[rockadanny]

Finally have a contract on our next home, closing next month, so trying to lay out basement floor plan. Basement has two possible areas where I could set up my system (speakers are box semi-transmission line rear ported with dome tweeters). Picture below shows one possible location. On which horizontal plane (A, B, C, D, OTHER (where?), or YUK-ALL-BAD) would you set up speakers and seat? (drywall walls, 7.5' drop ceiling, carpet over concrete floor, windows in the cove but I will cover if necessary)

[youngho]

You usually want to have conventional speakers at least several feet from the nearest wall, so that makes A or B rather difficult because the speakers could end up being rather close together.

If you position them in the D plane and sit at position C (or even B), you basically eliminate the first side reflection point. Still would be desirable to use absorption on the wall room in front of you, but the wall behind you would be far away enough that you could consider  the use of some diffusion.

Alternatively, if you position them in the C plane (where the negative effects of the nearby corners should be minimal) and sit at D, as close to the wall as possible, this used to be recommended by the Audio Physic designer Joachim Gerhard. Again, virtually no early lateral reflections.

Young-Ho

[ArthurDent]

Congrats Dan, was just going to send an inquiry on how it was going. Not enough of a 'phile' to speak very knowledgably, but I think 'C' & 'D' locations as speaker/seating would be dependent on traffic flow to the wings. Is the drop ceiling T-bar acoustic tile ? Just thinking some batts on top would help isolate up transmission, if you can access.

Also depends on how you are setting up the seating, numberwise (ie 2-4, or 6-10 people). Will it just be the 2 channel, or HT as well ? A couple of GIK (or equivalent) 242s would take care of the sidewall reflections (from recent experience). With the semi-trans speakers they shouldn't be quite as sensitive to back wall positioning. I've actually moved my STs closer to each other and found the soundstage improved, of course I don't have a lot of room to work with to start. You know there are enough folks in the know here you'll get sage input.

Now you can sell the tractor, buy a push mower, and spend all the extra $ on more music & dinners for Mrs. Rocka.  Hope both closings go as planned. 

JD

[JLM]

Working with architectural plans for 40+ years and you've sort of confused me (congrats).

Read Floyd Toole's "Sound Reproduction" for all kinds of room related advice, including ideal room ratios and speaker/listening position layouts.  The worst shape is spherical, the next worst is cubical, next comes rectangular (but it is the most studied and best understood).  Any other shape would provide unpredictable results.

I assume the heavy lines represent the basement walls and that you'll need access to both left and right ends.  The obvious solution (to me) would be to create a room at the 13ft wide notch that extends into the long 10ft wide space.  Maximize the room size while avoiding simple room dimensional ratios (like 1:2 or 1:3).  Leave enough room to have good access to connect left and right ends.  The ideal place for a door would be on side wall, 3ft from back wall (to allow for possible corner treatments).

Experiment with speaker/listener layout.  Layout should be symmetrical, try to keep speakers and listening location away from walls (to minimize room effects).  In a room this size that pretty much defines the setup as near-field.

Insulate everything in the room (walls, ceiling, door, ductwork, electrical) if you don't live alone.  Use (insulated) staggered stud walls, (insulated) exterior fiberglass door (with weather seals), and flexible (fiberglass insulated/lined) ductwork.  Simple drop ceiling is a move in the right direction, but suspended drywall ceiling (loose insulation above) would be much better.  Don't put light fixtures or electrical boxes in the ceiling.  Run audio dedicated electrical circuit(s).  If you're alone and/or don't have a furnace you can ignore most of this detail advice. 

[ACHiPo]

Pick up a copy of Jim Smith's "Get Better Sound" and it will help you.  He suggests starting with an acceptable layout (from an ergonomic/traffic flow perspective), then laying out grids for listening position and speakers, optimizing listening position best for bass, then speakers for tonality.

For 2-channel I'm thinking speakers at D, listening position at B.  Speakers about 4' out from the wall (closer if you use absorption and/or diffraction) and about 8' - 9' apart.  Listening position about 10' - 11' from the speakers.  No side reflections to deal with (you might even want to put some diffusors on stands as a pseudo wall) should give very nice stereo imaging.  Having your ears well in front of the back wall should help imaging as well.

