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post #1 of 34 Old 07-31-2018, 11:11 AM - Thread Starter
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Mad Hacker Theater 2.0 - Build Thread

Greetings all,
Almost two years ago my wife and I moved in to our new home, complete with a finished bonus room which was set aside for a DIY dedicated theater. Building a room like this had been a dream of mine since I was a teenager, and something I started planning for around 15 years ago when I first joined this forum. Believe it or not I have old Visio files with early concept sketches dating from 2008 for that "some day in the future" when I might get this chance. I've learned a ton over the intervening years, the plans have been reworked time and again as the state of the art changed, and of course once we found the right house I had to redesign around the room's layout. In any case, I've spent 7 months working on our theater now, and I hope to have everything finished around the end of the year. The time seems right to make use of all the photos I've been taking and get a good build thread started to show it all off!

Just for reference, in our first house we had a shared theater / living room space set up for 9.2 with PLIIx. I previously posted a mini build thread for my DIY 110" scope screen and A-Lens for that room here. I don't have a great photo of that room properly set up, only this ugly one when it was in the middle of a re-layout and re-wire:

So I'm calling that room '1.0' and plan to do significantly better this time around with 2.0!

This first post will act as a placeholder for a future table of contents. I'll come back later and edit with links to sections of the build as it grows. Fortunately, since much of the work is finished the juicy parts shouldn't get too spread out or hard to follow. At least not at first . Here's what I plan to cover, following the general order in which I built the room up:

Phase 1 build:
1.) General design and layout [LINK]
2.) Infinite baffle enclosure & screen wall [LINK - Part 1][LINK - Part 2]
3.) LCR speakers and subs [LINK]
4.) Seating riser [LINK]
5.) Bass traps [LINK]
6.) Surround and Atmos speakers [LINK - Part 1][LINK - Part 2]
7.) In-wall wiring [LINK]
8.) Equipment rack & gear [LINK]
9.) Acoustic treatments [LINK]
10.) Projection screen [LINK]
11.) Theater seats [LINK]
12.) Window treatments (complete)
13.) New projector (complete)
14.) Ceiling treatment (20% done)

[GRAND OPENING 10/14/18! - First movie watched: Ready Player One UHD]

Phase 2 build (planned upgrades in various states of design):
15.) Side cabinets and countertop
16.) Cine-bar & rear seating
17.) Decorations & accessories

There have definitely been surprises and compromises made along the way, even a couple mistakes. Some of you might find some "If only you had done this instead of that!" moments. Go ahead and lay it on me. Even though it's likely too late to change, I welcome the critique and I'll be happy to explain my thought process for the decisions I made.

I'm looking forward to start adding to this thread, hopefully some of you will be interested in reading it!

Last edited by Magius; 11-04-2018 at 07:00 AM. Reason: Adding links to TOC
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post #2 of 34 Old 07-31-2018, 07:30 PM - Thread Starter
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General Design and Layout

Alright, time to get started. Before we get into the details of the build, here are a few pictures of what I had to work with. First the house itself:

Mine is the one with all the solar panels It's a 2-story house on the right, with a covered porch connecting to the 2-car garage on the alley to the left. On top of the garage is the bonus room which will become the theater. We thought this was great because it's detached from the main living space, and should provide some isolation if someone wants to watch a late night movie while the others relax. We lucked out that none of the nearby neighbors opted for a bonus room or apartment over their garages, so there's less opportunity to bother them with our noise.

Here is the floorplan of the bonus room. I did not install the optional desk or wet bar, though the included bathroom was a great feature. No running over to the house when nature calls:

Our room is actually a mirror image of what you see, with the stairs and bathroom on the right, but it's otherwise identical. The builder's PDF only shows the one orientation

Finally, here is the virgin territory from inside the room itself just waiting to be conquered:

The builder had a very limited selection of paint colors, so I chose the darkest one they had. It's Sherwin WIlliams Cityscape, and it's something of a bluish-gray. It looks darker in the picture than it is to the eye, but so far it seems like it will work and I shouldn't have to repaint the whole room for light control.

