Long narrow room front left and right speaker placement

[fishzine]

Getting started on initial research and planning of putting a HT in my basement. The room is long and narrow 21ft x 11 feet and I am thinking to put the screen on one end and sectional sofa at the other end for seating. My rough plans seem to work ok for screen and viewing but figuring out speaker placement has been problamatic so I figured I would seek some more experience opinions.
My current thought is the move the front left and right speakers to about the mid point of the room to get the proper seperation angles for the left and right channel speakers but about this. Any thoughts or feedback for this type of speaker setup?

I actually have a visio rough sketch layout but can't post it yet till I get 5 post under my belt

 

[jostenmeat]

Post some jibberish here to get post count to 5.
http://forums.audioholics.com/forums/showthread.php?t=49318

Since you have a lot of lengthwise room to play with, the recommendation for listening position is 38% of room length, for best avoidance of axial modes, and it doesn't matter from front wall or back wall. Yes, lengthwise orientation is best. This % may drop to as low as 33% with the inclusion of non-axial modes, as I've learned from b pape, our resident GIK rep and acoustic expert.

Having speakers 10ft in front of the screen wall is going to be way too funky, if not distracting. However, a few feet, plus, would be nice. The first places to treat are the corners on the front wall (all of 'em if you can) for bass, as well as your first reflections on the side wall. After that, assuming bass has been tamed enough for your liking (which may mean other corners in the room): Next probably the ceiling. Next the back wall.

Some people who know a thing or two about acoustics would say the most important factor is where YOU are located in the room. Do not position yourself to be up against the back wall, which is so often forced in the common LR, as being within even several feet of that boundary will cause issues with bass, which in turn might even mask the dialogue frequencies.

I think you'll be just fine. Obviously, with only 11 ft in width, with so much more length, the speakers might get pushed close to the corners depending on how big of a screen you go with. The closer they are to the corners, the more you're going to want to treat that immediate area.

 

[fishzine]

Here is my room and one of my current rough layouts. The door placement is a little flexible along that wall. It can get moved closer to the back wall behind sectional sofa but can't go any further towards the fireplace/screen wall.

Been playing with lots of different layouts but haven't really found one I like. This longwise layout I know that the sound setup above is bad but alternatives just arn't jumping out at me. Been playing with some layouts going the other direction and seems sound is a little easier to setup that way but seating is harder.

 

[fishzine]

Another room setup I have been playing with. Make the room a bit of a more all purpose room, but has a big plus of being able to use the fireplace while watching a movie. Speaker placement is a little easier but still has me along walls and no real 7.1 options (I have played with some centered room seating placements and just haven't found any I like much.)

 

[jostenmeat]

The first is better than the second, if only for lengthwise orientation. However, please try to get off the back wall. MUST if be against the back wall? Are you dead set on the sectional style? I'm telling you man, HT seating is awesome. Your guests will love it too. You have enough space to do two rows as well I believe. What's the height of room? I'll check back in several hours, and after that I can't help you until next week . . . I'm sure others will take over where I leave off . . .

 

[AVRat]

The first is better than the second, if only for lengthwise orientation. However, please try to get off the back wall. MUST if be against the back wall? Are you dead set on the sectional style? I'm telling you man, HT seating is awesome. Your guests will love it too. You have enough space to do two rows as well I believe. What's the height of room? I'll check back in several hours, and after that I can't help you until next week . . . I'm sure others will take over where I leave off . . .

I agree. Rear listening about 3' off the wall. Screen size of 100" dia. or a little less. Door located in area of second shot, between seating rows would work but this is also the primary location for side surrounds.

 

[fishzine]

Thanks for the suggestions so far. I am slowly getting closer to having a finial room layout. It has been a bunch of comprimises and back and forth between different layouts (about 10 different ones so far). Also done some furniture shoping to firm up sizes and such. Including going to 'theater' syle seating, in the end that just single purposed the room to much.

Here is my current layout.

