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Discussion Starter · #1 ·




Greetings everyone,


I've been reading and participating in AVS Forum since 1999, when I worked at ReplayTV and was known here as "ReplayMike." Since then, I've worked at a number of other CE companies, in both the audio and video sides of the industry. In all that time, while I've had home theater and music gear that I've enjoyed greatly, what I've really wanted was to build a dedicated room. At last, the time has come!


In this thread, I'm planning to document the construction of my dedicated music and movie room.


I'm my own general contractor on the project, and I'm responsible for the technical design of much of the media system and the control system. The construction is being handled by a small team of superb craftsmen, without whom the project would be impossible. I'm extremely excited to say that I'm working with Keith Yates Design Group on several aspects of the room, including the acoustical design and treatment of the space.


My goal is to complete the room in September of this year. It's an aggressive goal, but the design work is behind us and construction is underway, so I think we can get there. [update: Yeah, that didn't work out at all. Construction went in parallel with the rest of the house for awhile, but then some of the people working on the house became the "critical path" for the project and all work stopped. At this point, I am hoping to be finished before June or before I collapse from stress or go broke.][update: Notice how I cleverly said "June", but didn't include a year?  That wasn't on purpose, but it has turned out to have been a clever omission.  
]


The room will have comfortable seating for seven, with additional bar seating for four more. I will be using an acoustically transparent screen with automated "Constant Area" masking for movies. The audio system is built around Aerial Acoustics speakers, and was designed to work well for both music and movies, erring on the side of music when those two uses were at odds. All of the acoustical treatments and some of the speakers will be behind stretched fabric walls and ceiling. All systems (electrical, media, HVAC) have been designed for low noise.


With all that said, this is not a "no holds barred" room. I am limited by some of the realities of the building, the site, and the budget. Nonetheless, I'm hoping that the final product will be a space that my friends and I will enjoy for many years to come. I look forward to hosting some HT meets, as well.


My goal with this thread is to share what I have learned so far, and what I will be learning as we go forward with the build. I have learned so much from what others have shared here in their own build threads, and I want to contribute to the community in the same way. I am also, of course, excited about a project that has been years in the making, and I want to share it with an audience that will appreciate it!



I plan to write a series of articles, each focusing on a particular aspect of the room's design, and post them in this thread. I'll also include construction details and progress reports. As I add major articles, I'll update this first posting to maintain a table of contents linking to each article.


I'll do my best to explain why certain decisions were made, especially when I think the tradeoffs and compromises may prove interesting to others. I also intend to spend a bit of time on particularly interesting technical aspects of the room, like the constant-area system.


I'm especially excited to be an early beneficiary of some new work Keith Yates and his team have been doing with the shaping of bass response in rooms like this, and I'll do my best to explain how that work has contributed to this room's design.


A few ground rules:
  • I work for a CEDIA member company, but I will not be discussing my employment or the nature of my work, at least for now. I do not speak for my company in any way, especially online!
  • I don't speak for Keith Yates and his team, either! I'll do my best, though, to accurately represent what they're doing.
  • I will not discuss costs, except to say that I have been extremely aggressive in controlling costs where possible, but this is definitely not a "low budget" project.
  • I will not discuss sources of equipment or materials, except to say that while some equipment was purchased specifically for this project, I am also using equipment that I have acquired over many years: some new, some used/B-stock, and some traded for other equipment.
  • Questions and comments are welcome, but I would appreciate it if we could keep the thread civil, informative, and on topic.


Fair enough? Okay! Let's get started.

Table of Contents:

1. Introduction (this page)
2. Mike's Money Pit
3. The Tyranny of Trigonometry
4. Ten Pounds of S*** in a Five Pound Bag (Construction Update #1)
5. The Art of Compromise
6. Seven Subwoofers! Surely You Can't Be Serious?!

7. Matterport 3D Scan of the Theater
 
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Discussion Starter · #3 ·
Well, how did I get here?