Early on I decided not to do any soundproofing. I had done all the research and knew how to do it right but I didn't want to sacrifice the room dimensions building new walls and ceiling all around, and it also didn't come close to fitting within my budget. Go ahead and give me flak for that.
I'd also decided long ago that an IB sub was the only way to go in the new theater, so the first question was where to vent it. I didn't want to go into the garage below, so the attic above was the logical choice. That said, I'd never really been thrilled about installing ceiling-mounted subs, as hard as it can be to work in the attic. Instead, my early plans had been to get a room long enough that I could sacrifice some space up front as a baffle wall. This would allow me to form the IB enclosure from a front slice of the room and as a bonus would also take care of the window placed right behind where I wanted the screen. If only you could have seen my wife's face when I told her the plan was to build a new wall across the front of the room.

So here's the basic layout I was looking at, without the clutter of dimensions:


Once I'd settled on the basic layout, I spent a good amount of time crawling around in the attic measuring all the possible obstructions. The room has recessed lights, junction boxes, two ceiling outlets and of course HVAC vents. Before I got too far into the design I wanted to make sure none of these would interfere with my planned locations for Atmos speakers. In the end I had to move the ceiling speakers around a little in the plans to ensure I could later expand to 6-way Atmos without any joists or obstructions being in the way.


So that's basically it for the high level layout. I don't want to spoil too much by showing more detailed drawings just yet. Next up I'll get into the IB enclosure & screen wall. Hopefully I'll be able to add a post every couple days after I collect the pictures and add annotations. From here on out it should get a lot more detailed...
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post #3 of 34 Old 08-01-2018, 07:44 PM - Thread Starter
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IB Enclosure & Baffle/Screen Wall

If it's not obvious already, nothing gets done in this build without plenty of pre-planning and to-scale modeling. This helps me make sure everything will come together the way I want, and also helps me generate parts lists for supplies as well as preliminary cut lists. The wall itself is standard 2x4 framing with 16" centers, except for two stud bays that are slightly narrower. I did it this way to maintain symmetry around the center rather than have an odd bay one one side or the other. The stud bays were insulated with standard R-13 rolled insulation. Both sides of the wall were meant to be sheathed with 23/32" OSB and then covered with 5/8" drywall for both stiffness and mass. My local Home Depot was unable to order the OSB, so they substituted 19/32" plywood and discounted it to match the OSB price. I ran the OSB horizontally and the drywall vertically to avoid any overlapping seams, and because I have 10' ceilings I used 4x10 drywall to avoid unnecessary joints. Here are the pics of the framing, insulation planning, and plywood/drywall cut sheets:



With all the major construction supplies identified for both the baffle wall and riser I placed a large order at Home Depot for delivery. The driver did a great job getting the stuff into my garage, since the forklift was too tall to drive inside. He even pushed it forward a little so the door could come down. Unfortunately, since he couldn't rotate the pile we couldn't even fit one car in there afterwards. The wife was not pleased so I ended up moving everything off the pallet one piece at a time to either the covered porch or the side of the garage. Here's what just under two tons of wood and drywall looked like when he dropped it:


I found that if I pushed REALLY hard with my studfinder I was able to detect the floor joists, so I marked those with tape and got to work. I didn't pull up carpet or anything, just cut a notch into the baseboard and started framing:


This is where it started to get tricky. Once I completed framing out the wall there would be no getting sheet material to the other side to sheath it. So all of the plywood and drywall necessary for the backside of the wall had to be pre-cut and staged back there. In the left picture you can see I have it all staged and have hung the first pieces of plywood on bottom, then in the right picture the remaining pieces are hung. You can also see I haven't added the lower crossmember to the center section yet, as that would make it harder for me to duck under and walk back and forth :


The next step was to drywall the back side, which you can see in the first picture. At this point I had cut out the space for the left subwoofer manifold and was using that as passage behind the wall. The second shot is after all drywalling was done on the back side, and all cuts had been made for the future speakers, subs, and access hatch. The sub manifolds are sitting in front of their locations for test fitting:


Insulation came next, followed by plywood on the front side of the wall, and finally drywall. At this stage I was also test fitting the front left and right speakers, since they had to be installed at an angle for proper toe-in. The sheet material was cut at an angle to match them as closely as possible, and gaps were sealed with caulk in the rear and later drywall mud in the front. As you can imagine, there is no intention of ever upgrading these front speakers.


