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Discussion Starter · #1 · (Edited)
I really should have posted this earlier, but I'm building a new theater. I've already done some of the basic construction, and am starting to plan the electrical. To do that I've been looking at equipment, which brought me back to AVSForum after a long hiatus. Seeing all of the great things being done here made me want to share.

The room, after framing, is 19' x 28' x 12' ceiling. In designing the physical layout, I've already made a few decisions that may be polarizing.

  • I've decided to limit myself to in-wall speakers or something similar that could be hidden in a relatively shallow column (I've actually quite liked some Polks I've used in the past and there seem to be quite a selection now).
  • I originally designed the risers to have a rather long suspension of specific length that can resonate, with the intention of putting transducers into the risers, but instead I think I'm going to just build subs into the risers as infinite baffle (there is way more than enough space to IB any subs I can realistically fit).
  • I've already designed and built the risers. I intend to have a back row of cabinet/counter space, with the equipment in these cabinets. I'll probably have the cabinet doors faced with some sort of iron screen or open grid to allow airflow.
  • I let the HVAC guy talk me into a mini split heat pump system to heat/cool. I'm not too sure about that aesthetically, but I'm told they're fairly quiet and are the best way to get a sealed room like this a dedicated climate control. I liked the idea of core cutting a bunch of big holes in the concrete and tying into the house HVAC but they didn't seem to think it would provide satisfactory performance for a room this size on the existing furnace.
  • I'm planning on wiring for a 9.x.4 system. I realize there's not much out now that will drive that (or process it and provide pre-outs for that matter).

You can see in the photos that I went to the trouble of 3D printing a model of the design to ensure that things felt right proportionally. Forgive the distortion on the panoramic shots. The riser stairs were a bit tricky to align with the doorway and to ensure I had enough steps of the right size to link all of the levels together and keep a good room height. I think the stairs ended up a little busy, but it gets the job done without being too weird.

Right now I'm a bit stuck on power delivery. I'm trying to figure out if I need something like a dedicated 240v 20A circuit for the sub amp and a separate 120v circuit for the surrounds and other equipment, and maybe a third 120v circuit for the room outlets and things like video players and game machines. Then another for lighting and projector... it's a lot of power. It seems like a lot of the pro amps people are getting are just being used to maybe a percentage of their capacity and are on circuits where they can trip the breaker. That or they're not really being rated for continuous power, though pulling up the manuals indicates some beefy circuits would be required.

Once I get electrical sorted and wired, I intend to have all of the outer walls and ceiling spray foamed. I like the idea of a spray foam as a thorough moisture barrier, as well as sort of locking the studs in place and reducing vibrations.

At any rate, I'll check in occasionally and see if people have input. I'm a bit lost at the moment as far as aesthetics goes, though I'm kicking around some ideas. I've been doing all of the work myself so far, it may take awhile but I don't intend to leave it unfinished!
 

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Wow - what a great space. I'm not sure the spray foam is best if you are going for soundproofing, but it would lock everything together like you say, but so will PL. Check the soundproofing thread for more info
 

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Discussion Starter · #3 · (Edited)
Wow - what a great space. I'm not sure the spray foam is best if you are going for soundproofing, but it would lock everything together like you say, but so will PL. Check the soundproofing thread for more info
Thanks, it has been a lot of fun so far to build.

I'm really not worried about soundproofing at all, as it has 12" of concrete on all sides. The spray foam would be strictly for heat retention, moisture barrier. Sound absorption, on the other hand, will need to be handled on the surfaces that I have yet to plan.
 

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Nice space you got there sor. I have a similar space at 17x28x9, it's on hold until the rest of the house is done.

Quick question regarding the second raiser. Did you consider not adding it in, and just place the bar at the same level as the second row? I'm thinking of how to get a direct line from the second row to the rear speakers. Seating at the bar is typically higher than a recliner anyway.

Hope you find a good 16 ch prosessor before your build is done. I'm keeping an eye one the Emotiva RMC-1.