You won't get much in the way of bass pressurization, so not sure what you're thinking in the way of subs?

[rockadanny]

youngho - Thank you for your reply.

If you position them in the D plane and sit at position C (or even B), you basically eliminate the first side reflection point. Still would be desirable to use absorption on the wall room in front of you, but the wall behind you would be far away enough that you could consider  the use of some diffusion.

I really like the idea of NO first reflections on the sidewalls. That would free up the four GIK 244 panels I already have, which I could deploy on that front wall. And this gives me an excuse to buy some GIK Diffusion panels for back wall (and possibly side walls of that notch area (the 13' x 10' area) too if necessary). 

I hope speakers at the D plane work out best as that would keep all of my gear near a wall and not cut off easy access to that notch area (as I would like to put a game table in there for playing cards).

JD - Thanks bud!!   

Is the drop ceiling T-bar acoustic tile ?

I believe so. This is what it looks like (picture is not of the notch area, but of the area to the right of my diagram - I am only providing a picture to show the ceiling tiles.):



And seating will be for one person only - me - king of the basement!  Exclusively 2-channel.

Now you can sell the tractor, buy a push mower, and spend all the extra $ on more music & dinners for Mrs. Rocka.

Ha!    Actually, I was hoping for NO grass at all, but this home does have a small patch in front only. Hmm ... Wonder if I can cover that with pine straw and a few plantings? Hmm ... The option of having NO grass is SO appealing!

JLM - Thank you for your reply.

Working with architectural plans for 40+ years and you've sort of confused me (congrats).

  Awesome! 

I assume the heavy lines represent the basement walls and that you'll need access to both left and right ends.

Yes, to the left is a large area with a pool table the seller is abandoning, and to the right is a large area with a bar. Would prefer to leave those areas as they are if I can get the notch area to work for audio. Hmm ... making a room out of the notch, eh? Hmm ... interesting idea. Hadn't thought of that. Hmm ... I'll have to think about that one. I'd either have to leave the opposite wall open (hallway) to get through from the pool table to the bar, or make two doors to connect the two areas. Hmm ...

AChiPo - Thank you for your reply.

I have the DVD from Jim Smith, which I picked up for only a few dollars from the Goodwill store. I need to review that again.

For 2-channel I'm thinking speakers at D, listening position at B ...

Boy, I am liking the idea of NO sidewall reflections. And diffusors on stands is an interesting idea I hadn't yet considered. Cool idea.

I will be running a pair of subs (ACI Titans - 12" powered driver in each), wired in stereo. If I sit at B/C I wonder if placing them in the notch area might help to pressurize, at least somewhat? Hmm ...

[youngho]

Some listeners can prefer early lateral reflections to create the impression of a broader soundstage and wider images, but if you like the near-field effect or tend to have your speakers toed-in and facing directly at you (or even crossing in front of you), speaker position D could work well for you. If so, and if you choose diffusion, I might focus on the back wall of the alcove, since the sound would tend to reflect off the alcove side walls towards that surface, anyway, and true diffusion is supposed to benefit from a little distance from the listening position, but you could always add more diffusion later.

Depending on position, you could consider replacing some of the ?2x4' ceiling tiles with more absorbent drop-ins like the Real Traps: http://realtraps.com/p_ceiling.htm. The carpet looks thin, so you might also address that between you and the speakers, as well.

Subwoofers in the alcove itself may create more modal issues, but it's probably worth doing some basic measurements and experimenting in situ, rather than speculating.

[JLM]

I've read Jim Smith's book, pretty basic, nothing earth shattering.  Floyd Toole's "Sound Reproduction" has tons more information and is based on his career with the Canadian Research Council and Harmon International.

As one big open space, the acoustics could be terrible.  Two Titans may not be enough.  One of my audio club members has a bit smaller and more squarish basement space (with bar/pool table).  His $20,000 system (with the biggest ACI subs) frankly sounds like crap (his Klipsch based AV system in the next room sounds killer).  Plus the noise that would transmit upstairs would be excessive. 

