[bpape]

Agree with the isolation 100%.  A quiet room offers a much better opportunity for good dynamic range.  However, don't equate quiet with dead.  I can build a very quiet room that is extremely live inside.  I can also build a very dead room that has horrible isolation from the outside.

Stiff walls IMO are good from an isolation standpoint.  Do they improve bass response?  No.  If anything, they require additional broadband bass control inside the room to balance out the scheme.  Having said that, I'm still a proponent of stiff walls. Their benefit in isolation wins the tradeoff.

Make sure you look at a balanced absorbtion scheme.  A bunch of thin absorbtion will only unbalance things by overdeadening the upper mids and highs and ignoring the rest of the spectrum.  There is a rough curve that can be calculated for every room based on it's size and desired usage that outlines the target decay times across the spectrum.  There will be a little rise allowable in the bottom and and a little more dead allowed on the top - but it's pretty much a flat curve.  2 channel listening rooms will have a bit higher decay time allowed than a multi-channel HT. 

Bryan

[JoshK]

Bryan,

Do you have a link to that curve you speak of?  I'd love to see it.   

Josh

[bpape]

Here is an excerpt from Bob Gold's page.  http://www.bobgolds.com/Mode/RoomModes.htm

These recommendations are for a 17x21x8 room.  This is a good page if you want to play with your room sizes.  It's also nice as it plots all of the Tangential and Oblique modes - not just the Axial ones.

Listening Room
RT60 (IEC/AEC N 12-A standard): 287 ms
-  ±50ms from 200Hz to 3.5kHz = 237 to 337ms
-  ±100ms above 3.5kHz = 187 to 387ms
-  <+300ms at 63hz = 587ms
-  300<RT60<600ms

Closer to HT Room
RT60 (ITU/EBU Control Room Recommended): 232 ms
-  ±50ms from 200Hz to 4kHz = 182 to 282ms
-  <+300ms at 63hz = 532ms
-  200<RT60<400ms

Generally, the range is targeted to be relatively flat from about 300Hz to about 2kHz.  Slightly longer below 250Hz and slightly shorter above 2kHz is allowable.  The ranges shown are at the extremes.  For instance, I would in both cases shoot for much shorter times down low than the over 1/2 second allowed by the ranges.

Obviously, every room is different and more complex models are used to whittle things down a bit but this will get you in the ballpark.

Bryan

[Scott F.]

Dude! That website is way too cool. I just wish I could interpret a bunch of what it was saying 

The Blue Room is 38 x 15 x 7.5 with acoustic ceilings
The Redrum is 16 x 13 x 7.5
The Grape Room is 10 x 11 x 8

[bpape]

Yeah - that's kind of Bob's hobby.  He's collected all kinds of stuff on absorbtion characteristics on different materials, DIY projects, pics, etc.  He wrote that calculator himself in Java.  I have found it to be pretty accurate when comparing against more complex room models.

Bryan

[Bob in St. Louis]

That is a very cool calculator.
However if your ceiling height varies and the room is "L" shaped and opens to a hallway at the end of one leg it doesn't help. 

Bob

[bpape]

Actually, for the decay times (yes - height modes will be off somewhat) you just use an average height.  For the L shape if you just want decay times, figure the actual volume of the space and fudge the dimensions to get that volume.

Bryan

[Bob in St. Louis]

Hmm interesting, I'll try that Bryan, Thanks.

Bob

[PaulFolbrecht]

I'm sorry I neglected the thread with so many great replies.

$50K?  I was thinking more like $20K, not including equipment.  Let me give some more information.

1st of all, my basement has only an 8' ceiling, so I guess that means NO stadium seating!  I can live with that.

I am not looking for exactly a SOTA theater here.  I want a good projector with a decent-sized screen (I guess the ceiling height limits that too) and the sound WILL be excellent, but super creature-comforts are not necessary.  Most of the time, it will be just me & my soon-to-be fiance down there, with occasional friends, and eventually kids, but that's a ways off. 

If I didn't mention this, I have all the audio equipment except for the surrounds, and will be buying two pairs of Green Mountain Europas for that.  I am planning on around $10K for a (probably used) projector and screen.  Is that enough to get a 1080p projector and the biggest screen I'd want down there?  Maybe not quite enough.

I will likely do little to no work myself.  I just don't have the time.  (In the little free time I have I'm trying to build an airplane in my garage among many other things.)

I am thinking $20K should be enough, if seating is basic, starting from an unfinished basement, including sound-treatment, but maybe I'm off.  If I'm off by a whole lot I will be pretty surprised. 

Paul

[Bob in St. Louis]

I want a good projector with a decent-sized screen (I guess the ceiling height limits that too)

Not by much Paul. Mine is a 140" 16:9 DIY screen that is about 5.5' tall, by 10' wide. The ceiling in that area of the room is 8'2" tall.

