Help design my sound proof dedicated theater (yet to be named) - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 54 Old 06-17-2016, 01:54 PM - Thread Starter
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Help design my sound proof dedicated theater (yet to be named)

I've been planning to create a build thread for quite some time.

I did what a lot of people have done and got my theater walls built and installed my projector and screen which has really slowed down my build progress.

My lack of skill and knowledge has caused me to have to redo things many times over and I want to put a stop to that because it has caused a lot of frustration and cost a lot more money than just doing it right the first time.

I'm at the point where I've realized I'm going to have to redo things again for proper soundproofing and although I have read 100's of AVS threads on the topic over the last few months, I still have several questions.

I've made a few videos that will hopefully help identify areas of concern and help explain my questions a bit more. The videos will also show the theater in its current state since I'm not familiar with Sketchup and don't exactly have a floorplan of the theater.

The theater in its current state is 20' x 27.7' x 7' 10" and is in a dedicated space in my unfinished basement.

The house was built in 2006 and we didn't finish the basement at that time.

The basement is divided into four main areas, pretty equally in size. There's the home theater and equipment room, directly in front of that is the lobby and model railroad, off to the side of the theater is the wood shop/workshop, and behind that is storage and a photography studio I use for my product reviews, which is another hobby of mine.

My family's last name is Evans but I really don't want to name the theater, "The Evans Family Theater" and would love some help coming up with a cool name.

My company's name is "Bulldog" (Computers & Wireless) but I don't want to go with that either.

In addition to audio and home theater (I started the popular REW thread here on AVS and am obsessed with taking acoustical measurements and learning all I can about small room acoustics) my other hobbies are model railroading and I'm starting to get into woodworking. I'm also a top Amazon reviewer and have started to review home theater products as well.

The acoustical performance of this room is more important to me than anything else, but I do also want the equipment and speakers hidden and like a modern and clean look.

I'd appreciate any advice and/or suggestions you may have that may help me increase the performance of the soundproofing efforts I'm now taking and I also need help finalizing the color scheme of the room.

So far I've just painted everything black but I'd like to go with another color for trim and haven't decided what would look best. I have no skills when it comes to Skethup or other software so I've just had to imagine other color schemes but I do know that although the ceiling and walls will be black for the best video performance, I do want a splash of color on the trim.

Thanks for looking and thanks in advance for any advice you may have!

--J
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post #2 of 54 Old 06-17-2016, 02:01 PM - Thread Starter
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Here are my questions regarding soundproofing.

I've already purchased the 12' 7/8" tall x 2.5" wide hat channel and have been in contact with Ted at thesoundproofingcompany but my questions go beyond the scope of how much he is able to help, so any effort to answer these questions "before" I start installing the ceiling and redoing the walls (again) would be much appreciated.

Any help you can give in any way would be much appreciated:

Do I start the clips/channel at each end/edge of the ceiling and each corner and edge of the soffit(s) or literally 6" in with no support at the edges? If 6" in, why is that the spec and why is there no support at the edges? I need support near the edges of the soffits to attach things like crown molding.

On the existing soffit (right side wall) that is covering wires and pipes and cannot be framed "after" the ceiling, rather must be part of the ceiling itself, should I start the channel at the bottom edges and corners or a certain amount above bottom edge and in from bottom edge of height/corners?

How many extra clips should I use to hold bass traps and a future star ceiling which will be made out of OC 703 (3lb / sq ft) or similar material? I'd like to use two layers if possible, which would be 6lb / sq ft. How many extra clips can I use before soundproofing/TL suffers?

How many extra clips should I use to hold a cloud above the stage which will contain OC703 and lighting?

How many extra clips should I use to hold the not yet built left side wall soffit for HVAC and should the soffit be made out of MDF or OSB or just standard drywall - which is best? If it doesn't matter and the performance would be the same, I like the "frameless soffit" idea as it seems easiest and quickest to build and gives me a good way of screwing on the crown molding since it's made out of OSB, but I want to build what gives me the best TL if there's a difference.