I figure I am able to get the back of the sectional about 18 inches off the back wall (4 inches needed for the recliner sections) before I start having problems with the door placement. I know this isn't the three feet but at least something. This gets the screen to viewer distance at about 14-15 feet, so that puts the screen in the 100" - 110" range. Still gets me my home theater but with sectional and sleeper sofa gives daughter her sleepover room too.

A bit more about room construction. Right now the room is dry wall with a 7 foot drop ceiling that has HVAC duct work running right down center of the room. Plan is to move this duct work to the edges of the room in a 18" wide sofit (This is the boarder you see in the older pics. Not pictured in lastest drawing but still plannin on it). There will still be some duct work running between the joist in the center of the room. This will get me an 8 foot ceiling in the center of the room and thinking that right now will probably be tounge and grove boards. Will put pink fiberglass between joist where ever possible. Unsure what I am going to make sofit out of but wanting to try and maintain some access to this area for running wires,plumbing, etc. in future without ripping out drywall, but not 100% sure here yet.

Two of the 4 walls in the room are currently covered with cork, but that is coming down and if prior experience suggests anything that means I will be replacing dry wall on those walls so they will most likely end up with fiberglass too. Might go ahead and just do all four walls, but won't decide till I get into construction.

Projector will most likely be right infront of the sofit on the opposite wall, or recessed in with some fan for air circulation.

So questions I still have at this point.

Screen placement should be right at edge of sofit along the fireplace wall area, and thinking that center channel speaker will actually be recessed into this sofit and angled down towards the seating area. Good idea, or any other suggestions for center channel speaker placement.

Front speaker placement is still isn't the best but seating moving forward helped a little. I still have to run the angles to figure out how far front I can move them and still get good differentation between left and right. Any suggestions? My reading has suggested you want them about 30 deg from center?

I am thinking I will build alcoves into the walls for the front and side speakers, with room to angle the front speakers towards seating. Should give me a couple extra inches and I think that will help with the narrow room and seating going pretty much to the edges.

Not sure about 5.1 vs 7.1 sound, been looking at some of the better HTIB systems probably Onkyo, and they pretty much all come 7.1 so figure I might but still undecided. A lot more research into the actual sound system to come yet!

Thinking about trying to add some shallow 1' wide shelves in the back corner to use some of that space behind the sectional. I know I want to keep this as open as possible for best sound but any thoughts on where would be best if I wanted to put some shelves back there? Bass traps in corner maybe instead? Anything I can do to help with sound for only having 18" back there?

Any suggestions for the duct work in the ceiling to limit its impact on the sound? Right now it is just the standard rectangular duct work, would the flexible insulated round ducts make a big improvement in the sound here? Or maybe foam insulation around the regular ducts?

 

[fishzine]

update just did a little exploration in the walls to see what they currently are. The two walls that meet at fireplace are exterior concrete block walls, on top of the concrete they have about 2 inches of foam insulation board, then a layer of 1 x 3 inch furing strips and on top of that is the dry wall. Those are also the two walls that have cork on top of the dry wall.

Other two walls are 2x4 interior walls (the long wall with the door is a load bearing wall) and they both already have pink fiberglass in them. Did I mention that the person that built the house from what I can tell was a bit of an audiophile! The upstairs living room was wired for what was at the time state of the art sound with in wall speakers and whole room has added insulation (there was a in wall plug for a vacumn tube right next to the wall speaker plugs ). So good news that at least I won't have to rip out good drywall to put in insulation, but still suspect that trying to get the cork off the drywall isn't going to work (a couple of the walls in that upstairs living room also had it on them too).

 

[jostenmeat]

I think some photos will help others help you. Otherwise, I can't be of much assistance, however there are others that can help you here. If you want some more opinions/thoughts, I think this would also be another proper subforum.

As for the back wall, at least you have some space, and close proximity effects can always be ameliorated with broadband treatments.

You can trust me that you will want better than an HTIB for this room. Start saving those pennies. Even if you can only afford two speakers to begin with, for say a year, you'll be saving money in the long run, IMO.