One final shot of the "finished" wall, prior to tape and mud. With the speakers installed and subs laid out this should serve as a great teaser for the next post.
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post #4 of 34 Old 08-01-2018, 08:38 PM
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Looks great. Did you do anything with the window in the IB chamber and have you run a full volume test?
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post #5 of 34 Old 08-01-2018, 09:28 PM - Thread Starter
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Thanks Jeff! I was going to call you out in a few posts when I get to the riser part of the build. I shamelessly stole your design approach and it worked out great! As far as the window in the IB chamber I didn't do anything to it. I had a couple concerns about it but I found ways to address both.

First, I was concerned that the pressure of the IB might crack the glass. As a long time lurker at the Cult of the IB I remembered an old thread where someone wanted to build a wall similar to mine with a sliding glass door behind it. ThomasW all but guaranteed them that the door would be blown out of the house Unfortunately, since all the posts prior to their proboards transition are lost to history, I was unable to locate that original thread. I ended up posting over there while downselecting builder floorplans, to ask whether a window behind the wall would be a problem. He chimed right in and told me that a standard sized window would be fine, given the low relative glass to wall surface area. The other concern I had was completely sealing off the front of the room, while allowing light and heat in through the window, creating somewhat of a greenhouse. I wasn't sure if that could lead to condensation and mold, etc. So to prevent that I installed an air register at the top of the wall, and of course I have an access hatch at the bottom of the wall which isn't air tight. The thought was that natural convection should draw in cool air around the hatch, and allow hot air to escape at the top, which happens to be right next to the A/C return vent. By allowing air to circulate hopefully there won't be any moisture issues.

I'm not entirely sure what you mean by a full volume test, but the speakers after Audyssey calibration can definitely hit reference level. I was testing some movie clips this evening, running at -5.0 and when it got loud the SPL meter hit 99dB, so that's just about right. I was shocked how loud it actually was considering how clean and comfortable it sounded. In the past I never listened anywhere near reference level, usually -20 and at most -15. I will admit though, when I went up to -2.0 tonight things started sounding a little harsh to my ears.

The subs aren't re-calibrated at the moment so I don't know what their peak levels are, or how low they would be able to dig while measuring 115dB. A few months ago I was playing with them, prior to acoustic treatments in the room, and with a calibration target of 80dB they could EQ flat with the -3dB point just under 5Hz (pre-EQ graph below).

Given the crazy amount of room gain there, I'd guess I can probably get to ~15Hz at reference level, but that testing will have to wait for another day. Of course I also have some work to do to get rid of those room nulls around 46 & 82 Hz. I have some future plans that might involve a couple of 12" subs to fill in those holes...
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post #6 of 34 Old 08-02-2018, 04:55 AM
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The reason I asked is even though you don't have any neighbors in the near field around the garage, you still have neighbors and low frequency sound waves can do some crazy things. The topography and the surfaces of adjacent structures might set up some standing waves. When you get a chance put on a track with some serious bass and take a stroll around your neighborhood just to see what might be in your future.
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post #7 of 34 Old 08-03-2018, 08:32 PM - Thread Starter
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I see what you meant now about the test. It turns out I did that kind of test early on, and I was quite surprised by the results. I put on some thumpy EDM music and turned it up much louder than I'd normally listen to it in room. Just a little below reference I believe. I then went outside and walked around the perimeter of the garage area, and really couldn't hear much of anything. In my own garage just below the theater I could definitely hear the thump-thump-thump, but out in the yard it was nothing. It's not quite representative of the low frequencies of an LFE track, but it was easier to guarantee a steady stream of high output using music vs. a movie. In addition, I would suspect the neighbors to be less upset by a single low rumble a few times an hour than a steady stream of bass heavy dance music. So overall I think I'm going to be alright.
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post #8 of 34 Old 08-03-2018, 08:39 PM - Thread Starter
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LCR Speakers & Subs