Should just the outside walls be built, then the ceiling, then finally build the inside walls after the ceiling is finished screwing the top plate for the interior walls to the ceiling to keep the decoupling or should both sets of walls be built then build the ceiling just inside the interior walls? If the latter, then there would be no ceiling (and there would be a gap all the way up to the bottom of the subfloor above) in the space between the two sets of walls. What is the best way and proper order to build the ceiling and interior walls? Does it matter or make a difference either way?

How far apart is the proper screw spacing for ceiling, soffit, and walls?

I can only afford 1 tube of gg per sheet of drywall, if that. I may not be able to do the gg at all on the ceiling, depending on the rest of the material costs. I definitely can't afford 2 tubes per sheet. Will this make a significant difference in the ceiling performance? At what frequencies, roughly?

Which brand (if that matters) and which type of screws are suggested - how many screws per clip and how long should they be for the clip, which length for the first layer of drywall, and which length for the second layer of drywall for the soffits and the ceiling?

Is it better, worse, or the same to use 3/4" osb for first layer of the ceiling so I have an easy place to screw stuff to?

The video will explain this (by showing it) much better, but I need to know if it would be better to take down the existing outside walls and reframe them with IB-3 clips under the headers so both sets of walls are decoupled? Is it better to have BOTH sets of walls decoupled or would it make a difference if only the inside walls are decoupled? The existing outside walls are built just plain wrong in every way. They are coupled "everywhere" and are 16" on center, the drywall is on the inside instead of the outside, etc. So I don't mind tearing them out and redoing them if it will make a difference, but the question is does it matter or make any difference as long as the inside walls are built correctly, or would it be best to just tear down the existing walls and start over? SEE VIDEO:

Again, the video explains this much better and makes much more sense, but is it ok to run two HVAC supply ducts in one extra wide (2') decoupled soffit? I was thinking of bringing one supply duct (6" insulated flex) from the rear left of the theater (in from the top corner of the wall instead of down through the ceiling) and bringing the second supply duct in from the front left of the theater (again, in the top corner, through the wall, not down from the ceiling), each passing each other in the same 2' wide soffit so the duct coming in from the front wall would terminate in the rear of the room close to the back wall and the one coming in from the back wall would terminate in the front of the room near the front wall. This would create two 6" holes which, when seated, facing the screen, they would be the top left corner of the front wall and the rear top left corner of the back wall, but both holes/duct work would be covered up with a soffit built after the ceiling is built. Building them this way would allow the duct runs to be very long and both would be run in the same soffit. This way there wouldn't have to be any penetrations in the ceiling at all. Is this advisable? If I do it this way, other than wrapping the 6" insulated flex duct with more insulation, is any other prep work necessary or is there a better way to run the ductwork? No matter what I do there has to be two 6" penetrations "somewhere" and although I've researched this and thought about this a lot, I just cannot grasp how (even with this plan) my soundproofing attempts won't all be negated by bringing the ductwork in, no matter where I bring it in or run it. What do you think of this plan? SEE VIDEO FOR CLARIFICATION PLEASE -

As shown on the floor plan, the front wall is only one wall and a double wall hasn't been planned. The current wall is about 12" in front of the poured concrete foundation wall, so do I need a 2nd (interior) front wall or is one ok and can I just build a second wall for the side walls and back wall since they aren't near the foundation?

What is the cheapest kind of caulking I can use (and how much do I need) for the ceiling to wall joints, bottom of drywall to floor, etc.? Can you recommend a certain make/model?

For dead vents, I see a 6-in PVC Pipe is used to go from the inner (theater side) wall through the double walls and into the dead vent. How far inside the dead vent should the PVC pipe protrude? In my area a 6-in 20' (smallest I see) PVC pipe is almost $100 with tax. Is there anything I can use as a substitute for PVC pipe that will work similarly such as steel round duct pipe which is only $4.00 for a two foot section? Can I not just use flex duct for everything?

I've been thinking about using steel studs for the interior walls because they will be flat, won't warp, and I believe they will be easier to work with and get perfectly straight walls. Is it better to use steel studs for interior walls, though? Can I expect better performance and TL/soundproofing with steel studs? Are there any downsides or reasons I shouldn't use steel studs?

