Axiom Home Page Forums General Discussion Home Theater Perfect size movie room

what is the perfect room size for and decnet inhome theatre ?
also, is it better sitting facing the long wall or the narrow end. I know it is best to make it with a non-denominal factor but for a 92" screen wonder what the best size would be. Also, my centre position is the important one as for speaker placement lol

I am thinking 15.5w x 21L x 7h
I would sit 11ft from the fronts which would be 10' apart. With a 92' this would be about 7ft. allow 1.5ft space on either side of the screen to the mains. and about 1.5' to the side walls from the L/R. another 1ft spacing between the Main and the sub. about 2 ft for the sub and 1.5' from the wall. I am thinking you would have no other way. It would be pointless to run dual subs if they are in the middle side by side.

dual subs is never pointless :-)

I would always try and sit facing the narrow wall. With your room dimensions and sitting distance having the room 15' wide and 21' deep seems ideal.

There is no perfect room as each room has it's own issues due to it's size. You would want your mains to be as far apart as you are sitting away from them and you do want ample room to have space to the side and behind the seating area for surround speaker envelopment, the more space the better suited direct radiating speakers will be, the closer confines allows the QS series to shine, at least with my experiences.

The center speaker, if it is a horizontal design, is best near ear level but I have also had very good luck at any postion above or below the screen with the speaker angled down or up towards the seating postion.

It sounds to me like your room should work quite well, I would just watch that first reflection point from the side walls as the mains will be quite close to them.

There isn’t going to be any “perfect” one-size-fits-all room for all situations. For example do you plan on one or more rows of seats? How many seats across? Why restrict yourself to a rectangle? How many speakers, (wide and multiple surrounds can accommodate longer rooms better)?
With only one row of seats placing the screen on the long wall is a viable option since a wider room allows more flexibility in placing the mains and with greater standoff of the surrounds you can get a more even surround sound field over you entire seating area than if the surrounds are very close to the side seats.

Based on the rooms I’ve used so far I would make the length and width such that the standoff distance to the nearest seat from a side or rear wall is proportionally greater the more rows/columns of seats I have. So say for one row of 4 seats across I would want a minimum of 5 feet to the sided and back walls from the closest seat. I would add a few feet in each direction for every row/column of additional seats. This creates a more even surround field for all the seats rather than just the sweet spot.

I would also want to be able to place the mains outside the farthest L/R seats, also proportionally farther the more columns there are, while always keeping at least a 3-4 foot standoff from the speaker to the wall to allow some flexibility in placement to create the best front soundstage.

Also, just because you don’t want length walls to be equal, doesn’t mean that a square listening area doesn’t work great. The most seamless 360 degree soundstage I’ve had was in my apartment where the room was 16 feet long by 12 feet wide. By building a curtain wall in the front I turned the listening area into a 12x12 which allowed me to place my speakers in a perfect circle around my seating. This created a perfectly seamless soundstage with only 5.1 while maintaining the advantage of a rectangular rather than square area for standing waves.

Additionally by having more distance to the side walls while also sitting closer to the screen it greatly cut down on reflected light from the screen bouncing off the walls (both my apartment and present home theater had/have black curtains, floor and ceiling). But even with total blackout some light reflects off the side walls making it harder to suspend disbelief in my present home theater than in my apartment where the screen just seemed to hang in empty blackness. So don’t assume that only acoustics are affected by room size/shape.

I am just trying to figure it out for the draftman.
I don't want to in a year or two wish I did this or that different.

I plan on Two rows of seating most likely four across. And if the fronts are 11 ft apart then I will sit close to 11 ft away if 13 ft apart then I will sit 13ft. The last rom will be about 5ft behind to the wall. 32" for the couch and another 24 inchs of walk way in front. This will put me 5 ft from the rears. if my room is 15.5 then I guess I will be 7.75ft from the sides.
My biggest concern is, 92" or 102" Front projection or 60" Plasma. I want to sit in the sweet spot were it seems I am right in the movie. I don't want to see side walls nor do I want to move my eyes to see the sides of the screen. I guess I will have to experiment in sitting in front of a project or 60" tv's and measure.
However if I have two M80's a VP180 and Two EP500's how much space across the front do I need with out cramming them in. If I am sitting 11ft away then that means my speakers are 11 ft apart, therefore 2ft from the walls. I do not want the subs against the wall but maybe a ft away that in itself takes up 6 ft of floor space. Can I place the M80's butt up to the subs or should I allow a ft between sub and M80.Actually I have my M80 planned at 4.5ft from the side walls if I place it along the 21 ft wall. if against the 15.5 then things are going to be tighter.

