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The Plains Theater

251K views 3K replies 122 participants last post by  J_P_A 
#1 · (Edited)
After reading as much as I could on this forum over the past several years, I’m finally ready to post my own build thread (my 500th post seemed as good a time as any). On one hand this seems like a huge step forward because I’ve waited so long to start, but on the other it’s still going to be a long time before I even get to put up the first 2x4. So, fair warning, this is going to be very slow, particularly to begin with as we have to build the house before I can actually start on the theater. Fortunately, to some degree we’re designing the house around a space for the HT, and this is what we’ve got in mind:

1) I intend to use the pro layout service, but I want to get the orientation of the room with respect to the rest of basement hammered out before I have the room designed by the pros. I will need the scale drawings from the architect to make sure I give Dennis and company the correct dimensions of the space.
EDIT: I ended up using two Pro Design Services. I first contracted Dennis to do a layout and acoustic plan. Dennis heavily favors the Quest treatments, but they weren't in my budget, and I didn't feel the DIY treatment plan he provided was detailed enough (essentially just replace all the panels with fiberglass panels). From the room layout standpoint, Dennis' layout was a good sanity check for everything I "think I know". Interestingly, my proposed layout, what I worked out based on what I read here, was within an inch or so of the layout Dennis provided. The big differences were screen size (Dennis didn't like my 160" screen :) ).

Once the room was drywalled and I was getting ready to finalize speaker locations, I decided I wanted a DIY'able acoustic plan that would take better advantage of the extra space I had available for treatments. I contacted Nyal at Acoustic Frontiers. You can see the resulting plans in post two below. Working with Nyal was a great experience, and I highly recommend contacting him as soon as you decide you're ready to commit to a space! There were lots of small tweaks to my layout that he recommended and I feel like the acoustic plan is a good compromise between engineered products and DIY. The money I saved using Nyal's treatment plan as opposed to Quest products more than paid for Nyal's analysis of my room


2) The theater will be in the basement with no exterior windows.
3) We want to have at least an 18’ x 24’ x 9’ space, but I would like to go as much as 19’ x full width of the basement if I can (around 32’ not counting odd nooks).
EDIT: The room ended up being 18'-10" x 30'-3" x 9'. There is an odd section at the back that adds another 2' for a total length of 32'-9" for half of the room, and a beam that will lower the ceiling by 2".
4) Right now I’m planning to use DD+GG, but I haven’t decided on which method to use for decoupling the walls yet (Room-within-a-room if possible, clips and channel if not).
EDIT: After talking with Ted, I've decided on clips and channel for ceiling and walls with a joist mufflers to isolate the HVAC supply and crossover duct to the adjacent room.
5) We are planning to have two rows of seating with a bar at the back for overflow seating. We intend to use this primarily for movies and gaming, but we also enjoy football and would like to host football parties during the season.
6) I would like a 2.35:1 AT screen, and after reading Tony123’s thread, I’m thinking 14’ wide sounds pretty good.
EDIT: I went with a 160" wide by 67.5" high screen (2.37:1). This should optimize 2.35 as well as 16:9 content for my room. I'll have bars for both, but they don't really bother me, and I can always add a DIY masking system later

EDIT: I don't like trying to pick the equipment before my room is done because the current tech changes so quickly. However, I've learned that I need to at least have an idea of what I'm going to use in order to locate things in the room. With that in mind here's a couple things I'm considering: 
7) I'm considering either a Panny AE7000 or Epson 6010 for a PJ. a 12' or 14' screen is really going to be pushing either of these, but PJ technology improves every year. I'd rather build my room for a larger screen and update my PJ than have to redesign my room once the PJ will support a larger screen. I like the Panny as it would allow a memory zoom for 2.35 content, but I believe the EPSON is a little brighter.
EDIT: I went with a Sony VPL-HW40ES and a Panamorph UH480 A-lens. I got an amazing deal on both, and I'm very happy with the results. Even with the huge screen the image is plenty bright for my tastes, and I have zero regrets about going with such a large screen. This is an area where all the pros will tell you not to do it, but if you have to go with what you like!
8) Speakers are going to be a bit of a challenge as they will need to be high efficiency. I'm thinking something DIY like 4 Pi's or possibly the new SEOS project might be a good way to go.
EDIT: I went with three DIY Soundgroup Fusion 15s up front and Volt 8s for surrounds (two rows of side surrounds plus back surrounds). I'm also installing RSL C34E overhead speakers for atmos.
9) With a room this size, 7.x is a no-brainer. It may require multiple side surrounds due to the multiple rows. I'm not sold on the 9.x or 11.x just yet, but it shouldn't be too hard to retrofit in a room with soffits and columns.
10) For subs, I'm thinking 3 or 4 to help with room modes. I'd love to get some of the Danley DTS-10's, but I'm not willing to pay for the assembled units. If they do another kit, I may pick up a few. Otherwise, something like 4 F-20's might be a good option.
EDIT: I went with two lilWreckers up front. LOTs of output! More subs for room modes would be helpful, and I'm still lacking some mid bass punch.
Here's a top down view of the basement and theater. Again, the theater is 18'-10" x 30-3" x 9'



