of 410 Old 07-23-2016, 08:24 PM
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Originally Posted by HT Geek View Post
I don't recall if I mentioned this in my past posts or not, but I decided to build a concealed storage area into the wall that is shared with the bedroom. The purpose of this storage space is 3-fold: 1) WAF (always wants more storage); 2) someplace to put my DVDs; and 3) another buffer between HT and bedroom.

The space is only going to be about 7 1/2" deep, but it's deep enough to store and hide (when desired) all my DVDs and a few other things. Since I'm planning on fabric panel wall coverings, the fabric panels will be placed over the storage areas (thus concealing it). I plan to build shelves between the 3 columns along that wall.



Here you can see the result after framing the inside portion of the supports for the storage area. The columns will ultimately be attached to these posts. The front of the posts is missing atm. I still need to decide on the final configuration plan for the concealed storage area. I'm thinking of drywalling over it and then cutting out holes for the shelving. The shelves will either be cabinetry veneer on the sides, or more likely stained wood. I'll drill some peg holes to allow the use of shelves.
Really nice idea here. Should work out well; anxious to see it finished.

I'm with you, simply can't get enough storage. My guess is you will love this Geek.
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post #123 of 410 Old 07-23-2016, 08:43 PM
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Originally Posted by audiovideoholic View Post
Keep applying the sealant or glue or whatever between your joints and where objects meet! I went stupid crazy overboard with screws and glue on my entire build and can crank my subs over 140db with very few rattles that I can spot treat.
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Thanks for the tip. I'll admit that when I began attaching the soffit ladders I didn't think it was necessary to use glue or sealant. The thought occurred to me when I was on perhaps the 5th or 6th section. Hopefully, it won't matter. I've made a mental note to use acoustical sealant when I get to the stage of applying the facade to the soffits. And I did leave a small gap between most joints, so that I can retro-actively apply acoustical sealant there.

We'll see. As you pointed out, I want to avoid rattles!
Benn very curious how my HT will perform regarding the rattles as well. My drywall is already up so for me it may be a moot point but...

What sealant and joints are you both referring to? Spot treat rattles? Would you elaborate please?

Geek you going to have a very nice HT. keep up the good work.
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post #124 of 410 Old 07-23-2016, 08:54 PM
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Originally Posted by HT Geek View Post

Finally got the circuit breakers tackled a couple of weeks ago.

Unfortunately, due to the box configuration and the type of breakers installed, the existing breakers had to be re-arranged so everything would fit (the box is now almost full). That means I now need to re-label most of them as they're no longer all lined up with the correct labels. The issue was these new AFCI/GFCI combo breakers are BIG inside the box, compared to regular breakers.

Upside is it saves me from feeling like I MUST have GFCI outlets in the room. My outlets in the HT room will be behind a pull-out network rack, and will be difficult to access for GFCI-push-button-reset purposes. I'll probably still use one for the electrical outlets in columns and rear seats though, just in case someone does something foolish involving liquids and electricity.

Fun Fun Fun!!!
As is the case most times Geek I'm still learning from your incredibly thorough research and implementation. The GFCI, with the exception of the riser outlets, why do you feel the need to have GFCI outlets in your ht?

What are the AFCI/GFCI combo breakers and should I be considering these for some reason?
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post #125 of 410 Old 07-23-2016, 09:27 PM - Thread Starter
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Quote:
Originally Posted by ddigler View Post
Benn very curious how my HT will perform regarding the rattles as well. My drywall is already up so for me it may be a moot point but...

What sealant and joints are you both referring to? Spot treat rattles? Would you elaborate please?

Geek you going to have a very nice HT. keep up the good work.
Hey Dig. Thanks for your comments, btw.

This has been a point of consternation for me, simply because this is my first HT build. I don't know what to expect until I get to it, and I don't know what to expect when I'm done.

What I was referring to above are the joints where my soffit is attached to the ceiling or walls, and a few other cases such as (in the photo you re-posted above), where the supports for the storage area meet the wall and floor.

When I began constructing the soffit, I didn't think about this. When I started it, I did leave a slight gap between my ladder soffit support and the walls (maybe 1/8" or so, 1/4" max). I subsequently shifted that idea to making wall contact because it allowed extra support for the soffit frame, but I used Green Glue Noiseproofing Sealant between the wood and the walls. For the ceiling, I used SikaBond Pro Construction Adhesive. I tell you, the latter is amazing. Those soffit ladders are never coming off the wall unless the drywall goes with it!

On a related note, this week I finally got around to installing conduit in my soffits. I hemmed-and-hawed over where it was or was not worth using conduit. The main benefit I see is 'future proofing,' but in my case there were a few other reasons as well. I'll endeavour to post pics and details tomorrow or Monday morning. However, relative to squeaks, rattles, etc., I used electrician's putty around the tubes on about half the clamps for my conduit, so that on the off-chance the move or squeak, they should remain quiet (I think/hope). OTOH, I'm not sure I'd notice anyway since if that happens it will have to be during an intense (and loud) movie, etc.

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post #126 of 410 Old 07-23-2016, 10:09 PM - Thread Starter
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Quote:
Originally Posted by ddigler View Post
The GFCI, with the exception of the riser outlets, why do you feel the need to have GFCI outlets in your ht?
I'll give you the TLDR version first, and then explain further.

There's no need for GFCI on the A/V equipment circuits. In fact, that's just asking to be annoyed in the future as once my equipment is in, it will be difficult to access the plugs behind it. Because no human should be contacting those outlets, there's theoretically no need for GFCI there.

But there IS a need for GFCI on any circuit that will have electrical plugs or switches where someone might have wet hands (e.g., beer) or a few other scenarios (but mostly it's a concern relative to liquids, people, and electricity). Anyhow, in my case I haven't decided if the lighting circuit will also power electrical plugs, such as in the columns, etc. so it's probably wise to presume that I shall do so, and just go with GFCI for that circuit.

One other tidbit. The NEC changed in 2014, and now the list of rooms requiring GFCI is even more confusing. So, again when in doubt... err on the side of more caution, per se.


Now, here's all the crap that 95% of people prolly don't care about (i.e. details)

The primary concern would be the riser outlets; as you suggested above. Forgive me if I'm explaining what you already know, but GFCI (in a nutshell) was invented to try and prevent people from getting killed by electrical shocks via outlets and frayed wires. What they are supposed to do is detect very small changes in the electrical flow of a circuit; the kind of flow change that would be caused if someone's body suddenly becomes a good ground source for the flow of electricity in the circuit wiring. For example, touching an electrical outlet with wet hands. The device detects abnormal changes in the line voltage and cuts off the power, ostensibly before the amperage across the line is enough to kill you.

