Laying VOT's on their side for Home Theater

[GM]

Originally posted by ClassicComics:
Any other thoughts would be more than appreciated!!

<font size="2" face="Verdana, Helvetica, sans-serif">Greets!

Obviously the best solution is to use an acoustically transparent screen and three identical front channels, but in such a small space there's not enough room to use even a high $$$ THX certified HT perforated screen unless you sit at the back wall, but IMO a cinema's visual experience is second to its audio experience, so I'm with Earl Geddes's opinion that the slight loss in peak clarity with a DIY screen made from a pressed low thread count (cheap) white bed sheet is the Hot Ticket in a light controlled HT now that even relatively inexpensive projectors have enough contrast ratio to meet the SMPTE screen lumens spec once dialed in. According to folks who have watched movies at EG's claim the ~$20 Wal-Mart screen looks fine.

With 24" deep speakers that need to be toe'd in a bit though, room depth is reduced to less than 17 ft, which may, may not pose a problem, especially if further reduced by a peaked rear wall profile if used to help dissipate standing waves from the screen wall.

With 30" wide speakers, this leaves only ~4.5 ft on centers, which equates to a DD/DTS recommended ~7.794 ft viewing distance that in turn specs a max screen width of 5.196 ft with a 2.923 ft height (~71.5" diagonal) if the 16:9 HDTV aspect ratio is used.

Assuming a 3 ft eye/floor distance, then the floor/screen height would be 2.026 ft, ergo the HF horn's horizontal centerline should be at 3.974 ft to meet the 2/3 screen height rule, so if the A7 is upright with the 511 on top it theoretically is almost spot on in this scenario.

If a large as practical screen size is the primary goal, then its height will dictate viewing distance, etc.. and even a king size sheet won't be long enough.

Anyway, if you still choose to lay them down on short stands, horn side toe'd in as required in the corners and EQ any excessive gain out of them, placing the HF horns angled up over the woofers. I recommend tossing a big roll of fiberglass insulation in the cavities behind them.

GM

[ClassicComics]

I guess I should have posted this at the begining so all the info was available.... the projector I have is a JVC RS2, arguably the best projector under $10,000 made, and some might argue at any price (but I wouldn't go that far)... also, I may have misread GM's post, but I thought I saw something about a screen width of 5 ft, actually the screen I will be using is over 11 ft wide. and almost 5 feet tall. The screen I have been considering is a fixed Da-Lite DaSnap borderless wraparound screen with Cinema Vision material. On Monday I am going to see if they make an AT material for this screen set-up, but you're right I don't really like the idea of losing 2+ feet of my room..... bringing it down to 18' or less from back seats to screen. Also, my back row is on a riser and I have two rows in front of that....

I really like the looks of these speakers and really would prefer they were seen. I wish I had a couple more feet of ceiling height....

Would the fiberglass behind the speakers be for sound absorption? Please explain....

I could always cut a hole into my garage to theater wall and flush mount the speakers.... but I don't think the wife would be happy with that solution.... if the theater wasn't already built, I could swap sides and put the speakers through the gym wall... but it would be a lot of work to move the carpeted riser etc....

more to think about I guess....

<font color="#FFFFFF" size="1">[ June 14, 2008 11:36 PM: Message edited by: ClassicComics ]</font>

[GM]

Originally posted by ClassicComics:

I guess I should have posted this at the begining so all the info was available....

also, I may have misread GM's post...

Would the fiberglass behind the speakers be for sound absorption? Please explain....

<font size="2" face="Verdana, Helvetica, sans-serif">I guess..........

No, you didn't. When you set up a HT to DD/DTS specs the mains c-t-c spacing dictates the prime listening distance which in turn sets the screen width, so if sloping (false) walls are used to reduce 'slap echo' as done in any properly done cinema, etc. (which I forgot to note my specs assumed), then a nominal 14 ft wide room doesn't leave a lot of usable screen wall width with wide speakers.