Unless you are willing to move seats around between single and multi-viewer seating you will not have any one seat in the sweet spot, equilateral triangle with the mains. Also if you plan on mostly HT and not as much 2ch music then the equilateral triangle becomes less important though not totally irrelevant as you add more speakers. If you want to optimize for multiple viewers then you would want the apex of that triangle falling in the middle of your 4 center seats or even a little farther back IMO. The reason I say that is that in my experience I’d rather have the mains a little wider rather than a little narrower if I had to pick between the two.


IMO and that of THX, a 60” plasma will look tiny at 11-13 feet.
http://myhometheater.homestead.com/viewingdistancecalculator.html
The THX ideal seating distance for a 102” diagonal 16:9 screen would be 11.4 feet. Obviously this isn’t a hard and fast rule but a good place to start from. However, the larger the screen the more light you’re going to get reflected around the room. OTOH the smaller the screen the less “movie-theater-like” the presentation and the less it will draw you in because it will fill less of your field of vision. I hate reflected light but IMO the immersion of the larger screen more than makes up for it.

Also since you plan to have your main speaker 11-13 feet apart a larger screen will keep the picture and soundstage in sync. With a 60” plasma and speakers 11-13 feet apart some of the on screen action will sound like it’s coming from several feet off to the side, something I find very distracting. I find that keeping the mains within a foot or so of the edge of the screen works best.


As long as the subs aren’t blocking the M80s drivers I wouldn’t worry about that. Hell you could even put the M80s on top of the subs to see if you like how they sound elevated. It might go well if you plan on having the second row of seats on a riser. However, the advantage of using two subs is to even out the bass response of the room which is often best achieved by placing the subs opposite each other. So if one is in the front left corner the other might work best in the right rear corner. Opposite centers of each side wall and even the front and back wall are also generally superior to left and right front corner placement for bass flattening. If you don’t plan to use the dual subs for bass flattening then I would save my money and only get one. IMO using two, unless in a very large room, is a waste if you just want it louder, and then if it’s louder you want a single EP800 would probably do better than dual EP500s.

My HT/family room has a 58" Panasonic S1 and my seating is ~12' back, my mains are ~11' feet apart and I think everything sounds great. I do wish the 58" was at least a 70", not that the 58" looks tiny bit you really don't get the movie theater experience and I think the 70" would still look a little small for an HT experience but it would work very well for the general use I put my system through.

Good advice!

One other consideration is using a cinema scope 2.40:1 instead of the anamorphic 1.78:1 used by TV's. The 2.40:1 can cost more if you mount an anamorphic lens in front of the projector. Most people are perfectly satisfied with the 1.78:1. Myself, I'd rather go with the wider screen and watch 1.78:1 with the bars to the left and right of the screen, than to watch the 2.40:1 with the bars at the top and bottom of the screen. That way I get more of the theater effect.

Thanks all
well I may go with three in the front row, me being centre. and four in the back on a riser.
I find with the 60" I am only about 9 ft away and it is too close and tiresome after a while.Also, I want the movie theatre experience.
Mostly for movies grunt. However I do like watching concert videos and therefore, I perfer 2 ch or 2.2.
I was thinking the EP800 in a verticle position up front and below the centre channel. However couldn't quite see how this would be better than a single, given the duo's are so close together. Basically how is it much different than the EP600, besides volumn and power.
That is good to know that having duo subs EP500's are best one up front and one rear.
So, one up front and one out of phase in the rear is better than two upfront as in SirQuack theatre pics ?
hmm, playtime placement I guess.
yeh, that is also a point I was thinking about with the 60" is I want the speakers within a foot of the sides but, find 8 ft apart puts me too close.

How far from the side walls would the M80's work best, acoustically treated walls and what is the best seperation between te two. I was thinking 10 - 11 ft and me being 10 - 11 ft away. Therefore a 100" +- screen would be great.
So, if I went with a 102" screen, which is 9ft and allowed 6" to the M80's this would put me at 12ft to the outter edges of the M80's. and about 10ft from centre stage. if I but up a EP500 on either side that makes the rm 15 ft wide and no spacing between subs and walls. If however I went to the insides of the M80's then I can allow 2ft from the M80's to the side walls at a 15.5ft width ..perfect now that means the subs will be upfront and 3 ft from the side walls and 8 ft apart. is this too close for a dual sub system. unless of course I go one up one back and centred. maybe two EP600s in a verticle postion front or back or one EP800 ?

