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Discussion Starter · #1 ·
For a front-projection set up, what is good room geometry? Let's say for a 7-8 foot wide 16:9 screen.


Is there an optimal ratio for room lenght to room width? Do you want a square room, or a more rectangular room for the best acoustics?


Thanks,

-Scot
 

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For proper room acoustics the proper room shape should be rectangular. The reason this shape is ideal is the room dimensions are not multiples of each other.
 

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Actually, it seems something other than a rectangle (square being the worst) seems to be acoustically better. Perhaps more of a trapezoid with the least number of parallel walls. That would seem to reduce reflection from what I have seen. Wider in back, narrower in front. When I set up a new HT it will be about 14' wide at the screen and about 18' at the back with a 20 ' length. Currently have 12.5X 19.


Jeff
 

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I agree the shape should not be square. I have a 12' by 20' dedicated theater, which works out great for the family, yet contains the audio well. My screen is 100" diag which, when sitting about 10 to 12 foot away, more than suffices to immerse you in the movie.

If you are running subwoofer(s), I would suggest calculating your standing wave ratio and/or run two subwoofers in opposite polarities to eliminate "dead" areas.
 

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I thought of the trapezoid room shape design as well. Many sub cabinets have that shape. I do not know if reviews have been been as to the perfect room shape and size. I believe commercial theaters have rectangular room shapes. From a CEDIA training seminar I attended in 1995 by Russ Herschelmann entitled "Home Theatre: Essential Elements" "The right room: Room size: 1000-CF (figure cubic feet Lx Wx H). Room shapes: a. rectangular preferred, b. dimensions should not be multiplies of each other (e.g. 8x16x20, 10x16x20, 8x14x28-are all bad!)


Other room shapes in the real world: square (bad), circular, bay windows, L-shaped rooms, the killer: open floor plans (kitchen/family room, etc.) Openings to other rooms (e.g. archways) increase the acoustic volume of the space, since the subwoofer "sees" the entire room area as ONE ROOM. Rooms that have arches/openings/alcoves to other rooms (with no doors) will require significantly more bass energy (both in raw drivers and amplification) than a room where you can close doors. In a medium-sized house with archways or no doors between the theater and the rest of the house, the theater could be well over 20,CF or so an absolute nightmare for bass reproduction!" (Herschelmann, 1995)


He goes on to suggest ways of dealing with odd shaped rooms and the key he said was to achieve balance. From what I critically read from his findings is that acoustic and light pollution problems occur with other than a proper room shape. I had a friend, just Sunday at church ask me if a round room was the best. I said it feel into an odd shaped, unideal room shaped acoustically. He said he meant a sphere room. I asked him how many times you see a sphere room. I can't answer if a sphere room is good, but round shaped room seem to not be ideal.
 

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Round would be bad because, using engineering, all sounds would geometrically return directly back from where they came from.
 

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Discussion Starter · #8 ·
how about a room with angled cielings? i have seen alot of 1.5 story bungalow houses that usually have a 20-30 foot long by about 10 feet wide upper room, which would be probbably be good for a HT, but they have the angled cielings. Would that affect accoustics very much? would the angled cielings create horrible reflections, and bad sound, or would they actually help to reduce unwanted resonance?


I ask because I have been looking at houses online, and some sites give room dimensions.


Also, alot of houses that i have seen have 9' to 12' x 10' to 14' ft bedrooms. Is that way too small for front proj?


-Scot
 

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Anthony, you are just a trapezoidal kind of guy :)
 

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Scot, don't know about ceiling, but I think the biggest question is what do you want. at 9' wide it is a bit narrow for seating and at 14' long it will be harder to add a second row. so if you want a place for two people then a 9x14 is not a problem, but if you want 10 people then AI think the room might be a bit small
 
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