If no sloping walls are used, then screen width/height increases to ~6.467 ft/3.638 ft or ~89" diagonally if 16:9 ratio, still tiny compared to an 11 ft wide screen that requires the first row set of eyes to be 16.5 ft away to stay in the max viewing arc of even the most lax recommendations (720P). All my data is pre-HDTV though in that at the time it was calc'd that the max viewing distance before its extra resolution was 'lost' to our relatively poor visual acuity would be a theoretical 19.8 ft in your case.

Bottom line, using a max width oversize screen with a motorized masking system is a nice luxury to adjust each movie to the max acceptable viewing size, but it forces a highly compromised sound stage in all but the largest typical HT rooms, though judging by pics of numerous HTs of all sizes/shapes, no one cares these days. Indeed, I was ~run off from the various HT forums I use to spend most of my DIY speaker building forum time on because I still 'preached' the 'gospel' according to DD/DTS/THX WRT HT layout design, speaker specs, etc. since they believed I was somehow profiting from it, not to mention I had to be full of $#!^ because I was adamant that such 'incredible' (their word, not mine) performing speakers such as the $$$ B&W 800 series, etc. were extremely poor choices for HT apps (directivity? What directivity? We don't need no stinkin' directivity!). And they wonder why their movies are so poorly mixed, often having to boost the CC a bit to get clear dialog............

Right, it's been my experience that large speakers diagonally placed in corners can generate audible cavity resonances and while in the screen wall corners of rectangular rooms it ideally needs bass traps designed based on measured room modes, I found that my quick/easy solution one day worked well enough to my ears. As always though, YMMV.

GM

[Steve Mac]

Originally posted by GM:
...
Right, it's been my experience that large speakers diagonally placed in corners can generate audible cavity resonances and while in the screen wall corners of rectangular rooms it ideally needs bass traps designed based on measured room modes, I found that my quick/easy solution one day worked well enough to my ears. As always though, YMMV.

GM

<font size="2" face="Verdana, Helvetica, sans-serif">Hear hear...
I have a large room and the bass developed... although it is one of the easiest rooms I've listened in...I can tell it still needs room treatment. In the hundreds of posts in the audio forum I moderate, the issue of music in relatively small rooms is concerned with audio guys plagued by bass nodes. As large as my area is comparatively...I do know there are nodes that need to be treated. Bottom line...Bass traps are critical in smaller rooms.

[scharron]

hey there,just wanted to add that my A7's are just outside of the screen width, so when the screen is down, it is slightly lower than the speakers, and they are toed in about 8 or 10 inches. I toyed with the idea of putting the horns on top but the floor is level in the room and I like the idea, after flirting with sound mixing and playing for the past 30 plus years, that looking down the throat of the horn is a good thing., and you are right when you say that hanging a screen above A7's puts the screen waaay up in the air, kind of like sitting on the front row of an old theater and having to look up at the screen! another thing to consider, and I am often reminded of this by my very understanding better half, movies are really not that much fun at 110 dbs, and it seems like everyone wants to run ht super super hot. that being said, the combination I am running can obviously be stupid, or is that super, loud, but we have found that reasonable volume levels are much more everyone friendly, and the theater experience remains a pleasant one. old addage I have to be reminded of every once in a while, just because you can doesn't mean you should! I too only had eight feet to work with as far a ceiling height went, and after sitting on the bare floor during construction and just staring at the whole room for a while, decided it had to go up to at least ten feet. expensive decision but way worth the investment, and even our friends,the realtors said it was a very good idea! just make sure you are happy with it now, because it gets really expensive once the drywall and paint, and carpet and all the trimmings are in. wrong time to say, I think we should have....... enjoy the ride, its very satisfying and there really is nothing like an altec home theater!