Index: I thought I would start an index of posts that I've found helpful while researching my theater. For now, it's just HVAC related, but I hope to update it as I run across useful stuff. Also, a good deal of this is lifted directly from the Dark Knight Theater, so you should really check out that thread if you're interested in a more comprehensive list of information.

HVAC
1) Your HVAC contractor is concerned with volume. They will calculate room requirements as Cubic Feet per Minute (CFM). They will size the ducts according.

From a noise perspective, we are concerned with Feet Per Minute (FPM) or velocity. To keep your diffusors (registers) from creating a lot of air flow noise, you do not want more than 250 FPM through a slotted or bar type diffusor. Therefore, let the HVAC contractor size the system but you insist upon the velocity...which will mean larger ducts and larger diffusors.

From a capacity perspective, the HVAC contractor needs to look at the demand of the room to be on the same order as a kitchen (that's if you cannot calculate latent and sensible BTU requirements). For example, six people sitting in the room will require 3000 BTU's/hr. (exclusive of equipment, etc). - Dennis Erskine


And another similar recommending that you size your HVAC based on a kitchen - by Dennis Erskine


2) Returns are high mounted (ceiling) and to the rear of the room. Noise transmission in the returns should never exceed the noise from the supplies and the system must be designed this way. Supplies are in the front of the room, high mounted (ceiling) and not near the screen. Diffusors should be Lenticular, slotted or bar type (www.nailor.com) and located in such a manner as to avoid drafts directly into seating locations. We typically will use the soffit as a duct chase to avoid direct penetration of the drywall barrier.


CFM counts when determing the cooling requirements of the air handler; however, for noise criteria, FPM is critical and should not exceed 250 FPM. The noise created by various diffusors may require a lessor velocity. - Dennis Erskine


Here's another post pertaining to the maximum desired velocity of 250 feet per minute.
3) Equally useful, is to increase the size of the duct by one size, have your HVAC contractor balance the system so that the VELOCITY of the air at the registers is 250 feet per minute or less. (Don't let them get confused between VELOCITY (fpm) and volume (CFM)). In other words, you want them to deliver the required CFM but at an FPM of 250 or less. - Dennis Erskine
4) Nah...don't think so. You'll want two supplies (typically in the front of the room, high mounted) and two returns (high mounted) in the back of the room. You do not want air flow directly on any seating location. You do not want a velocity of more than 250 FPM through any vent (diffusor). You want the HVAC system to maintain a temperature of 70 degrees F with an outdoor temperature range of -30 to 100 degrees F and to maintain a relative humidity of not less than 25% nor greater than 50%. You want six air exhanges per hour and 15 CFM of fresh air per person. - Dennis Erskine

HVAC SIZING
1) This theater has a single 8" flex supply line and no returns. From the table below, this should provide approximately 160 cfm of cooled air. It will be slightly less as the total length is greater than 25'



2) 1 Ton of cooling is equivalent to 12,000 BTU/Hr
3) 1 Ton of cooling can supply approximately 400 cfm of cooled air. This is a general rule of thumb used for sizing HVAC and will vary.
4) Each person generates roughly 500 BTU/hr at rest
5) Not considering the bar area, the theater will seat 8 people. This will require 4000 BTU/hr of cooling (8people * 500BTU/hr/person). I am assuming that when the theater is full including the bar at the rear (10 or 11 people), we will likely be watching a sporting event like the super bowl and will have the door open anyway.
6) The required cfm of cooled air is approximately

400 cfm/(12000 BTU/hr) * 4000 BTU/hr = 134 cfm


7) This is less than the 160 cfm supplied by the 8" duct.
8) The rule of thumb is at least 6 air exchanges per hour. The room is roughly 19x31x9 = 5301 c.f. (closer to 5,000 c.f. once the riser and stage volumes are accounted for). So 5301 c.f * 6 exch/hr * 1 hr/60 min = 530 cfm
9) The 8" supply will provide approximately 160 cfm, this leaves 370 cfm that must be provided by dead vents.
10) Here is a link to the Panasonic FV-40NLF1 fan that moves ~ 400 cfm.