Cheers
 

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Great Project!

You might consider a ducted mini split, that way you don't have to look at and hear the air handler hanging on a wall. You also need to plan for introducing fresh air into the space. Either that or leave the door open. With seating for 13 at capacity, the CO2 levels in a sealed room will rise.
 

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Amazing space.

But I already see a lot of issues cropping up already. I can spell them out if you like.

I would suggest you look at Rob Halm's build, and The Savoy. The Savoy is very unique in the use of a htpc and a MOTU 1248 as the front end.
The Cave would also be another room to see high end design put to work in such an awesome space. The Cave built by The Big Picture would
also be another design inspirational for such a space.
 

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Discussion Starter · #7 ·
Nice space you got there sor. I have a similar space at 17x28x9, it's on hold until the rest of the house is done.

Quick question regarding the second raiser. Did you consider not adding it in, and just place the bar at the same level as the second row? I'm thinking of how to get a direct line from the second row to the rear speakers. Seating at the bar is typically higher than a recliner anyway.

Hope you find a good 16 ch prosessor before your build is done. I'm keeping an eye one the Emotiva RMC-1.

Cheers
Oh no, 9.1.6 this year! I didn't think my build would be outdated so quickly :)

I agree about the bar, for that reason I may end up going down to counter height, or it might be cool to even put a few lounge chairs back there with something like a tall coffee table size cabinet, depending on how much space I need for equipment.

I just had all that height to work with and really like the multi-tier theater aesthetic. I think the rear speakers may end up mounted a tad high to avoid occlusion, even just from the first row being blocked by the second, but there's enough height in the room that I won't have to get them too close to the ceiling to do that. If the speakers are ~4' 4" up off the rear platform, they'll be 10" above even a bar height bar and still ~4' 4'' from the ceiling, which is probably about as good as most home theaters can manage. I just need to draw some lines/angles and see what the right combination is between speaker position and counter height.
 

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Discussion Starter · #8 ·
Great Project!

You might consider a ducted mini split, that way you don't have to look at and hear the air handler hanging on a wall. You also need to plan for introducing fresh air into the space. Either that or leave the door open. With seating for 13 at capacity, the CO2 levels in a sealed room will rise.
Thanks, I'll look into those. I do plan on having two sets of double doors, there's a bit of a hallway leading to this space so I wanted to build some sort of foyer into it. The point being that the doors immediately at the theater probably won't need to be closed in order to get some isolation. The air return for the rest of the basement is very near the door and ducted partially into this foyer area, the HVAC guys seemed to think the return would cause enough recirculation in the area to keep things fresh. I hope they're right. Alternatively I could do a core drill just for a return to try to mix things up a bit more.
 

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Don't get too caught up in 120 vs. 240 volt circuits. 240 volt circuits can use exactly the same wiring as 120 volt, but provide double the amount of power over the same wires.

You only "need" 240 volt power if you have something that requires a lot of power. Examples include ovens, clothes driers, welding equipment and industrial motors. However, 240 volt circuits can be more efficient and less expensive than 120 volt circuits. Lots of electronic equipment with smaller power needs can be switched between 240 and 120 volts. Something that uses 20 amps at 120 volts would only use 10 amps if you switch it to 240 volts. That means that you can power TWO of them on one 240 volt 20 amp circuit. If you were to use the same devic on 120 volts, you would require two 20 amp circuits.

If your devices (primarily hight powered amplifiers) can be used on on 240, it would probably make sense to run them on 240. There will likely be other devices that are fixed at 120 volts, so you would likely need 120 volt circuit(s) as well. It is really a matter of understanding your requirements and doing the math.

As BIG suggests, you really need to think about fresh air requirements. Heating and cooling is only half of the picture. The room will get humid, "stuffy" and may build up enought CO2 be give people headaches in a short amount of time with more than a few people.

What a great space to work with! Many people would "die" for the ability to build their theater inside a big concrete bunker! Have you considered beefing up your door and the space around it (currently stuffed with insulation)? That will definitely be the weakest link in your sound isolation.