This question is much better explained in the new video, too, but I'll try to ask it in writing as well. Whether I use wood or steel studs, how do I attach them and the drywall to the headers? Please see the video for a better explanation of this question because other than the HVAC ductwork and the soffit for it, this is my biggest and most important question, I believe. I'm really afraid of not understanding and getting this wrong again and it costing me a lot of money and time to fix if I don't do it right again as this is already the second time I'll be building these walls.

Basically, I'm still not sure how to work around the headers which are the demarc points for the width of the room right now and are exactly 20' apart. The existing side walls are built directly below the headers and aren't decoupled from them at all. The top plates for the walls are screwed to the bottom of the headers. (Headers are made out of 3 2x12's with a piece of ply sandwiched in between each layer and held up by metal posts every 12' or so.) So the existing walls are only 80" tall and the rest of the height up to the bottom of the floor joists is made up by the headers themselves. Is this ok for the interior wall? The exterior wall, too? I could use IB-3 clips to decouple one or both walls from the headers, but even if I do that the header itself would still be the actual wall from 80" on up to the floor joists. I could add drywall to the headers. I could add clips, channel, and drywall to the headers, and lose a few inches of width. Or should I lose all the space, making the room about 18' wide instead of 20' wide and just build the walls up to the ceiling (in front of the headers) after the ceiling is decoupled and fully installed so nothing touches the headers? What would you do? Have both walls "under" the headers, one wall under the header and one in front, losing about 6" of width on each side, or neither wall under the header, losing the max amount of width?

Again, this is a difficult thing to describe so please see the video which will show exactly what I mean and am asking. SEE VIDEO FOR CLARIFICATION PLEASE

I'll put the videos in the next post.
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post #3 of 54 Old 06-17-2016, 02:02 PM - Thread Starter
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post #4 of 54 Old 06-17-2016, 02:02 PM - Thread Starter
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This video better explains my HVAC questions and hopefully my other questions as well.

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"Which brand (if that matters) and which type of screws are suggested - how many screws per clip and how long should they be for the clip, which length for the first layer of drywall, and which length for the second layer of drywall for the soffits and the ceiling?"

Deckmate
depends on the model clip some use one some use 2
with engineered joists (per video) any thing longer than 1 5/8 is not necessary.

screws for drywall into metal channel, first layer 1 1/4 second layer 2 inches. I like the Grabber brand designed for light gauge metal studs (Fine Thread)
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post #9 of 54 Old 06-17-2016, 02:35 PM - Thread Starter
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Thanks Big,

I have a Lowe's 5 minutes away but the closest HD is an hour away so I'll check out Lowes.com and see if they have those right now.

I appreciate your time and interest.

I'm really trying to figure out if I need to tear down my existing side walls (built "under" the header) or if I can leave them and just build new walls in front of them attached to the ceiling once it's installed to get my decoupling that way.

Thanks again,

--J
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post #10 of 54 Old 06-17-2016, 02:36 PM - Thread Starter
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I've put a few pictures of the theater in its current state in post one but they only show up as thumbnails and even though I rotated them and saved them before uploading, they're also upside down.

Does anyone know how to make them big and rotate them?

Thanks,

--J
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post #11 of 54 Old 06-17-2016, 02:38 PM - Thread Starter
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I've found what looks to be identical clips to the IB-1 that thesoundproofingcompany sells for $2.25ea for only $1.75ea at Trademark Soundproofing.

http://www.tmsoundproofing.com/TMS-V...lips-A237.html

These are the Resilmount A237 clips. Has anyone used these before?

Thanks,

--J
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post #12 of 54 Old 06-17-2016, 04:22 PM
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post #13 of 54 Old 06-17-2016, 04:23 PM - Thread Starter
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Me too, and $.50 adds up when you need a bunch. Hopefully this savings will help me get the green glue so I don't have to skip that step.
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post #14 of 54 Old 06-20-2016, 12:48 PM - Thread Starter
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One of my main questions that I need answered ASAP by anyone who knows for sure is whether both of the walls need to be decoupled or if it is ok to only decouple the interior (theater side) walls.

If anyone knows the answer to this and can help out I sure would appreciate it.

How much of a difference does it make if both sets of walls are decoupled vs just the interior walls in a double wall setup like I'm building?