Hmm just me and my daughter so maybe I will cancel the rear seating and get two sets of 3 theatre seats for each corner in the rear and put a EP600/800 in the rear cente and one up front. Not it is (1) EP800 or (2) EP600/500's . I am allowing $2500 - $4000 for my sub expense and want the best for this rm and size.

I am still trying to figure out if M80's or bookshelfs are best for movies yet. lol So , I may end up with two systems in one rm yet

oh, one more thought Grunt ...
the THX means nothing to me really, I just loved the sound of the M&K's so thought I would try them out for theatre.
Not quite sure I like the drop off at 80hz. I am getting an idea of there sound and capibilites now with out a sub as my sub amp is toast. But will hopefully have my sub soon.

I don’t even buy a concert video if it’s not in surround sound any more. Most of the BD video and even a few of the multi-channel DVD ones are far superior to anything 2.0 or 2.1.


Each step up the subwoofer chain will give you more SPL at a given frequency especially at the lowest frequency. If you want deeper bass you generally want a bigger more powerful subwoofer. If you want flatter in room bass response (usually more important IMO) then multiple subwoofers may help with that but only if placed to do so. IMO two subs placed close together aren’t going to give you much more than a +3dB boost in SPL. Two subs up front placed with the mains may give you better stereo response from your subwoofers but only if you run an external crossover and send the deep bass and lower midbass meant for the mains to each subwoofer respectively (costly for little gain IMO if running M80s).


Opposing placement is a generalization. Every room is unique and the best way to find optimal placement is by experimenting.


If both subwoofers are not in phase they will sound terrible. Also dual subwoofer placement is much easier to manage with a receiver capable of .2 with discrete distance and SPL settings for each sub.



How far is room/seating dependent. The general rule is to have at least 3 feet to prevent certain frequencies from having interference from their counterparts reflected off the wall. This could certainly be mitigated by treatments but some sound reflected off the walls is good for expanding the front soundstage. Only experimentation will tell.

I hung my screen so that it’s above my M80s so I’d have freedom to move them around w/o worrying about blocking the screen. However, I have really big chairs so I can easily see over them. a dual riser for both the front and back row would take care of that, but you’d also need to have a high enough ceiling to accommodate the width of the screen you want.


Not allowing for spacing between the subs and walls is a bad move. They may sound great there or they may sound like crap but if you leave yourself no other options. . . . Just as much if not more importance to overall sound quality is subwoofer placement. If you are looking for the best possible sound then be prepared to place the subwoofers darn near anywhere since you won’t now their optimal location until you use them.

The odds that you will be able to get the “best possible” sound out of your system, and also have an esthetically pleasing look when it comes to subwoofer, placement is unlikely. You may get lucky you may not. You’ll just have to decide which is more important to you in the end.




Bookshelf speakers are usually easier to place in relation to walls but for the absolute best HT experience I would get the M80s/VP180 unless you have a fairly small room.


Also don’t get too hung up on the equilateral triangle between your mains and sweet spot. Like all the other factors I’ve mentioned and you’ve likely read about it’s just one of many variable. Having your mains closer to each other than the distance to your seating but with proper side wall reflections could very well sound better than having and equilateral triangle and give you a more even front soundstage. Experimenting with speaker placement is the only way to optimize your sound. Following the general guidelines you read about is a good starting point but It’s a good idea to give yourself some wiggle room.


I didn’t make any reference to “THX certification” if you are referring to the screen distance calculator I only linked to that to give you a starting point from which to decide on a screen size in relation to your seating distance. Some people like either a bigger or smaller screen but I find the THX recommendation gives the best results in filling your field of vision w/o being so big you have to turn your head to follow on screen action.

Info is good, I like that site too Grunt.
I think I need a 102" screen if I am 11 - 13 ft away.
Just need to experiment I guess.
I have the bookshelfs I am ordering M80's for music upstairs, I will test and compare them to the MK's and see where the differences are. Atleast with the bookshelfs I can put them over the Subs and still have two - three feet clearance to the wall and still have a 11ft seperation.
Don't want to put the 80's on top of the subs.
Just really trying to figue out the room size for a 102" screen and M80's and also a dual sub, for reasons you have pointed out.
I just read a few times that if you have a sub up front it is in phase and if another in the reay to put it out of phase so the waves do not cancel out each other. Then I also read that makes the room boomy.
I may also try going 15ft across the front and 19ft across the back or visa versa ?

well, I thought and thought about this but, I think I will build it 15.5'w x 19'L x 7.5'H

if I space the subs across the front ( hopefully this will sound best ) but at 1/3 intervals. I would hav then 5ft from the walls and 5ft apart. this will put the M80's closer to the walls and about 2ft away. giving me 11ft seperation. I am sitting 11ft from the front screen which will be 102".and allows for 1ft spacing between the sides of the screen and the M80's.