Mass is obviously a huge factor in sound isolation, the heavier that something is, the harder it is to vibrate. However, once they do vibrate, solid objects transmit sound much more effectively than air. Concrete is actually a very good conductor of sound. Think about the old trick of putting your ear to railroad tracks to hear the train coming long before you can hear it in the air. Your concrete is so thick and heavy that it probably won't make a lot of difference, mainly because it is so heavy that it will be hard to vibrate in the first place. But a theoretically better approach would be to have the walls, ceiling and floor (especially the riser) completely isolated from the concrete walls, rather than bonded to them.

Be careful with your using your resonant floor for an infinate baffle. The resonance of the floor may cause undesired "boominess" and coloration of the low frequency sounds. Ideally you want an IB setup to be as stiff as possible, not resonant at bass frequencies.
 

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Nice space you got there sor. I have a similar space at 17x28x9, it's on hold until the rest of the house is done.

Quick question regarding the second raiser. Did you consider not adding it in, and just place the bar at the same level as the second row? I'm thinking of how to get a direct line from the second row to the rear speakers. Seating at the bar is typically higher than a recliner anyway.

Hope you find a good 16 ch prosessor before your build is done. I'm keeping an eye one the Emotiva RMC-1.

Cheers
Oh no, 9.1.6 this year! I didn't think my build would be outdated so quickly :)

I agree about the bar, for that reason I may end up going down to counter height, or it might be cool to even put a few lounge chairs back there with something like a tall coffee table size cabinet, depending on how much space I need for equipment.

I just had all that height to work with and really like the multi-tier theater aesthetic. I think the rear speakers may end up mounted a tad high to avoid occlusion, even just from the first row being blocked by the second, but there's enough height in the room that I won't have to get them too close to the ceiling to do that. If the speakers are ~4' 4" up off the rear platform, they'll be 10" above even a bar height bar and still ~4' 4'' from the ceiling, which is probably about as good as most home theaters can manage. I just need to draw some lines/angles and see what the right combination is between speaker position and counter height.
The main reason for putting in a bar height counter and stools for the back row is headroom. It gets the sightlines when seated above the row in front without raising the floor when standing. It looks like you likely have enough headroom that you could build the riser higher in the rear and use conventional seating rather than bar stools.
 

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Discussion Starter · #11 ·
Don't get too caught up in 120 vs. 240 volt circuits. 240 volt circuits can use exactly the same wiring as 120 volt, but provide double the amount of power over the same wires.

You only "need" 240 volt power if you have something that requires a lot of power. Examples include ovens, clothes driers, welding equipment and industrial motors. However, 240 volt circuits can be more efficient and less expensive than 120 volt circuits. Lots of electronic equipment with smaller power needs can be switched between 240 and 120 volts. Something that uses 20 amps at 120 volts would only use 10 amps if you switch it to 240 volts. That means that you can power TWO of them on one 240 volt 20 amp circuit. If you were to use the same devic on 120 volts, you would require two 20 amp circuits.

If your devices (primarily hight powered amplifiers) can be used on on 240, it would probably make sense to run them on 240. There will likely be other devices that are fixed at 120 volts, so you would likely need 120 volt circuit(s) as well. It is really a matter of understanding your requirements and doing the math.

As BIG suggests, you really need to think about fresh air requirements. Heating and cooling is only half of the picture. The room will get humid, "stuffy" and may build up enought CO2 be give people headaches in a short amount of time with more than a few people.

What a great space to work with! Many people would "die" for the ability to build their theater inside a big concrete bunker! Have you considered beefing up your door and the space around it (currently stuffed with insulation)? That will definitely be the weakest link in your sound isolation.

