# Building new house + theatre = Need Recommendations



## scottrichardson (Oct 14, 2009)

Hi guys,

Hope you're all well?

Not long ago we finished building our current house complete with a dedicated home theatre room which is 4.4m wide x 5.4m long (14.43 ft x 17.71 ft) with 8 foot ceilings. I was happy for the most part with the room, apart from the fact that my ideal seating positions had a lot of bass nulls.

So, here we are almost a year later, and we're planning the next house. We have another baby on the way, and I'm using this as a good excuse for building a bigger house. With a bigger house comes a bigger home theatre! 

So, I'm doing the floor plans now. I'm basically unlimited in terms of space (realistically).

So, I come to you guys, who know a lot more about ideal room dimensions than me. I am seeking some room dimensions that will hopefully circumvent some, or most of my bass null issues.

I'm looking to have two rows of seats this time, with the rear row (4 seats) on a riser of about 1 - 1.5ft higher than the front row/floor (2-3 seats). I'm expecting to make the room both wider, and longer. Additionally I am able to push the height of the ceiling up to 8.5 or 9 foot for the room. I'll be acoustically treating inside the walls with Rockwool, and then again with internal bass traps/panels in the corners. I will probably go Super Chunk this time, and have the builders create 45˚ angle corner sections into which the Bradfords Ultratel material can go. 

I'll be using a 130" 16:9 OZTS screen and no doubt whatever the high end JVC projector is at the time - ie: something comparable to my current HD950 (maybe they will have 3D support by then?).

So... put simply.. my question to you guys:

*What room dimensions will be ideal for me?*

I really appreciate any advice you can offer.

Kind regards,

Scott


----------



## bpape (Sep 14, 2006)

What is the 'shell' that we can work within?

Don't have your builders build anything in the corners. If you do, it would be just framing and AFTER the room is drywalled or you'll lose your isolation.

Bryan


----------



## scottrichardson (Oct 14, 2009)

You're pretty much free to work within whatever you want 

I mean, it''ll be a wooden framed house, concrete slab floor, and gyprock/drywall walls. One of the walls, possibly two may be external walls so will be drywall internal with brick external. Also, there will be NO windows. I have windows now and all I have done is spent money covering them up with black polarfleece shades and blockout curtains! So...... NO windows. I'll get air in via air-conditioning or something 

Scottie


----------



## bpape (Sep 14, 2006)

Start with a 10' ceiling if you can. Extra height is always a benefit in terms of extra spaciousness to the surround field as well as avoiding modal problems from ceiling height - especially in the back row.

16x26x10 would be a very nice room indeed.

Bryan


----------



## MatrixDweller (Jul 24, 2007)

Ideally you would want to have a nice wide room so that you could plop in any furniture you wanted, like a 4 or 5 seat Berkaline jobby with arm rests. Maybe you don't need that and 2 rows would b better. You'll still want to be 15ft or 16ft wide. Ideal also is taller ceilings, 9 or 10 or even 12ft (you did say the sky is the limit). So based on 10ft ceilings 16ft wide by 26ft could be ideal (1:1.6:2.6 [HxWxL]) as Bryan pointed out. If you're stuck with 8ft ceiling then 8 x 12.8 x 20.8ft works. That ratio was formulated by the Ancient Greeks thousands of years ago and is still used today.

A note about "no windows". You'll most likely need a door to the exterior then to provide egress. Building codes dictate that rooms need two methods of escape (a window being one method). If the builder doesn't bring that up, then I would question everything else he is designing for you.


----------



## scottrichardson (Oct 14, 2009)

Hey guys,

Thanks Brian. thanks Matrix.

OK, so Matrix, 8 x 12.8 x 20.8 is somewhat too small for me. I actually feel my HT is not wide enough at the moment, which is 14.4ft wide. I don't have enough room to hold the subs and the mains and the cabinet all on the floor. My mains are on top of my subs (as per a recommendation by a member here).

I would love to go 17.7ft wide, or thereabouts.

Brian the only problem with your recommendation for me is that 7.9 meters (26ft long) may be just a bit TOO big. Is there some way to compromise a little? How would we be going for acoustics then?

From what I can see, my problems with my current HT are to do with floor-ceiling standing waves more than front to back or side to side. So I am quite keen to push the ceiling up......or.... drop the floor down.. if that makes sense? I could drop the slab for the HT room down a little lower than the rest of the house - this would save on having to muck around with variations in the roof heights at that end of the house.


----------



## MatrixDweller (Jul 24, 2007)

If you go to the Room Mode Calculator sticky at the top of this topic section you can plug your own numbers in a get a feel for what the room modes will be.


----------



## scottrichardson (Oct 14, 2009)

Yeah I did, but to be honest I don't know what to make of it all! 

What I need is a spreadhseet that calculates the frequency response curve AT the listening position, rather than just the modes. I find I can't comprehend the results of the room mode calculators too well.

If someone with a better understanding could punch in some dimensions and explain to me what's going on, I would definitely be very appreciative! I'd love to understand it all some more!


----------



## bpape (Sep 14, 2006)

That particular ratio works very well. If we can't use it, that's fine. The issue is that when you try to keep that ratio and you shorten the length, you need to narrow the width and shorten the height by the same percentage. You essentially end up with the same width that you have now.

Don't get me wrong - there are a lot of great sounding rooms that don't really follow the 'perfect' ratios. EVERY room still has modal and decay issues regardless of their ratios.

