[royalswin]

It looks like we are going to build a dedicated addition on an existing house for a theater. What do you think is the perfect size for a theater with 10 foot ceilings a 16:9 100 inch diagonal screen? I was figuring on something like 15 - 17 feet wide but 20-25 feet long (I do understand the no multiples rule), but I could go longer or wider if necessary.


I realize this is a little like asking who the prettiest girl is (i.e. plenty are just fine), but all help would be appreciated.


Drew

 

[Dennis Erskine]

Something like 16 x 23 x 10; however, you have a whole list of other considerations as well. How many seating positions do you require in how many rows. What projector are you using? The screen size you've suggested would appear small in such a large room. Where are doors, windows, and equipment to be located. Further, you're not likely to end up with a 16x23x10 room, are you? You're going to have a raised seating platform...that change's the dimensions of the space. You going to have soffits/bulkheads? Proscenium? Speaker columns? All of these thing change the dimensional chacteristics of the room. Even the existence of a window will push the effective dimensions for a portion of the room (at low frequencies) to virtually infinite.


Net out: focus first on seating, what you want for video presentation and other requirements...then deal with size.

 

[royalswin]

Dennis--


Thanks for your response.


OK, assuming 16 x 23 x 10:


1. Video presentation - I'm planning on either Sharp Z9000 with Faroudja NRS or Seleco HT300 (both DLPs) for video. I planned on using a 100" inch diagonal fixed 16:9 screen--either a Greyhawk or something brighter, depending on what looks best. Assuming it's the Greyhawk, that screen is 4'8" high by 7'10" wide (with frame). I can ask them to build the ceilings so that, when finished, the drywall is 10 feet from the floor (leaving carpe aside). So, even with the 1 foot riser, in the back, the height ought to be enough.


The problem is that I want the room to be wide enough to accomodate the screen, as well as not having my big front speakers not block any of it. (Center channel, which is a couple of feet high, would go in front of and be lower than screen). Using the calculations at the Cardas Audio web site for speaker placement in rectangular rooms, in a 16 foot wide, room, I get about 4 1/2 feet in for each speaker, leaving room for a screen only seven feet wide. So even the 100 inch diagonal looks a little big. Or am I doing this wrong?


2. Seating - I'm planning on having seats at either 10 and 16 feet (if I do my math right, that's breaking the room vertically in sevenths, seating at 3/7 and 5/7), or 14 and 19 feet (3/5 and 4/5). The former is preferable, because I'd like the space at the back of the room. The second seating position would be on a 1 foot riser. What screen size would you recommend at either set of seating positions? And with a bigger size, how would you deal with the front speaker placement issue?


No windows, but the soffit is a good question. I guess it will have to be in the back, so as not to interfere with screen height. (OK as long as the people sitting on the riser can stand up comfortably, right)?


Thanks again for all your help.


Drew

 

[Dennis Erskine]

For that room, the max width on the screen is 12'-6". The center speaker belongs behind the screen. With either of those projectors, on that screen, your projector will be hanging from the ceiling in the room...I presume that's OK with you...not my favorite.


So 10' is 3/7ths. 11' is 1/2. So you're not going to have recliners, lean your head back and put X's on the to mark the perfect lateral seating positions? (So called "good" positions and "bad" positions differ by .54' and .41') And, then, I have to presume, based upon your being exactly perfect in the seating position, you're doing proper acoustic treatments in the room.


I'm not attempting to be abrasive here; but, you are embarking down the path common to disappointing results. Your focus is on but one of many, many considerations in putting together a theater...and, one of the minor ones at that.

 

[royalswin]

Dennis--


Abrasive? You're helping me out, and certainly know a ton more than I do, so I take no offensive whatsoever (nor do I think you are being abrasive) in the least.


So how to I avoid "embarking down the path common to disappointing results"?


I think that, consistent with your comments, consider seating first. Assume I just use couches (no reclining seats) with the head listening position usually at around 11 feet and about 17 feet. (Exactly where "around" 11 and 17 depends on what you think I'd do for room size). The second set of seats will be raised by enough to see over the first set of seats (i.e. to see the whole screen), whatever you think that amount of raising is.


Video presentation second, I assume? I realize that the best solution is a projector in a separate room, but I want a large room (to someday put a bar in the back), and I want a DLP (for cost and simplicity reasons vs. CRT). With the more recent DLP projectors, that limits me to a projector in a room. Frankly, I don't really care about screen size, other than to say bigger is better, but too big is bad. But I have no idea what size will look good for those seating distances? 92"? 100"? 106"? 120"?