Acoustic Treatments
1) I've read on the boards that the RT60 needs to be between 0.35 and 0.4.

Seating Information

1) Below is the often referenced seating distance chart.


Speaker Locations
  1. Below is one of the many speaker layout guides. This is the Audyssey layout for 7.x/9.x/11.x. The Dolby recommendations for PLIIz are pretty similar for heights, so this seems reasonable for layout purposes.
  2. Audyssey recommends +- 10 degrees for their azimuth positioning shown in the above guide. My front columns look like they will be at about 67 degrees from the center seating position. so this will be perfect for the front row, but I'm ~40 degrees from the back row. I suppose you can't make them all a money seat.
  3. Audyssey also recommends putting the front heights slightly wider than the L/R and as high on the wall as possible. Obviously, 45 degrees will not be possible in my room.
  4. Wides are recommended before heights when considering a 9.x setup.
  5. Wides should be set at ear height.

Other Threads About The Plains Theater
  1. Return Duct In Riser- I've decided against this due to the length of the duct run. I'm planning for a short just muffler/dead vent for the return.
  2. Clips + Channel at Outside Corner
  3. Beam 2" Below Ceiling - Need Suggestions
  4. Door Location and Size Advice Thread
  5. Soffit Heigh Advice Needed
  6. Where Do I Locate My Conduit and Power Feed for My PJ?
  7. Questions About Drywall And Green Glue on Back of Subfloor - Also includes link to 1-1/8" screws that are needed.
  8. Custom Door Jamb Question - Use 3/4" Ply or a ripped 2x8 for trimmer when a wide jamb is used.
  9. Fire blocking decoupled walls - There is also some good information on fireblocking here as well.
  10. Attaching trim to decoupled walls - Short thread, essentially just use liquid nails and finish nails or brads into the DD
  11. Light Spacing - Thread discussing light spacing the theater. Some good info here for determining the layout.
 
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#979 ·

Quote:
Originally Posted by HopefulFred  /t/1339540/the-plains-theater/960#post_23405023


TMcG is describing what I'm planning. I'll mount the door bottom inside the theater instead of mortised because iirc the stc tests better that way.

Fred,


Can you tell us how much better the STC rating is? I have the "best" seals and I was leaning towards mortising for aesthetics but I don't want to shoot myself in the foot just for looks.
 
#980 ·

Quote:
Originally Posted by J_P_A  /t/1339540/the-plains-theater/960#post_23405092


I had not planned to use those because I will have interlocking doors. It seemed overkill, particularly with how well the door seals now.

JPA,


By interlocking doors you mean a double door system? I am also doing double doors but still went with the seals. The impression I get from the experts is that the interior door is much more important. Once sound gets past the interior door it will also makes its way to flanking paths in every possible direction. But, the seals are extremely expensive and everyone has to decide how to best spend the money available. I definitely understand that.


Edit:

There is a post somewhere in Vik's thread describing some disappointment after firing up his Orbit Shifter bc there was quite a bit of sound getting out of the theater. They discovered a very small gap around the casing or somewhere around the door I don't remember exactly. Anyway, after sealing this very small gap he said it made a significant difference. Maybe I can find the post. I guess just do what you can to make the best seal possible is all I was offering up which is admittedly a "well duh" thing to say.
 
#981 ·

Quote:
Originally Posted by HopefulFred  /t/1339540/the-plains-theater/960#post_23405023


TMcG is describing what I'm planning. I'll mount the door bottom inside the theater instead of mortised because iirc the stc tests better that way.
Quote:
Originally Posted by jedimastergrant  /t/1339540/the-plains-theater/960#post_23405093


Fred,


Can you tell us how much better the STC rating is? I have the "best" seals and I was leaning towards mortising for aesthetics but I don't want to shoot myself in the foot just for looks.

This difference is barely a few STC points: http://www.zerointernational.com/catalogpage.aspx?pageID=53 and http://www.zerointernational.com/catalogpage.aspx?pageID=54 The 119W will do more for you than any difference in mounting the bottom door gasket, fyi.


Personally, I will be recessing the automatic bottom and getting one of the aluminum thresholds with integrated gasketing from Zero, but as my signature says - If it's worth killing, it's worth overkilling!




JPA - are you planning for two sets of doors on the same jamb with alternating the lockset location?
 
#984 ·
I was assuming my hardwoods would extend through the entire doorway, and the carpet would cut straight along at the edge of the wall. The door would, I assumed, recess far enough into the doorway that the seal would land on wood.


