Build log: DIY rotary sub for contemporary HT in 100 year old house?

Goal
I would like a contemporary HT with clean and unique looks that is high performance for the price of materials and my labor. The HT will be used for my computer room, HT, and perhaps a band jamming room, disco and baby play room (baby is due in January!). Big ideas, I know! The following is a starting vision for how it might look. I want a "clean look" with no stage or exposed speakers. Colors and design are not final.



The HT will be part of a whole basement finishing project. The HT will be my main focus and the reason for the project. I've wanted one for years now. The basement will also contain a bathroom, stairway anteroom and utility/storage room. I have the go ahead from my wife now that I have finished on her (year long) attic project that included a huge walk in closet, laundry, bathroom with nice tub and storage. I'll include some pictures of it in a later post for fun.

I am starting from scratch on a basement in a 100 year old house. The distance from concrete floor to the bottom of the joists is 7 feet. From the floor to the bottom of the one beam that goes right down the middle of the room is 6' 4. I also have hot water heating pipes that are about the same height running through the room. There are a few regular water lines that need to be moved as well. So, I have a bit of a height issue and a need to move the beam up and move some pipe around the room.

Below is the pic of the beam. It also has a support in the middle of the future HT that you can see. Also there is a chimney support pillar and 4 waste line on one wall that will require framing around it.



The waste line continues around the room. This is the top wall in the plan. I plan to use this space to run the water lines and the heating pipes when I move them.



On the bottom wall of the plan, you can see there are stairs. These stairs have a landing for a side door into the house. The door is lower than the first floor of the house. In the basement the landing brings the height of the ceiling for about a 3.5 x 3 foot area in the corner of the HT to about 5' 8. Some of this is a joist for the landing area which could be changed to something with less depth to regain some height. I was thinking of closing this off and making this into some storage within the HT. You can see the landing from the basement in the next pic.

The proposed floor plan is below. I haven't quite figured out the bathroom area yet, so disregard some of that in the plan. There is a sump pump well in the middle of the left side of the basement plan that complicates it.



Finished HT size should be around 19 feet long and 16.5 feet wide by 6' 9 tall. It will be the biggest room of the house! I wish the length was a bit more, but I plan on using non reclining seating for the last row so I don't get them too close to the rear surrounds. The width of the room is great.

As far as AV equipment, I don't/won't have that much so am thinking of placing it outside the HT below the stairs.

I will be trying to isolate sound as much as possible using DD/GG and clips/track in the ceiling. I am not sure how I want to handle lighting because of this. I don't think I have the height to put in a soffit around the perimeter of the room, and I'm not sure that would give me enough lighting at the center of the room. I would like to have good lighting to allow use as a baby play room. I have to balance that with wanting dark colors for movie watching. I was thinking of using light colors for the walls, but then being able to pull dark curtains over the wall as used in this build: http://www.avsforum.com/avs-vb/showthread.php?t=1254505

This balanced with how much I like the look of fabric panels on the wall. This is something I can worry more about when I actually have walls!

I will be putting thick sound absorption on all walls and corners of the walls. I don't think I want to put any on the ceiling because of height. I am using line array so I have less need to treat the ceiling, but if I had more height, I would. On the floor, I was thinking of using the Delta-FL covered by foam play tiles: http://www.amazon.com/We-Sell-Mats-A...034295&sr=1-21

I would then use an area rug over the top of the foam tile. I am up for suggestions though. I have mixed feelings about carpet. It feels nice, but doesn't stay clean. You can't just swap it out because it is expensive and needs to be installed. We have cats too and they don't help the situation. An area rug is cheaper and can be changed easily. With the foam tile, it will be insulative and soft to walk on, but maybe less luxurious and stylish.but it will be priced to match at <$1/sqft. The other question I have is whether I can use the Delta-FL with the foam tile since it has those bumps on it. I may consider just using 6 mil plastic or the like for a vapor barrier.