True there is no 'perfect' room, but math hypothesizes that use of the golden ratio should reduce alot of the sound reflection problems in otherwise static rooms.

An example of the idea is here:
http://www.cinemasource.com/articles/room_modes/modes.html

An example of the sweet spot and speaker placement based on the math concept is here:



Just another piece of info to cram into your already busy thoughts on room concepts.

axiom_man,

You are supposed to avoid having any of the dimensions divisible by the same number if at all possible. Since it sounds like you will be picking the dimensions then you can avoid having them all divisible by 3 (15.5 is nearly divisible by 3). I would just change them all slightly to avoid this issue, which can cause acoustic problems.

many studies have been made on this subject, here's a site about it:
http://www.acoustics.salford.ac.uk/acoustics_info/room_sizing/?content=index

I guess what I am more concerned with is how much space up front i need ? if I have M80's, a 92- 108" screen, dual Subs most likely they are 2' wide so that takes up 4ft.

Basically how much space between the side walls and the M80' s do i need? say 1.5ft away given the M80's are 10" ea. so, that will require 4.5'. if I allow 1 ft from M80 to screen that 6.5' screen 8ft that's 14.5'. now that would put the subs 6ft apart up front the room 14.5'.
So should I allow more space to the side walls ? is 6ft space between two EP500's not enough ?

What would be the ideal space from the left to the right allowing for good speaker positioning ?
If dual subs is better than one, I would assume they not be side by side? That has already been answered in another topis, by Jake though.
Which leads me to ask is one EP800 better than two EP500's ?

The room will be approxiamalty 2300sq ft give or take a couple hundred

Never heard this, I have heard the three sides not divisable between them or by a number. something like 15 x 21 x 7, where 3 or 7 would be a common or 12 x 16 x 7 where 4 would be the common

I'm in the same boat trying to figure out if we will finish our basement and if so what dimensions work for the media room. I'm currently looking at roughly 16x10x8. I'm debating only doing a partial wall (half wall) in the back, but don't know what that will do for sound. The reason for this is that a bar will be on the other side of the wall, so with a partial wall you could potentially sit at the bar and still be able to see the screen.

We are having trouble finding room for a media room, bar, playroom, bathroom, and storage down there, so trying to make it all work is getting a little frustrating.

I read this in a good article somewhere but don't remember exactly where. It's just something that has been ingrained in my memory for a while now. The best I could find in a quick google search was this link: http://www.gcmstudio.com/acoustics/acoustics.html . About a third of the way down it mentions the following.

"Redundant room dimensions or evenly divisible room dimension ratios will compound standing waves so this is why room shape is almost as important as room size"

So, like I said since you are building the room and are free to choose the dimensions then just try to add or subtract one foot to each dimension so that they are not all divisible by the same number. Then you will have essentially the same size room, but less problems with some frequencies being boosted or missing in certain locations in the room.

Axiom_Man,

Here are a couple of articles on the best locations for multiple subs as a starting point. Like the article says these are just suggestions as starting points and then you can measure the results in the room and slightly tweak the location from there if necessary. Then EQ if you can.

http://www.audioholics.com/tweaks/get-good-bass/subwoofer-connection-guide

http://www.audioholics.com/tweaks/get-good-bass/multiple-subwoofer-setup-calibration-1

i don't think it has been said yet, but if you use a projector screen you should paint the side walls and maybe the ceiling a medium to dark gray to absorb reflections so they don't wash out the image on your screen.
this should be done near the screen going towards the audience.
no need to paint the whole room.

Regarding ideal room dimensions, i found an extract from a book by James Mair: "High Quality Sound Reproduction" where he recommends that room dimensions not be multiples of one another; he gives examples of room dimensions that will evenly distribute room resonances:

small room: 1 x 1.25 x 1.6
medium room: 1 x 1.6 x 2.5
large room: 1 x 1.25 x 3.2

there is also a good site on the net: http://www.acoustics.salford.ac.uk/acoustics_info/room_sizing/?content=index

where it says:Louden [3] calculated the modal distribution for a large number of room ratios and published a list of preferred dimensions based on the standard deviation of the intermode spacing to achieve evenly spaced modes. The method produces the well known room ratio of 1:1.4:1.9.

hope this helps. :-)

Oh no, no, no bad all divisable by 2.
not good.

room is all dark blue, I have no WAF

Flat black should be better than dark gray to absorb reflections. Perhaps some black velvet cloth would work even better.

matte paint.

