What is the ideal room size/shape for a home theatre? - AVS Forum | Home Theater Discussions And Reviews
Forum Jump: 
 3Likes
  • 1 Post By Bill Fitzmaurice
  • 1 Post By DonH50
  • 1 Post By FMW
 
Thread Tools
post #1 of 12 Old 09-28-2014, 08:03 PM - Thread Starter
Newbie
 
Join Date: Sep 2014
Posts: 13
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 8 Post(s)
Liked: 1
What is the ideal room size/shape for a home theatre?

I'm going to be building a house from scratch and not much restrictions in 1-2 yrs and want to know for designing a theatre room what should one aim for?
OdinGOW is offline  
Sponsored Links
Advertisement
 
post #2 of 12 Old 09-29-2014, 06:18 AM
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 15,491
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 5778
Quote:
Originally Posted by OdinGOW View Post
I'm going to be building a house from scratch and not much restrictions in 1-2 yrs and want to know for designing a theatre room what should one aim for?
One with no parallel surfaces. That means a more or less oval shape, including the ceiling. It's not terribly practical to do so, but it's quite effective. Take a look at a picture of Carnegie Hall, for instance. Perfect sound, and when built in 1891 there was no such thing as amplification, so a singer's voice had no help reaching 2800 listeners.
Djoel likes this.
Bill Fitzmaurice is offline  
post #3 of 12 Old 09-29-2014, 06:53 AM
AVS Forum Addicted Member
 
DonH50's Avatar
 
Join Date: Feb 2010
Location: Monument CO
Posts: 12,466
Mentioned: 71 Post(s)
Tagged: 0 Thread(s)
Quoted: 3341 Post(s)
Liked: 3488
Barring that, setting the L, W, and H dimensions in prime or "golden" ratios to reduce the impact of room modes is worthwhile. There is also some debate about ovaloid rooms since reflection patterns can make for weird imaging...

You should also consider using Kinetics IsoMax clips and/or other techniques to float (isolate) the walls and ceiling (floor if not on the bottom level), including caulking all places walls/floor/ceiling meet, and using a minisplit unit to isolate the room for the rest of the house HVAC system. By doing all that I have almost no audible incursion from the rest of the house (could not completely isolate the ceiling so heavy footfalls above transmit slightly) and I can play music or watch a movie with almost no transmission to the rest of the house.

Don't forget to run extra high-current lines (e.g. 20 A) and put the room on separate feeds/breakers to the electrical service box. Add whole-house surge and lightning protection -- cheap now, more expensive later.

HTH - Don
Henrick Rennow likes this.

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
DonH50 is online now  
Sponsored Links
Advertisement
 
post #4 of 12 Old 09-29-2014, 08:26 PM
AVS Forum Special Member
 
mtn-tech's Avatar
 
Join Date: Feb 2013
Location: Nevada
Posts: 1,204
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 234 Post(s)
Liked: 181
Some web sites that were used to decide how high to make my basement ceiling - they include some of the golden ratios:

http://www.bobgolds.com/Mode/RoomModes.htm
http://www.cinemasource.com/articles...des/modes.html
http://forum.studiotips.com/viewtopic.php?t=684
http://www.salford.ac.uk/computing-s...ng-for-studios

2-Ch (HT L/R): Oppo BDP-105 BD, Adcom GFP-750 pre, Bryston 10B Sub Xover, Bryston 4BSST2 / Paradigm Signature S4 v.2 (L/R), (2) SVS SB12-NSD (Subs)
Home Theater: Bryston 4BSST2 amp / Paradigm CC-590 (C), Outlaw 7700 amp / (4) Def Tech UIW-RSSII (LS/RS/LB/RB), Samsung 46” 3D LCD

