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Commercial Theaters

post #1 of 71
Thread Starter 
Since some films are now being released in true 7.1 sound, example- all future Disney movies will be released in 7.1 sound, I'm curious as to what the commercial theaters speaker configuration is. Obviously they have the L/C/R Sub and Side Surrounds. That's 5.1.

Are theaters adding Rear Surrounds?

Or are some of them adding Rears and some adding Heights?

Are most still 5.1 and if so how do they handle the 7.1?

The more I think about it the more I'd like to try and duplicate what a commercial theater has going.

I've always used auto detect and just made sure the movies I get are DD or DTS true 5.1. I've never really liked the matrixed PL2 and other modes...that is for movies that weren't DD or DTS. But I've also been HTIB forever.
post #2 of 71
Most theatres have long arrays of surround speakers along the side walls and across the back wall. As the number of channels have increased over the decades, the number of speakers have stayed the same.

Back in the '70s and '80s, a matrix-derived mono surround channel was sent to all the surround speakers. In the early 1990s, discrete 5.1 soundtracks had 2 surround channels, with each one going to all the speakers on its respective side and half the back wall. In the late 1990s, Surround EX was introduced to convert 2 discrete surround channels to 3 matrix-derived channels so that left wall, right wall and back wall arrays each got different content. Finally, a few years ago discrete 7.1 was introduced, so each side wall array and each half of the back wall array got different signals.

The only time additional speakers have been added is for theatrical formats introduced last year, like Dolby Atmos and Auro 3D, both of which use height speakers. Other than those relatively few installs, the number of speakers has not needed to change, just get divided up into more groups.

If you want to get this effect at home, the easiest way (short of using speaker arrays) is to use dipole surrounds. Their diffuse nature will give you the general left-ish, right-ish, back-ish directionality you hear at commercial cinemas rather than the precise stereophonic imaging you would normally get with monopole surrounds.
post #3 of 71
Thread Starter 
Thanks for that info.

My room is too small for dipole surrounds. I'll be using side surrounds and possibly rear surrounds, but then I'm back to the matrix thing again. Still debating.

Sounds like most current and future 7.1 content will be geared towards rear surrounds vs. front heights and/or wides.
post #4 of 71
Originally Posted by pdxrealtor View Post

My room is too small for dipole surrounds.
Are you considering some giant dipole speakers or is your room really tiny? How big a space are you working with?
Originally Posted by pdxrealtor View Post

I'll be using side surrounds and possibly rear surrounds, but then I'm back to the matrix thing again.
That's the norm for 7.1 set-ups.
Originally Posted by pdxrealtor View Post

Sounds like most current and future 7.1 content will be geared towards rear surrounds vs. front heights and/or wides.
Front heights and wides are a home theatre invention, not anything to do with commercial theatres or movie soundtracks.
post #5 of 71
Thread Starter 
Originally Posted by sdurani View Post

Are you considering some giant dipole speakers or is your room really tiny? How big a space are you working with?
That's the norm for 7.1 set-ups.
Front heights and wides are a home theatre invention, not anything to do with commercial theatres or movie soundtracks.

Room is 16x12 - 14x12 after 2' false wall w/ AT screen.

I was having a hard time working in heights w/ ceilings only 8'6" and still getting decent L/C/R placed properly behind the AT screen.

The more I thought about the more I really just want what's in a movie theater, and maybe have the 7.1s for the rare times a movie is coded for them. Or maybe I'll like a PLx or NEOx mode with the rear surrounds. I think it's worth it doing the setup phase to just add them.

Dipoles just don't seem like they'd sound as good in my setup vs. side surrounds and rear surrounds.
post #6 of 71
Your room is big enough to do a terrific theatre, assuming proper placement of speakers and seating. However, you have to understand "what's in a movie theater" so you can decide whether you truly want it. Using dipoles for your side and rear speakers will better imitate the diffuse surround field of a movie theatre. If you don't like the idea of doing that, then maybe you don't really want what's in a movie theatre. Movie theatres don't use surround processing, so 90% of the time your rear speakers would be silent. If it bothers you to lose that wrap-around envelopment, then maybe you don't really want what's in a movie theatre.