13ft x 16 ft room with one door or 13ft x 20ft room with two doors?  The bigger one is closer to the Cardas "Golden Cuboid" room that I have (8ft x 13ft x 21ft) and probably wouldn't look too weird with the doors left open.  If you fixate on this kind of stuff you can make one of the room dimensions smaller than the available space (I did).  Bigger is always better, until the shape gets strange (like the current space) approaches one of those simple dimensional ratios (like width 1/3rd the length or twice the height).  Either way I foresee the speakers set up on the top (enclosed) end of the room. 

I have six GIK 244 panels set vertically on the floor at first front/side wall reflection points and in the front corners, but frankly they don't do much for me, which I attribute to using the proper room dimensions, near-field setup, and transmission line speakers.  Recently I loaned them a local BBQ restaurant after chatting with the new owner and we agreed that the dining room had a huge echo problem (so bad that foam had been glued to the bottom side of the tables).  The panels made a noticeable difference in his 50ft x 50ft room (with sloped drywall ceilings and concrete floor).  He's in the process of installing GIK panels and a new air handling unit (previous owner had an air curtain at the front door to try cutting down on drafts which never works in a restaurant with all the air sucked out by the hoods) and I can't wait to return to learn what he and Glenn came up with and how well it is working.

[ACHiPo]

Danny,
JLM may be right regarding room-within-room construction (certainly he is if you're concerned about containing sound--not sure if that's a priority in your case?).  I'm with you, however, in wanting to at least experience a set up without the constraints of sidewalls (and their reflections), not to mention room boundaries large enough to support deep bass.

You may want to approach it with an incremental plan--when results are better than the alternative of spending more money/time, then stop.  Theory is a good foundation when optimizing sound, but you're going to need to experiement--there are just too many unaccounted-for variables.  While there are good and bad principles (e.g. symmetry vs. asymmetry) that are safe generalizations, you're going to discover things when you get set up that you didn't anticipate.

AC

[ArthurDent]

I believe so. This is what it looks like (picture is not of the notch area, but of the area to the right of my diagram - I am only providing a picture to show the ceiling tiles.):

Yep, that's what I was talking about. Depending on the amount of space, how the ducts (?) & electrical are run, you should be able to push up on each tile & see the extent of the space above. (qualifier- try to keep the tile level as there is always dust, bits of tile, and occasional other odds & ends left on top out of sight - lift towards corners rather than middle)  Grab your flashlight & take a look. As a finished space the prior occupant or even builder may have installed insulation in the floor joist channels to knock down noise transmission. You'll be able to see if ducts are insulated, and how much space you may have to work with for adding additional insulation on top of the ceiling tiles.   



And seating will be for one person only - me - king of the basement!  Exclusively 2-channel.

Well, you might want to have an extra chair or two for visitors.  Never know when I might make it back east.   

Ha!    Actually, I was hoping for NO grass at all, but this home does have a small patch in front only. Hmm ... Wonder if I can cover that with pine straw and a few plantings? Hmm ... The option of having NO grass is SO appealing!

Some friends up in Bellingham are doing that exact thing, though given our climate they are turning their small front yard into a "rain garden". Lots of options for no maintenance landscaping these days. Should be achievable without too much time & $ .    I like the idea, am getting tired of fighting the moss in my yard.

As JLM & AC note, some of it will be trial & error. If you are going to keep/use the bar & pool table might be nice to have them accessible to the sweet tunes as well. In any case I'm sure it's going to be fun figuring it all out. Keep us updated on your thoughts, and I'm guessing you'll get a good bit more input before your done.

Hang in there for the next month or so till you can get the main system set up again, then you'll be able to play with some of the less involved options to see if they are viable. If not you can always build the room. 

PS  The T-bar (metal runners that support the acoustic tiles) are usually 1 5/8" tall, and there will likely be 2 support wires (possibly 4) that will provide some resistance to raising the tile. Lift gently, if they won't raise above the runners then there's something (pipe, conduit, duct) right above the tile. They aren't real fragile, but use of too much force can break them.