The thing that gets me is whether or not the door bottom reaches jamb to jamb. If it doesn't, there's an opening between the edge seal and the bottom seal. That's why it was surprising to me when I read that the mortised bottom was not superior.
 
#985 ·
Take a look at one of the doors in your house that will swing the same way. My doors are flush with the jamb, and then there is a casing that extends another 1/4"-1/2" past the jamb. The carpet in our bedrooms runs even with the jamb (under the casing). So if I put a Zero seal on the face of that door, it will be over the carpet, unless I put it on the face outside the theater. Am I missing something?
 
#987 ·
In terms of order of operation, is the door typically done after drywall? Won't they be a nuisance while building? Are you doing a soffit around the room for HVAC or lighting?
 
#988 ·
I'd say most builds I've seen put the door in later. Ted and John recommend putting it in before drywall because it lets the drywall guys run the drywall all the way up to the jamb to keep the gap around the door as small as possible.


I am planning a soffit all the way around the room. I'm planning to run lights in it, and minimal ducting for my HVAC. I'm also toying with the idea of running a short coffered ceiling to house some lights for the seating, but I'm waiting to see how low the ceiling feels once the riser is in to make up my mind.
 
#989 ·

Quote:
Originally Posted by Mr.Tim  /t/1339540/the-plains-theater/960#post_23407396


The Zero seal gets mounted on the push side of the door. It's the contact between the seal and the door jamb that handles the retracting.


Tim

You are right, typically speaking. I was flying when I was typing. The disadvantage with this approach is having to cut the handle side at a slight bevel so it will swing clear of the door stop, thereby creating a weaker point in the soundproofing. It can be mounted from the pull side but the jamb has to be deeper. Most theater jambs are deeper on the pull side because of the additional drywall thickness / channel on the theater and use long-throw butt hinges. Perhaps this install is different for subsequent steps with the trim and panel work.
 
#990 ·
I used a door on a custom jamb to handle the extra thickness of the DW, clips, and channel, so my door is flush with the interior jamb. At any rate, I'll probably order a Zero seal and put it on the push side.


I have managed to get my dead vent finished up. The pictures are horrible because it's such an small space to try to get into, but I know how you guys are. First a little framing:

http://s546.photobucket.com/user/j_p_a/media/Plains Theater/Ventcopy_zpsfd28d7da.jpg.html


Then some insulation, and the first bit of drywall:

http://s546.photobucket.com/user/j_p_a/media/Plains Theater/Vent_zpsc2b0974c.jpg.html


And the finished product:

http://s546.photobucket.com/user/j_p_a/media/Plains Theater/Vent1_zps91d7bb76.jpg.html


Since I had to have a removable panel for access to my junction box and fan, I used a layer of 5/8" ply, and put strips where my studs are to give me something to put screws through. If I expected to be in there more often I might have gone with something that would hold up to repeated installation and removals, but I think this will be good for what I need. I filled in the space between strips with 5/8" drywall since it's heavier. It's not pretty, but that part of my equipment closet is not likely to get finished......... ever! I'm planning a removable panel between the rack and the wall there to allow access to the back. With the cover on there, the fan is just barely audible, and is certainly quieter than the jet engine I have for a server.


The bad news, however, is there is quite a bit of wind noise at the opening into the theater. Now that my door seals (extremely) well, I can't hear my server in the theater anymore, but it makes it painfully obvious just how much wind noise I'm getting at the return opening. I'm hoping once I put my soffits up I can duct the vent around to the back of my theater, and give it a large opening to get the velocity down. If that doesn't work, I'll probably be looking for a new fan since this one can't be slowed down.
 
#991 ·

Quote:
Originally Posted by J_P_A  /t/1339540/the-plains-theater/960#post_23420407


The bad news, however, is there is quite a bit of wind noise at the opening into the theater. Now that my door seals (extremely) well, I can't hear my server in the theater anymore, but it makes it painfully obvious just how much wind noise I'm getting at the return opening. I'm hoping once I put my soffits up I can duct the vent around to the back of my theater, and give it a large opening to get the velocity down. If that doesn't work, I'll probably be looking for a new fan since this one can't be slowed down.
Can you refresh my memory and explain how it's set up currently? Mostly just for comparison as I get toward that point also. Are you dealing with just a standard boot and no grill? What CFM and velocities do you think you have now?
 
