2.35:1 in smaller rooms, screen size? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 12 Old 05-19-2017, 04:25 AM - Thread Starter
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2.35:1 in smaller rooms, screen size?

Building a HT in our new house.

I have two options right now. AT screen (not sure about speakers) or place speakers below (Klipsch Heresey III for both moveis and HiFi) the screen.

The room dimensions are: 11.5ft wide x 16,5ft long x 9ft high.

2.35:1 screen, and zooming out for 16:9 content.. as this will mainly be used for movies in scope.


What I am not sure about is what size screen can I manage to put in, with the 2.35:1 format, with such a small throw distance. If I do a AT screen, the max length I can get is 13ft throw.

With speakers underneath, I can get 15ft throw..



But I am wondering if the zooming to get a 2.35:1 screen will also effect how large the screen can be. Obviously I want the largest possible for that immersive feeling.

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post #2 of 12 Old 05-19-2017, 05:38 AM
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My room is small at just over 8 feet wide. I have an AT screen that is wall to wall and sit at 2x the image height. I do also use an anamorphic lens.

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post #3 of 12 Old 05-19-2017, 09:28 AM
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Quote:
Originally Posted by Northman83 View Post
Building a HT in our new house.

I have two options right now. AT screen (not sure about speakers) or place speakers below (Klipsch Heresey III for both moveis and HiFi) the screen.

The room dimensions are: 11.5ft wide x 16,5ft long x 9ft high.

2.35:1 screen, and zooming out for 16:9 content.. as this will mainly be used for movies in scope.
Sounds familiar, my room is about the same width, but only 7.5' high, but it's sort of open floor plan to the back.

I've got a 110" wide scope screen, it's using pre SMX AT material sitting in front of a set of Klipsch Reference fronts.

Quote:
What I am not sure about is what size screen can I manage to put in, with the 2.35:1 format, with such a small throw distance. If I do a AT screen, the max length I can get is 13ft throw.

With speakers underneath, I can get 15ft throw..



But I am wondering if the zooming to get a 2.35:1 screen will also effect how large the screen can be. Obviously I want the largest possible for that immersive feeling.
Just on theory, I'd definitely go AT, but you'll want to see how big it will be from your seating distance. With a JVC and 13' throw you could go to 111" wide scope screen:
http://pro.jvc.com/pro/lens_calc/HTML/jvc_REF.html
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post #4 of 12 Old 05-19-2017, 09:46 AM
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Your room is very close to mine and I took a different strategy and put the screen along the long wall. I didn’t go AT and have my mains just outside the image and the center below aimed up. For many years, I did a phantom center and I may still go back to that as I really liked it. I may switch between phantom and center also depending if it is just the two of us watching or a full house. Instead of two rows of seating I went wider wanting all seats to have the same immersion even if slightly off center. Plus with 4 -6 people it is much more social sitting in the same row.

Only you will know your audio desires. I like the wider sound stage for music and zero losses going thru a screen. I have a simple 5.2 setup with all these new movie modes you might need the longer room if you are into that.

Doing mine that way and with using Zoom I have total control over immersion all the way from Imax down to TV size imagery.

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post #5 of 12 Old 05-19-2017, 08:32 PM
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As to going AT, for me, I wanted to recreate the cinema experience in the home. Cinemas use AT screens. Therefore, I use an AT screen.

There is often a 2 camps of division here fore and against AT screens and I know quite a few people that have moved from the against camp and now use an AT screen. Because once you hear sound cues coming from the picture, it is very hard to go back to sound coming from below or above or generally outside the picture. In short, ONLY with an AT screen, can the sound actually matches the visuals.

As I said, my screen is wall to wall. Basically I build my room around it (it is a room in a room) because that the screen I had at the time. These days, I have my own supplier of the same AT fabric formerly known as SmX and had I had this supplier back in 2010, I would have made the screen and the room, larger than it is. Anyway, it is what is it and I am still satisfied with the end result.

My screen is curved and I went so far as to calculate the 16:9 width and place my L and R speakers just inside this width on my baffle wall. Unless you are using non AT masks, I don't think it is that crucial to the overall effect if you simply divided the Scope screen width by 3 and centred each LCR to each 1/3rd panel. At 2x the image height, being just inside the 16:9 area equates to 45 degrees. Being slightly wider won't matter that much. However, this placement does make 16:9 and even 4 x 3 content better than having the speakers at the limits of the Scope screen.

If you do go AT, you do want to acoustically couple your speakers with a baffle wall. The easiest way to build a baffle wall is to make the panels from MDF (start with 8 x 4 sheets) and make the cutouts just big enough for the speakers.

You do need to treat this with approximately an 1" of convoluted foam, though I have used black car carpet (stapled, not glued) and got a similar result. The treatment is about preventing HFs from bouncing off the back of the AT screen and on to the baffle wall. Carpet is fluffy and actually absorbs this. We are talking about frequencies above 2KHz BTW.

Build a timber frame behind (and glue and screw the MDF to that) with studs and no noggins required, and you are good to go. You do need a rubberized adhesive so the panel does not vibrate against the frame.