$10K for a (probably used) projector and screen.  Is that enough to get a 1080p projector and the biggest screen I'd want down there?

That's plenty Paul. Waayyy plenty.
I highly recommend against used projectors. That's is unless your really wanting to spend that kind of cash on a PJ. A super high quality/high dollar PJ might be a better 'find' it it's used, but a NEW PJ that's 1080p can be had for more much less (with screen).

I will likely do little to no work myself.

That's where the money will go. "Buying other people" gets expensive. Equipment starts looking cheap when you have to have other folks do the work.
Where do you live (roughly)

Bob

[PaulFolbrecht]

Thanks, Bob.  I know very little about projectors and will not start doing research till I'm close to buying.  Thanks for the price guidelines.

[Bob in St. Louis]

No problem Paul. "Look me up" when your ready.

(and NO, I'm not trying to sell you mine  )

Bob

[shokunin]

Thanks, Bob.  I know very little about projectors and will not start doing research till I'm close to buying.  Thanks for the price guidelines.

Projectors have extremely fast depreciation, gone are the days where many projectors were $7-10K.  New price is $2-5K.  Not too many people want to fork out $10K+ to have it depreciate down to $5K in less than a year.  Look what happened to the Sony Qualia 2 years ago 20K+, 1 year ago Sony Ruby $10K, now Sony Pearl $5K (all are 1080p).  I'm not saying tha Pearl will kill a Qualia, but there are advances and benefits with each new generation and lesser priced models.  Don't buy a projector until you are nearly done with the theater.

Glenn

[JLM]

To the big boys, HT means a minimum 12 ft x 20 ft x 30 ft room with isolation, absorption, stadium floors, purpose designed seating, movie theather aesthetics, etc., hence the $50k price tag.


When you give up ceiling height, you also give up:

Stadium seating;

Bigger rooms as the proper room dimensional ratios dictate narrower and shorter dimensions;

This forces the audience to either squeeze into the resulting smaller acoustic sweetstop (to avoid spl imbalance from various surround channels for different listeners);

Unobstructed views (vertically from the lower ceiling and horizontally from the closer surround speakers) for each member of a larger audience.


This whole ceiling height problem is what quickly convinced me that my family room would be a "TV room" and not a true HT.  Personally I'd rather leave the surround channels out than have one overpower the rest because everyone can't sit in the sweet spot.  The comment above regarding professional design is quite valid, but can be very espensive.

There are various guidelines for viewing distance vs. screen size.  I recommend using paper/cardboard held in place to gauge this.  Most think they need bigger than they really do, based on image resolution and how wide of angle you truely concentrate on.  One problem with larger screens is where to put the front 3 speakers to keep them near the center of the screen and ear height.  Of course a HT will be dedicated to A/V pursuits and barely livable for anything else.

Don't confuse isolation/insulation with room treatments (as some above apparently have).  Isolate the room electrically and acoustically from the rest of the planet, then treat the room to sound better.

[bpape]

Let's not go too overboard here.  I design HT's all the time - some on a budget, many middle of the road, some with basically unlimited budgets.  You don't need dedicated seating - my recliners/couch work just fine - and so do many of my customers'.  Isolation, if you have the option, absolutely.  However, most people think this is purely to keep the sound from disturbing others in the house.  To me that's secondary (but important).  To me, the idea is to keep the INSIDE of the theater as quiet and with as low an ambient noise floor as possible.  It will only help your apparent dynamic range.

Yes - ceiling height helps and is preferable even if you only have one person in there.  But, you can still do a very very nice theater both visually and acoustically with an 8' ceiling.  Sure, if you have 8' height, you can't have 4 rows of risers, but you can certainly have 2 or even 3 tiered rows of seating with no problem.

Also, you make it sound like an 8' ceiling condemns you to a long narrow theater - it doesn't.  Now, should you pay attention to the width and length dimension?  Sure.  The idea is to not have one dimension be a multiple of another.  So, a 24x16x8 theater isn't recommended.  Don't get too hung up about perfect dimensions - there aren't any.  ALL rooms exhibit modal issues.  The idea is to avoid ones that are particularly horrible.  However, would I give up 4' of width and 6' of length just to fit one of the 'golden' ratios?  No way.  I'll take the extra space and room volume any day.

As for seating, the idea isn't to try to squeeze everyone in the sweet spot.  It's to keep all the seats out of the particularly bad places - like up against walls, dead center of the room, etc.  Then, you CREATE a wide sweetspot via the use of appropriate room treatments.