I use 7 of the same bookshelf speaker all the way around. Keeps the sound consistent from left to right and front to back. Since they're monopoles, I get nice imaging between the speakers for a seamless surround field. Typical movie theatres can't do that sort of precise imaging because they use diffuse arrays of surround speakers. To scale 5.1 soundtracks to my 7.1 layout, I use surround processing, which splits the 2 surround channels into separate pairs of side and rear components. Movie theatres can't do that because the same surround info goes to the speakers at your side and behind you.

It's a completely valid choice to want to imitate the commercial theatre experience. But understand that there are people that want their home theatres to go beyond the sound of the typical auditorium at the local multiplex. If you do want to use 4 monopole surround speakers, then your system won't sound like a movie theatre. Personally, I think it will sound better. But it's up to you to choose.
post #7 of 71
Thread Starter 
I think when I say I want what's in a movie theater I mean first in terms of speaker placement I.E. the reason for this post was to inquire about commercial theaters and their use of heights and wides. You cleared that up for me. Which sends me the next step closer to what's in a theater in terms of speaker placement.

Also when I say I want what's in a theater I'm referring to sound as well, but not necessarily down to the detail of using dipole speakers. With sound I'm more after the clarity, the in your face surround your body, blow your eyes out crystal clear sound that blends so well with the picture.

I don't know if I will want to use a matrixed 7.1 surround, but I think installing the speakers during the construction would be wise since more and more movies will be geared towards 7.1 and that 7.1 will be rear speakers, NOT heights and wides. Add to that fact the fact there are already some blu-rays that have been coded in 7.1, few but they're out there.

I'm pretty sure I don't want to use dipole speakers as I've always enjoyed the regular surrounds from my HTIB systems.

I'm also very hesitant to use one brand of L/C/R and a different brand surround. I've looked at Klipsch as a first choice due to their good reviews of having that theater like sound. However the more I read the more I'm now leaning towards JBL pro line.

3 JBL 3677 for the front -- http://www.jblpro.com/catalog/General/Product.aspx?PId=71&MId=1
4 JBL 8320 for the rear -- http://www.jblpro.com/catalog/General/Product.aspx?PId=279&MId=1

And I'm looking at Rythmik FV15 -- http://www.rythmikaudio.com/FV15HP.html

Not sure on screen size yet, between 105-130" (could go shorter and place L/R outside of screen but behind framing) long, but it will be 16:9, I don't mind the bars for 2.35 films. I'll be watching too much HDTV in this theater to put up a 2.35 and I'm not sure I want to mess with masks etc.

There is so much to choose from. I hope I'm not giving mixed signals here. I'm in the figure it out stage right now and while I'm not that hard to please it seems every time I click on the next link something new pops up. This industry moves at lighting speed in terms of new tech etc....
post #8 of 71
There are over 700 titles on Blu-ray with 7.1 soundtracks and almost 100 more with 6.1 soundtracks (e.g., all 6 'Star Wars' movies, all 3 'Lord of the Rings' films), so the speakers on your back wall will get use often enough.

Try to put your main seating 1/3rd of room length (64 inches) from the back wall for smoother frequency response (fewer peaks & dips). This will also give you good rear-vs-side separation in the surround field.
post #9 of 71
Thread Starter 
Cool. Thanks for the info.

I just put a HT sized sofa so my seating position was as you suggested above and it will work just fine assuming I can get rid of the 29" piece of concrete slab that is intruding into my viewing wall. Waiting on our contractor. I'm sure he can figure something out but if not I'm gonna loose almost 9" off the 16' mad.gif
post #10 of 71
Those JBL Pro speakers you linked to have pretty good specs. Your 12' wide room will resonate at 47Hz and multiples thereof. You can minimize the first few of these room modes and make the sound more consistent across your entire HT sofa by placing your subwoofer at the midpoint of room width (below the centre speaker) and spreading your L/R speakers 8' apart (the middle of the woofer should be 2' from the side wall).

The side speakers should be directly to the sides of the seating area to stabilize lateral imaging. The rear speakers should be spread 6 feet apart on the back wall, so you can hear stereo separation behind you (where our human hearing is not so hot). Like I said before, this arrangement should give you excellent rear-vs-side separation in the surround field, as well as wrap-around envelopment that you can't get with only 2 surround speakers.
post #11 of 71
Thread Starter 
Yes, they get a lot of great reviews. Thanks for the placement suggestion. I've been wondering about ideal starting points. I'm not sure if that changes though, because my room is L shape.