I have made a few now and I like to make them in 3 parts so I can toe in the L and R speakers if need be. This is also useful if you had to curve the screen. Do this ONLY if you will use an anamorphic lens. If not, keep the screen flat.

One plus to Scope screens in a smaller room is that you end up with room above the screen and this is useful for adding heights later.
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post #6 of 12 Old 05-20-2017, 02:20 AM
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I went AT last year and it was one of the biggest improvements to my set up I've done. However, this is also partly due to me using the space behind to add a large bass trap in the form of a 1' deep Rockwool filled false wall.

I used to have the speakers line up just below my previous screen (to avoid putting my left/right speakers tight into the corners) and it worked quite well in the dark. But once you hear the voices actually coming directly from the screen you realise how it is meant to be.

Mine is 3 metres wide 2.40:1 though due to the room layout we have to view from about 4.5 metres. My viewing angle is a little less than my previous non AT set up (we changed ends of the room so furniture positions aren't as close to the screen), but I still prefer it.

Yes, definitely a convert.

Attached a few pictures, early one showing the MK MP300s before I hid them away, then I upgraded my guitar speaker for a 2 x 12 one recently and some pictures of how it is now (still not 100% finished as I've a black velvet retractable ceiling cover to sort out and some bits of trim to finish).
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post #7 of 12 Old 05-20-2017, 08:36 AM
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Quote:
Originally Posted by CAVX View Post
As to going AT, for me, I wanted to recreate the cinema experience in the home. Cinemas use AT screens. Therefore, I use an AT screen.

There is often a 2 camps of division here fore and against AT screens and I know quite a few people that have moved from the against camp and now use an AT screen. Because once you hear sound cues coming from the picture, it is very hard to go back to sound coming from below or above or generally outside the picture. In short, ONLY with an AT screen, can the sound actually matches the visuals.
^So much this. I initially had a solid "screen" (paint on wall with a border) and the speakers were below it. I thought everything was OK. Then I went to an AT screen and therefore was able to put my speakers at the right height so the tweeters were right in line with my ears. The difference was truly unbelievable. Adding an AT screen was the biggest boost to my sound system I could have ever imagined. Now anytime I see a setup where there's a horizontal center channel below the screen/TV I think how much better that speaker could sound if it was at the proper height (and, of course, if all the front speakers were the same, but I digress).
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post #8 of 12 Old 05-20-2017, 05:37 PM
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Originally Posted by blastermaster View Post
^So much this. I initially had a solid "screen" (paint on wall with a border) and the speakers were below it. I thought everything was OK. Then I went to an AT screen and therefore was able to put my speakers at the right height so the tweeters were right in line with my ears. The difference was truly unbelievable. Adding an AT screen was the biggest boost to my sound system I could have ever imagined. Now anytime I see a setup where there's a horizontal center channel below the screen/TV I think how much better that speaker could sound if it was at the proper height (and, of course, if all the front speakers were the same, but I digress).
Our eyes and our ears are practically at the same height off the ground. We have no issue setting up a visual system to give us the best line of sight, yet we happily compromise on the sound. The AT screen allows us to have the best of both.

Funny thing about typical MTM centre speakers is that Dr. Joseph D'Appolito designed that array in the 1970's, it was supposed to be run vertical. Yet for cosmetic reasons above a CRT TV of the 1980's/1990's, these speakers were laid down. As we moved into affordable front projection by the 2000's, the bad habit of keeping this centre speaker horizontal remained, even when there was ample room to stand it up. So what you have is controlled vertical dispersion for L and R and controlled horizontal dispersion for centre. Basically an acoustic phase difference of 90 degrees.

Panning of dialogue is rare, but if that ever happens and you are seated off the centre axis is such a system, this is when you will hear the failure of the horizontal centre speaker. Other sound effects like a car passing do the same, but dialogue is so much easier to hear the timbre change. Stand that speaker up and the problem is resolved.

When I did my first Scope screen, I did have my speakers close to seated ear height with the screen above that. I didn't like having to look up, so I lowered the screen and tilted up the speakers. It worked better, but what I found myself doing was tracking the audio by looking at the speakers, not the screen. With an AT screen, the sound comes from the picture and I can actually sit back and enjoy the movie.

I have had my AT screen for almost 11 years now.
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post #9 of 12 Old 05-21-2017, 02:00 PM
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I would be willing to bet that 99% of the time most of us are in our home theaters alone or with one other person. Those of us that have more than two people I’m guessing the others are going to be blown away by the sound and visual even slightly off axis as I doubt they are profound audiophiles. For years we had stereo and many of us still use headphones. I remember when stereo took off there were lots of sound effect records you could buy to feel the total effect of movement. A sound presented to both ears identically sounds like it is right in front of us. The classic recording all these records had was the race car going past us and around the track. You could point to its location on the track without any visual.

I ran a phantom center channel for many years with right and left full range mains just outside the screen at ear level. About a year ago I added a matched center just below the screen angled up. I can’t say it added much to the experience and I think I had a better moving sound stage without the center, from my center position seating. Lately I have been going back to phantom most of the time.