One last note about sound isolation: I really want to build a rotary sub. I know, you have probably heard someone say that and it never happened. I will tell you that I have the skill and tools to build one. I have a CNC router that I made, plus I was a model RC airplane designer and manufacturer for a number of years. The issue I have with the rotary sub is how to isolate sound with it. With a baby on the way and close neighbors, a rotary sub (and my THT) will be worthless if I can't use them as a volume to shake human bodies. Do I need to isolate the utility/storage room if I vent the rotary sub there? I've heard that I probably don't because the rotary subs waves sort of cancel between the two waves. I'm not sure I believe that. The other issue is: what can I do to keep the rest of the sound in/out? I don't want to hear the furnace in the HT or the HT in the rest of the house. If I isolate the utility room, then I have to supply air to the gas furnace and water heater. Then I also have to figure that the hole the rotary sub has into the room will act as a HVAC return, so I have to put the supply in a different place. Anyway, if anyone has some insight, please let me know. I'm sure I will have future posts on this issue.

It would be much easier not to do the rotary sub - and not because of making the actual sub, but the room construction headaches! The thing that keeps pulling me back is how cool it would be to have.

I’m thinking of all the little touches that can make a room so cool. I won’t implement all or most of these, likely. I’m just throwing ideas out there.

Rotary sub
Lighting: Lighting can really make the room awesome - both utilitarian lighting and accent lighting. I would like recessed lighting in the ceiling, but that would mean making boxes to prevent sound transmission. I am not against that, but would like other options as well.

Accent lighting: RGB lights, EL wire, or rope lighting between fabric frames like in the following pic.



Dark curtain to be pulled over lighter colored walls for movies.
Custom couches/seating: I am thinking of either building my own couches or modifying existing couches to a funky shape. This would be with a matching ottoman(s).

More ideas will be placed here as I think of them.

Projector: Epson Powerlite Home Cinema 720 (have)
AVR: Denon 1911 - 7.1 (proposed)
Source material: HTPC (have)
Speakers: THT for sub and TLAHs for LCR, half TLAHs for 4 surrounds (THT and LCR have)
Crown XTI 1000 powering THT (have)
Possibly Buttkickers and DIY rotary sub!

Screen will be AT and as big as my projector will allow. When I’m close, I’ll test out firing the projector at the wall to see what I can get away with. I’m thinking 120”+ 16:9. I’d like to do CIH, but I’d be zooming if anything. I’m going to be pushing the image size with 16:9 as much as I can, so I won’t be able to zoom out anymore for 2.4 without getting too dim. For that reason, I think it would make sense to go with 16:9 and consider an adjustable masking system for top and bottom, even if it is just manually operated.

Reserved

Oh, and if it is not apparent: I have some lofty ideas, but am very willing to hear all suggestions and ideas. I don't like being told it cannot be done, so please keep that in mind. I'm pretty skilled at coming up with unique, creative solutions though!

If you like something, let me know. It will certainly help motivate me to hear a few kind words.

Other details: budget is whatever it takes to do a quality job without being extravagant, but I would like it to be $10k or so.

Here's is my wife's attic that I just finished up for around the same price.

Before:



This is the tub before flooring:



Before trim:



Completed:

I haven't gotten much feedback except via pm. Feel free to give me your opinion. Maybe I'm on the right track....? ....or not...?

I also wanted to say I haven't decided on whether I'm going to make the rotary sub. I think making the sub will be the easy part. The more difficult part is figuring out how to: sound proof HT and rotary baffle room/HVAC and air circulation for HT and basement/air supply for gas furnace and water heater.

I also am unsure whether I should put details of the rotary sub build online. I don't want to take away from Thigpen's business. There is no way I would be able to get my wife to agree to a $20k sub, so building it would be the only way to try it. Maybe the population that would build something like this would not be the same as those buying it, so maybe there is not an issue? Give me your thoughts

Thanks for the reply, Ted.

I would probably be willing to take up that amount of space. I may have to reduce the width of the theater a bit and/or have a smaller utility/storage space (likely the latter). Would dead vents allow rotary airflow, but disallow bass from leaking out? They must have a frequency below which they don't work, correct?

So, a regular sound isolated room would have these dead vents if soffits were not possible.

The dead vents would do nothing to stop very low frequencies (but would stop low frequencies of my regular sub (>15hz)).

Very low frequencies would not need a larger dead vent, but may be an issue in the house. I'm thinking likely the ceiling of the vented (utility/storage) space would be flexing without isolating that whole room....? Is there anything I could do?

Would I also have to make the walls stronger/stiffer in the HT?