For a long time, GFCI circuits were only available as a special type of electrical outlet. Only plugs placed in series after the GFCI outlet (and the GFCI outlet itself) are protected. Anything between the circuit breaker and the GFCI outlet is not. A few years ago, GFCI circuit breakers became available and solved that problem by adding that protection from the breaker box outward, which leads to your next question....

Quote:
What are the AFCI/GFCI combo breakers and should I be considering these for some reason?
Yes, you should consider them. In 2014, an update was made to the NEC (National Electrical Code). Two significant changes were made regarding circuit breakers in residential installations (and which, btw came as a complete surprise to a lot of people): 1) standardization regarding the use of combination GFCI/AFCI circuit breakers; and 2) expanded list of the type of rooms where AFCI/GFCI breakers are required.

Prior to the 2014 code changes, depending on the room in your house and some other factors such as when your house was built, you may have been required to use regular circuit breakers, GFCI circuit breakers, or AFCI circuit breakers, but you were not required to use a combination of these at the breaker box itself. [AFCI = Arc Fault Circuit Interrupter; it is designed to detect arcing of electricity on a circuit, and shut the circuit down before a fire starts.]

Now all that said, many jurisdictions still don't require the use of the 2014 NEC. Some do, but many still have codified the use of 2011, 2012, or earlier versions of the NEC.

What does all this mean? In my case it means I figured I might as well use the latest breakers, so I bought the 2014 versions. Who wouldn't want to use circuit breakers that are supposed to prevent you from getting electrocuted and prevent fires inside walls??? And - technically - this is what I should do (though since my jurisdiction still cites the 2012 NEC as 'code,' whether or not I needed to do that is debatable and quite frankly, effectively means that I didn't have to... but I think that's dumb, so I installed them anyway). LoL.

The previous generation AFCI breakers generated mixed reviews from many electricians (mostly due to faulty breakers, not their intended function), but so far the breaker manufacturers seem to have done a better job with quality control of the newer AFCI/GFCI combo breakers. Time will tell if that is truly the case or not!

FWIW, I have a breaker panel chock full of about 60% AFCI breakers (circa 2010), and I've had 1 persnickety breaker that likes to act weird once-in-awhile. So far, I've been too lazy to replace it because it is intermittent in its errant behavior and the replacement costs $50 (plus the fact my family hates it when I kill power to the entire house... which in this case is better than me electrocuting myself).
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post #127 of 410 Old 07-24-2016, 09:46 AM
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Quote:
Originally Posted by ddigler View Post
Benn very curious how my HT will perform regarding the rattles as well. My drywall is already up so for me it may be a moot point but...

What sealant and joints are you both referring to? Spot treat rattles? Would you elaborate please?

Geek you going to have a very nice HT. keep up the good work.
The spaces mine still has rattles is around the door framing- header and studs when the drywall starts really flexing. I just need a few more screws in that section. I put screws every 6" on drywall where it meets any framing and I put glue plus screws on all wood framing(soffit, screen frame, baffle wall, etc...). My room is 99% rattle free and will be 100% once I add a few screws around the door framing.

140+db makes Sheetrock flutter pretty much so that is why I went overboard. That and I didn't use two layers since my room doesn't need sound proofed. No way to sound proof my system without an underground concrete bunker.

If you use glue and screws everywhere two objects meet you should be good. Ted White from the sound proof company commented on my use of screws on the drywall but couldn't tell if he thought it would hurt or help the room acoustics. He was sort of amazed is how I took it.

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post #128 of 410 Old 07-24-2016, 08:06 PM
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Quote:
Originally Posted by audiovideoholic View Post
The spaces mine still has rattles is around the door framing- header and studs when the drywall starts really flexing. I just need a few more screws in that section. I put screws every 6" on drywall where it meets any framing and I put glue plus screws on all wood framing(soffit, screen frame, baffle wall, etc...). My room is 99% rattle free and will be 100% once I add a few screws around the door framing.

140+db makes Sheetrock flutter pretty much so that is why I went overboard. That and I didn't use two layers since my room doesn't need sound proofed. No way to sound proof my system without an underground concrete bunker.

If you use glue and screws everywhere two objects meet you should be good. Ted White from the sound proof company commented on my use of screws on the drywall but couldn't tell if he thought it would hurt or help the room acoustics. He was sort of amazed is how I took it.
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Hey Dig. Thanks for your comments, btw.

This has been a point of consternation for me, simply because this is my first HT build. I don't know what to expect until I get to it, and I don't know what to expect when I'm done.

What I was referring to above are the joints where my soffit is attached to the ceiling or walls, and a few other cases such as (in the photo you re-posted above), where the supports for the storage area meet the wall and floor.

When I began constructing the soffit, I didn't think about this. When I started it, I did leave a slight gap between my ladder soffit support and the walls (maybe 1/8" or so, 1/4" max). I subsequently shifted that idea to making wall contact because it allowed extra support for the soffit frame, but I used Green Glue Noiseproofing Sealant between the wood and the walls. For the ceiling, I used SikaBond Pro Construction Adhesive. I tell you, the latter is amazing. Those soffit ladders are never coming off the wall unless the drywall goes with it!

On a related note, this week I finally got around to installing conduit in my soffits. I hemmed-and-hawed over where it was or was not worth using conduit. The main benefit I see is 'future proofing,' but in my case there were a few other reasons as well. I'll endeavour to post pics and details tomorrow or Monday morning. However, relative to squeaks, rattles, etc., I used electrician's putty around the tubes on about half the clamps for my conduit, so that on the off-chance the move or squeak, they should remain quiet (I think/hope). OTOH, I'm not sure I'd notice anyway since if that happens it will have to be during an intense (and loud) movie, etc.
Thanks for the explanations.

I must admit I'm surprised rattles are even noticeable relative to the loud volumes we are talking about??
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post #129 of 410 Old 07-26-2016, 08:33 AM - Thread Starter
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Thanks for the explanations.

I must admit I'm surprised rattles are even noticeable relative to the loud volumes we are talking about??
I believe in most circumstances you're right about that.

The only scenario I can imagine where it could be an issue would be a movie scene with a burst of LFE and simultaneously an absence of mid and high range sound, and if one was either seated very close to where the rattle occurred or something's really loose. I don't really see this as likely to be a problem at all.

Just to err on the side of caution, I've made an effort to caulk where various solid objects meet. For example, when building my soffit frame, where 2 2x4's meet edge-wise, I've placed some acoustic caulk in between them (sort of a sandwich effect), just in case that on the odd chance they might otherwise rub against one another.