From having read various posts of yours before, I realize room acoustics is also more important than room size. I would of course plan on building the walls, floor, and ceiling as you've described in previous posts, and adding acoustical material to the walls. Obviously, the use/placement of acoustical is critical, but that's a whole set of decisions that I take it can be dealt with as room construction begins.


So now what? I realize room size is not particular important from a theatrical/acoustical perspective, but I probably do have to tell the builder how big to actually build the room. (Big grin).


Thanks again for your help (and please, don't ever worry about telling me I'm misguided)--


Drew

 

[Dennis Erskine]

Quote:

So how to I avoid "embarking down the path common to disappointing results"?

Hire professional help. Yes, a blatant rules violating plug.

Quote:

I think that, consistent with your comments, consider seating first. Assume I just use couches (no reclining seats) with the head listening position usually at around 11 feet and about 17 feet.

So, based upon standard couch sizes, you're leaving 2' of foot room between the rows?! This is where a scale drawing will begin to help...and measure that furniture before you plug it into the drawing.

Quote:

The second set of seats will be raised by enough to see over the first set of seats (i.e. to see the whole screen), whatever you think that amount of raising is.

Again, a scale drawing will help with line of sight testing...people, projector and screen position. A a general rule...measure the distance between your shoulders and the top of your head...now you have a reasonable riser height.

Quote:

Video presentation second, I assume? I realize that the best solution is a projector in a separate room, but I want a large room (to someday put a bar in the back), and I want a DLP (for cost and simplicity reasons vs. CRT). With the more recent DLP projectors, that limits me to a projector in a room. Frankly, I don't really care about screen size, other than to say bigger is better, but too big is bad. But I have no idea what size will look good for those seating distances? 92"? 100"? 106"? 120"?

Well, seating distance will depend upon the resolution of your projector and it's scaler. DLP projectors have long throw distances, make lots of noise, and are bright enough to handle large screen. It does seem to me, however, that if you're really clever with your bar design, you'll have a cabinet in the bar that would double as a projector housing. Hum. Imagine that.


Quote:

From having read various posts of yours before, I realize room acoustics is also more important than room size. I would of course plan on building the walls, floor, and ceiling as you've described in previous posts, and adding acoustical material to the walls. Obviously, the use/placement of acoustical is critical, but that's a whole set of decisions that I take it can be dealt with as room construction begins.

Dealt with BEFORE construction begins. (Rule of seven P's - Prior Preparation Prevents Piss Poor Performance). Well, let's see. Bulkheads and soffits will help kill right tricorner effects and alter some of the room's dimensions. Hiding speakers in columns on the side and rear...need a couple extra for everything to match. Oops..changed some of the room's dimensions again. Oh, and a Proscenium up front to hide front stuff (curtain rods, speakers). Drat...just changed dimensions of part of the room again. Geeze, guys (gals) all these dimension changes are really screwing up my room modes. I hate it when that happens.

Quote:

So now what? I realize room size is not particular important from a theatrical/acoustical perspective, but I probably do have to tell the builder how big to actually build the room. (Big grin).

Why? You think he's really going to follow the plan anyway?

 

[Michael7272]

Dennis,


I have tickered with several ideas using that 10x16x23.3 "rule" for a basement installation. How important is the ceiling height when designing a theater? I don't know of too many 10ft ceilings in basements. Could those room width's and lengths work with an 8-9ft ceiling? I know.. HIRE YOU..I hear ya!


Michael

 

[proufo]

Quote:

Originally posted by royalswin It looks like we are going to build a dedicated addition on an existing house for a theater. What do you think is the perfect size for a theater with 10 foot ceilings a 16:9 100 inch diagonal screen? Drew

The perfect dimensions for a HT are 20.54x18.60x9.78 ft. An addition, as opposed to using an existing room or basement, would allow you to build these dimensions exactly.


For an explanation, request (free) my Mediaroom spreadsheet by sending mail to [email protected]


Good luck with your theater.

 

[Dennis Erskine]

Pablo has done a good job on his spreadsheet; however, there are no perfect dimensions for a home theater...just more optimal and less optimal. (In fact, if you'd follow the advice of such a speadsheet, you'll find the 'perfect' room (from a modal perspective) is one with almost infinite dimensions.)


Second, such examination of modal properties work only for perfectly rectangular bounded spaces (with 0 sound transmission). If you have a perfectly retangular room, you will have problems far more annoying than room modes. None of these speadsheets will accommodate rooms with raised platforms, stages, bulkheads, sofit, columns, steps, seats (yup, putting your seats in your theater changes modal characteristics), splayed walls, etc.


Third, no speadsheet can predict the amplitude of any given resonance frequency; hence, you could be chasing problems that don't need a fix.