Thank you very much for the info Ted. You are pretty much *the* expert on AVS when it comes to sound proofing, so I value your input.

I do understand that I cannot make a room that is quite as effective as Get Smart's "cones of silence". I just want to do the best I can with reasonable effort and expense. Building for my current system and building for my current system plus a rotary sub is what is throwing me. Seems like a rotary sub has its advantages and might be cool and fun. I just don't want everything else to go down the toilet because of it!

So, I'll plan on using dead vents. I'm thinking I will make the return (much)bigger to accommodate airflow for the rotary. The supply vent will likely end up under my stair landing in the corner of the room.

Ha ha! That was always one of my favorite parts of the show. I was glad they kept that in the recent movie.

I do have a design in my head mostly thought out. I used to build RC slope planes as a business using my CNC router. Some of us fly what are called wingerons that twist their wings in relation to each other instead of using ailerons for rolling the plane. That is the type of mechanism I will be using for the pivoting of the blades.

I will be CNCing the blades with a real airfoil, which I have experience doing hundreds of times! I will have a metal rod glued into the airfoil, and the rod will slide into a brass tube that is glued within three layers of plywood. At the end of the rod, near the center of the plywood disc, the rod will stick out of the brass tube and the plywood will be cut away there. I will make some aluminum linkages that clamp to the rod and will twist the rod within the brass tube. In this way, the brass tube is the bushing.

I'm planning on using angular bearings to mount the shaft that goes throught the center of the plywood disc so it won't require the motor shaft to take that stress. I can then use spider couplers to connect the blade hub shaft with the motor shaft.

There are a bunch of details beyond that, plus how the linkages are connected to the driver. The pivot point of the blade is important to reduce aerodynamic forces also.

Clear as mud?

Well, the rotary sub will never get built if I don't get the rest of the room first! I do plan to take pics of the process.

I plan on starting Thursday on the basement since I only work Mon-Wed. Luckily I can start on the more mundane stuff that doesn't require as much thought. I will be finishing a French drain that I started a while ago. I need to rent a jackhammer again.

There are still a couple of questions I have. If I am going to go rotary and use the utility room for a venting space, will it be bad to not have an airtight space from an isolation standpoint? I'm thinking not since airtight will not stop the very low frequencies. The reason I ask, is I need to get airflow in for the boiler and water heater.

Thanks for your input Adam! You have made some good points.

I was wondering if putting my budget out there was putting people off. It is not a hard and fast number, but I did my attic with that much, so it is not impossible. If I spend a bit more, then that's fine too. I already have all my electronics other than a $400 receiver. I know some people quote $25k and then say they will be spending $10k for their equipment and subbing everything out. What is more believable $10k for a total DIY room or $15K for a contractor built room? I think I am being realistic, but please call me out if you think I'm nuts. (I am, by the way....in a good way.)

The rotary sub would only handle 20 hz and below, and therefore be the only frequencies transmitted to the rotary back chamber. From what Ted was saying, I surmised that these very low frequencies would not be stopped by a sealed room anyway. I may have misunderstood.

I do want to do this right, so tell me if I'm not doing this the right way. The nice thing is that if I plan wisely, I could always try using the fan and see how much it carries in the house and outside. I could then reinforce the utility room, use the rotary only when it won't bother people, or just not use the rotary.

Ted, you are killing me! I have to read your posts 10 times.

Facts:
I will be isolating my HT room using all of the good methods (DD/GG/airtight/dead vents/clipped ceiling/double walls/heavy, sealed door).

An adjacent room will be used by the rotary sub to shuttle air for 20-25 hz and below.

Question:
What do I need to do to that adjacent room? Since I am only using the room for sub 20-25 hz, does it need to be sealed? Heck, would it even help?

Thanks so much for the info Ted. So my game plan looks like it will be:

Make and isolate the HT.
Make rotary sub.
After completing each of above, compare isolation performance vs Cones of Silence.
Consider further isolating utility room.

I'll play it by ear, so to speak. I'll just make sure I have room for dead vents and plan for supplies and returns.

Now that is an idea. I have not seen one that works 100% yet.

If I can build this, I figure I can build a silly little propeller.



You'd be amazed what you can build with a little lumber and steel.