Axiom_Man,

I would listen to AV Rant 191. This was put together by two guest hosts, while Tom was moving to Australia last summer. I remember listening to it last summer and being blown away by the amount of very good information about almost everything you need to know about putting together a home theater room. I'd heard or read just about everything that they talked about at some point (a lot of which I had forgotten), but it is all here in one location to listen to and take notes. If I remember correctly, they address nearly all questions that have been asked here. They also talked about much much more. Here is a link.

http://www.avrant.com/?p=1449

That's awesome thanks
and flat black nah was thinking a semi gloss or silk and there are no windows so no light besides ceiling

Don't forget that the display is a large light source.

no lights in the room is ok, but i'm not talking about that;
i'm talking about corrupting the shadows on the screen and diminishing contrast in the images.

Explanations and examples:
Supposition 1: your wall on the side is a shiny white.
when you project an image on the screen, light will spill to the wall on the side; as the side wall is very shiny, that light will reflect back to the screen and will degrade contrast and give an overall haze effect to the image. same thing as if you were to put a light on in the room.

Supposition 2: your wall on the side is a nice green.
when you project an image on the screen, light will spill to the wall on the side; it will be strongly tainted by the green color of the wall and then will be reflected back to the screen.
you will then perceive that your images on the screen will have a distinct green overcast, in spite of the fact that your projector has been calibrated by an expert. shadows will now be green too, and not very dark.

my recommendation:
paint both side walls a neutral gray, not very light and not very dark and also the ceiling.
you only have to paint those surfaces starting a couple of inches back from the screen, right up to where you're sitting.
the paint must be matte or nearly so, to absorb the light even more.

the gray should be very acceptable - remember it was the fashion some years ago to have gray painted walls, and i think it looked very good.

if you do that, i can guarantee you will have images on your screen as good as the projector is well calibrated, the room will have no bad effect on the quality of the images.

hope this helps. :-)

We could probably change the 16 to either 15 or 17. The 8 for height is a rough guess, as we have 9 foot ceilings in the basement unfinished but will lose some when we finish. If we put the room where we think we will at the moment, the 10 across is about as wide as we can go due to the steps to the basement being in the middle of the basement.

The link is to a layout of what I'm working with, but the picture is really small. You should be able to zoom and make it bigger, but blurrier too....hopefully it helps a little.

Basement layout

your link is a sign-in page for Windows Live/Hotmail.

I had a feeling that might happen. It was working for me after I logged out of hotmail, so it was hard to tell. Unfortunately, I don't have somewhere to post it so it can be viewed and I can't attach it directly.

Just give us your password and we'll root around for it.

They'll be divisible by 1, too, no matter what. I thought they meant none of the dimensions should be the same number or have any of them being divisible (or, conversely, a multiple) of one of the dimensions.

I thought they meant that none of the walls can share a common denominator. Other than of course 1.
not quite sure about that ratio thing though ?
the 1,1.4,1.25 works, just doesn't seem right

I get if the ceiling is 7.5' then the ends of the room are 7.5x 1.4 = 10.5' so then the lenght would be 13.5'

The picture won't help much anyway now....I am reconfiguring and I think the new room is roughly 18x12 (I can modify slightly to get rid of the divisible by 2 issue) however the 12 direction takes it up to where a metal support post is holding up a beam. There is another 6 feet available past that, with a window on that wall. I'm not sure what to do about that. Possibly make the room face the other way and have the beam equal with the back row of seating, but then the window is in the back which my wife didn't like the idea of (I don't like the idea of a window at all, but I can get blackout shades or something of the sort.

We have to look at it more tonight. The media room was moved mostly so the playroom would be the first thing at the bottom of the steps, which makes more sense.

Jason, there really isn't a "divisible by 2" issue. The studies in this area vary quite a bit. Probably the only point that's worth giving any consideration to is to avoid having the length or width being precisely one, two or three, etc. times the ceiling height or one, two, three times each other.

ANY number is divisive by 2.

"Without a fractional part remaining" is implied.

I just meant a room with 8 ft cielings and 12 ft wide and 24 ft long is not perferrable or 8x10x16.
I was told and found that a roomwith no common denominator was best as it 7x13x19

If you were to want a room to be roughly 8x10x16, but want to avoid any of them being divisible by the same number then you just have to make sure to find the two closest primes for the length and width, since the height of the room would probably be the one that you wouldn't want to change if you don't have to. So do 8x11x17. There is no need to have them all as prime numbers.

well, I am preety well sure it is now down to 7.5'h x 13.6w x 19.6L

here's some other info that you might find helpful:
http://www.cinemaquestinc.com/ive.htm