As seen above, the front three speakers and my two sub manifolds had to be built into the baffle wall. If it wasn't obvious, I went with three HTM-12's from DIY Sound Group, and four Fi IB318v2's for the subs. Anyone who's even considered buying from Erich before knows about his legendary packing, but it doesn't seem right to have a build thread without a picture, so here's what unboxing a single HTM-12 looks like:


There are a million other places to see assembly threads for DIYSG speakers, so I won't belabor that part here. Just two quick pics showing how I used denim batts in the cabinet, placed the crossover on the side wall, and simple banana plugs out the back:


Building the manifolds got a little more interesting. The boxes can be seen in earlier pics, and they're made from 19/32" plywood on the inside laminated to 3/4" MDF on the outside. Cutting the hole for the subs was a challenge, as I'd never used a router prior to this project. I received the router as a housewarming gift and the circle jig as a Christmas present, both off my Amazon wishlist As many of you know, what I was trying to do here was fairly simple in theory. Using a 5/8" straight bit and the circle jig set to 18 1/8", I wanted to clear out 3/4" deep to where the MDF met the ply. Then I wanted to reset the jig to 17 5/8" and do the same thing to widen the lip where the subwoofer would eventually sit. Finally, using a 1/8" straight bit and the jig set to 17 5/16", I wanted to cut all the way through the ply, removing the circular plug. Here are two pictures showing the results of the first step and the final step, now ready to mount a driver:


The eagle eyed among you might be wondering about the odd divot just left of center in that second picture. That was the result of the first major mistake of this project - not respecting the power of my new router. Since I was doing this indoors, my process was to hold the router firmly with one hand and follow it with the shop vac in the other hand. That coupled with trying to clear too much depth of material at once caused the router to stick and jump straight out of my hands. It skipped across the box (away from me, thankfully), made that divot and ended up on the floor . Luckily it stuck the landing and only made one hole through the carpet into the subfloor while I ran to yank the power cord.


At the end of the day it could have been a lot worse, and it turns out the sub fit the opening like a glove. Plenty of room around the surround and a nice snug fit against the basket.


When I finished routing both manifolds I screwed them into their places in the wall, at which point they became a favorite plaything for my daughter . I then used grill clamp kits from Parts Express to mount the drivers. Eight clamps per driver, screwed down into T-nuts, and it's absolutely solid.


With everything installed in the wall I decided to get some baseline in-room measurements with REW, so I could compare against results after later applying room treatments. I have a calibrated UMIK-1 as well as the Audyssey mic on my tripod in this photo, and that should just about complete this section!
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post #9 of 34 Old 08-03-2018, 09:02 PM
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my issue with a side wall being out of sync/farther away causes huge variance from L/R freq response. good luck with getting them same, I have seen members get it done, but I cant

Power: Marantz sr7008, NAD C 275Bee x 2, Video: Oppo 103, Samsung 75un6300
Speakers: Focal aria 948, Focal cc900, Klipsch synergy KSF 10.5, Magnepan LRS
Subs: Rythmik FV25HP, Rythmik FV15HP
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post #10 of 34 Old 08-03-2018, 09:05 PM - Thread Starter
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Oops! I forgot to include this pic from behind the wall after the speakers and subs were installed. You can see I didn't bother to finish that side (tape & mud), and as of yet I haven't insulated it either. I expect to have some leftover insulation and I plan to stick it back there for lack of anything better to do with it, but I elected to ignore the advice that said I should line the entire cavity, like you would the inside of any normal enclosure. I can always go back and do that after the fact if I choose.
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post #11 of 34 Old 08-03-2018, 09:08 PM
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post #12 of 34 Old 08-03-2018, 09:09 PM - Thread Starter
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Quote:
Originally Posted by torii View Post
my issue with a side wall being out of sync/farther away causes huge variance from L/R freq response. good luck with getting them same, I have seen members get it done, but I cant
Yes this was a huge concern of mine with the initial floor plan. I'm not going to ruin the surprise just yet, but I'll say that I did in fact solve this problem, and my L/R surrounds will be perfectly matched. Thanks for posting, and stick around a while to find out my solution!
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post #13 of 34 Old 08-03-2018, 09:15 PM - Thread Starter
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Quote:
Originally Posted by mikela View Post
Looks all too familiar
I love your theater Mikela, and congrats on HT of the month! You even got the name perfect for that black hole of yours, lol.