When I was looking at houses five years ago, I carried along with me a laser measuring tool, because I knew I wanted to be able to do a theater room in my new house, and I had some ideas of how big that room needed to be, based upon the setup I had in the house I rented previously. My requirements were that the room should be 17-19 feet deep, and at least 12' wide.


When I saw the house I would eventually buy, sure enough it had a family room in the walk-out basement that was 15x18 feet, so I thought this would be perfect. There was even a bathroom and a wet bar area adjacent to the room! Here's a primitive schematic of the space as it was then. Note that the garage was extra wide, with room for two cars and storage along the side as well.




After I moved in, I put my 108" Stewart Firehawk up on the ceiling and my Sharp XV-Z9000U projector on a pole in the back of the room, and enjoyed some movies with friends.


I soon figured out that there was a problem. If I wanted to have more than a few people over, then we ended up pushing some folks way out to the sides of the room where the image brightness started to fall off, and the sound wasn't so great. I couldn't do a second row very easily, because the first row needed to be 12.5 feet back from the screen for my preferred viewing angle, and that meant that a second row would be hard against the back wall, which was inconvenient for foot traffic through the room, and also bad for the second row's sound. I started thinking about bumping out a wall by a few feet at the front of the theater so that I could do a second row on a riser.


It turns out that my house is already maxed out for the lot, though, so that plan soon died as I couldn't add any square footage. The chimney stack was on the back wall, so I couldn't expand that way without losing both of the house's fireplaces. I had several contractors and an architect in to advise, and they all suggested compromising the theater in some way.


Then, I spoke with the husband of a former co-worker. An electrician by trade, he's also a builder and cabinetmaker, and quite a lateral thinker. His suggestion: take out the left side wall of the family room and relocate the wet bar and bathroom that were behind the wall into a storage area in the garage (therefore not adding to the house's square footage). Rotate the whole theater 90 degrees, so that the former depth became the new width, and the extra size gained by removing the wall would create the depth needed to have the second row. That would create this layout:




That wall was a load-bearing wall, so we'd need to put in a steel I-beam to support the upper floor, which would mean pouring some new footings. But, the result would be a room that was 18' wide and a whopping 24' deep. That would be enough room for three comfortable chairs side by side (or two love seats) with good walking room on both sides. And, deep enough for two rows of seats with a third-row bar at the back. Now, we were talking!


At around the same time, I became aware of Keith Yates via an article about the "Listen Up" theater showroom that he designed in Denver. As I read Keith's design philosophy for how he approached acoustics, it all just made total sense. I was convinced that Keith was who I wanted to do the acoustical design of the room. I also spoke with a friend who had had Keith design a room, and he told me how impressed he had been with the design. I soon made contact, and after some discussion, we reached an agreement on goals and budget for the project.


In addition to the acoustics, I requested that Keith's team work on the interior design of the theater, since I was so impressed with the looks of the "Listen Up" room. I also asked them to consult on making the HVAC system low-noise.


The first issue that came up was how to do the two rows of seating so that we could get the best viewing angles and lines of sight. There needs to be a height difference between the two rows so that both rows can have an unobstructed view of the screen. Well, my room only has an 8' ceiling! We could build a riser for the second row, but they would be feeling a fairly low ceiling. Add to that the need for a soffit around the room for the HVAC ductwork, and it was feeling pretty iffy.


What was the alternative? Well, my theater room is in the walk-out basement. The floor is the slab. The alternative was to bring in a concrete saw, some jackhammers, and a whole lot of concrete, and pour a lowered "pit" for the front row.


I was skeptical. But then Keith's team produced a couple of renderings that totally sealed the deal. First, they did a set of renderings showing a riser:




Then, they did a set showing a lowered front row:



As soon as I saw those renderings, I knew that the pit was the way to go. My prime seat -- the "money seat" -- would be in the front row, in the pit.


And thus, Mike's Money Pit was born!