How much length and height can you tolerate? That was kind of my original intent behind the envelope question.

Bryan


----------



## spartanstew (May 7, 2009)

Since you're set on a 130" 16:9 screen, I'd calculate seating distance and work from there.

IMO, with that size screen you'd be looking at seating distances of 13'-14' & 19'-20'. You'll want some space behind the rear seating, so the I wouldn't go any smaller than 24' in depth. If you can do it, the first recommendation of 26' would be perfect. You could have great seating distances and still have room for a stand-up bar behind the rear seats if you wanted.


----------



## bpape (Sep 14, 2006)

The problem with all of this is that we're putting the cart before the horse. Ideally, you set the seats for best audio performance and THEN select the appropriate screen size for the distance you'll be sitting. 

Forcing seats into spaces just to say one has a 130" screen will likely severely sacrifice audio performance. For example, seating at 13' in a 26' room puts you dead center of the length which is a horrible place to sit due to severe bass mode issues. Ideally, front row would be more like 62-66% of the length from front wall (not screen) to seated ear position.

Bryan


----------



## scottrichardson (Oct 14, 2009)

Spartan,

I guess seating distance tastes vary from person to person. Currently I'm sitting about 13ft from my screen, and would love to be maybe 3ft closer - just to have that 'enveloping' sensation. It doesn't feel like a HUGE screen at the moment. Just feels comfortable. 

I guess 7m is probably about as long as I could tolerate, so 23ft. I can probably push the issue and get 10ft ceilings, though 9ft ceilings will be far easier to get over the line. I think the rest of the house will have 8.5ft ceilings. 

I have no desire to have a bar or anything substantial behind the rear seats, aside from the rear surrounds and acoustic panels/traps/curtains etc. So I don't need TOO much space back there. 

I definitely want to have TWO sets of surround L/R speakers, to simulate that full cinema feel and create a more enveloping surround field.


----------



## scottrichardson (Oct 14, 2009)

bpape said:


> The problem with all of this is that we're putting the cart before the horse. Ideally, you set the seats for best audio performance and THEN select the appropriate screen size for the distance you'll be sitting.
> 
> Forcing seats into spaces just to say one has a 130" screen will likely severely sacrifice audio performance. For example, seating at 13' in a 26' room puts you dead center of the length which is a horrible place to sit due to severe bass mode issues. Ideally, front row would be more like 62-66% of the length from front wall (not screen) to seated ear position.
> 
> Bryan


Agreed, and to be completely honest, I am more concerned with audio performance / bass response than the screen feeling the perfect size for the seating position. I don't mind if the screen feels a bit BIG for the front row. Realistically, so long as we're far enough back that we don't notice the pixel grain, then I'm happy. Given that from about 11ft or further, you can't see it, then we should be fine


----------



## bpape (Sep 14, 2006)

Could you go something like 9x16x23? It's not a known ratio but the dimensions fall nicely without a lot of overlap, give you good space beside the screen for speaker placement away from the wall, and plenty of length for a good surround field.

Bryan


----------



## MatrixDweller (Jul 24, 2007)

scottrichardson said:


> I guess 7m is probably about as long as I could tolerate, so 23ft. I can probably push the issue and get 10ft ceilings, though 9ft ceilings will be far easier to get over the line. I think the rest of the house will have 8.5ft ceilings.


You cold always go with a vaulted ceiling. That would be cheaper to build than raising the whole roof or lowering the foundation. If you went with a fully vaulted ceiling it would help the acoustics. If the outside wall is 8.5' then going up to a 12' peak would not be unheard of. if your room is 16' wide and the outside wall height is 8½' then the vaulted angle to go up to 12' would be about 24° (not too steep). That is assuming that the trusses run the width of your room.


----------



## scottrichardson (Oct 14, 2009)

MatrixDweller said:


> You cold always go with a vaulted ceiling. That would be cheaper to build than raising the whole roof or lowering the foundation. If you went with a fully vaulted ceiling it would help the acoustics. If the outside wall is 8.5' then going up to a 12' peak would not be unheard of. if your room is 16' wide and the outside wall height is 8½' then the vaulted angle to go up to 12' would be about 24° (not too steep). That is assuming that the trusses run the width of your room.


By 'vaulted' do you mean an angled roof? In Australia I think they call that a 'raked' roof.

I am pretty sure that we will be able to have the HT with a higher ceiling. 

So does a higher ceiling really make that much of a difference?

I have been working on the floorplans. At this stage it looks like around 5m x 6.4m is the space I have to work with. I wish I could make it longer but it's just starting to blow out of proportion now in terms of the overall size of the house. I think I could go for 10ft ceilings without too much hassle.


----------



## MatrixDweller (Jul 24, 2007)

Sorry had my terms wrong. I meant to say cathedral ceiling. The difference being that a vaulted ceiling is where the ceiling is angled up in one direction. Cathedral is peaked in the center. I think raked roof means that there is no access to the attic space between the ceiling and the roof. That can be OK in warmer climates (like most of Australia) where you don't need piles and piles of blown in insulation. Radiant shield and batt (or board) insulation would suffice.

A higher ceiling enables you to get a bigger room and still stay in line with ideal room dimensions for acoustics. More room volume can help bass reproduction.

I punched in your numbers into a room mode calculator and that width and length work well for a multitude of heights. With 9, 10 or 12 foot ceiling height there aren't too many overlapping frequencies although it does improve with a greater height. 8 foot ceiling are pretty close to half your room width so you get a bit of bunching up there.


----------