Thanks a bunch.
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post #15 of 54 Old 06-20-2016, 01:10 PM
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Decouple the theater side walls in double wall construction, that keeps the theater wall vibration from shaking the joists. Doing the other won't hurt nor really help.
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post #16 of 54 Old 06-20-2016, 01:11 PM - Thread Starter
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post #17 of 54 Old 06-20-2016, 01:19 PM - Thread Starter
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Another thing I'm a bit confused on is the order in which to do things.

My plan (but I need corrected if this is wrong) is to have the four exterior walls built (and they will be coupled - just using standard construction) and then build the ceiling.

After the ceiling is finished (clips, channel, 2 layers 5/8" drywall) then I was planning on building the interior/theater side walls under the ceiling and attaching to the ceiling to get my decoupling that way.

Since the ceiling itself will already be decoupled, by attaching the top plate of the interior walls to the ceiling, I will maintain the decoupling.

Is that right? Can I do it this way? If not, how should I do it differently?

This way the ceiling will extend all the way to the exterior/coupled walls instead of there being a void between the two walls.
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post #18 of 54 Old 06-20-2016, 04:40 PM
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there is actually a flaw in your design. The ceiling drywall which is mounted on clips and channel should not touch the surrounding coupled framing or other structural items like the rim joist or sill plate. It should float without touching anything otherwise vibration could be transferred. I use 1/2 scraps of wood as temporary spacers when hanging the ceiling drywall.
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post #19 of 54 Old 06-20-2016, 04:42 PM - Thread Starter
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Thanks Big,

So as long as I don't allow the drywall (or channel obviously) to touch any of the existing walls, leaving a 1/4" gap (that's what was planned, but I can increase it to 1/2") my plan would be ok then?
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post #20 of 54 Old 06-20-2016, 04:44 PM - Thread Starter
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My plan was only for the interior/decoupled wall's top plate to touch the ceiling. That's how I planned to get by without having to buy IB-3 clips and without having to redo what I have already done (which is the exterior/coupled walls...They're already built).

I hope my plan will be ok so long as I don't let any of the drywall or channel touch the outer walls but if not, is there any other way I could do it without having to redo what I've already done?

Thanks a million for all your help.
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post #21 of 54 Old 06-20-2016, 04:46 PM
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1/4 is fine, my experience is when you try to do 1/4 inch due to irregularities it will actually come in contact somewhere.
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post #22 of 54 Old 06-20-2016, 06:48 PM - Thread Starter
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That makes sense, so I'll shoot for 1/2" then and more than likely end up with 1/4" in some spots.

I can then use that rubber backer rod stuff and caulk for the edges. Is that advisable?

Other than that, is my plan to do the ceiling install, then last do the interior/decoupled walls with the top plates of those walls attached to the bottom of the ceiling for decoupling ok? Any issues with that?

Thanks so much for all your help. I really appreciate it.
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post #23 of 54 Old 06-20-2016, 07:53 PM
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personally I wouldn't want wall framing attached to the drywall at the top, assuming it is rigid enough if you screw into the channels, in the event of a burst pipe and the need to replace the ceiling you're pretty much fracked.
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post #24 of 54 Old 06-20-2016, 08:00 PM - Thread Starter
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That is a good point.

I don't know how else to do it since my first (coupled/outside) walls are already built though.

I totally understand what you are saying about a burst pipe, but the interior (decoupled by attaching to ceiling) walls would only be 6" in front of the coupled/outside walls and there is no pipe of any kind in between the two walls.

Am I missing something else? I feel like I am.

If there were ever a burst pipe somewhere out in front of the walls, I'd just have to remove that section of drywall for access and I'd have to do that anyway no matter where the walls were, right?

I'm not trying to argue for doing it this way (well, I am, but I want to know all the caveats at least) but I honestly just don't know how else to do it since I don't have the budget to do it all at once and am doing it in sections and trying to get it buttoned up a little at a time since the outside walls are already built.

Other than a burst pipe, just thinking of soundproofing reasons only, is there any reason to not do it this way, with the interior wall's top plates attached to the bottom of the ceiling for decoupling?

Thanks for reminding me about access, though, as it is something to consider.