Who knows, maybe someday I'll install two more manifolds above the existing two and turn my baffle wall into more of a bass array like yours.
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post #14 of 34 Old 08-04-2018, 05:52 AM - Thread Starter
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IB Enclosure & Baffle/Screen Wall - Part 2

With the speakers and subs installed it was time to finish (ie: tape, mud, paint) the wall. I've never done drywall before and I honestly didn't really try, which I now regret and consider my second mistake. I didn't own a sander then, so I made no attempt to sand down the mud and the seams definitely came out lumpy. Fortunately, 90% of this wall will later be covered by acoustic treatment and/or the PJ screen, but it still bothers me knowing I could have at least tried to do a better job. Here are some pics of the mudding process, and you can see I mudded the speakers right into the wall to ensure no air gaps around them.


The entire wall then got two coats of primer, since I could see the mud stripes through the first coat, and I had half a can left with no other plans for what to do with it.


Next I had to choose a paint color. Who knew there could be so many versions of black!? I went to Lowes, Home Depot and Ace Hardware and took every sample card they had in the black family. I then slimmed down the choices by holding a few next to each other at a time and removing those that looked "too red", "too green", "too brown", etc. I don't remember exactly which one I chose in the end, but it was one of the Benjamin Moore's, maybe 2129-10? Flat black of course, and I ended up going with the cheapest off-brand paint I could find at Ace because I had a coupon. That I consider my next mistake. The paint was super thin, barely covered anything and took 4 coats before I was reasonably happy with the outcome. Going on wet it looked great, super dark, but once it dried it appeared lighter, and any roller marks were painfully obvious. In addition, if you touch the wall, just rub your finger down it, it seems to alter the color as if some of the paint scrubs off (though there's nothing on your finger). I should have just spent the extra $10-$15/gallon on my 2 gallons and gotten a good paint.



At this point I was down to just finishing touches for the wall. First, I colored the HTM-12 woofer rims black with a sharpie. This will probably make no difference in the end, but I didn't want anything reflective behind the screen later and it was an easy enough thing to take care of now. Next I built a "plug" for the access hatch at the bottom of the wall. It's built from layers of scrap MDF and plywood sandwiched together, with drywall on top. I was careful to preserve that piece of drywall when I originally cut the opening for the hatch, so it's a good fit. I also added two cabinet handles which my home builder had left behind as extras, and some baseboard to match the trim around the rest of the room. It's not ideal to have shiny white baseboard on the screen wall, but it's quite a distance from the screen and I like the aesthetics compared to the stark rough bottom of the wall itself.


So here's the final photo of the almost finished wall. I don't have a picture of it, but I later came back and applied crown moulding (painted black) to the top of the wall, to cover up the ugly mess where my drywall met the ceiling. The other final touch was a drop-down "speaker grill" for the manifold throats. I put some magnets in the wall just above the holes and sandwiched some burlap fabric behind the baseboard at the bottom. Then at the top with some scrap baseboard (painted black) I have a screw and washer to be attracted by each magnet. So in normal operation the large holes are covered, but when I want to show a friend the massive 18s the grill pulls down away from the magnets. With the plug installed in the access hatch it's clear that I haven't run cables through the attic and behind the wall yet, so I still had to pass them through the hatch. That will all get cleaned up in a future post.
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post #15 of 34 Old 08-05-2018, 12:04 PM - Thread Starter
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Seating Riser

I'll be honest right up front. I wanted a riser because I think they look cool, not because I necessarily needed one. I don't intend to have a row of seating in front of the riser, however in emergency scenarios (kid's birthday, big game watch party, etc) I could throw temporary chairs in front and not worry about blocking those behind. In addition, I was interested in experimenting with the riser as a large bass trap, whether or not that concept has been fully accepted or proven in the community. So, for good reasons or bad, there was going to be a riser in my theater.

