Home Cinema Orientation - Suggestions

Sam Ash

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In a dedicated home cinema room that measures 6 meters by 4.5 meters, I am interested in having the biggest fixed screen width possible on the 4.5m wall without compromising viewing comfort. I intend having two rows of seating with each row having 4 seats. I want to have the 2 rows of seats as far back a possible in order to achieve the maximum screen size but don't want to go back against the wall as I need the 7.1 speaker configuration to be positioned correctly. A double edged sword really :D

The back row of seats will be elevated about 6 to 8 inches above the front row for easy visibility. I'd like to hear from experienced home cinema experts and enthusiats - How far should the first row of seats or the head of the person seated in the middle front row be away from the screen ?

Any idea how far he people on the second row should be from the screen ? considering that enough leg room is needed between the two rows.

I am quite keen on a 120 inch (3m) wide screen (not diagonal) but I'm thinking it may be far too wide/big. I don't want people on the first row to toggle their eyes/heads left and right trying to figure out what's happening on the screen - at he same time I need a little space at the back for 7.1 to work properly and for people to pass.

There are various suggestions on calculating ideal seating position: 2.4 x the image height, 1.5 times the image width, 2 x image width.

Any input from the pros or experienced blokes out there will be appreciated
 
I'm sure there must be someone out there who can shed some light on the matter ???

Any help will be much appreciated.
 
A general rule for Full HD screen size is that the screen size should be no more than two thirds of the viewing distance. So for a 3m screen, you'd need to sit 4.5m away. With two rows of seating, you are likely to be at the border. The problem with a screen that is too large is not merely that of needing to turn one's head, of far greater impact is that the pixel size is greater than the eye's resolution (Wikipedia gives the angular resolution at 0.02°-0.03°), similar to the feeling of wearing the wrong glasses.
 
A general rule for Full HD screen size is that the screen size should be no more than two thirds of the viewing distance. So for a 3m screen, you'd need to sit 4.5m away. With two rows of seating, you are likely to be at the border. The problem with a screen that is too large is not merely that of needing to turn one's head, of far greater impact is that the pixel size is greater than the eye's resolution (Wikipedia gives the angular resolution at 0.02°-0.03°), similar to the feeling of wearing the wrong glasses.

Thanks Mark, I really appreciate your input.

By the way, what is your area of expertise ? I believe I saw some of your posts which were related to home automation.

Cheers,

Sam
 
1.5x width is a good starting point. You have to consider the projector you are using - 1080p resolution is a must for a 1.5x width viewing distance. Also consider if it will be bright enough to handle this screen size, given any ambient light or light reflective surfaces you might be battling in the room. Will you be running 2.35:1 aspect? If you already have the projector will it fit the throw?

Assuming the screen is fixed to the end wall (rather than say 50cm forward to accomodate speakers behind it) then the first row is 4.5m to say the centre and the second row is on the back wall. I would work backwards from the room to end up with the screen size. You want say 75cm behind the back row to get past as per your requirement and it moves the back row off of the back speakers. Depending on your type of seats you will want 150cm for each row so the back of the front row is going to be 225cm from the back wall at the very least, i.e. 375cm from the front wall. This is basically dictating a 2.5m wide screen. Personally I would still go bigger because I'm greedy and anyone that is uncomfortable with the screen size can sit in the back row!!! Really need to see the furniture and the room to get a feel for it.

If you haven't got the speakers yet since space is tight you really want on-wall surround speakers or in-ceiling. You don't want to be eating up more depth with speakers on stands or floorstanders. If the budget is there definitely put the front three speakers behind the screen!
 
Liam makes good points here. I would start by deciding what aspect ratio you want the screen to be. Personally I recommend 2.35 these days for fixed masking in dedicated cinema rooms where most content will be movies, not HDTV. Obviously if you have the luxury and budget to afford motorised masking to go between 2.35 and 1.77 then even better.

Then you need to work out the optimum screen size by calculating the viewing angles (i.e. angle of the screen side edges from a particular viewing position) at the various seating positions. From my days in professional cinema with Dolby our specifications were a viewing angle range between 40-60 degrees at optimum seating opsition of 2/3 distance from the front.

THX recommends a viewing angle on the back row of a cinema of 36 degrees, with an absolute minimum of 26 degrees.

SMPTE recommends a viewing angle minimum of 30%.

So take your pick between these slightly differening standards - it usually ends up a compromise between the different seating positions anyway.