Fourth, IMHO, the best way to design a theater is from the inside out. Accommodate seating, design elements, picture/screen/projector elements, egress, speaker placement, speaker type, and then place the walls.


Fifth (and my bigger complaint with these speadsheets) is they place an undo emphasis on one aspect of acoustic room design at the expense of other, equally, if not far more important considerations in the design process.


And, sixth, this is not directed toward Pablo ... he expects my lecture will accompany his posts. Such a review is an interesting exercise in any design process and does not fall into the category of vodoo acoustics (like being able to tune more than one position in a theater without averaging).

 

[Cain]

Let me make this simple..


Hire Dennis..


You will thank me for suggesting it..


He is worth faaaaaar more than the sum he charges for his work..


Do yourself a favor, and hire Dennis to design your HT.


"Just do it.."


-- Cain

 

[thebland]

If you are planning on putting in a heavy duty set up don't play around with tips here and there about how to shlep together a good room.


If you are putting a significant amount of money into a built out addition for the purpose of home theater, you owe it to yourself to get an expert to design that space.


At building prices at about $300-$400 a foot for a addition with nice amenties, I couldn't imagine not hiring an expert for the job. It is foolish unless you have money to burn or have low expectations for your theater.


My soon to be built room is quite large and will complement the home with its unique design. I had my archtect work in concert with Dennis in designing the room. They, in fashioning the design, came up TOGETHER with a design better than I had imagined and better integrated it with the rest of the home (entry way, projection room, etc.).


Let the experts handle it and you enjoy the fruits of their labor.


Jeff

 

[proufo]

Hello royalswin and Dennis.

Quote:

Originally posted by Dennis Erskine Pablo has done a good job on his spreadsheet; however, there are no perfect dimensions for a home theater...just more optimal and less optimal. (In fact, if you'd follow the advice of such a speadsheet, you'll find the 'perfect' room (from a modal perspective) is one with almost infinite dimensions.)

I have been offering this spreadsheet as a tool for sometime now, as Dennis points out. Once I started mentioning that an optimal dimension set was already derived from it there have been much more interest. I like this, as it improves the odds for someone to build a room based on this work. Hence the use of the word "perfect". I can cop out and say that it is perfect because, AFAIK, the default dimension set can't be improved ;-)


I believe that, for reasons explained in the ReadMe doc, the default dimension set derived from the SS is optimal. It is not based on ratios but on an specific dimension set.


Would love to be proved wrong. Would love for others to develop a better dimension set. This is not an ego trip, but yes, I'm proud of what I've done so far and would love to go forward.

Quote:

Second, such examination of modal properties work only for perfectly rectangular bounded spaces (with 0 sound transmission). If you have a perfectly retangular room, you will have problems far more annoying than room modes. None of these speadsheets will accommodate rooms with raised platforms, stages, bulkheads, sofit, columns, steps, seats (yup, putting your seats in your theater changes modal characteristics), splayed walls, etc.

Yes, the dimension set is just an starting point. This is mentioned in the Read Me file that is sent with the SS.


Finite element analysis for developing more complex rooms is way out of the purpose of this work. The intent from the beginning was to develop a smallish, simple and cheap room.

Quote:

Third, no speadsheet can predict the amplitude of any given resonance frequency; hence, you could be chasing problems that don't need a fix..

It's just an starting point. Transmission is an important part of the room design. It is the main way to get rid of very-low-frequency resonances, whatever the neighbors think about it.

Quote:

Fourth, IMHO, the best way to design a theater is from the inside out. Accommodate seating, design elements, picture/screen/projector elements, egress, speaker placement, speaker type, and then place the walls...

Here I disagree. Please note that I have not any experience building home theathers while Dennis is a full-time designer and builder perhaps. But conceptually it is clear to me that if you are going to have resonances in any case, the dimensions that provide the less damage are to be selected at the very beginning. Unless of course there are other considerations that can't be bypassed.


Whatever you do from then on for getting the best sound would be more effective if the bare room faults are lesser.

Quote:

Fifth (and my bigger complaint with these speadsheets) is they place an undo emphasis on one aspect of acoustic room design at the expense of other, equally, if not far more important considerations in the design process.

Again, idimensions are just an starting point, perhaps the most basic one. But must be the right ones from the beginning.

Quote:

And, sixth, this is not directed toward Pablo ... he expects my lecture will accompany his posts. Such a review is an interesting exercise in any design process and does not fall into the category of vodoo acoustics (like being able to tune more than one position in a theater without averaging).

LOL. Will keep pushing the SS here. I hope to continue getting valuable input from you and from all members. My dream is to develop a public-domain full design that can be built cheaply.