[ClassicComics]

Thanks for all the advice guys!! I am trying to make this the best over all combination of video and audio I can. I love my altec speakers, and this is actually a rebuild of my theater. I started the original in about 1997 or 1998. I have had these VOT's for almost that long and I am trying to figure out the best solution to maintain the sound quality while allowing me to go bigger with the screen size. Driving the speakers in my theater I have a Mondial Designs Act III pre-pro/processor and 5 Altec Monoblock amps (the ones for the rears are bi-amp, splitting my highs and lows between a pair of di-pole speakers and a set of bazooka subs under my rear riser. I currently have a powered Klipsch sub, but I am planning on doing a DIY build on some subs. I can't go up any higher on the ceiling as I would be in my family room, and it would be quite expensive to dig out the basement (and I just added a 3 car garage and addition... so I don't think that is going to happen). So, I think I am going to try laying them on their sides, pulling out the horns and putting them above the woofers. I will slightly toe out the speakers so that the woofers face towards the walls a little (Am I understanding that correctly?), and then slightly angle up the horns towards people's ears. I will then put insulation behind the speakers and add bass traps at the rear of the room. Let me know if this sounds right, and I am still open to any thoughts, suggestions, etc...

<font color="#FFFFFF" size="1">[ June 15, 2008 04:41 PM: Message edited by: ClassicComics ]</font>

[GM]

You're welcome!

Bazooka subs?! I'm curious, when did they start building anything other than car audio one note boomboxes? Anyway, ultimately you'll want at least two (preferably four or more) separate subs in a rectangular room.

No, I recommended toe'd in, i.e pointing towards the listening focal point, same as the HF horns, not toe'd out, reflecting off the side walls. This will create two triangular cavities and I recommend stuffing the rear one at minimum and if you're willing to invest in bass traps, then make triangular shaped ones to fit ~the full room height. In theory, filling in the smaller one created by the cab's top/wall, floor junction with a separate stuffed cavity should be done also to blend them together.

As for the rest, if I'm understanding you, the screen will be mounted near/at the ceiling which forces all except possibly the last row to view it outside our ~15 deg vertical visual acuity range, so in theory the picture won't be as sharp for youthful eyes, though not sure about us older folks since I don't recall ever watching a movie in an HT this far out of recommended specs. IOW, in theory the front row line of sight should be no lower than 1/3 screen height and the back row no higher than 2/3 screen height, which in your case would put some folks uncomfortably close to the ceiling and if you lower the screen to its theoretical floor/screen height, then the rear riser height calcs at only ~9/16" if near the back wall, ergo these folks won't be able to see the bottom of the picture.

GM

[ClassicComics]

You are exactly right they are the Bazooka car subs, they are perfect for my use. We have the crossover for the rear signal bi-amps so that only that range of bass is going to these subs under the riser and they provide a great rumble under the seats during explosions etc...

For my actual sub I have a Klipsh sub in the front of the room, to the side. I will be building some subs to go across the front when I build a little front stage, which will also house the center speaker.

I think I understand what you are saying about stuffing the cavity, but if you can give me an even more detailed explanation it wouldn't hurt... I am a visual person....

Yes the top of the screen will be at ceiling, but keep in mind it goes down to almost 3 feet from the floor, so the center of the screen should be good viewing for most seats. Also, for where I sit in a full size theater this should be a similar viewing experiance. Yes, it won't be perfectly to spec, but it will be very similar to going to an actual theater, which is what I am looking for. The big screen and sound experiance.

I am trying to take in all suggestions and adjust as best as I am able and still be able to do the set-up I am trying to achieve.

I notice you are in Chamblee... I am in Marietta.... small world....

[Steve Mac]

I'm a little confused...as usually happens...so I drew up a few pics based on the following..right/wrong assumptions:
1) home theater wall is 8 feet high, 14 feet wide
2) screen size...approximately 138" x 58"
3) a7 cabs on their sides/horns on cab


Is that close to what you had in mind?

I was thinking a transparent screen and an orientation like this:

[ClassicComics]

1. Ceiling - Right around 8ft
2. screen size - I think I am buying a 58" x 139.2" screen but right now I will be using 56" x 134.4" (I think - finalizing still)
3. that is the way I am leaning now... to stand them up, I would have to get an AT screen which does not come in the gain or material I want, plus I would lose about 2ft+ of my room depth moving the screen forward enough to accomadate the speakers behind the screen.

Looking at your pictures they sure don't look as good on their sides... but it seems like the best compromise at the moment...