Then as Liam says, once you've spec'd the screen size, its time to look at the projector lens ratios to see where the projector needs to be mounted to fill the screen. These ratios become even more crtictal if you plan on using something like a Panasonic 4000 projector to go between 2:35 and 1.77 preset zoom positions becuase you have motorised masking.

If you can use a CAD system then I find its easier to draw a CAD floor plan then start playing around with all the measurements and angles - I also have spreadsheets which calculate all the angles etc for me.

Hope this helps.

Good luck with the design.

Graham
 
Just thought I'd add a pic to help you get an idea of some of the numbers with respect to seating distance - it's very important IMHO since having a big screen can be negated by sitting too far back. Similarly, as has been said, sitting too close with a projector zoomed on a scope screen can produce issues with pixel size, especially if you still use SD source material.

allscope.gif


Those are for a cinemascope screen but seating distances still work out if you use the image height relationship as a guide rather than width. Like gce123 I would try the 2.35 approach to be honest - scope movies were designed to be wider than 16:9 and can further improve the viewing experience - especially when you consider how small scope movies look in a 16:9 screen. I tend to go for the 2.4 x the image height for 1st row (scope with anamorphic lens), but as Liam said, you may be dictated by working from the back - other than needing a gap from the back wall, you don't want the back speakers (or side speakers for that matter) too close to people.

Gary
 
Thank you everyone for the wonderful help.

Just to clarify, it will be a 16:9 screen. A 100" (2.5m) image width (not diagonal) seems to be the ideal size. Would have been very nice to go 120" (3m) or 110" (2.7m) but that may be uncomfortable for people on the first row of seats. I will look into the issue with some care.

Also, would it be better to have the seats arranged on a very slight curve rather than straight on ?

or, have the 2 centre chairs in the middle straight on and the 2 on either sides slightly angled ?
 
Whats the ideal height for the side speakers and the back speakers. I believe most people recommend that the side speakers be at ear level and the back speakers be slightly higher.

What is the optimum for the side and back speakers in a 7.1 configuration ?

As I have two rows of seating with the back row raised about 8 inches, I'd tend to average between the 2.
 
Everything wants to be ear height but as you say you will need to compromise for the surround speakers. In general if you make the surround back and sides above ear height then it will mean the person sitting next to you or behind you is not going to block the direct path of sound from the speakers. Many speakers have aimable tweeters or the PMC Wafers actually have two differently opposed tweeters in a single unit to allow you to choose the best one for the orientation you are using. So long story short, probably put them a little higher than ear height to average out the two rows.

Seating wise I tend to do a love seat in the middle front, and slightly angled seats either side. But this is immaterial to picture quality or viewing angle etc, more about fitting into the room and giving a little angle so you can talk to each other and share a coffee table or whatever.

What seating are you using, once you accomodate the seating size you can work out your forward most viewing distance and thus the screen size. I would want to cheekily get 2.7m in myself.
 
Everything wants to be ear height but as you say you will need to compromise for the surround speakers. In general if you make the surround back and sides above ear height then it will mean the person sitting next to you or behind you is not going to block the direct path of sound from the speakers. Many speakers have aimable tweeters or the PMC Wafers actually have two differently opposed tweeters in a single unit to allow you to choose the best one for the orientation you are using. So long story short, probably put them a little higher than ear height to average out the two rows.

Seating wise I tend to do a love seat in the middle front, and slightly angled seats either side. But this is immaterial to picture quality or viewing angle etc, more about fitting into the room and giving a little angle so you can talk to each other and share a coffee table or whatever.

What seating are you using, once you accomodate the seating size you can work out your forward most viewing distance and thus the screen size. I would want to cheekily get 2.7m in myself.

Thanks Liam,

As far as the seating goes, I need really cost effective stuff - does not have to be cinema spec or anything. However, it would be nice to have comfortable seats that are joined together to share an arm rest so that I get 4 seats per row in the 2 rows making a total of 8. Alternatively, I'm considering getting rid of the rows and just have a living room arrangement which is much more cozier.

Any idea where I could get good seats at excellent prices ? - They don't have to be leather or conform to George Lucas standards.
 
HAHA there's no THX standard for seating. But you still get what you pay for. If you want a well built, steel framed, comfortable reclining chair you are going to have to pay for it. Generally speaking from the more dedicated manufacturers you are talking £1-2k per bum for the best stuff. I know KHC do a cheap brand which is about £900 a bum. Otherwise you are best to just try hit a DFS sale for a massive L or U shaped sofa. These big cinema chairs do make the difference though
 
I'd like to thank everyone on this post for their valuable and kind contribution :thumbsup:
 

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