The concept of my riser design borrows heavily from Dennis Erskine's advice and the article he published years ago. The practical construction elements are heavily influenced by Jeff, aka BIGmouthinDC. I didn't build mine exactly the way these gentlemen might have, but the advice they imparted here was invaluable to me.

I did the calculations for the riser height as if there would someday be a front row of theater seats on the floor in front of it. It'll never happen, those seats would be far too close to the screen, but why not at least prepare for the worst case scenario? Using my wife's seated eyeball height as the model, it said that the riser only needed to be 8" tall. As such I decided on 2x8's for the perimeter (7.25") which when added to two layers of 19/32" plywood gave a height of just under 8.5". I was definitely not going to put in a step, regardless of code saying that's about 3/4" too tall. Since both of my seating rows would be on the riser, it also needed to come relatively far off the wall. I wanted there to be 4 feet or so between the rear row and the rear speakers, so the riser needed to be around 10' deep. To make it easy on myself I decided to use uncut 10' boards for the hangers/joists, which added to the two 1.5" 2x8 perimeter boards gave a total riser depth of 10'3". The joists were hung on 16" centers except for the two closest to the perimeter. This allowed me to easily fit 14" floor registers between each joist, hopefully allowing plenty of air exchange with the bass trap beneath. I also decided to overhang my plywood layers by 2" on each side, leaving room to staple the carpet underneath as well as add an LED light strip.


I planned for two layers of plywood decking on top of the riser, one laid horizontally and one vertically to minimize overlapping seams.


All of this design and planning was done long in advance, so that I could put in the one large delivery order from Home Depot to build both the baffle wall and the riser. With the plans out of the way, time to get into the building.

For the joists I hung regular 2x4's, ensuring a good air gap through the bottom of the entire riser space. Mid-span supports were installed using leftover 2x8 from the perimeter boards. As with the baffle wall, I didn't put anything under the riser, just started framing on top of the existing carpet. Once the woodwork was done, I installed the first roll of pink fluffy insulation.


Here's where I should mention that while the house was under construction I paid the builder to install a floor outlet in this area, somewhere around where I thought the middle of the riser would be. I didn't want to go the traditional route and use an extension cord or similar to "plug in" the riser to the wall. I wanted the electric to be done correctly on the inside. To that end, at this point I removed the floor outlet and installed the existing wire in a junction box. I then wired up four runs of Romex to distribute the power where I needed it.


The plan was to install two floor outlets in the riser deck to power four recliners, one outlet in the front corner to power LED lighting (see far left of second photo), and leave one wire capped in the riser near the box for later use in a Cine-bar. Once the wiring was done I laid in the rest of the insulation.


In order to make sure I could find these wires again later I took measurements and made myself a map :


The decking was straightforward. A layer of plywood oriented vertically, a layer of roofing felt laid horizontally, a second layer of roofing felt vertically, and finally a second layer of plywood laid horizontally. Many folks recommend green glue instead of the roofing felt between layers, but the felt is a cheaper alternative that seems to work well. Many also recommend three layers of plywood instead of two, but this seemed plenty solid in my opinion. In combination with the literally hundreds of screws I used through the decking, there are no creaks, no flexing, and no other unwanted noises or movement. The riser is solid and silent.


Thanks to that map I was able to easily find the wires underneath for my floor outlets. There's nothing like cutting the outlet hole with a jigsaw and seeing the coil of wire exactly where you expected it to be At this point I also had a realization about how sharp the corners and edges of the riser were. Having never owned a router before I hadn't thought of rounding off the edges previously, but that thought came to me now and it turned out to be a good one. I included a before and after of the corner for comparison.