We did some further refinements of the original design. We had to stay clear of the new footings holding up the steel beam, and I also didn't want the speakers to be so far above my ear level, as they would be if the "stage" up front was at the original floor level. So, we split the difference.


When my room is completed, the front row will sit 12" below the original level of the floor. The left and right speakers will sit on a 6" high stage at the front of the room, splitting the height difference between the two floor levels. The stage also acts as the step to get from the original floor level down to the front row. Here's how it will look:










(note that the last two images show an earlier, angular stage design that was later replaced with the curve)
 

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Subscribed. Really looking forward to following your build. Renders look awesome!
 

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Discussion Starter · #5 ·
Thanks! Next up I'm planning a little piece about screen sizing and viewing angles. It's mostly written. Just want to review it and the diagrams again before I post it.


I'm also planning to write some stuff about the constant-area system I'm planning to use, and then get into the really fun stuff with the acoustical treatment plan and the bass management (to be entitled, "Seven Subwoofers? Surely You Can't Be Serious?!")
 

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Quote:
Originally Posted by Dingaling2004 /forum/post/20784491


Subscribed. Really looking forward to following your build. Renders look awesome!

You have to do more than bug a buddy to get renderings like those!
 

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Discussion Starter · #7 ·

Quote:
Originally Posted by tony123 /forum/post/20786016


You have to do more than bug a buddy to get renderings like those!

Indeed! Those are the fine work of KYDG.
 

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Can you talk a little bit about your decision process of 16:9 versus 2.35:1 screen format and the size of the screen you are showing in the renders?




The reason I ask is it just looks a tad small if you watch a lot of 2.35:1 format content.


Other than that it looks like a beautiful space and I look forward to your progress reports.
 

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Discussion Starter · #10 ·

Quote:
Originally Posted by BIGmouthinDC /forum/post/20786197


Can you talk a little bit about your decision process of 16:9 versus 2.35:1 screen format and the size of the screen you are showing in the renders?


The reason I ask is it just looks a tad small if you watch a lot of 2.35:1 format content.

Yup, definitely! I will have two full postings discussing exactly that. The short answer is that the screen is designed to give the front row a 36° horizontal viewing angle for 2.35:1 content, which is the size that I find most comfortable after extensive viewing tests. The angle for 1.85:1 content will be 32°, using a subset of the screen, and IMAX-type content (Planet Earth, etc, etc) will use the entire screen.


The renders show a 108" diagonal 16:9 screen. I will actually be using a 110, not that that makes much of a difference. (It's a matter of standard sizes...) Also, keep in mind that the render you quoted is showing the second row view. The "prime" row in my theater is the front row.


Stay tuned for all the gory details!
 

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Discussion Starter · #11 ·
I hadn't fully appreciated the benefits of a very large room and a very large screen until I started working on the calculations for my screen size and seating distances. I intend to discuss my screen sizing and masking strategy in detail in an upcoming posting.


Before I do that, though, I've noticed that a lot of people seem to use online calculators for things like screen size and viewing angle, but I'm not sure they always know how they work, so I thought I'd just explain the concepts. Once you know how this stuff works, you can design your room however you like, without being limited by somebody else's tools. Caution: there is math ahead, but it's easy math!


Let's start by figuring out how to calculate a few key numbers. The first is the width of a screen of a given diagonal size. We need to know the width of a screen because it's the width that determines the horizontal viewing angle, which in turn is a key factor in setting seating location.

Calculating Screen Width

The obvious way to calculate this is with a tape measure or a spec sheet!
If you don't have the screen yet, though, and you only know the diagonal size of the screen, it's still easy to find the width -- all we need is a simple ratio. If we know what the ratio is between the diagonal and the width, then given any diagonal, we can find the corresponding width.


Let's say our screen is a 108" diagonal 16:9 model. That means that the width is proportional to 16 and the height is proportional to 9, but what about the diagonal?