Will post the ReadMe file (long) later. It provides more info on where does this work comes from and its use as a tool.


Best regards.

 

[royalswin]

OK, I get it. Based on the recommendations here, I'll e-mail Dennis to discuss designing a room.


Seems like a stumbled into a long-standing argument between Dennis and Pablo here. A few novice comments.


Pablo, isn't your "perfect" room a bit square (is that really 20 feet wide by 18 deep?). I always thought a rectangular room (as the 16 X 23 room Dennis discussed) is better. Also, where are your front speakers? Dennis is putting his behind the screen. Unfortunately,


Dennis, doesn't Pablo have a point that "if you are going to have resonances in any case, the dimensions that provide the less damage are to be selected at the very beginning."


For example, let's assume I came to you and said I want you to design a room for a theater. FOR NOW, I only have the money to build the room and stick the already-owned equipment and two couches (normal size, three person couches) in it; since, I don't know, my wife wants to remodel the kitchen, I don't have money for anything but walls (built to your specs), a ceiling (built to your specs) and carpet in the room. (And the room has to built now, because it's a basement and a remodeled kitchen of the same size is being put on top of it as part of the same construction project).


Notwithstanding that, you can design me a room of any size you want, up to, say 20 x 40. You'd have to start somewhere, right? Where? Determine the seating positions? OK, say I want the primary seating position to be 12 feet back from the screen, with additional seating at 18 feet back from the screen. So now what? How big/tall is the room to minimize future problems (i.e. when we finish implemening your design)? 16 x 23 X 10? 20 x 18? Something else


By the way, I confess to have no idea what a proscenium is. (Grin).


Drew

 

[proufo]

Quote:

Originally posted by royalswin OK, I get it. Based on the recommendations here, I'll e-mail Dennis to discuss designing a room. Seems like a stumbled into a long-standing argument between Dennis and Pablo here. A few novice comments. Pablo, isn't your "perfect" room a bit square (is that really 20 feet wide by 18 deep?). I always thought a rectangular room (as the 16 X 23 room Dennis discussed) is better. Also, where are your front speakers? Dennis is putting his behind the screen.

Hello royalswin.


That's what the math gives. I lost lots of time refusing to test squarish dimensions.


Sadly, there's no long-standing argument; I could learn a lot arguing with Dennis ;-)


Re speakers positioning (from a previous post):


You may like to take a look at this article:

http://www.surroundpro.com/2001/07_08/feature1.shtml


The images are not in the online version of the article. FYI, Fig. 1 is a setup with L-C-R in the same line with dipoles to the sides of the mid row of seats.


Figure 2 is similar to what you can see here:


"Listening conditions for the assessment of sound programme material",Walker. EBU Tech 3276-E available from the EBU WWW site at http://www.ebu.ch/tech_32xx.html. A supplement indicating the requirements for multichannel systems is available from the same URL.


Currently, diamondbacks win ;-)

 

[royalswin]

So it is 20 feet wide by 18 feet long?


The link you posted to the spreadsheet doesn't work, or I'd have tested it myself.


Thanks--


Drew

 

[proufo]

Hello Drew.Send me e-mail to [email protected] and I will reply attaching the ss. My server is between hosts.


Re speaker location: go to http://www.aes.org/technical/documents/ and download for free the document "Multichannel Surround Sound Systems and Operations (2001)".


I just found it. It looks like the Walker EBU paper.


Reasonable dimensions are 20.5 x 18.6 x 9.8 ft


Best regards.

 

[Dennis Erskine]

Please...there is no argument between myself and Pablo. He's a true enthusiast and needs to be complimented for the many hours he's taken to put his work into the public domain. The first comprehensive research in this area was published years ago by BBN to address a very vexing issue in smaller spaces. Just understand the limitations and, as Pablo correctly states, it is a guideline.


While my views (as stated above) are widely known, I don't care to suggest that such tools are of minimal value. By the same token, you cannot build an airplance with just a spanner.

 

[royalswin]

Fair enough. Should have used the word discussion.


Would somebody please tell me what a proscenium is? My curiousity is peaked.


Drew

 

[amillians]

A proscenium is something that will cause your builder to go insane and your wife to wonder why anyone would need 2500 lbs. of sand, much less inside the house.


Dennis can give a more technical/correct definition, but it's basically a gently curved stage, filled with lots and lots of sand, that acts as the "base" for your front speaker array, screen, etc.

 

[Dennis Erskine]

Proscenium...well..the stage area. More specifically, the elements to the left and right of the screen that hide the curtain and the thingy that runs horizontally across the top (doing the same thing). Think "in front of".