I was thinking of building a half wall, at the L opening, from the ground up and putting a pillar or column from half wall to ceiling. This would allow me to mount the surround against a wall at the proper height. Vs. using a speaker stand on one out of 3 surround speakers.

Here's a picture. The stars represent imaginary boundaries. The stars on the left is where I'd build the half wall and column.

post #12 of 71
Originally Posted by pdxrealtor View Post

I'm not sure if that changes though, because my room is L shape.
If you don't actually have a 12x16 room, then all those calculations change. I can't tell by your drawing but is your room 12' wide or 12' + 2'6" (width of the door) wide? Also, where were you planning on putting the screen, the north wall or south wall?
post #13 of 71
Thread Starter 
Screen on south wall. Equipment on north wall in alcove area. Can cover that or leave open.

The room is actually 12 feet plus approximately 3 feet 2'6" door plus mill work around door. I have 12 ft for front screen and speakers.
post #14 of 71
With an irregularly shaped room, the better option might be to place the subwoofer in the nearfield, like right behind your couch. You'll hear less of the room and more of the sub, giving you tight clean bass.

On the front wall, I would mount the right speaker just inside the door and the left speaker the same exact distance from the opposite side wall. This will make sure their side wall reflections are symmetrical, otherwise you'll end up with a lopsided soundstage that sounds wider on one side than the other.

BTW, I have an L-shaped room as well, so I'm in a similar situation to your's.
post #15 of 71
Thread Starter 
I am getting 2 15" subs , not sure if I mentioned the fact I was getting two. I'd like to keep them up front if possible as I planned to build a stage in front of the screen / front sound to conceal the subs and give some room aesthetics.

Would it help at all to build a wall 3.5 feet high where the L begins? How do you handle your L shape room?

Shoot, if I'm mounting equal distance, about 3 feet from both side walls, I might not have to deal with my foundation intrusion that is 9" deep and 30" into my south wall on the left.

EDIT- placing the right speaker just inside the door will put it right in front of the screen frame. Currently the screen is 104" long (120 diag.) Centered on the viewing wall leaves 19.7 inches on either side of the screen. The speaker is 25.625" wide.
Here is a sketch of the viewing area. I've not updated it but I think I'm going to drop down to 3 seats, one row. Not the four pictured. Also haven't added the rear surrounds or adjusted seating position to the 1/3rd you suggested, 64" from back wall. And, the false wall will not be 24" out from floor to ceiling. It will be out just enough to accommodate the speakers.

I'm just showing it to you so you can see the dilemma with placing the right speaker at door opening.

I could go a bit smaller on the screen, so the frame would not interfere but I hate to do that.

Edited by pdxrealtor - 5/25/13 at 11:37pm
post #16 of 71
For the sake of acoustics, I would make the centre line of the system the true centre line of the room (7.5' from each side wall).

That means you will have your L/R speakers about 3' from the side walls (avoiding the foundation intrusion). The speaker is about 26" wide, so the centre of the speaker will be about 13" in from the edges. As long as the frame of your false wall and/or screen is not in front of the tweeter, it won't interfere with the sound. So the edge of the screen (frame) can be either just inside the L/R speakers or just outside. If you do the latter, then your screen will be about 9' wide (a bit larger than you were considering).

The screen would stretch from just inside the door (a couple of inches for the frame/bezel) to the same distance from the opposite wall. Below and above the screen will be your false wall. All 3 speakers will be behind the screen. Personally, I would end the false wall at the left edge of the screen, just like it is on the right side (to accomodate the door). You can then cover up the foundation intrusion with a rack or media cabinet (you have 3 feet of width and a couple feet of depth to work with.

Centering the couch at the room's true midpoint will give enough space on both sides for walkways. Thinking of the space as having a 15' width (as opposed to a 12' width) means you can have a really wide (4-seater) couch.