I strongly suspect I'm over-thinking this. However, this is my first-time build and I'm trying to anticipate potential problems so that I don't run the risk of tearing out work that is difficult to access, and then re-building something. And I don't see how I'd create problems from over-engineering a solution (albeit for a problem that may not exist).

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Quiet Glue: Why Not to Use It

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post #130 of 410 Old 07-29-2016, 04:19 PM - Thread Starter
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A cross-roads... of sorts

So, I just realized this evening that my revised plan that called for 45° angled L/R speakers on the front stage is a wee bit potentially incompatible with my plan for 3 columns on either side wall.

My columns are 4' apart and the front-most column as it stands atm, will be probably 1' or so from the stage. Possibly less. I'm starting to think that is too close to the stage and somewhat pointless to have a column there.

OTOH, if I were to go with a flat screen wall and not have the ends (L/R) angled in-ward, at that point it could make more sense.

I'd welcome any input/suggestions or related thoughts.

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post #131 of 410 Old 08-01-2016, 07:45 AM - Thread Starter
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I believe I more-or-less answered my own question this past weekend.

I had an epiphany of sorts.... I think I've finally realized and accepted that some of my design elements (such as the location of my 2 front-most columns) boil down to the constraints of my room. In particular, I have two windows on the right side of the room (when facing where the screen will be). I want at least one of those windows accessible, for emergency fire-escape purposes since this room is on the 2nd floor in a corner of my home. Placing a column in front of a window would make it inaccessible - at least from a practical standpoint (I'd prefer not to create a modular column that comes apart for this purpose... tho that is another option, I suppose).

Here was the view during during the independent wall-frame construction:



The 2 windows are adjacent. They are essentially halves of one window, but they open independently. It doesn't matter which side is accessible, as long as one of them is. The current plan calls for the left window being accessible, while the right window will be partially covered by the center column on that side of the room.

I'm going to play with the numbers a bit today to determine if a 3' 6" distance between columns might be acceptable, and possibly work better vs. the 4' spread. The main issue is in the current configuration, the front columns cannot be moved further back, because at that point both windows would be blocked (the combined width of both windows is roughly 6'). They are currently the furthest back they can be, unless I re-arranged them and blocked the left window instead of the right, which I'm not even certain is possible atm given how it would impact the other two columns (center and rear side columns).

We'll see. I'm going to play with the column gap and column position today to verify what is or is not physically possible, then see how it would impact acoustics and other issues.

The bottom line is that the constraints presented by the room shape and features that I 'inherited' per se from its previous design may ultimately drive some of the HT room design features, such as the stage placement, and whether the front wall is angled on the sides for the L/R speakers or if I shall end up placing them behind a flat front wall.
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post #132 of 410 Old 08-01-2016, 08:35 AM - Thread Starter
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Posting a few progress pics from the past few weeks.

Test-fitting the A/V server rack concept. I flipped the original layout 90°. When I began the test fitting, it dawned on me the fabric wall panels and rear columns were going to require moving it further away from the wall. After playing around with the dimensions, it seemed prudent to simply flip the A/V rack to open the other way. Access room between the A/V rack, finished walls, and future location of the rear seat row were also factors. I need a minimum of 4.5" clearance on all sides to pull the rack out and allow full rotation. I decided to add a little extra (0.5" or 1"... can't remember how much now) just to be on the safe side and allow for any variances.

The white "box" is a SMC that will house various 12v circuits and relays for planned and/or future toys. It's so tall that I didn't think it was feasible to place facing the same direction as the A/V rack.






It's raining cables!




Conduit to above the entry door; just in case I decide to do anything fancy w/door sensors, locks, etc. This will make that possible if I choose to go that route, and if not... no biggie....




Low voltage wiring; 12v + 2x CAT-5 in conduit; the CAT-6 was so thick I just laid it along the soffit joists. If I were to run that conduit over again, I would have done 2" wide everywhere. Oh well. There is space for more 12v wiring to be run if needed (inside the 1" conduit). I ran 8x CAT-6 wires along the left wall (2 to each interior column support, and 2 to where the hidden DVD shelves will be). If I need more than that, someone is doing something wrong. LoL.




Here you can just make out the 2" grey conduit in the center, peeking above the CAT-6 run. That conduit is for the PJ A/V wiring. I still need to mount a 120v plug for the PJ up there (forgot about that when I ran the other 120v wiring... doh... lesson learned). The dangling yellow romex to the left is for the smoke detector and fire-alarm relay; it is networked directly with the other units in the home.

The air vent is a return that is intended to help vent the PJ. I'm undecided at this time if the PJ will be housed in a separate hush-box or if it will be enclosed inside the soffit. I decided to punt that decision down the road, after the rest of the soffit is up. I'm so used to that line of thinking from years spent working in software development. You'd think my mind would work the same way when it comes to construction, but no... I'm learning that some skills do actually crossover well between hi tech and low tech worlds.

Incidentally, I decided to stick with the MDF/Drywall layering for the bottom of the soffits. It will make the bottom more rigid and provide two different materials with different resonance absorption characteristics, so I think it will work out well. We'll see in the end.

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Quiet Glue: Why Not to Use It

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post #133 of 410 Old 08-02-2016, 08:24 PM - Thread Starter
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I recently came to the conclusion that soffits are way more complicated than I expected. Especially with as wide as my rear soffit is going to be, I really can't seal it up until I get all the wires run and insulation installed, plus anything else I can think of.

I spent some time the past couple of days thinking about how the supply HVAC vents are going to enter the room, since they need to go through the soffits. The original room structure had 2 supply vents on what will become the 'left' side of the room (facing the screen). Although I know placing them both in front of the room would be ideal, I've opted to keep them where they were originally entering the room because as-is they are of equal length. They are 7" vents that "Y" off of a 9" trunk. If I were to extend one of them and move it over to the other side of the room, it would add 20-25 feet to that line. It seems prudent to me to keep the lines as even as possible with regards to length, so the airflow is distributed evenly.

At any rate, I'll have 2 supplies in the room... and that seems good.

So, the issue for me with the soffit vents has been one of how to handle them. Over the past few months, I've had to ponder this (along with obviously many other things), and I've settled on down-facing diffuser grilles. The current challenge is now figuring out how to get those grilles in the soffit along with everything else in there.

After much consternation, I settled on my column positions based largely on where other features of the room must go, cannot be moved, or would otherwise be impractical. And, as in these projects one item's constraints invariably leads to another, as luck would have it I want to put my soffit can lights in the same spot as the HVAC supply vents... and I don't want either in front of my columns (or would prefer not to... especially the lighting).

My 4" recessed cans for the soffits are AT (Air-Tight) but not IC (Insulation-Contact) rated. Now, that really doesn't mean a whole heck-uv-a-lot. 1/2" clearance, basically. Though that is the minimum clearance to combustibles.