Mass is obviously a huge factor in sound isolation, the heavier that something is, the harder it is to vibrate. However, once they do vibrate, solid objects transmit sound much more effectively than air. Concrete is actually a very good conductor of sound. Think about the old trick of putting your ear to railroad tracks to hear the train coming long before you can hear it in the air. Your concrete is so thick and heavy that it probably won't make a lot of difference, mainly because it is so heavy that it will be hard to vibrate in the first place. But a theoretically better approach would be to have the walls, ceiling and floor (especially the riser) completely isolated from the concrete walls, rather than bonded to them.

Be careful with your using your resonant floor for an infinate baffle. The resonance of the floor may cause undesired "boominess" and coloration of the low frequency sounds. Ideally you want an IB setup to be as stiff as possible, not resonant at bass frequencies.
Thanks for all the great feedback.

Re 120v vs 240v, I'm aware of the options, I mostly just want to go through the exercise of picking out equipment so I can be sure I don't paint myself into a corner. I know I could probably just run some 12-2 and decide 120 vs 240 later, but I want to be sure I don't end up with equipment that *needs* [email protected] or something. I've also got breaker space to worry about, a 240 circuit chews up two slots, whereas I can fit four tandem 120v circuits in the same two breaker box positions if I need to.

You're right that I may need to stiffen up the floor if it starts to color the sound, I figure I can always easily crawl in and add stiffeners/support as I go to tune it in if the idea is horrible. just one bracing wall in the middle would make all the difference, I think. From what I was calculating, the volume of air in that thing is big enough to not really cause compression/pressure at all on the risers, really, unless I ducted in 6x18" subs or something like that.

The studs are floating off of the concrete by 1/2", with some selective anchoring in a few spots. Definitely not enough contact to get the concrete moving, I'd imagine. I'm expecting the spray foam to keep vibrations down in the studs, but it's ultimately flexible and shouldn't transfer too much to the concrete either.
 

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Discussion Starter · #12 ·
Amazing space.

But I already see a lot of issues cropping up already. I can spell them out if you like.

I would suggest you look at Rob Halm's build, and The Savoy. The Savoy is very unique in the use of a htpc and a MOTU 1248 as the front end.
The Cave would also be another room to see high end design put to work in such an awesome space. The Cave built by The Big Picture would
also be another design inspirational for such a space.
I probably don't want to hear them if it would mean tearing down what I've done :) but I'm always up for some constructive feedback. I feel like I'm still at a stage where I can make a lot of adjustments to the plan.
 

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Maybe a little rebuilding but nothing serious at this point.... There's lots to love there already.

That's a serious throw distance for the front speakers, so what Polk's are going to get you the high frequencies, in the second and third rows?

The foam will couple the walls to the concrete, and concrete is a pretty good conduit for bass. You might find yourself with some walls upstairs,
radiating noise.

That step at the entry is a serious trip hazard.

The third row is right on top of surround speakers. How do you propose to set the levels of the rear surrounds, so the front row can hear them,
without them overpowering the rest of the surround system, for those seated in the back row.

Do you actually need all of those seats? That's serious $$$ tied up, that might just be better spent elsewhere. So I'd want them filled, and used often.

So much space, would be the opportunity to build inwards to accommodate acoustical treatments a la The Cave, while maintaining the tall separation of
seating levels. That third bar row isn't exactly audio friendly, so I'd question if it is something that's expendable, and would let me have the second row
at entry level. I would be tempted to raise a wood floor at the lower level too, and build it plus the riser with a little give, to add tactile feedback. Now the
throw distance isn't so challenging for the LRC, and the second row is well of the surrounds.
 

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although the thread and pictures are long gone Big Red did a desk height back bar and high top executive desk chairs for his third row and it turned out really nice. He also had goose-neck mini task lights installed on the surface.
 

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Discussion Starter · #17 ·
Maybe a little rebuilding but nothing serious at this point.... There's lots to love there already.

That's a serious throw distance for the front speakers, so what Polk's are going to get you the high frequencies, in the second and third rows?

The foam will couple the walls to the concrete, and concrete is a pretty good conduit for bass. You might find yourself with some walls upstairs,
radiating noise.

That step at the entry is a serious trip hazard.