--J
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post #25 of 54 Old 06-20-2016, 08:02 PM - Thread Starter
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By the way, the walls will not be screwed into the ceiling directly, rather they will be screwed to the underside of decoupled soffits.

The soffits extend 2' into the room on either side wall due to duct work and pipes so the interior/decoupled wall will be built up to the bottom of the already decoupled soffit and attached to it.

So the wall won't go all the way to the ceiling. Is this ok?
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post #26 of 54 Old 06-20-2016, 08:05 PM - Thread Starter
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So that means the ceiling itself will only be 16' wide with a 2' soffit on either side wall which totals the 20' width of the room.

The first/exterior/coupled wall is built under a beam that holds the floor above up (seen in the second video) and I plan the interior/decoupled wall to be built to the bottom of the decoupled soffit which just so happens to be the same height as the beam as it is about 11" tall. The bottom of the soffit will be at the same height as the bottom of the beam.

The video explains or at least shows what I'm working with much better.

Does this make sense?

I don't know how to build a wall all the way to the top of the ceiling and do the soffit later because too much "stuff" is in the way, which is the reason for the soffits to begin with, which is why I'm planning to do it this way.

I hope this plan makes sense and will work.
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post #27 of 54 Old 06-20-2016, 08:50 PM
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The normal way to build a room with in a room with decoupled walls and ceiling is to first frame up the inside walls, frame them one inch short and anchor the top plate with IB3 clips every 48 inches If you are doing double wall framing set the inside wall one inch inside the outside frame.

Then add clips and channel to the ceiling inside the framing

put up a layer of DW on ceiling not touching wall framing
put up a layer on the walls Caulk the seams
add 2nd layer to the ceiling with GG and screws
add the 3nd layer to the walls
Caulk
finish drywall normallin areas where it will be visible.
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post #28 of 54 Old 06-20-2016, 09:18 PM - Thread Starter
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But what about when you have "stuff" in the way on both side walls (that method will work for my front and back walls, though) that requires a soffit that must be built before anything else, meaning clips/channel/drywall will have to go on the "outside" of the soffit in order to get decoupling?

What would be the normal method then?

No matter how I do it, I can't see how I can get by without building the soffits first then building both side walls underneath and connecting to the bottom of the soffits.

I guess my question is this. Even though it isn't the normal way, am I missing any coupling issues and/or is there any reason my way of doing it won't work?

I realize it isn't the normal way of doing it but I truthfully cannot figure out the "right" way of doing it when soffits have to be built first.

I want to thank you again for all your time and answering all my questions. It means a lot. If I can ever be of assistance to you in my field of expertise (REW and in room measurements/acoustics), let me know. I owe you!

I guess I'm just looking for an, "Ok that isn't the normal way, but I don't see why it wouldn't work" OR an, "Here's what you're missing and why it will NOT work."

I've read the SIM manuals on soffits and the IB-1 clips and just don't see any way to do it by the book with my weird and big soffit locations but I'm all ears and would love to learn.

Thanks again,

--J
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post #29 of 54 Old 06-20-2016, 09:24 PM
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If your walls can't go all the way up you use the IB3 clips horizontally from an outside wall or the foundation. build your walls and ceiling with a gap in the corner. Then hang a soffit box off the decoupled ceiling and the decoupled walls Hiding the gap.
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post #30 of 54 Old 06-21-2016, 03:27 PM - Thread Starter
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This is where I get confused.

So when you say exterior walls, you mean the outside walls that are already built/coupled?

I'm calling exterior walls the outer walls and interior walls the walls I can see from inside the theater.

So in my case, since I have soffits on both sides, you're saying I need to have the outer walls AND the interior walls built with IB-3 clips?

The soffits are already built. There wouldn't be anything to attach IB-3 clips or anything else without them due to the pipes and things you see in the video.

So since I've already built the soffit, I could attach the new interior wall (yet to be built) to the bottom of the soffit with IB-3 clips but the outer wall is already built under that beam and attached to the bottom of it. I thought it was ok because the outer wall didn't have to be decoupled?

Sorry for being dense. Let me know if based on what I've just described I understand what you are saying correctly.

Thanks!
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