Still, I finally managed to devise a design that will work and give me 1 1/2" clearance between a custom supply plenum/register box and the can lights.

The downside, per se, is my vents will be approximately 1 5/8" from the fabric wall panels, which is why I posted an independent question on the subject of distance and vent angle of supply vents, here.

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post #134 of 410 Old 08-11-2016, 07:30 PM - Thread Starter
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It's been an eventful week (or two) for the HT room.

After much consternation I decided to re-locate my HVAC supply and return vents. Originally, I wanted to go with my original room's configuration, more or less. My room was a tear-down of a builder "media room," and at the time it seemed prudent and easier to simply leave the HVAC supplies where they were. I did decide at the time to adjust the returns, and split it into 3 runs for the main room, A/V rack, and PJ.

So, fast forward to today and after reading many posts on the subject on AVS, roughing in my columns, and some other factors, I concluded it was preferable to follow the advice of many who have come before me and move my supply vents to the front of the room, while re-positioning my main return vent to the rear.

What a pain. And oh, this is definitely on my list of "what I'd do differently next time." Namely, the planning of the routing of my HVAC vent locations. Why didn't I do this when the room was demo'd and a blank canvas??? Quite honestly, at the time I was reluctant to tackle re-locating any HVAC portions I didn't have to because I'd never done any HVAC work before. That was my thinking at the time. Call it fear, or laziness, or whatever. The end result is I've now got more work and longer HVAC runs to thank for it!

If I hadn't inadvertently dropped my phone and cracked the camera lens over the course of this adventure, I'd have pics to post with these comments. Alas....

So, as it stands; I've spent the past few days building plenums out of MDF for both supplies and returns. I've come up with some creative duct-routing techniques to handle the re-location of the vents while attempting to maintain a relatively similar length of supply ducts to try and keep the flow even, and to allow the return to still act like a decent return. The upside is that should I choose to add in-line fans in the future, I believe I'm sizing these plenums to be able to accommodate the increased airflow without the expense of increased noise.

My new plan calls for roughly 5" x 34" supply vents (x2) and on the return side a single 16" x 16" main return vent (with filter), plus a 4" round duct to the PJ and a 5" round duct to the A/V rack. The 16x16 will feed into an 8" round duct. All the returns feed back to a 9" round, which in turn meets up with my sub-plenum.

Bottom line of the new plan: supplies up front, returns in the rear.

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HTGeek -

just wanted to say thanks for your detailed plans and explanation of thought process and the course corrections you've made along the way. I'm considering doing something similar in a dedicated theater room when we get into our new home. All the additional framing and sheetrock looks like it has the potential to become nightmarish, but I'm sure I'll be coming back to your build thread as I begin my own.

Thanks again,

Mike
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Adding a bit more detail to my last post.

After deciding to re-locate the supply and the main return HVAC vents, the next choice was whether to schlep up into the attic and pull the existing duct runs, move them across the room, cut a new hole in the double-layer ceiling, drop the vents, and patch the old hole in the ceiling; or just run some new flex duct in the soffit. Well, I decided to go the latter route and run it through the existing soffit. I figured it can't add much additional length, if any. The fact that it's August - in Texas - might have had something to do with the decision making process. Just sayin'.

No matter. However, I soon discovered that my choice created some new headaches. Sure, I didn't need to worry about making new holes in the ceiling and patching the old ones, however when I set out to extend my 8" return duct, and cross it over one of my ladder-joists that comprises the soffit's frame... "Oh." was I believe what came out of my mouth. Just try stuffing an 8" insulated flex duct into a space 6 1/2" wide. Not gonna happen. So, I tried removing the insulation. I calculated that being far enough into the soffit cavity, and being a return duct, I should be fine. Er. No. 8" crammed into 6.5" does not bode well. So, back to the drawing board per se.

Ultimately, I created another plenum of sorts. When the 8" return duct enters the room, it runs along the soffit for a few feet and then terminates in a small plenum with 2x 6" ducts on the opposite side. This provides plently of airflow capacity while allowing me to use un-insulated flex ducts that can actually fit in between the soffit 2x4's.

Incidentally, my supply ducts run the length of the soffts, and therefore don't need to cross over them as does the return vent. So, even though they are 7" wide (before adding thickness for their insulation), it wasn't such a big deal to re-route them.

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Quote:
Originally Posted by mjmcmahon67 View Post
HTGeek -

just wanted to say thanks for your detailed plans and explanation of thought process and the course corrections you've made along the way. I'm considering doing something similar in a dedicated theater room when we get into our new home. All the additional framing and sheetrock looks like it has the potential to become nightmarish, but I'm sure I'll be coming back to your build thread as I begin my own.
Mike,

Thanks very much for the kind words! It means a great deal to me to know that I'm not just talking to myself in this thread! You're giving me some inspiration to dig out one of my old digital cameras to upload some photos.

AVS is also a means to document my journey. I'm confident my current home will not be my last home with a HT room.

I hope that by describing my challenges, others may discover and hopefully avoid some of the headaches I've run into. I spent about 2 years researching the concept of a "true" HT room, mostly on AVS. Yet I continue to discover new challenges and run into pitfalls. There is so much detail in this process. Unfortunately, I believe one really cannot conceive of how much detail there is, until you're in the middle of it.

Here's a brief example: Yesterday evening I built two HVAC supply plenums that I'll place in my soffits over the next few days. They will serve two purposes. First, they will help slow down the velocity of air-flow into the supply vents. Second, they will house lineal diffusers I'm planning to use for this purpose.

The point I'm leading up to is while custom building my supply plenums, I quickly realized the duct connectors will need to be sealed somehow, otherwise they're almost sure to leak air into the soffit. So, the question then became what to seal them with? Mastic or tape? I chose mastic as it seemed like the best option given the fact the shapes are not uniform (I'll try and post pics over the weekend so you can better understand what I'm referring to). But then I thought, where or what portions do I cover with mastic? The outside only, the inside, both? As I said, one query leads to another; yet these are good thought processes to have, eh? I find myself trying to think like a HVAC technician. Where will the air be travelling from/to? How will it want to find its way around? What are the paths of least resistance?

I'm sure I've saved myself some headaches, yet so many lessons in life are gleaned from doing versus watching. There's only so much you can get in terms of learning vicariously from others before you have to take the plunge yourself.

#1 thing on my Wish List is I wish I'd started with a vetted checklist - in order - of which design elements should be figured out first. There are so many dependencies with this type of project that it's exceptionally difficult for someone who hasn't done it a few times before to figure out which design decisions are critical and may impact other decisions down the road.