Last edited by mtn-tech; 09-30-2014 at 08:40 AM.
mtn-tech is offline  
post #5 of 12 Old 10-01-2014, 12:34 PM
AVS Forum Special Member
 
fbov's Avatar
 
Join Date: Nov 2006
Location: Bushnell's Basin, NY
Posts: 1,650
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 335 Post(s)
Liked: 208
Quote:
Originally Posted by Bill Fitzmaurice View Post
One with no parallel surfaces. That means a more or less oval shape, including the ceiling. It's not terribly practical to do so, but it's quite effective. Take a look at a picture of Carnegie Hall, for instance. Perfect sound, and when built in 1891 there was no such thing as amplification, so a singer's voice had no help reaching 2800 listeners.
Bill, have you ever looked at a plan view of Carnegie Hall, say from a seating chart?
http://www.docstoc.com/docs/687764/C...-New-York-City[1]

The hall is rectangular, with rounded corners, not oval. Rectangular is one secret to good music hall design. A practical example is the recent renovation of the Eastman Theater here in Rochester. Build originally as a movie theater to showcase George Eastman's products - Kodak film - it was mostly used for orchestral performances once movie theaters became commonplace. They say George's seat was particularly bad, but then Eastman was partially deaf so it was no great loss.

The biggest change in the renovation was moving the splayed side walls in, to they were parallel to each other. It cost the theater a lot of seats, but greatly improved the sound quality.

Now, a stage area may well be ovaloid, in order to focus sounic energy toward the audience. But the seating areas in great theaters have parallel sides...

HAve fun,
Frank
fbov is online now  
post #6 of 12 Old 10-01-2014, 01:54 PM
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 15,491
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 5778
Quote:
Originally Posted by fbov View Post
Bill, have you ever looked at a plan view of Carnegie Hall, say from a seating chart?
I've been there, many times. The side walls are flat, the back wall and ceiling is not. Some curvature of the side walls wouldn't hurt, though they're far enough apart that the standing wave action takes place at too low a frequency to be an issue. In a smaller room it can be.

Last edited by Bill Fitzmaurice; 10-01-2014 at 02:04 PM.
Bill Fitzmaurice is offline  
post #7 of 12 Old 10-01-2014, 03:24 PM
AVS Forum Special Member
 
fbov's Avatar
 
Join Date: Nov 2006
Location: Bushnell's Basin, NY
Posts: 1,650
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 335 Post(s)
Liked: 208
Bill, my point is that a concert hall with curving side walls that sounded like crap was "fixed" by creation of acoustically straight side walls.

Orignal seating chart
http://www.rpo.org/p_549/Seating_Charts_-_test_version/

Renovated seating chart
http://www.rpo.org/s_7/p_340/Seating_Charts/

Originally, the goal was that every seat could see the screen, resulting in a flared shape to the orchestra seating area.

The renovation added stub walls to create box seats at the orchestra and balcony levels, backed by wall segments that straighten the flared areas. Scroll down the second link to see the added walls where there used to be left and right orchestra seating (center three sections are substantially unchanged, save for their depth).

I can't argue the other surfaces, front/rear, ceiling/floor. Acoustics is an art in many ways, and odd things, like a granite block under the stage at Carnegie, or trash in the basement of the Philadelphia Academy of Music, can affect soudn quality. However, I don't see any data supporting an oval theater layout as you suggested.

HAve fun,
Frank
fbov is online now  
post #8 of 12 Old 10-02-2014, 05:24 AM
Newbie
 
Andrew Steele's Avatar
 
Join Date: Jul 2008
Location: London, United Kingdom
Posts: 6
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
OdinGOW,

Great idea to be planning ahead.

Before we get lost in another obligatory AVS Forum debate on acoustic fundamentals , let's establish a ballpark figure on what room size you're looking at.