Well, the side and bottom of the screen form the two sides of a right triangle, and the diagonal is the hypotenuse. The Pythagorean Theorem tells us that in a right triangle, the square of the length of the hypotenuse is equal to the sum of the squares of the lengths of the other two sides. This allows us to easily find the length of the diagonal in a right triangle whose other sides are 16 and 9. Then all we have to do is scale the size of that triangle (using a ratio) to find the width of any 16:9 screen we want.




So, as we can see from the image, if our width is 16, then our diagonal is 18.358. The ratio of width to diagonal, then, is 16 / 18.358. That ratio will hold for any 16:9 triangle, so now we can figure out the formula for the width of a 16:9 screen, given the diagonal:


width / diagonal = 16 / 18.358

width = diagonal * (16 / 18.358)

width = diagonal * 0.872


All we need to do is plug in our known 108" diagonal to get:


width = 108 * 0.872

width = 94.18


So, our width is about 94". This formula works for any 16:9 screen -- just plug in the diagonal in place of 108. If your screen isn't 16:9, you need to calculate the appropriate ratio starting from the right triangle. Just plug different numbers into the square root in order to find the number to which the diagonal is proportional.

Calculating Horizontal Viewing Angle

The size of the screen that you want is determined in large part by the horizontal viewing angle. When you hear people saying, "You want the distance from your eyes to the screen to be 1.5 times the width of the screen," they're really basing this number on viewing angle, and making some assumptions about the aspect ratio of the screen.


If you know how to calculate the horizontal viewing angle, and if you know the angle you like, you can figure out the ideal distances for any screen size and ratio and not have to resort to rules of thumb. Here's a little drawing that illustrates the angle we're interested in:




To calculate that angle, the easiest way to do it is to split it in half, so that we can use the geometry of right triangles, specifically the trigonometric function called the "tangent":




In this diagram, 't' is the angle at that end of the right triangle. The definition of the tangent of the acute angles in a right triangle is that it is equal to the length of the side opposite, divided by the length of the adjacent side. Referring to our diagram:


tan( t ) = ( screen width / 2 ) / distance to screen


We know the screen width and the distance to the screen, and we want to solve for 't', so we need to use the arctangent (the inverse of tangent) to convert the equation. Just take the arctangent of both sides to get:


t = atan( ( screen width / 2 ) / distance to screen )


Let's do an example using the screen we talked about above, which was 94" wide. Let's say that the viewer is 12' (144") back from the screen. We get:


tan( t ) = ( 94 / 2 ) / 144

tan( t ) = 47 / 144

tan( t ) = .326388

t = atan( 0.326388 )

t = 18.07 degrees


(If you're noodling along, be sure your calculator is set to "degrees" and not "radians"! If you like plugging formulas into The Google, you want "atan(47/144) in degrees".)


Now, remember that this angle is only half of the viewing angle, since we split things in half to give us a convenient right triangle to work with. Multiply by two, and we see that our viewing angle is 36.1°.

What's all this about "Tyranny"?

Phew! Okay, now that we know how to calculate the horizontal viewing angle, let's see what it can tell us about room sizes and seating locations.


I have done extensive viewing tests to see what my preferred screen size is. It turns out to be extremely consistent for me: I prefer a screen that is sized such that, when watching 2.35:1 content, the screen creates a 36° horizontal viewing angle. 40° is consistently too big for my liking, but 36° is spot on perfect. I know others here (like Art Sonnenborn) prefer a larger screen, and more power to them. It's all about what you like, since it's your theater! For me, 36° is as big as I care to go.


(As a side note, with this screen size in a constant-height setup, I find 1.78 content to be too small. That's why I'm going with a constant-area approach, which I'll discuss in a later article. 2.35 is the widest content, though, so it sets the overall screen width, and is what I discuss here.)


From the examples above, we know that to get a 36° viewing angle given a 94" wide screen, my seat needs to be 12' from the screen. How convenient that all my examples are what I actually need in my room!



