I'm working on plans for a baffle wall, which will double as the screen wall for an AT screen, as well as the separator for the front and back waves of an IB sub. My plan was to build the front 3 speakers right into the treated wall (flush mount), and I'm convinced that I'd like to use three Cinema 88 Specials for this. The questions I have are in regards to Toe-in. I can really only see 3 ways to build this: 1.) Build a flat wall, mount the speakers flush, with no toe in. 2.) Build a flat wall, mount the L/R speakers "sorta"-flush, but toed-in so a corner protrudes from the wall. 3.) Build a flat wall, mount the L/R speakers *on* the wall, instead of flush. Using some kind of mount (like an LCD arm ) the position and toe-in could even be adjustable this way. 4.) Build a segmented wall, angled on the two sides, and mount the speakers flush in the wall. I've attached pictures of all but #3, from various plans I've been scratching together. I'd really prefer not to have to build a segmented wall, as I'm not sure how I'd go about framing that and hanging drywall appropriately. Should I not be letting that scare me? Is it the best answer? Meanwhile, doing the "sorta"-flush mount with toe-in seems like the kind of job that becomes a "there-I-fixed-it" meme, and the speakers would probably have to be spaced wider than the screen this way, not even hidden... yuck. The flat wall with monitor arms or similar adjustable mounting is a nice compromise, and gives the most flexibility, but you lose the benefits of a flush mount baffle wall. Finally, flat wall flush mount is the easiest to build by far, but then you lost the benefits of toe-in. So I'd like to know if toeing the waveguide speakers in is really a make-or-break decision. Are other people who've built SEOS into/onto walls as the LCR toeing them in? Should I build and test the speakers first with various toe-in amounts before committing to wall plans? Thanks for any advice!
I personally don't cross fire my baffle wall. It's flat. The cross fire is an imaging thing, and generally with movies the image is controlled by the channel placement moreso than stereo imaging. So depends how much music listening you plan to do. Stereo music listening at that. Having said that, the toe in cross fire isn't a total waste on movies. It still provides a better image. I just am not sure it's a critical difference. Does that help or...? Not sure I answered you question.
Thank you so much for that response! I should have mentioned that my usage would be 90%+ movies, and any occasional use for music would be far from critical listening. Not to mention I'd almost surely be the only one in the room for music, so as long as one of the seats ends up in a good spot... By not toe-ing in I suppose I'd have to pay more attention to acoustic treatments on the side walls? The wide horizontal dispersion of the waveguide should throw a lot of energy at those walls, no? For what it's worth I had seen your thread about the in-wall deltas, which gave me some hope since you stated there you would not be toeing them in. Like you I am planning an AT spandex screen (and thank you for all your testing of that material on AVS!). I'll likely be posting soon in that forum about concerns with how far the spandex can be stretched (the plan in pic #1 above is 69" tall...) and whether a half-way decent PJ can handle a scope screen that large after A-lens loss, etc. Don't want to take this forum way off track though . Thanks again!
Good point on the sidewall reflections. By toeing in you would keep more sound off those walls. That's not much of a problem for me since my side walls are far away. As long as you have a bit of distance there and plan to treat them I still think you'd be ok. Again, the ultimate choice is to cross fire, but if the practical side is important I think you'd be ok.