Let's consider the following questions:
  • How many would you like to seat?
  • How many of those seats do you want to be great seats?
  • Screen type? (Easy to assume front projection, but you may have a 4K OLED in mind)
  • What screen size would you like? (Alternatively, do you have a target viewing angle at your seat)
  • How important is sound isolation? (do you have a family sleeping upstairs when you're watching Black Hawk Down at reference level)
  • Is the room dedicated to theater? (i.e. no pool table)
  • Subwoofers, refrigerator sized DIY units, or are JL Audio Fathom f113s more your style?
  • Will equipment racks be located outside the room? (Can be located in a dedicated equipment/projection room, integrated into an air-lock or theater foyer)
  • Do you have any space restrictions?

Regards,

Andrew

Last edited by Andrew Steele; 10-02-2014 at 05:29 AM. Reason: Spelling correction.
Andrew Steele is offline  
post #9 of 12 Old 10-02-2014, 06:48 AM
 
Bill Fitzmaurice's Avatar
 
Join Date: Nov 2009
Location: New Hampshire
Posts: 15,491
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 5778
Quote:
Originally Posted by fbov View Post
However, I don't see any data supporting an oval theater layout as you suggested.
Flat parallel surfaces have two issues. One is that they promote standing waves at a fixed frequency in the lows, the other is they lead to comb filtering in the mids and highs. Non-parallel surfaces, especially when curved, fix both of those issues. For that matter so do room treatments, but if you don't have parallel flat surfaces causing problems to begin with then you don't need to do as much treating to fix them.
Bill Fitzmaurice is offline  
post #10 of 12 Old 10-02-2014, 07:05 AM
FMW
AVS Forum Special Member
 
FMW's Avatar
 
Join Date: Jun 2007
Posts: 7,480
Mentioned: 13 Post(s)
Tagged: 1 Thread(s)
Quoted: 1654 Post(s)
Liked: 1711
For the OP, in my experience an ideal listening room will be rectangular rather than squarish. The sound source will be at one of the short walls and the listening position will be away from the opposite short wall, leaving significant space between the listening position and the wall behind. Avoid squarish rooms and seating positions too near the wall behind. After that it is merely a matter of positioning equipment and any required treatments.
jdlynch likes this.
FMW is offline  
post #11 of 12 Old 10-02-2014, 09:14 AM
AVS Forum Special Member
 
fbov's Avatar
 
Join Date: Nov 2006
Location: Bushnell's Basin, NY
Posts: 1,650
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 335 Post(s)
Liked: 208
Quote:
Originally Posted by Bill Fitzmaurice View Post
Flat parallel surfaces have two issues. ....
Flat parallel surfaces have one great advantage - predictability. That seems like a huge advantage when planning to make something.

A case in point is the guy who boxed in an open-back midrange driver with a cylindrical section, then had to stuff the heck out of the space to eliminate the focused reflection. Concave surfaces focus sound, which does not seem beneficial in a home theater. Convex surfaces have dispersion benefits, but you can't use them to make a closed space.

I see an oval room plan as a great idea for a whispering gallery, but not a home theater. I agree that it would supress standing waves, but what would come along with that? As to combing issues, they're ubiquitous, and quite possibly a huge factor in auditory perception. We've disagreed before on the completeness of human understanding of auditory senses, so I doubt we'll agree here, either.

Have fun,
Frank
fbov is online now  
post #12 of 12 Old 10-06-2014, 11:12 PM
Member
 
Yubbie's Avatar
 
Join Date: Oct 2008
Posts: 51
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Oval room for a home theater? No thanks. A parabola or an ellipse will focus acoustic energy... This is a very bad idea for a home theater. There's a big difference between a room designed for natural acoustics and a room designed for amplified sound. In terms of eliminating standing waves before room treatment, you do want to avoid parallel surfaces. If you really need a symmetrical space, a fan-shaped room will work, but it also requires creating some unusable space. However, a larger rectangular room with "proper" room treatment will work just fine.

OdinGOW, I would suggest that you consider answering Andrew's questions above. That will allow for more accurate advice to be given.

Last edited by Yubbie; 10-06-2014 at 11:19 PM.
Yubbie is offline  
Sponsored Links
Advertisement
 
Reply Audio Theory, Setup, and Chat

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off