As for my room: my right side wall goes 102" back before disappearing into a dining area, my left side wall goes 160" back before disappearing into an archway to other rooms. I sit 120" from the front wall, so the wall to my right side has disappeared 18" in front of me while the wall to my left side continues for another 40" behind the listening position. That means I hear a strong imbalance in the soundfield, since the room is open on only one side (if my listening position were closer, I could have avoided this problem because there would have been walls to both sides of me). What I ended up doing was covering the last 58" of my left wall with thick absorbtion. This kept the wall from reflecting sounds, mimicking the opening on the opposite side, giving me a consistent experience left-to-right.
post #17 of 71
Thread Starter 
eek.gif I can see that getting a plan might be the hardest part of this entire process.

If I set my seating in 1/3rd, 64", (or back 128") and my right side wall disappears at 94" into the room that leaves approximately 33" in front of me with no right side wall. Whereas you only have 18" in front of you with no side wall.

On top of that my entire room would be off centered which I'm kind of a freak about. I'm weird like that. All my light switch covers in my home have the screw slots facing the same direction- horizontally. I think they call that OCD. I was going to move all my canned lights over because right now they are centered to the room being 15 feet and would have been off center to the room as I had planned to set it up. Anyways....

Couple of ideas come to mind:

1) What if I flipped the entire room to face the East wall? There are three windows on that wall, and the foundation (same dimensions - 45"hx8.75"deep) runs the length of that wall. Measurements are taken from ground so 45" up I have an extra 8.75". This is not an issue for layout unless it's an issue for sound. See picture.

I would insulate/block window light with foam insulation panels. I would then frame it all off from floor to ceiling using 1x4 s, and treat with insulation above the top foundation line (45" up to ceiling). Using 1x4 would allow a very little intrusion to measurements. The 4" would lie flat against wall. I could do this on south wall as well. I'd have a black velvet theater. Paint the ceiling to match.

2) Really don't want to, but I could, throw up a wall to make my original "imaginary" 12x16 room a real 12x16 room. Door at back of room.

Option 1 would still put seating at 10' from screen, leave 5' behind for rear surround. If I had a 12' wide four seat setup I'd have 2' from edge of seating (not center) on each side for side surrounds. I'd still have the L shape but it would be behind me now.

What are your thoughts? I really appreciate all your input as it is raising issues I would most likely not have caught.

Edited by pdxrealtor - 5/26/13 at 11:10am
post #18 of 71
Rotating the set-up 90 degrees would make it easier to mount the side speakers, since you'll have walls directly to both sides of the couch. The additional foot of width will make it all the more easier to use a 4-seater couch. If something is happening in the area with the desk, it will be less distracting when it is behind you rather than at your side (in your peripheral vision). All good reasons to flip the theatre to face the east wall.

If you blow across the mouth of an empty Coke bottle, you can cause that small chamber to resonate, making that deep 'oooooooh' sound. Expand that chamber to the size of your room and it will still resonate, just at different frequencies. The 16-foot width of the room will resonate at 35Hz, 71Hz, 106Hz, 141Hz, 176Hz. If you were to play a test tone at any of those frequencies, you would hear severe peaks & dips as you walked across the width of the room. That means each of the 4 listeners on your couch will hear the soundtrack very differently.

To cancel those resonances, you can place a pair of subwoofers with the middle of their drivers exactly 8 feet apart. Since you'll probably be crossing over the subs at 80Hz or so, they won't be able to help cancel resonances above that frequency. In order to keep the next 3 modes from being excited, you'll have to use your main speakers, placing the middle of your L/R woofers exactly 10'8" apart.

Screen size will depend on where you place your seating and how wide a viewing angle you are comfortable with (too wide and you will get fatigued from moving your head left to right and up & down to follow on-screen action). Screen size will determine whether the L/R speakers end up behind the screen or just outside it (though still behind the false wall). I'm guessing it will be the latter.
post #19 of 71
Thread Starter 
So it sounds like East wall is the way to go. Is this speaker placement going to eliminate the need for acoustical treatments?

Will speakers need to be a certain height or are we still aiming for typical tweeter at ear level height?

Will I need to address the area from top of foundation ledge to ceiling?

How should I handle the alcove area, acoustically, that is 6 feet off the East wall?

This alcove area is also the place my equipment will go. It can go in the lower part, or the upper part whatever is best for sound. Lower part measures 23" deep x 43" wide x 23" deep. Upper is the same shape but 8.75" deeper from 45" off floor up to ceiling.