For example, my recent choice to relocate my HVAC vents meant that I had to re-think the following factors, which otherwise seemed unrelated:
  • Recessed lighting placement
  • Column position
  • Soffit design
  • Duct run length/distance
  • Impact of longer HVAC duct runs on FPM/CPM of airflow

If I had approached the room as a blank canvas in the beginning - as I should have (but didn't) - I could have avoided these issues by coming up with a plan that put the supplies up front and return(s) in the rear to begin with. In my case it would have meant minor re-routing of the original supply ducts, but since I already had the walls and ceiling torn down at the time, it really would have been a trivial matter.

I can tell you in your case - a truly fresh canvas with a new home - don't be bashful about insisting upon changes in plans prior to and during construction. Just be sure you have as clear a plan as possible before-hand. Start with your end results as your primary goal, and then work your way backwards through the dependencies as best you can. Also know that you WILL run into unforeseen issues!

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Quote:
Originally Posted by HT Geek View Post
Mike,

Thanks very much for the kind words! It means a great deal to me to know that I'm not just talking to myself in this thread! You're giving me some inspiration to dig out one of my old digital cameras to upload some photos.

AVS is also a means to document my journey. I'm confident my current home will not be my last home with a HT room.

I hope that by describing my challenges, others may discover and hopefully avoid some of the headaches I've run into. I spent about 2 years researching the concept of a "true" HT room, mostly on AVS. Yet I continue to discover new challenges and run into pitfalls. There is so much detail in this process. Unfortunately, I believe one really cannot conceive of how much detail there is, until you're in the middle of it.

Here's a brief example: Yesterday evening I built two HVAC supply plenums that I'll place in my soffits over the next few days. They will serve two purposes. First, they will help slow down the velocity of air-flow into the supply vents. Second, they will house lineal diffusers I'm planning to use for this purpose.

The point I'm leading up to is while custom building my supply plenums, I quickly realized the duct connectors will need to be sealed somehow, otherwise they're almost sure to leak air into the soffit. So, the question then became what to seal them with? Mastic or tape? I chose mastic as it seemed like the best option given the fact the shapes are not uniform (I'll try and post pics over the weekend so you can better understand what I'm referring to). But then I thought, where or what portions do I cover with mastic? The outside only, the inside, both? As I said, one query leads to another; yet these are good thought processes to have, eh? I find myself trying to think like a HVAC technician. Where will the air be travelling from/to? How will it want to find its way around? What are the paths of least resistance?

I'm sure I've saved myself some headaches, yet so many lessons in life are gleaned from doing versus watching. There's only so much you can get in terms of learning vicariously from others before you have to take the plunge yourself.

#1 thing on my Wish List is I wish I'd started with a vetted checklist - in order - of which design elements should be figured out first. There are so many dependencies with this type of project that it's exceptionally difficult for someone who hasn't done it a few times before to figure out which design decisions are critical and may impact other decisions down the road.

For example, my recent choice to relocate my HVAC vents meant that I had to re-think the following factors, which otherwise seemed unrelated:
  • Recessed lighting placement
  • Column position
  • Soffit design
  • Duct run length/distance
  • Impact of longer HVAC duct runs on FPM/CPM of airflow

If I had approached the room as a blank canvas in the beginning - as I should have (but didn't) - I could have avoided these issues by coming up with a plan that put the supplies up front and return(s) in the rear to begin with. In my case it would have meant minor re-routing of the original supply ducts, but since I already had the walls and ceiling torn down at the time, it really would have been a trivial matter.

I can tell you in your case - a truly fresh canvas with a new home - don't be bashful about insisting upon changes in plans prior to and during construction. Just be sure you have as clear a plan as possible before-hand. Start with your end results as your primary goal, and then work your way backwards through the dependencies as best you can. Also know that you WILL run into unforeseen issues!
For clarification: we'd originally thought we were going to be moving into new construction with a dedicated theater room above the garage. Unfortunately, the builder decided it was more important to back out of a $5000 discount on a custom kitchen because we "took too long"....long story. Anyway, we've made an offer on an existing home that we like just as much and will be upwards of $100K less than the new custom build.

I happened to be at the new home for the inspection today and took the opportunity to walk off the size of the room: 19' x 21' with 9' ceilings. Should make for an awesome theater room! I spent a little time looking into room treatments (first time for me - my existing "theater" is the living room and bass traps and absorption panels have a low WAF.

Have you started down that thought process yet?

I'm going to spin up a build thread of my own...I'm sure (especially knowing my handyman handicap) that my build will not be as impressive as some that I've seen here, but I'm sure it'll evolve over time.

PJ - Sony VPLHW45ES / Screen - EliteScreens 120" CineGrey / BD - Sony BDP-S5100 / AVR - Yamaha RX-A3030
Speakers - B&W 683S2/ HTM61S2 / 685 Surrounds / Fluance Signature Bi-polar Rear Surrounds/ PSA S1500 & XS15se subs
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HVAC Woes

As mentioned above, I reluctantly concluded recently that it would be best if I relocated my HVAC supply ducts AND my main return duct.

Here is the default HVAC layout before the old room was demo'd.




Here was my original plan for the HT room, which involved leaving the original supply vent locations in place, splitting and re-locating the return into 3 intakes (main, PJ, and A/V rack), like this:




As the weeks and months of my build progressed, I became increasingly aware of the fact this layout was not optimal. Unfortunately, I realized this well after the point when I had my attic space wide open (old ceiling demo'd), when I could have quite easily made some changes that would have eliminated all the work I'm currently doing to correct my oversights regarding the HVAC. Yes, I could have left well enough alone; however, being somewhat the perfectionist, I didn't want to regret that later on.... so, I am now re-arranging the HVAC to a more sensible layout.

Here's the *New and Improved* plan.




You can see the differences are 1) the main return is being relocated to the rear of the room, in between the A/V rack return and the PJ return; and 2) the rearward supply duct is moved to the front of the room.

The main objective of re-evaluating and improving my HVAC layout was motivated by the idea that the supply vents should ideally be in the front of the room. I began to get concerned that with a side-wall configuration, guests on the same side as the vents might get too cold, and guests on the opposite side might get too warm. Quite frankly it probably wouldn't have been a big deal, but since the pain of making a change is less now than when the room is complete, I decided I should do this now. Once I was firm on that decision, my focus turned to the return vents. Same line-of-thinking. As long as I'm tearing things up for a re-do on the supply side, it seemed prudent to re-evaluate the returns as well. I decided to leave the A/V rack and PJ vents as they were, but move the main return to the back of the room. After all, with the supplies moved up front, I really wanted to be sure the air got pulled fully back across all the seats.