The third row is right on top of surround speakers. How do you propose to set the levels of the rear surrounds, so the front row can hear them,
without them overpowering the rest of the surround system, for those seated in the back row.

Do you actually need all of those seats? That's serious $$$ tied up, that might just be better spent elsewhere. So I'd want them filled, and used often.

So much space, would be the opportunity to build inwards to accommodate acoustical treatments a la The Cave, while maintaining the tall separation of
seating levels. That third bar row isn't exactly audio friendly, so I'd question if it is something that's expendable, and would let me have the second row
at entry level. I would be tempted to raise a wood floor at the lower level too, and build it plus the riser with a little give, to add tactile feedback. Now the
throw distance isn't so challenging for the LRC, and the second row is well of the surrounds.
Lots of good things to consider.

I’m not sure I plan on using Polks. There’s quite a range of available speakers, and honestly I could even double up if I decide I need to. Those front corners are going to get some more framing and could probably accommodate larger speakers as well. The fronts and centers will definitely be higher output than the rest, and the ceiling and other surrounds will need to be in-wall.

As with most setups, I’m optimizing for the middle row. I don’t really expect that the back row or front would even be used often, except for preference of wanting a closer or farther view. The back seats are definitely not going to be tuned for an audiophile to sit down and critique the spatial accuracy of the surround sound. I’m not concerned with tuning the rears such that they won’t overpower people sitting there. I may not even put seats there and just leave it as a place to put out a spread. It really comes down to the fact that you don’t want your prime space right up against the rear, so what else are you going to do with that void... might as well make it usable.

As far as cost, eight recliners is pretty average on these forums, no?

I disagree about the trip hazard, I don’t think it’s any more of a trip hazard than any other stair. I’ve been going in and out, carrying materials, had guests in and never even had to think about it, and that’s before any special stair lighting. I paid extra attention to common build practices for things like hallway stair landings, stairs on corners, and at entries/exits and ensured there was enough width and landing to avoid feeling awkward.

I think bringing up that second row to door height and having six stairs to ground level would make a pretty awkward looking, disproportionate riser. The alternative would be to build up the base level... just seems like a waste. As it is now the height adds a grand feel.

I agree that I could have done without the third tier, but I really love the aesthetics.

I do appreciate the input and it gives me things to consider. I don’t want to come off as defensive, I’m just trying to clarify some points and indicate that some of these things are intentional and why they work for me, even if they’re “wrong”. :)
 

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That step at the entry is a serious trip hazard.


I'm pretty sure having just a small step inside a door is a code violation you really need a landing.

I know the train has left the station but imagine sitting in the second row seating and deciding that you want to move to the first row, you have to step up to step down or make some crazy mid air traverse to get to the steps.

It is not too late to rethink the riser plan. Maybe raise the hole thing up closer to the door level and elevate the floor at the front of the theater. Nothing wrong with a 10 ft tall theater room.

One thing I've learned in my DIY life is the difference between a good DIY builder and a poor DIY builder is the willingness to acknowledge mistakes and take two steps backwards to make forward progress. It is only your time that you have to spend, most of the materials can probably be recycled.
 

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I believe that code requires a 36" landing inside a doorway before you step down. The idea is that people walking through the door many not realize that they need to step down on the other side of the doorway and could stumble and fall. Because it is likely to be a darkened room, that probably increases the importance. You are used to it, so you know where to step. A visitor may not. Even he he/she navigates properly the first time in, they may miss it if they go out and come back in without paying attention. It wouldn't take a lot to make a landing at the doorway height and make the steps go down from there.
 

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One can have aesthetically pleasing, and have great audio. Both should be goals of such an outstanding space.

But when the room's primary use is 98% in the dark, maybe you can get the wow factor in other ways? I'd
personally take a masking system, over an unused row of seating. Or that potentially might be money to move
up the projector ladder.

Just spotted another issue. The room should have been dry-walled, before the riser went in.

Raising the lower floor might eat up some height, but it could also give you tactile feedback, and you could use that
space for some serious subs.
 
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