#992 ·
Without measurement gear, it's pretty tough to come up with a good estimate, but we'll take a swag at it. The fan is rated for 420 cfm, but I doubt it's moving that much air with all the bends in the duct. Just guestimating it at 400 cfm, and my current opening is about 6 x 12, that puts the velocity at about 800 fpm. I don't think I believe that, but I don't have anything else to compare it to.


I need a grille that is about 1.6 s.f. to get the velocity down to 250 fpm. I've got plenty of room for the grille, but the problem will containing the noise at the room entrance while I get the velocity down. Obviously, the alternative is to just slow the fan down, but that sacrifices air exchanges.
 
#993 ·
I think these exhaust fans are deceiving since they give you such a small duct outlet. At 420CFM you need to be using 12" flex. I'm sure the fan probably has a 6" inlet.


Increasing the grill size alone won't help. The noise is from the end of the flex. I think Big ran into this same problem in Black Cat theater (may have been this same fan, too). I don't remember how they resolved it, but there's probably some good into in that thread.


Tim
 
#994 ·
This fan actually has an 8" inlet/outlet, but you are correct that it's a bit small. However, a 12" duct wouldn't have been feasible anyway.


I can use my soffit at the back of the room as a duct to move around to a location with more space, but my issue is preventing the noise at the entrance to my room from reaching the grille or being audible through the soffit. I'm extremely space constrained on my soffit so sound isolation options are limited.
 
#995 ·
When the HVAC guys came out to my house to check flow for stale air we get in the guest bedroom, they seemed surprised that we were only getting about half (maybe 60%?) of the flow out the registers that the math would suggest. My whole house is flex duct and they wanted to blame the loss on the box style junctions and splits the ducts were connected with, instead of "Y" fittings. I think they just were mostly ignorant of the losses that should be expected. Maybe I'm wrong.


Anyway, I'm just saying that I bet you're well below 800 fpm. I know your setup is not as long and convoluted as mine, but I would be surprised if you were actually getting more than 650.


I think I'm going to use plywood and duct liner to build mufflers in my soffits. Terminating the duct about 4 feet short of my register boot should give some space for a baffle or two to absorb the sounds - no actual direction reversals, like you might see in automotive mufflers, just some baffles. Here's the solution Big and Morph1c came up with. http://www.avsforum.com/t/952113/black-cat-theater-now-going-big/120#post_22028590
 
#997 ·
#998 ·
If you find that the fan is supplying too much air you could always go back and retrofit an in-line Y-fitting to dump the extra CFM in the equipment or other nearby room....kind-of like a ******* pressure relief valve for HVAC plenum. Just thinking out loud because you're right - the options you have available to get the right amount of non-turbulent air velocity are limited.
 
#999 ·

Quote:
Originally Posted by rabident  /t/1339540/the-plains-theater/990#post_23421664


Ben said the design he & his HVAC contractor came up with worked well. He used mutiple 8" lines that dropped into a couple giant sound proofed plunums before entering the room. http://www.avsforum.com/t/1416719/the-withrow-build-erskine-design-equipment-from-everywhere#post_22152399

Unfortunately, I've used about the only place I can that will give me some level of sound isolation. The only other option would be to run a duct the full length of the room and exit at the front, but with a 7" tall soffit, I'm pretty limited on the duct size that can fit in there. I'm not saying I won't do it, but it would certainly be a last resort.
Quote:
Originally Posted by TMcG  /t/1339540/the-plains-theater/990#post_23422328


If you find that the fan is supplying too much air you could always go back and retrofit an in-line Y-fitting to dump the extra CFM in the equipment or other nearby room....kind-of like a ******* pressure relief valve for HVAC plenum. Just thinking out loud because you're right - the options you have available to get the right amount of non-turbulent air velocity are limited.

I was thinking of this as well. I need to ventilate my equipment room, anyway. I may just add another 8" duct near the inlet of my fan. I can adjust the flow by blocking the vent. I hate to because it sure kept things nice and cool in there while the drywall was being hung, but I've got to do something about the noise. I'll probably get my soffits up and see how much noise it's making then before I start tweaking anything. It looks like I'll be able to open my inlet up another inch as well which will help some.


Thanks for all the suggestions, guys!
 
#1,001 ·
Thanks! I gave it a whirl. looks to be pretty close to my back of then envelope estimates. Of course, I'll use that link from now on because I won't have to dig out my calculator



Wow! I feel like I've reached a milestone! 1000 posts in my humble thread!


I'd like to thank all the people that have helped make this possible.
  • George Washington
  • Gandhi
  • Mr. Clean
  • and last, but not least, Mr. Spock.

J/K! I appreciate all you guys following along and helping out!
 
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