This is probably a good time to re-cap the physics of the return layout. The original return was a 9" duct, and as it enters the sub-plenum that 9" duct is still there. In order to encourage the return duct system to help with cooling my A/V rack and projector, in the attic I split the 9" into one each of 8"/5"/4" ducts. The 8" return duct is the "main" return, the 5" is above the A/V rack position, and the 4" is above the planned projector location.


Soffit Challenges
I can't believe I still don't have the soffits completed. I've said it before... it's more complex than I could have possibly imagined in the beginning. A soffit with nothing in it is no big deal, but when you add duct work, conduit, all kinds of wiring, etc.... well, it quickly turns into a BIG DEAL. Lol. That said, if the soffits were done then I wouldn't be re-doing the HVAC positions. Double-edged sword per se.

Now that I've started making the HVAC changes, I realized today given the height constraint of my soffit, I was going to have to re-position the 2" conduit that runs from the A/V rack to the front speakers. The issue is the main return duct currently enters the room inside the soffit along the same wall. Given the fact it's an 8" flex duct (which btw is 11" wide when one factors in the insulation around it), and the fact my non-IC lights are planned to be centered 13" from the wall and 11" from the soffit edge... well, let's just say the math doesn't all work out. Yes, I know it sounds like the 11" from the soffit edge would work, however there is a 2x4 in the way (one vertical and one horizontal), which is part of the ladder design that I chose for the soffit frame.

Even after removing the flex duct insulation so the net width would be 8", it still won't work due to - again - those 2x4's. The 2" conduit pushes out a maximum of 4 3/8" wherever it's held in place. That max length is actually for the clamps that hold it in place. The duct itself sits about 3.25" off the soffit framing. Furthermore, whether there's insulation on the side of the flex duct or not, it will necessitate a barrier between it and the recessed light fixtures that are not IC (and even if they were IC it wouldn't help against non-insulated flex duct). So, that means building a backer box for at least 1 or 2 of the light fixtures. I've calculated that to require a minimum of 6" for the box, which will include space inside for cement backer board and a minimum 1/2" between the fixture and cement backer board per UL guidelines. Personally, I'd much prefer a 1" buffer minimum on all sides, so the backer box may grow a little wider. We'll see how it will fit when I get around to building it this weekend.

Atm, my plan is to split the 8" duct into 2x 6" ducts. The 6" ducts will just barely fit between the ladder rungs of the soffit framing. To refresh your memory, my soffit is 9 1/2" tall before adding 1 layer 1/2" MDF + 1 layer 5/8" drywall. So, on the outside the soffit will be 10 1/8" tall. On the inside, it is framed in such a way (with 2x4's) that the minimum clearance in any given spot internally is 6 1/2". That means I'll have a 1/2" clearance to squeeze 6" non-insulated flex duct between those framing members inside the soffit.

Now, how to do this? I built a small box to handle the transition from 1x 8" to 2x 6" duct. Sort of like a small duct muffler. Here's a photo after it was built. I applied drywall tape and then mastic around the exterior connections where it meets the MDF. I later applied UL listed foil tape after attaching the 6" flex ducts. I want to be sure this is air-tight, though quite frankly it's not too big a deal if it isn't as any leaks would simply pull from within the soffit anyway. Given the fact the soffit is already air-tight and sealed from the remainder of the house, it shouldn't be a huge deal if that were to happen. But that said, of course I don't want that to happen.



I did a test fit this evening. So far, so good. This weekend I'll finish re-locating the conduit, positioning this - whatever this thing is (above) - and hooking it up. If all goes well, next week I'll order the return and supply grilles from Dayus.

Reminds me... one other note on the returns. I've determined the returns do not need duct liner and they do not need to be insulated while inside the room/soffit. I'll have insulation for about 2-4 feet or so inside the soffit and close to where it enters the attic, just to be sure there's a little stretch there that is insulated to guard against any possible condensation build up from the change in temps. However, based on my research + real world observations, this is much, much less of an issue versus supply air where it's a real issue given the wider range of air temperature differences (room temp vs. HVAC temp vs. attic temp). If I were dealing with a basement construction project, this whole issue wouldn't be a big deal even for the supplies (most likely), but being a 2nd story HT room it's definitely a concern that should not be taken lightly.

The Supply Vents
Onto the supplies....

I decided since I was going to muck around with relocating the supply vents from one side of the room to the front of the room, I might as well plan for installing some rather long lineal diffuser vents. The act of relocating the supplies meant some new logistical challenges. First, both of the duct runs would need to be extended. I could have left one of them as-is (the one already in the front of the room), but doing so would have made the duct runs uneven in length. So, I decided to take the existing one in the front of the room and extend that to the other side of the room (via the front soffit), and take the one originally toward the rear of the room and extend it to the front along the same side wall. Since I was doing all this, it seemed like an opportune time to consider what I might want in the way of vents (e.g. diffusers) and also take into consideration how whatever I put together would fare if I decided in the future that I needed to install push/pull in-line fans for the supply and exhaust. Essentially, I did not want to have to go through this process AGAIN in the future if I determined at some point the airflow was insufficient.

So, to that end I settled on a 5" wide by 36" long template, which basically yields about a 32-34" max or so length after installing duct liner.



I've made two of those. Butt-ugly, I know. But functional.

It was a bit of a challenge to come up with the size for several reasons. First, it obviously needed to fit into the soffit. With a 7" wide duct and a 9 1/2" max height soffit, that was not a trivial task. Not much room for error. Second, my biggest concern was how the vent would line up with the fabric walls, lighting position, distance from the front screen wall, etc.

With the 5" vent opening that I came up with, the soffit ducts (for the diffuser vents) are 7" wide (allowing for 1" thick duct liner on either side). My plan is for the recessed lights along the walls to be centered 13" from the wall. After accounting for the fabric wall panels, this will give them the appearance of being centered in the soffits. It also means the edge of the light fixtures inside the soffits will be 11" from the wall, which in turn means I could technically position something else up to 10 1/2" from the wall. Except for the fact there's a 2x4 frame member in the way. In fact, it's a bit more complicated than that due to my plans for recessed storage shelving along one side wall.

Bottom line is if I were to position a vent next to a recessed light, I'd have enough clearance to not require a backer box for the light. However, after mulling over this issue for several days, I've concluded it would be better (IMHO) to not center the vent where a recessed light is centered.

The subject has been a bit of thorn-in-the-side for me because the alternative to placing a supply vent adjacent to a recessed light fixture is to place a supply vent adjacent to the front columns. On balance though, I think that's a better option after considering different angles and how they will appear.