We only have two ears and the brain is quite amazing taking that slight delay it takes a sound coming from one side or behind and hearing it twice slightly delayed and telling you where it is coming from.

HT is vastly different than commercial cinema. We don’t have seating spread out over 100 feet or more. My suggestion would be to experiment before you buy a screen on a painted wall. If you have the width try placing them outside the screen and then set them inside the image and see how that sounds. I have done this experiment many times and personally haven’t seen an amazing difference in the sound stage.

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post #10 of 12 Old 05-21-2017, 04:17 PM
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Originally Posted by bud16415 View Post
HT is vastly different than commercial cinema. We don’t have seating spread out over 100 feet or more. My suggestion would be to experiment before you buy a screen on a painted wall. If you have the width try placing them outside the screen and then set them inside the image and see how that sounds. I have done this experiment many times and personally haven’t seen an amazing difference in the sound stage.
If done right, the only thing different is the size of the rooms. My cinema is 1/10 scale of an 80 foot wide cinema and it works from every seat in the room.

Commercial cinemas use horn loaded speakers to give wide spread of sound, combined with the 202 X-Curve.

In the home, you can buy speakers with controlled vertical directivity (they behave similar to horns without the harsh sound) and thanks to "Enhanced for Home Theatre" soundtracks, we no longer need re-eq in the home. For the older stuff, there is still THX re-eq.

But the placement of the speakers should be the same where in a cinema, the L and R speakers are just INSIDE the masking limits if 1.85:1. If you do this in the HT, you will find that even Scope film soundtracks match better than speakers out wider than the screen.

About 12 years ago, I had a flexible set up that allowed easy speaker re-location and I spend weeks listening and testing on various soundtracks before coming to the conclusion that wider was not better when sound was matched to a picture. Audio only? Sure, 60 degrees works wonders. Add visuals and you want be closer to 45 degrees separation.

As for the centre speaker, I use it 100% of the time - even music. It locks the soundstage. I still remember the first time I added a centre speaker back in 1992 (I've always had identical LCRs) to my then Pro-logic system and not liking what I heard Vs the phantom image.

Move to now and now way would I lose the centre speaker. My LCRs are synergistic. They are flush mounted into a baffle wall and acoustically coupled to create a seamless wall of sound.

This all came about from researching how the pro systems are done, scaled down and it works remarkably well.

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post #11 of 12 Old 05-22-2017, 03:59 AM
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If done right, the only thing different is the size of the rooms. My cinema is 1/10 scale of an 80 foot wide cinema and it works from every seat in the room..........
This all came about from researching how the pro systems are done, scaled down and it works remarkably well.
Scaling isn’t actually scaling. In your 1/10 scale example let’s say your room is 8x8x12=768 cubic feet and the 10 times scaled theatre is 80x80x120=768,000 cubic feet.

768,000/768=1000:1 relationship in terms of volume. It doesn’t matter what the dimensions of the room are when scaling it will always be the scale cubed.

Scale models are great for visualizing spaces but in terms of structure and sound they are not good predictors. In the case of sound what we want our ears to hear as a duplication of what might be expected in a large venue, I think it should be easy to see how sound waves formed in a room with 1000 times more space will not be the same by just simple scaling.

I don’t have a preference what others do in terms of AT. I would hope they look at both sides and experiment as you and I have and draw their own conclusions and do what they like best. I would never want a phantom center in the 768,000 cubic foot example above also where seating is stretched in width to the limits of the industry standards. But at home in most peoples under 1000 cubic foot rooms where seating is very good and the sound reflections are much closer who knows?

After all King Kong in reality wouldn’t even have the leg strength to stand up at his scale. His bone strength would go up by the square of the scale and his weight would go up by the cube of the scale.

Bud
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post #12 of 12 Old 05-22-2017, 04:56 AM
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Scaling isn’t actually scaling. In your 1/10 scale example let’s say your room is 8x8x12=768 cubic feet and the 10 times scaled theatre is 80x80x120=768,000 cubic feet.
I'd never build a room with any LWH ratio of 1:1.

My scaling comment is the width of the screen. 80:8 is the same as 10:1.

What I did find interesting was a emails from Tom Holman and the guys at THX regarding Re-EQ. As it turns out, the rate at which the HFs are rolled off is actually based on distance not cubic room volume even though the specs "Ultra" and Select are for greater than 3000 cubic feet and under 3000 cubic feet.

I had no idea how my room was going to sound when I built it. All I wanted to do was make it sound better than the last, so this room got a full internal treatment. And whilst I think is sounds good, REW and the the RT60 reading say it is over damped.

The more I think about this section of AVS, the more I think this is actually the higher end of the group, regardless of price point. Sure there is an "ultra high end" section where guys spend more than $20K on a single piece of kit, but the design and the attention to detail of the layouts here seems to be more consistent than other sections of the forum.

There are those quite happy to have a flat panel and call it HT.

I first drew a plan on paper in 1994. It was a sketch with an AT screen even before I knew CIH was possible with HT.
The next year, I got a room design from THX showing what they considered to be the ideal room. Again, it was centred around an AT screen. The interesting part of their diagram was that it also covered acoustics in the room and that became my point of reference for my own room.

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