When planning a room, this is the progression I go through:

- How many people?
- Design a shell that fits that many people with all seats in non-bad positions (no, not all in the middle all huddled together)
- Select the appropriate screen size for the desired effect based on the seating positions.  DO NOT make the mistake of letting screen size drive seating position. 
- Select the appropriate projector for the screen size/viewing distance/PJ throw distance/available mounting positions
- Plan doors appropriately (if flexible) to allow easy entry/egress without compromising treating the room AND without causing undue disturbance of the rest of the people when someone enters/leaves

There are a ton of other things to consider but these are the big physical design ones.

Bryan

[Bob in St. Louis]

To the big boys, HT means a minimum 12 ft x 20 ft x 30 ft room with isolation, absorption, stadium floors, purpose designed seating, movie theater aesthetics, etc., hence the $50k price tag.

To the big boys, it's a heckuva lot more than fifty grand. The big boys have fifty grand in the projector alone. The big boys are well into the six figure range for a dedicated room.
But I've not seen anyone here that fits that bill. I think most of us are "regular Joes".

When you give up ceiling height, you also give up:Stadium seating;

One has to think about how many times your going to have a dozen plus people in their house. Sure, I thought about about having a second row raised on a platform behind the seating I've got, but realistically, how often would I want eight people in here? An eight foot ceiling is plenty to have another row raised up but why?  Am I doing this for me, or am I doing this for others? If your doing this for others you should charge admission.

Don't confuse isolation/insulation with room treatments (as some above apparently have).  Isolate the room electrically and acoustically from the rest of the planet, then treat the room to sound better.

I agree 100% with the second sentence. However disagree with the first one. A fellow could have the perfect room acoustically, but if he's hearing noises from other rooms, or outside the house, then what's the point of a properly treated room? If the sound from the room is bleeding into other rooms aggravating people, your "well treated room" is useless when they come-a-knockin' on you HT door telling you to turn it down! 
Insulation and isolation are first. THEN build the room, THEN treat the room.

Bob

[JLM]

Evidently we have differing definitions of what constitutes a "Home Theater".  For instance my family room is pretty much a dedicated TV room, nothing more. 

In a basement ceiling height is the predominate form factor as width and depth are typically more than sufficient and more flexible.  Of course you can "cheat" on the ideal dimensional proportions, but the farther you get away from the classic Greek ratios of 5:8 (which is remarkably close to ideal acoustic ratios anyway) the more the room will seem awkwardly narrow and/or low.

Agreed that isolation is important in both directions and that treatments come later in the process.

The bigger the room, the bigger the sweet spot (and the less the room reflections affect the sound). 

[bpape]

I guess we just have different perceptions.  I can show you rooms that have 'perfect' dimensions that don't sound very good and others that are nowhere near any 'ideal' proportion that sound wonderful.

Also, the reflections in the room will effect it's sound no matter the size.  The additional volume simply pushes them farther back in time and the air acts as a HF only absorber.

Lastly, the larger room obviously creates a larger sweetspot.  But, that's simply because you can get more seats at least 30-36" away from all boundaries.  You can do the same thing in a 10x15 room with an 8' ceilling - as long as you don't  try to cram 8 seats in it.  4 seats in a room that size can provide an excellent multi-channel experience. 

The one thing a smaller room does normally require is additional bass control as a percentage of wall surface in relation to a larger one.  This is simply because the bass waves are so strong that they can 'bounce' multiple times in the smaller space with the same intensity.  On the other hand, the smaller dimensions do force the room modes up higher where they're a bit easier to deal with.

Bryan

[PaulFolbrecht]

Thanks, Brian, for these thoughts!  Also helpful.

I think I have covered this pretty much, but I'm certainly not looking for a SOTA, "perfect" theater room for a large number of people; I'm looking for a dedicated room for 6-8 people to be able to watch films in comfort on a large screen with 1st-rate audio and decent creature comforts.  $20K for the room construction and furniture is my budget, flexible but not extremely so.

I basically have an entire unfinished basement (2000 sq ft) to work with if I want, but the room will be nowhere near that size. 

I do want reasonable acoustic isolation for both of the advantages: keeping sound out and keeping sound in.

After very quick research I now know I'll not be spending more than $5K for a projector, tops; I'm not sure about the screen yet.

I may get started - start looking for a contractor, and decide (myself) on the dimensions and seating within a week or two.  I've got the funds I need at the ready. 

[ctviggen]

Evidently we have differing definitions of what constitutes a "Home Theater".  For instance my family room is pretty much a dedicated TV room, nothing more. 

Supposedly, a "home theater" room is a room where you basically watch movies and cannot do anything else.  If you can do something else, then it's a multipurpose room (or some such nonsense). 

I bought a home automation book because the cover talked about home theaters and projectors. These places were incredible.  One home theater had a realistic version of the western PA night sky put into the ceiling with LEDs.  That alone must have cost a fortune.  Many of these had equipment costs that ranged in the 50-100k area.  The rooms were truly stunning and must have doubled that cost.