A considerable issue in my decision making process was the thought that if I were to position the supply vents and lighting next to each other, it would actually be quite a tight fit. Aside from whether or not it's even possible for them to physically co-exist next to each other (it is), there's the fact that the lineal diffusers I'm planning to use (Dayus) have ~1" lip all the way around the vent. So, that means +2" in width. Then consider how close does one want these supply vents to be to the fabric walls? Well, there's obviously a minimum 1" due to the lip of the vent, but that would place the vent and fabric panel immediately next to one another and likely touching. Aside from potential issues with squeezing in one or the other, there's the fact that I don't think that would look the greatest. And functionally, how good of a job are those supply vents going to do if they're blowing right up against the edge of the fabric walls? Therefore, it seems prudent to push the vent out from the wall a few inches.... which means by default they cannot go next to the recessed lights.

The 5" width of the duct I arrived at while meddling with figures on airflow (CFM, FPM), surface area, and a desire to keep all the ducts as discreet as possible.

The original supply vents were 12" x 6" or 72 sq. in. of (theoretical) area. In reality, it's significantly smaller as the metal of the vents takes up quite a bit of that area. But for comparison sake, let's call it 72 sq. in. The max vent size I've chosen then is 170 sq. in. (5x34). Why so much larger?

I didn't have any issues with noise. The HVAC system for the room was designed rather well it seems to me from the original installer. It has 1x 9" supply duct that branches to 2x 7" supply ducts and 1x 9" return duct. So, the supply/return values are even. I've seen comments elsewhere on this forum speculating that the ratio should be 1:2 for supply:return, but quite frankly I have not seen that in the real-world (I've looked at other HVAC systems besides my home's). That said, it's not a bad idea necessarily either. But since I started with a 1:1 ratio, I don't have any plans right now to make the returns larger.

Anyhow, what does that have to do with my supplies? I wanted 1) linear diffuser slots; 2) quiet; 3) unobtrusive visual design; 4) forward-compatibility in the event I decide to add a blower (in-line fan) in the future (i.e. increased FPM should not result in more noise). All those things pointed toward some kind of soffit diffuser of sorts, between the flex duct and the actual vent. It also means I don't want really wide vents.

The end result I came to was to build soffit diffusers, make them as long as I reasonably could, and then before I make the final cuts in the soffit bottoms, decide how long and wide the supply vents will be initially (but at least I know they CAN be up to around 34" long and 5" wide).
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Quote:
Originally Posted by mjmcmahon67 View Post
For clarification: we'd originally thought we were going to be moving into new construction with a dedicated theater room above the garage. Unfortunately, the builder decided it was more important to back out of a $5000 discount on a custom kitchen because we "took too long"....long story. Anyway, we've made an offer on an existing home that we like just as much and will be upwards of $100K less than the new custom build.

I happened to be at the new home for the inspection today and took the opportunity to walk off the size of the room: 19' x 21' with 9' ceilings. Should make for an awesome theater room! I spent a little time looking into room treatments (first time for me - my existing "theater" is the living room and bass traps and absorption panels have a low WAF.
Perhaps the turn of events will be better for you in the long run. Saving $100k is certainly worthwhile.

That's a good size room. Is it 2nd floor, 1st floor, basement? One thing to keep in mind is you want to be sure your finished room size is not square (say 18 1/2' x 18 1/2'). A square shape is the worst shape, acoustically. I'm only mentioning this because your LxW dimensions are close to one another. Just something to keep in the back of your mind.


Quote:
Have you started down that thought process yet?
Yes, to some extent. I've wavered a bit on how to handle the soffits in terms of using them as a bass trap. For now, I've settled on stuffing them loosely with insulation where feasible, but I'm undecided on whether to line the sides with fabric and have it open behind the fabric. I'd say atm, that's not likely to be the end result. Drywall on the sides is a more likely end result, but we'll see. I'll sort it out for sure when I get there.

Besides that, I do plan on having some corner traps where feasible. They won't be an ideal thickness. I just don't have the space. But there will be something there for the tri-corners.

The walls will be fabric covered with 1" or 2" insulation behind it. Another item that's a variable atm.

One other thing is you may wish to become familiar with (if you aren't already) is Bob Gold's coefficient database of insulation materials and their acoustic properties. Although I have yet to clean it up and share it on AVS, during my research I took Bob's data, sorted and ranked it based on best and worst performance for each frequency range in the charts, and cross-referenced with unit cost. That process has helped me digest the big picture of what is possible (best case results), at what cost, and what thickness. It's also given me insight into the fact there is no silver bullet regarding insulation and sound attenuation. You really need to choose the portion of the audio spectrum you are most concerned with, and then look at the rankings of products for that portion of the frequency spread.

I'll give you a comprehensive example. I ranked a total of 50 insulation materials. Of those, the No. 1 material for best LFE absorption was Ultratouch Denim by Bonded Logic. However, I need to throw in a few caveats to that statement. First, by "LFE" I mean the 125 Hz frequency band. That's not LFE to some folks, but it's the lowest freq range you'll find in the compared acoustic lab tests of insulation materials. It's also required to be 5 1/2" thick to get that result (R19). And Ultratouch is a controversial product with regards to whether or not it's OK to breathe in dust from it for prolonged periods of time. Among other things, it is heavily treated with boron, which is known to cause irritation of the lungs, nose, and throat to some people from repeated exposure over time (for a good reference, see Eisler's Encyclopedia of Environmentally Hazardous Priority Chemicals, by Ronald Eisler, (c) 2007).

IMHO, in a concealed cavity where there is no risk of airborne disturbance (e.g. inside a wall cavity), you can't beat Ultratouch for absorption of 125 Hz and, incidentally the 250 Hz freq range as well. It placed No. 1 in overall NRC rating, tying it with the proverbial gold standard: OC 703 (4" thick no less). Note that Ultratouch is a fraction of the cost of 4" thick OC 703 (~$3.25/sq ft + shipping vs. ~$1/sq ft + shipping). No other insulation product can make that claim. It's quite frankly amazing given it's relatively low mass of 1.4 pcf (Pounds per Cubic Foot). Btw, the thinner Bonded Logic (R13, 3 1/2" thick) ties it for No. 1 ranking of NRC.

Continuing this line of thinking, what should you use if you don't want to risk bronchial issues yet you want the best LFE absorption? Your next best bet is actually old-school "pink fluffy." Owens Corning R19 (6 1/4" thick, UNfaced) fiberglass batts. The catch is you'll need to position them 16" from the wall. If you can't or don't want to manage that (e.g. you don't have 2 feet of room for it), you could use their kraft paper faced R19 and stick it to the wall (paper side out) and you'd get almost as good results in the low end and actually some slightly better performance in some of the mids.

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I'm going to spin up a build thread of my own...I'm sure (especially knowing my handyman handicap) that my build will not be as impressive as some that I've seen here, but I'm sure it'll evolve over time.
I'm looking forward to your build thread!

