In-wall MTM center design?

[Mazeroth]

I'm in the planning stages of the basement theater and want a very clean looking install for the speakers. I'm pretty much set on using Natalie P in-walls for the L+R and Modula in-walls for the surrounds (unless someone can convince me otherwise) but can't seem to find a center channel that will keep up with the Natalie P's. I want the ability to play loud as they will be flanked by a formidable IB subwoofer. I also like having MTM speakers due to the decreased vertical response to minimize floor and ceiling reflections. The room won't be very large, only 11w by 16d, which is out of my control. Something about my wife needing a computer/office area in the basement as well...

With that, does such a design exist and I just can't find it? Would using a horizontally mounted Natalie P be that detrimental to the off-axis, even though the room will only be 11' wide and only have a single couch in the center?

[Jed]

I would think the NatP as a center would work fine for you given the 11w room.

[Landroval]

Why not mount the center NatP also vertically? Or a vertical Modula MT?

[Mazeroth]

Thanks for the response, Jed. That's what I was thinking.

Why not mount the center NatP also vertically? Or a vertical Modula MT?

A vertical MTM under the screen wouldn't work very well as the tweeter would be about 1.5' below ear level since I'll be using a rather large projection screen. Also, I don't think a Modula MT will be able to keep up with the MTM mains, or the IB sub.

While at the tent sale yesterday I saw that PE had marked these Peerless 6.5" drivers down to $10 for the event with a big skid of them:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=299-250

Well, I talked to the man in charge and asked him if he would cut me a deal if I bought a large quantity for some line arrays. Well...a few minutes of talking and I got out of there paying $6.40 each for these (72). Both of my brothers want large speakers built for them so that was the main reason I bought them. Then I got to thinking about the theater room and how I could put in-wall arrays in rather inexpensively and do some crazy things for the center channel and all the surround channels.

Now, as far as surround channels go has anyone ever experimented or read about using multiple point source speakers for the rear effects channels, to make them wider and harder to localize? Or, will this just create nasty cancellations? These are all going to be in-wall speakers I'm building so I could put something like three woofers wide, spaced out a bit, and a single or multiple tweeters to make the rear and side channels "wider". I know I ask a lot of dumb questions but when I get a thought in my mind I just have to find out its feasibility. Remember, these will be cheap to make!

Here's an example of a $6 million theater that has many speakers per channel. Something to this effect, but about $5.997 million less.

http://boardsus.playstation.com/playstation/board/message?board.id=ps3&thread.id=2534367

[Paul W]

Localized surround channels don't float my boat either. Dipole surrounds have lousy polar response, so that doesn't seem to be the answer.

Sooo... I'm trying Floyd Toole's approach of additional surround channels with "delay and contouring". Today, with a lot of work on the room still to finish, I temporarily parallel/paired 8 surrounds and was very pleasantly surprised by the increased envelopment and decreased localization. (The speaker setup is 0, +-30 degrees, +-60, +-90, +-120, and +-150.)

The surrounds at +-60 (in front of the listening position) really filled in the soundfield to the front and sides of the room...maybe Audyssey DSX is going to be worthwhile! There is undoubtedly combing between paired speakers in my temporary setup (maybe HRTF helps) but it is a huge improvement on ping-pong surround.

Try experimenting.

[Mazeroth]

Paul, I hate to slow a man down that's making progress but is there any way to get some pics or a drawing of what you've just explained? If you have a link to Toole's approach I'd appreciate it.

EDIT: Found some time and researched that DSX technology. Looks to be pretty cool! Do you have DSX currently? Looking at their website only one Denon receiver offers it ($1999) but I read they plan on releasing a true 9.1 receiver soon that will allow you to add both the width and height DSX channels.

[---k---]

Paul,

Are you discussing for movies or music? And, are you using programing that was designed for surround sound or upmixing?

According to Toole, my surrounds are all wrong! Directly behind me, 3-way monopoles. I've been somewhat feeling down as I read Toole's book and read about how my room is all wrong. But then I watch a movie and am happy. Watched Bolt this weekend, and was very happy.

Maybe it is a effect of moving images on the screen that distracts me from the sound (Toole does suggest this). Or maybe it is just the programing being better and having proper delays, etc. built in. I think it is a little of both.


FYI:
Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms (Paperback)
by Floyd Toole

http://www.amazon.com/Sound-Reproduction-Acoustics-Psychoacoustics-Loudspeakers/dp/0240520092/ref=sr_1_1?ie=UTF8&s=books&qid=1247578757&sr=8-1

[Paul W]

Mazroth,
Toole's book "Sound Reproduction" provides a lot of insight into the psychoacoustics of apparent source width and listener envelopment. He also includes a couple of plugs for six channels of surround for improved audience coverage in larger rooms. I am/will be adapting his six channel concept for eight surround channels to improve envelopment and decrease localization. (I highly recommend this book to anyone doing a room.)

To visualize the setup I described, sit in your listening chair. Straight ahead is the center channel (0 degrees), the right front channel is +30 degrees, +60 is the first surround, +90 is straight to the right, then +120, and finally +150 degrees (right rear quarter). Temporarily, I simply paralleled +60 with +90 and +120 with +150 using the standard Surround and Rear Surround outputs. The left side got the same treatment. (If this isn't clear, let me know and I'll find a picture.)

Ryan,
Yes, music and movies, both true multichannel and upmixing. (My main priority is concert video.) Yup, I too used to focus on side/rear surround until I read Floyd's book and it finally dawned on me (duh) that I would continue to fight a loosing battle until I started working on envelopment from the front/sides. Now I'm stoked about finishing the system with Toole's decorrelated surrounds...and look forward to hearing Audyssey DSX with width and height channels.
Paul

[Mazeroth]

Paul, I see you posted exactly when I edited my first post. :B

What threw me off was the +-, but once I saw a picture of it, it became a "duh" moment.

I'm currently drawing up my theater plans to see if a system like you're proposing is feasible in the small room that I'll be dealing with (11.5x16).

Oh, and I put an order in for that book. Can't wait to get it.

[Paul W]

No, I don't have a DSX system. Didn't know it was going to exist when I started the build about 10 months ago or I'd have made provisions for "height" channels as well. Height channels are still possible for me, if DSX or Dolby IIz works as advertised.