The overall depth of my room is 24', but by the time I factor in acoustical treatments, HVAC requirements, storage requirements and so forth, I have about 20' of usable depth from the screen location to the back wall. 12', therefore, is in a pretty good spot for my prime row.


Now, where to put the other row? Uh-oh. Here we get into the tyranny of trigonometry. Assuming that you need about 5' from row to row for legroom and walking space (6' for big recliners), we start to see a problem. If I put the second row of seats five feet behind the prime row, they're 17' (204") from the screen. Using the same formulas as above:


viewing angle = 2 * atan( 47 / 204 )

viewing angle ~= 26°


That's a bit small, but usable. What if I make the second row (at 17') into the prime row? How wide does my screen need to be? I have to flip the formula around just slightly in order to solve for width:


tan( viewing angle / 2 ) = ( width / 2 ) / distance

tan( 36 / 2 ) = ( width / 2 ) / 204

tan( 18 ) * 204 = width / 2

tan( 18 ) * 408 = width

132.5 = width


I need a 132" wide screen to get my 36° angle with the prime row at 17'. That's a big screen! What does that do to my guests in the front row, at 12'?


viewing angle = 2 * atan( ( 132 / 2 ) / 144 )

viewing angle ~= 49°


Either way you slice it, there's a very large difference in viewing angle between the two rows, just because of how the trig works out. The "other" row of seats may have an image that's a bit small, or (for me) uncomfortably big.


Imagine for a moment that I had a much bigger room, and I could put the prime row 24' back from the screen. To get 36°, my screen would be 188" wide (wow!). A second row at 29' would have a viewing angle, though, of 30 degrees. Or, put a row in front, at 19', and it would be at 44°. These are much less dramatic changes in angle!


In short, just because of how the math works out, a larger room with a larger screen will allow for a smaller row-to-row difference in viewing angle. If you extend this to a full-scale commercial theater, you'll understand why there's not a very big difference in viewing angle at all if you move forward or backwards one row.


For a theater in a normal sized home, though, the second row of seating is going to be a compromise one way or the other. In my case, I went with the prime row in front, at 12', and the "other" row behind it, at 17':
  • Given my bias against overwhelmingly large picture, I opted to have my guests have a smallish but comfortable image
  • Doing the larger screen would have required a very large and bright projector, which is both costly and probably noisier due to cooling fan requirements.
  • A 132" wide screen would be very tall with a constant-area setup. In a room with an 8' ceiling, it probably would have been difficult to avoid having the front row obstruct the screen.


In a later article, as I mentioned, I'll talk about my approach to a "constant area" screen and how I intend to do screen masking.
 
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Looks like a great plan so far!


Are you considering the acoustic impacts of having the prime seat very close to the middle of the room front to back? Not that its unworkable - I'm pretty close to that as well - but it does present some challenges. Maybe you and Keith have a plan to mitigate (many subs?).
 

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Discussion Starter · #13 ·

Quote:
Originally Posted by Brad Horstkotte /forum/post/20788301


Looks like a great plan so far!


Are you considering the acoustic impacts of having the prime seat very close to the middle of the room front to back? Not that its unworkable - I'm pretty close to that as well - but it does present some challenges. Maybe you and Keith have a plan to mitigate (many subs?).

Thanks! Yes, the middle-of-room factor was taken into consideration. The prime seat is not quite centered either front-to-back or side-to-side, so it's clear of the "danger zone". The bajillion subwoofers help, too! More on that in an upcoming article.
 

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Quote:
Originally Posted by JustMike /forum/post/20786658


I have done extensive viewing tests to see what my preferred screen size is. It turns out to be extremely consistent for me: I prefer a screen that is sized such that, when watching 2.35:1 content, the screen creates a 36° horizontal viewing angle.

I think the key here is "preferred". Often we suggest in this forum that the first time theater builder take the projector and shine it on the wall to get the feel for what they like before buying a screen. Not knowing better at the time, my first screen was calculated using the 1.5 width rule and I started out with a screen that resulted in a 35 degree horizontal viewing angle. For 5 years I thought it was a little small. When I converted to a scope screen I ended up with about a 46 angle and I love it. Now in a perfect world I would want my 16:9 content to be a little larger and if I could afford a 4 way masking system that is what I would have done.
 