Personally, it took me about 2 years of planning before I started. I wanted to be sure I knew what I was getting into, and I wanted to do it myself. It's an adventure, that's for sure. Make sure your significant other has the patience to let you work your way through it. In the end, it will be well worth it!

In the beginning, one of the first decisions you'll need to make is whether to come up with your own design or hire a professional. I have no doubt that the fact I didn't hire a pro has cost me more time in my entire build. However, the flip side of that is I have learned an incredible number of things I didn't know or understand before about residential construction. If I hadn't pushed myself to do this on my own, I would never have gained that experience. There's no wrong answer. It's a trade-off.

If you have not already discovered @granroth 's The Phoenix Theater Build, I strongly recommend taking the time to read through some or all parts of it. His documentation is A+.

I'd also highly recommend @Spaceman 's theater build as another icon. I still view his theater as my #1 inspiration when I need to remind myself of my ultimate goal!

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The Saga Continues....

Little progress made today. Family/Household obligations got in the way, unfortunately.

I did get the 2 backer boxes built that I believe I'll need for the 4" recessed lights in two spots. And I learned how quickly table saw blades get dulled from cutting cement board.




Letting them cure overnight. Now I understand why some people frequently claim they never have enough clamps.




BTW, I used the PL375 in the background to glue the MDF together before I nailed them w/a brad nailer. I used Green Glue (not shown) between the MDF and interior cement board layer.

I'll fill in the internal gaps tomorrow w/acoustic caulk, after the GG and PL375 have both cured overnight. After that they should be ready for placement.
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Here's the current state of my 'thinga-ma-jig' 1x 8" to 2x 6" converter for the return air flow. Hoping to attach the 8" section and hook it up tomorrow if the wife doesn't hit me up w/a a non-HT related To-Do list like she did today.



I can't wait to see if this idea works, or if it's a total CF.

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Originally Posted by HT Geek View Post
Here's the current state of my 'thinga-ma-jig' 1x 8" to 2x 6" converter for the return air flow. Hoping to attach the 8" section and hook it up tomorrow if the wife doesn't hit me up w/a a non-HT related To-Do list like she did today.



I can't wait to see if this idea works, or if it's a total CF.
HTGeek -

the room is a 2nd floor bedroom over the top of the garage. I'll likely narrow the room some to avoid it becoming completely square. How much off of 'square' does it need to be? If I took a 4' section off the west side for equipment rack (IIRC, I paced off from the back of the equipment rack space which is about 4' deep) leaving me with a 19' long by 16' room is that rectangular enough?

PJ - Sony VPLHW45ES / Screen - EliteScreens 120" CineGrey / BD - Sony BDP-S5100 / AVR - Yamaha RX-A3030
Speakers - B&W 683S2/ HTM61S2 / 685 Surrounds / Fluance Signature Bi-polar Rear Surrounds/ PSA S1500 & XS15se subs
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the room is a 2nd floor bedroom over the top of the garage. I'll likely narrow the room some to avoid it becoming completely square. How much off of 'square' does it need to be? If I took a 4' section off the west side for equipment rack (IIRC, I paced off from the back of the equipment rack space which is about 4' deep) leaving me with a 19' long by 16' room is that rectangular enough?
Depends on the wavelengths of the sound waves. I'm not an acoustic expert, so I don't know for sure if say 2 or 3 inches from square is good enough or not. I just mentioned it as I didn't want you to end up with - for example - a 15' x 15' room after you finished your build. That does not seem likely, but figured it was worth mentioning. If you arrive at say, 18' 6" x 15' 4"... something like that... you'll be fine. The only way you'd have a square room from your starting point would be if you walled off one entire length of wall for some reason (e.g. to create a hallway, A/V rack room, etc.). This should be a non-issue for you as long as you don't go that sort of route with your layout.

As I understand it, square rooms basically create an extreme problem of 'nulls' in your room where sound waves cancel each other out bouncing around the room. The ceiling height is also a factor, but I'm presuming the room will not be a perfect cube shape.

Here is a good thread that explains in more detail why square HT rooms are bad.

The attached file is a terrific tool (Excel) that will help you figure out where you will have nulls in your room (you will have them regardless of your room dimensions). The tool is useful to figure out where not to place your seats, and/or which frequencies to look at using acoustic treatments for (a starting point... tho REW is your friend in that regard).
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leaving me with a 19' long by 16' room is that rectangular enough?
Just re-read your last post.... yes, that's good! Having at least one prime number measurement is a good thing.

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HTGeek -

just wanted to say thanks for your detailed plans and explanation of thought process and the course corrections you've made along the way. I'm considering doing something similar in a dedicated theater room when we get into our new home. All the additional framing and sheetrock looks like it has the potential to become nightmarish, but I'm sure I'll be coming back to your build thread as I begin my own.

Thanks again,

Mike
I'm going to echo this right here. Geek your detailed explanations and help have been what keeps me going from time to time. Serious thanks to you for taking time.
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The bottom line is that the constraints presented by the room shape and features that I 'inherited' per se from its previous design may ultimately drive some of the HT room design features, such as the stage placement, and whether the front wall is angled on the sides for the L/R speakers or if I shall end up placing them behind a flat front wall.
And so you find yourself with 95% of the rest of us who have to make compromises. Keep smiling and keep on! Your going to have a great HT when all is said and done!
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Posting a few progress pics from the past few weeks.
Good progress! I'm amazed you clean your build looks lol. I need to clean up the room a bit haha
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post #149 of 410 Old 08-16-2016, 07:04 AM
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For example, my recent choice to relocate my HVAC vents meant that I had to re-think the following factors, which otherwise seemed unrelated:
  • Recessed lighting placement
  • Column position
  • Soffit design
  • Duct run length/distance
  • Impact of longer HVAC duct runs on FPM/CPM of airflow

If I had approached the room as a blank canvas in the beginning - as I should have (but didn't) - I could have avoided these issues by coming up with a plan that put the supplies up front and return(s) in the rear to begin with. In my case it would have meant minor re-routing of the original supply ducts, but since I already had the walls and ceiling torn down at the time, it really would have been a trivial matter.
Totally agree here Geek. If I build one again I will design and verify my entire plan several times to ensure it works PRIOR to starting construction. To the point that if I'm building a new home the plans factor into the home build to accommodate the forthcoming HT build. It makes it that much easier having it all on paper ahead of time IMO.
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Good progress! I'm amazed you clean your build looks lol. I need to clean up the room a bit haha
Good thing my camera on my phone seems to have finally broken for good. It's nowhere clean atm!!! HVAC parts all over the place....

Diggs, appreciate all your comments above. Thanks very much!

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