To include speakers behind screen it would have to be 132" long. 151 diag. 16:9, and I think that is too large for an approximate 9-10 ft viewing distance. I can still stick with my 120 diag screen and put the speakers on the outside without having frame interference.
Edited by pdxrealtor - 5/26/13 at 2:02pm
post #20 of 71
Nothing eliminates the need for treatments. The lower the frequencies you want to treat, the thicker the treatments need to be. Serious bass traps can be a couple feet thick. But if you can use placement to minimize problems in the low frequencies, then you'll only need treatments to address problems in the mid to high frequencies. Hence the exacting horizontal placement I was suggesting. Thankfully, other things don't need to be so precise.

Even in this day and age of surround sound, the front soundstage remains critical. Whether you're watching a movie or listening to music in surround, your focus will still be up front. To that end, I would try to get the acoustical centre of the speaker (line between tweeter horn and woofer) close to ear level. Maybe match the top of the speaker with the top of the foundation. Doesn't have to be exact (there is no exact ear height), just generally close.

I'd cover as much of the front wall as possible with absorbtion, to keep sounds from your surround speakers from reflecting off the front wall. You don't want surround information coming from the same direction as the soundstage and muddying it up, just want to hear sounds intended to come from that direction. The treatment need not be thick: 4 inches of Owens Corning 703 rigid fiberglass placed 4 inches from the wall. Do this mostly above the foundation. But since you'll have 38" of wall space between speakers, it wouldn't hurt to put a 2'x2' absorber between your L/C/R speakers. Should clean things up nicely.

Reflections bouncing around the alcove (even with gear in there) and reaching your ears will sound very different from reflections bouncing off the bare wall on the opposite side. Consider putting a door on the alcove, with some sort of fan on the inside to suck the heat out of your 'equipment closet'. This way, both side walls appear the same to the sound waves.

Finally, keep in mind that you'll have about 102" of space between your L/R speaker cabinets. So your screen width (including 2-4 inch bezel) needs to fit within that space. I don't think a 120" screen will fit; you might need to a few inches smaller.
post #21 of 71
Thread Starter 
This is great. I can't thank you enough for your guidance to this point. That's a great idea on the door for the equipment room and one I had contemplated.

I have a lot to do now with reconfiguring things, drawing it out, blue taping the room etc.

My contractor is coming tomorrow to talk about putting in a couple dedicated plugs on a circuit, stringing wires, and removing that section of foundation.

Two more questions for a while.

Assuming I want a uniform wall around the theater (front and both side walls), meaning no foundation showing, and I use my idea of 1x4 framing from the floor to ceiling, would wrapping that in black velvet material be OK (I know front speakers have to be behind AT material), or should I stick to an acoustic material so any sound treatments could go behind the framing if need be? I'd really like to do the black velvet (Joann fabrics #3) but sound is more important to me.

One rear speaker is going to be placed in the L area. I.E. no place to mount it. I can pole mount from ceiling or floor, or I can build a column, say 1.5'x1.5' or similar, from floor to ceiling or hang it down from the ceiling. The point is I can do whatever is best for that one rear surround. What would you suggest?

Again- thanks so much for all your advice. I'll keep you updated with new drawings and pictures. I now have a solid direction to take it to the next step.
post #22 of 71
The black velvet from Joann's is nice. I have a friend that covered most of his treatments with that, but eventually started to replace large sections with more acoustically transparent material. If wall-to-wall Guilford of Maine is not in the budget, then try speaker grill cloth from Parts Express. I think it's less than $8 a yard (70" wide).

For the rear speakers, you can use ceiling mounts that hang down about a foot. Might be better than having a column right in the middle of an open are between two rooms. Speaking of open area, if you're sitting in the sweet spot, sounds will reflect off the wall behind your right shoulder but disappear over your left shoulder (no wall). To avoid that difference, it would be worth it to cover a good chunk of the back wall with absorbtion.

While sitting in the main listening position, have someone walk a hand mirror along the back wall and see where the reflections of your right front speaker and right side speaker are. About a foot or two outside of that reflection is where you can start the absorber panels, working your way inward (away from the door) to where the wall ends. You don't have to go all the way to the floor, just from about a foot below ear level on up.

