My father is building a ht on his home from the ground up and he left me in charge of finding out the details.

What are the optimal dimensions?

what would you do with a blank slate if you were designing one? It cannot be wider then 24' of course that sounds awful big so maybe it could be 24' long instead but I dont know the ideal dimensional measurements.

Any help is greatly appreciated.

thanks.

Welcome to the Forum.

You are asking a pretty vague question because you haven't described your vision for this theater, How many seats, what type of video display, is the room dedicated to only HT, is this in a basement or new construction etc etc.

First thing I would do is read the Sandman's thread from beginning to end and then come back and tell us about your goals.

http://www.avsforum.com/avs-vb/showthread.php?t=574704

If you are talking about a stand alone construction this reference may be of use from gpowers:

http://www.stargateunofficial.com/SGU_tSearch.asp

Useful things to consider:

How many people do you want to seat in normal usage? How many max? What kind of seating? Home theater recliners, movie theater seats, or other?

Are you up for multiple rows of seating with the back rows on risers (elevated floor) to see over the front row heads?

What size screen are you talking? Are you planning on a front projector ceiling mounted and a screen on the wall? Do you plan to have your speakers in front of the screen, or mounted behind an acoustically transparent screen?

If you can start answering some of those, it'll help narrow things down a bit.

To give a starting point, I've got a 16x21' room. Screen will be ~110" wide on the 16' wall. I'm hoping for two rows of 4 seats each. With only 16' width, four good recliners is a bit tight. I'd love to have ~20' wide and 25-30' deep if I was building from scratch. With that depth, I could have the second row further from the back wall. With that width, I'd have more room for my aisle.

Good luck.

Check out the search term "sepmeyer ratio". Help on room dimensions.

Sepmeyer ratio link :

http://www.cinemasource.com/articles/room_modes/modes.html

excerpt:

http://www.cinemasource.com/articles/room_modes/sep_room.jpg

I can give you fifty more "golden" ratios if you want...

These are dimensions in which each author has used their "golden" criteria such that the modal frequency spacing resulting from the wavelengths that fit into each dimension - do not have any significant gaps or overlaps - thus not creating a serious problem of peaks or nulls in frequency response - as long as you are sitting in the opposing corner as the speaker ....

The problem is that even these room ratios will have peaks and nulls in their frequency response that you can still hear - because small home sized rooms are not big enough to have well distributed and overlapped modes such that the room becomes diffuse. Room dimensions do not make room mode problems go away.

So you have to deal with peaks/nulls anyways with treatment, listener/speaker positioning, and EQ to tune the room. If you know what you are doing - you can make a concrete cube sound good - so don't design a room that does not fit your house or the intended purpose of the room because you used a golden ratio. You will want a seating array with suitable distances from speakers/walls with reasonable viewing/listening angles - something the first ratio on your list is unlikely to support.

http://www.avsforum.com/avs-vb/showthread.php?t=793482

hi again, thanks for all the info so far I will try to answer some questions.

He is building this room specifically for the use of a home theater, adding it onto the house so it will not be a basement or room converted into a HT it is going to be built with this purpose in mind.

I only said 24' because he is also adding on 2 bedrooms to his home and that addition will be approx 24' so he wanted to just continue the same roof line.

As far as the my vague post really thats because I dont know what I am looking for. I have never done anything liek this and my father is pretty much technologically blind so he asked for my help.

I was thinking some reclining chair in a row with the butt shakers I saw some nice ones on some links for around 2k for a row of 4. I would post a link but I cant yet.

I would like to use somewhere in the neighborhood of a 100+ inch screen, as for the projector I guess whatever would be the best set up, ceiling mounted would be the best for space conservation I would think.

As far as occupancy I guess if he could get 8 people in there in those chairs 2 rows of 4 then perhaps some additional overflow seating that would be plenty. I imagine it will only be used by myself and my girlfriend anyway, I cant remember the last time my father sat through a movie.

Building a riser for the rear row of seats is not a problem as the building will be new construction anyway.

so if I read those dimensions correct if the room only has a 10' ceiling lets say then the width should only be about 13' and the length of the room should only be about 16'?

so if I wanted to have the room 20 feet across I would need somewhere in the neighborhood of 15.5' ceiling? that seems a little crazy. I guess it can be built any size you want but those are the optimal dimensions for sound purposes.

Read the thread I posted - don't overdo it with the ratios. Avoid multiples and squares, otherwise don't go crazy (a little extra height is nice though). Terry posts in that thread, he has an excel based calculator that can eliminate bad configurations.

Read Sandman's thread that big posted (at least skim it) - that should give you more concrete ideas.

Buy the projector last, as the tech changes fast and prices decline.

You mentioned that your father does not watch movies which makes us wonder why he is doing this. So one thing for you to decide is if you want a 16:9 aspect or a 2.35?1 screen which is more of a big MOVIE screen. if you want to go that route, try visiting the Constant Image height chat section in the Display area.
Some of your decisions are going to depend on what projector you buy so you need to make those decisions before you design everything. There really are a lot of things to think about before you do anything.