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Discussion Starter · #15 ·
Yeah, that's interesting and definitely my point -- I couldn't stand a 46° angle for CinemaScope content. I've tested this everyplace from home theaters to commercial cinemas. I go to where I find the image to be "just right", then measure, and it's always 36° +/- a degree. My friend can't stand 36°, and she always wants to sit at a point that gives closer to 32°. To each his own, especially in his own theater!



FYI, my masking system is going to be partially custom, since nobody makes a fully variable 4-way masking roll-down screen. Stay tuned for that article!
 

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Discussion Starter · #17 ·
Yeah, I saw that chart, and I did take it into consideration. However, I don't think it applies directly to a home cinema for a couple of reasons:
  1. This is for film content, which has a higher spatial resolution than 1080p home projection technology. With lower resolution content, the image "looks smoother" if you sit at a greater distance. (I can't swear to it, but the fact that I like 36° content at my local gigaplex may have something to do with the fact that their projectors are 2K digitals.)
  2. Those standards are also directed at substantially larger venues. I don't know this for a fact, but I have a feeling that when your eyes are focused, say, 40 feet away, you can more comfortably process a large visual field than you can when the image is only 12-15 feet away.


Those are general considerations. Then there are the considerations for me specifically:
  1. My visual acuity is very high (20/13 uncorrected vision), and I also work in user interface design, where I look at HD user interfaces all day long. Artifacts and picture imperfections bother me. By sitting where I get a 36° angle of view, I don't tend to notice jaggies and pixel structure.
  2. I'm also quite flicker sensitive, so I suspect that having less picture in my visual field is just more comfortable for me at a fairly fundamental neural level. [As an aside, I cannot watch a color wheel projector without noticing the rainbow effect. I can see the DLP refresh flicker on a 3-chip DLP (even a very nice one) if it's a bit on the bright side, like 17-18 foot lamberts. At a more reasonable 14-16 foot lamberts or so, though, I love 3-chip DLP, especially the gorgeous Sim2 models. I'm hoping to try out Sim2's MICO projector shortly to see whether the much higher refresh rate that they are able to do with LED illumination will still trigger my flicker sensitivity. If I wanted to totally go off the deep end on budget, I'd get a Sim2 C3X Lumis 3D Solo for the theater, although it might present noise issues with its larger cooling requirements. But I digress...
    ]


Finally, I was told by a movie industry veteran that for home video-type content (1080p), the angle that most people find comfortable is about 36°, which squares directly with my own experience. As with any statistical distribution, there will be people on either side of the hump in the middle. Fortunately for me, since it's my room, I can optimize for exactly what I like best.
 

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Mike.. Looks like it will be a great build, I like the Non typical approach/look for the tiered seating.


You've probably already seen this award winning theater, similar to what you are doing with the walk around platform, and the lowered front row:

http://www.electronichouse.com/slide...gory/8629/1222


Looking foward to more of your updates.


Brad
 

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Quote:
Originally Posted by JustMike /forum/post/20788324


Thanks! Yes, the middle-of-room factor was taken into consideration. The prime seat is not quite centered either front-to-back or side-to-side, so it's clear of the "danger zone". The bajillion subwoofers help, too! More on that in an upcoming article.

My front center seat is close to the center of my room and my front/rear subwoofer setup definitely helps a great deal when equalized correctly. Without the multiple subs the "danger zone" is at least a couple of feet in each direction.
 

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Discussion Starter · #20 ·
Thanks, Brad! I hadn't seen that room, but it's cool!


Moggie, first, I love your signature! Second, yeah, in my room layout, I'll have two subs directly in front of my seat, one on either side, and three behind at various points. We should have pretty even response at the prime seat and the others as well.
 
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