Tux is telling you that you can get away with not toeing in your mains but the counterpoint is it will work better if you do. Why compromise what looks to be an excellent plan with the IB incorporated?Is it worth the trouble? How much trouble is it? (Treatments might be equally as much trouble) I don't think very much trouble at all. Just frame the two segments independently and tie them together with long deck screws. Cut some 45 degree wedges to fit in the gap and put the screws through. Sheetrock mud will have not trouble smoothing the joint. If you aren't a pro, you might have a little trouble finishing the 45 degree junction but you (like me) would have the same difficulty in a 90 degree corner. The difference is that we amateurs need more sanding to achieve the same result. Good luck
That is an interesting counterargument, thank you for it. To be honest the subject still has me weighing my options. The prudent thing to do seems to be building the speakers before I build the wall, listen to them in-room, and decide whether the toe-in is worth it or not. I may end up doing just that, rather than have nagging doubts forever, or even worse, regrets... I'm thinking I want to have the boxes built anyway before building the wall, so that I could frame around them and be 100% sure they fit in the holes... (raise your hand if you've ever been off on something by 1/8" and had to do it over ) That said, I feel like if I did go the toe-in route, it'd be "best" to push the L&R into the corners as much as possible, which takes them out from behind the AT screen. Next thing you know we'd be discussing the tradeoffs of a wider sound stage and corner loading vs. sliding the speakers in behind the screen. Heck I could even slide the center down, skip the AT, and get a higher quality visual image at the expense of dialog - so many options, and none of them are "wrong". No matter what we're all making compromises and trading off piles of dependent variables. In any case, we're flying out next week to visit some home builders and hopefully decide where and what we're building. It'll be 8+ months before the house is built, never mind being able to start on the dedicated theater room, so until then I have plenty of time to plan, design, and enjoy my existing gear. Thanks again! P.S. - I've honestly only gone as far as to research how to frame a wall and hang drywall, not how to tape it or mud it, so your comments about having trouble whether the angles are 45 or 90 are dead on. This project will be a heck of a learning experience!
I would encourage you to toe in your baffle wall. It may not be necessary to use a toe-in angle as acute as you have drawn, however. With your wide screen, I believe toe in becomes even more critical for enhancing the stereo image across all of the seats in each row of seating. In addition to less concern about nearfield side wall reflections, the more important gain comes from the much broader stereo image created through Time-Intensity Trading. Bill Waslo wrote a great white paper discussing this concept and the SEOS waveguides respond very well to proper toe in and will reward you with a very broad sweet spot. Lastly, creating a segmented baffle wall with toe in will decrease the time correction needed for the speaker distances to the Main Listening Position ("MLP"). I would attempt to place all three of your L-C-R speakers on the same arc from the MLP so that no time correction is needed whatsoever, thus eliminating any need for DSP time alignment. I'm definitely envious of your screen size - Go Big or Go Home! Mike
Thank you Mike. I have read that whitepaper as well as the other couple of great resources on this site about the benefits of toeing in waveguides. That's what drove me to ask this question in the first place, actually. I do appreciate you linking it though. I just hate to build an AT screen and then only place the center behind it... but maybe that will be the best overall solution. I think I've made my mind up to build the 3 speakers before I build the wall, so I can see what they sound like in room and at various toe-in positions. Knowing me, I'll probably lay a grid out on the floor where the seating area would be and spend several hours measuring responses at the grid points in different configurations to see how big of a difference it makes. It'd be too simple to just trust my ears. All of that will have to come later though, since we haven't even selected the house yet, never mind put down a deposit to have it built. We're flying out tomorrow to meet with a few builders, so hopefully something good will come from that. Thanks again for your advice! P.S. - About my screen size, a little known secret is that with an hour or two in MS Visio you too can "have" as large of a screen as you want ;D My plans were based on a combination of what size was required to cover all three speakers, and the largest height I thought AT spandex could stretch. What ends up hanging on that front wall could be much different than the drawing, but one thing's for sure, it's going to be much bigger than my old 110" scope screen made from WilsonArt laminate!
I played around allot with toe in after I read Waslo's paper among others. I am now truly convinced that "econowave" speakers, especially with SEOS type wave guides should be towed in at 45 degrees. And listening position should be along a line where the toe in angle meets, but it can be very wide. This may seem excessive, but the imaging and the widened sweet spot in the room make this totally worthwhile. I am using Tempests and XO them to 73 liter 12" woofers at ~120 Hz. I also am running a pair of subs. What amazes me about the tempest's is I feed them 50 Watts a piece and they keep up with my 400 W each 12" woofers and my 240 Watt each (excursion limited) lab 12- 5 cubic foot TL subs. I have a 200 W/channel amp for the tempests, but am a little shy of trying it. I have neighbors, a 1/4 mile away Anyway, don't under estimate the advantages of toe in. Foghorn
Correct speaker placement for movies is behind the screen. As per the Dobly specs (page 2) you can see where they recommend you place the speakers for a 2.35 screen or a 16:9 screen, and also recommend toe in aimed at the MLP (page 3): http://www.dolby.com/us/en/technologies/dolby-atmos/dolby-atmos-specifications.pdf