Good luck with the contractor and post back when you make progress.
post #23 of 71
Thread Starter 
Checked out Guilford and that is certainly in the budget. No problem.

I re-drew the setup to specs per your recommendations and that sketch is attached. It's only speaker and seating placement. I will size the screen to fit. If I'm correct on my calculations I'm going to have to size down from 120" diag to a 114" diag. 104.5 vs 100" length. No biggie, at all.

Everything on this drawing is as close to scale as possible. I.E. a square on the graph paper is a foot in measurement.

I'm going to be ready to order all speakers in the first week of June. I have the AVR already.

Contractor didn't make it today, but that was my fault. I'm not sure how important removing that foundation is at this point. Would love your input on that as well as the above.

Do you get paid to do this? You seem very knowledgeable......
post #24 of 71
Arrangement looks like the best of possible options in that space. Until I looked at your latest drawing, I didn't realize a possible bonus: if you're sitting at a desk or working in the L area, you still have a view of the screen (lets you keep an eye on sports or movies being played in the HT area).

I wouldn't remove the foundation. It's symmetrical and finished with trim. Not like it's an eye sore. This falls into one of those 'spending money' vs 'wasting money' categories. If you can afford Guilford cloth, it's worth spending on. Even if you can afford to take out the foundation intrusion, I don't think it's worth wasting money to do it.

And no, I don't get paid to do this. Just a hobbyist, like you and most people on this forum.
post #25 of 71
Thread Starter 
The only foundation that would be removed is the left part that intrudes into the room 30" (29.75" to be exact). Uniform with trim does not really matter because I plan to take it all off and frame in the false walls with the fabric you recommended.

If you don't think that one side (West) warrants having the 30" removed then I will ignore it. I just want to be clear that we are on the same page so sounds come out as you suggest. FYI--- that wall with the 30" foundation intrusion is hollow beyond that. It's an interior wall that is not insulated, just 2x4 and sheet rock.

I hope to learn enough to help people like you're helping me. I started selling homes to 'help' people 10 years ago but it's always an uphill battle. I would love to have a down hill battle, or in other words would love to just help people.............
Edited by pdxrealtor - 5/28/13 at 12:04pm
post #26 of 71
Looking at the pic a few posts back, on the right side is the foundation intrusion. There is a similar ledge across the front wall (below the 3 windows) and along the left side wall. Are you planning on removing any of that or does it all stay intact behind the false wall?
post #27 of 71
Thread Starter 
The only part I intended to remove was the on the right side where it intrudes 29.75". I had planned on doing this so I could center things up with the first design. Now with everything on the wall with windows I plan to remove it so that wall is uniform in shape to the other side wall.

The foundation will remain around the rest of the room. Only the top ledge will be removed, as it is 10" whereas the actual foundation is only 8.75.
post #28 of 71
OK, makes sense to not have the right side wall get wider after 29.75 feet when that doesn't happen on the left side wall. This will change room width, since your original 16' width was between the foundation intrusions, right? If so, then remember to use the mode calculator to get new placement locations for your subwoofers and speakers.

On a separate note, I was looking at the light switches that I had installed when I first moved in and noticed that all the screw slots are horizontal. Also, I have a pair of Rythmik F-12G subs. And my Infinity speakers are from the same parent company as the JBLs you plan on getting. Great minds...
post #29 of 71
Thread Starter 
I actually left the intrusion out of the measurement, since it is only 30" into that wall. So I'm still a true 16x15x8'6"

......think a like wink.gif

Too funny on the light switch screws.!
post #30 of 71
Please accept my apology for hijacking this thread, but, I have a question for Sanjay regarding 7.1 Blu-rays:

I currently have a 7.1 speaker set-up; using a Lexicon MC-12BEQ v5.25, 5.1 analog inputs, and, an Oppo BDP-103.

I am using the Logic7 to extract 7.1 from the 5.1 source material.


Would discrete 7.1 sound much better than the processed Logic7 ? I am wondering if moving to a pre/pro such as the Marantz 8801, which offers true 7.1 decoding, might offer a better surround field than Logic7.

BTW, I also think Sanjay would be successful if he consulted in HT/Audio for a living.
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