Pad and carpet came next, as well as the required holes for 14" floor registers between the joists. I ended up with eight along the rear wall and 4 down the side wall, which I hoped would provide plenty of acoustic access to the insulation below. For anyone on the fence about building vents in their riser like this, I rationalized it this way: If you're building a riser anyway, you're probably planning to fill it with insulation (I hope!). Construction wise, the only adjustment you might need to make is to ensure your joists are smaller than your perimeter boards to create one continuous airspace, which actually saves you money. At that point, cutting holes and installing registers is a very nominal expense. The registers I chose were $10 each, so for $120 increase in my riser cost (minus any lumber savings) I get to roll the dice and find out whether or not it works as a bass trap. If it doesn't pan out, at least the registers make an interesting conversation piece, lol.



My process for attaching the carpet was pretty simple. On the sides that butted up to a wall I simply laid the carpet against the wall and tried to tuck some down into the gap between the riser deck and the wall. I stapled it straight down into the deck as close to the edge as I could. I then pulled the carpet to the other edge, around the riser lip, and stapled it up to the bottom of the lip. It was easy and effective, though my staple gun just barely fit under the lip at an angle. Any lower of a riser height and it would have been impossible. This also left a ragged carpet edge and/or a gap between the riser and the wall, so I bought some small base moulding, painted it the same as the walls, and used it to clean up the edge. This photo gives a look at that as well as the Art Deco style registers I installed.


The final touch was an LED rope light kit from Amazon, which I plugged in to the front corner of the riser and velcro'd (rather than stapled) underneath the riser lip. I hid the transformer inside the riser so all that you see is the power cord and the IR remote receiver from the outside. The LED strip can be changed to different colors and brightness levels with the IR remote, but I chose to leave it on a bright red. The intent is to illuminate the step in an otherwise dark room, so nobody falls off the riser trying to refill their beer or get to the restroom. You might also notice that the outlet I installed is Z-wave controlled, so I can remotely turn the riser lights on and off using Smartthings, Alexa, etc.


So that finishes off the riser build, and from that final photo you can probably guess what I'll be building next
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post #16 of 34 Old 08-06-2018, 02:14 PM
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Awesome write up so far! Looking forward to seeing it all come together.


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post #17 of 34 Old 08-06-2018, 08:10 PM - Thread Starter
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Quote:
Originally Posted by bafflesteppe View Post
Awesome write up so far! Looking forward to seeing it all come together.
Thank you! I'm having fun reliving the build by putting these posts together. Hopefully folks enjoy seeing it, or better yet find a nugget of advice or inspiration!
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post #18 of 34 Old 08-10-2018, 11:59 AM - Thread Starter
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Bass Traps

There's not much new to show in the realm of corner / wedge bass traps, but here's how I ended up building them. First the design plans of course! On the front wall I wanted to fill both corners floor to ceiling, while leaving a section in the middle open for future expansion to front wide speakers. On the rear wall I only have one corner, since the other side is open to the stairwell:

There's a sneak peak at the acoustic panels I planned for behind the screen, but the construction of those will be in a future section. This one is for the corner traps only.

I pre-planned the cuts for the insulation and the wood frames, so I'd know how many materials to order and minimize waste. Here's my sketch of that planning:

One of the minor adjustments I made at this step was to make each trap ~1.5" shorter than originally planned, so I could cut pieces for both traps out of a single 8' board.

Here's a picture of the first frame being test-fit in the corner, followed by all of the frames after some paint. I was nervous the wood edges might show through the burlap if I didn't paint them, but in the end I'm not sure if it was necessary.


Here's a close-up of my approach to supporting the insulation triangles inside, so they don't fall down on each other and compress. I've seen this done several ways with wire, eyehooks, etc, but I happened to have a roll of twine around so I just make a spiderweb platform of sorts to support each layer.


Here's a test-fit of the first frame in an upper corner, after it'd been strung and wrapped, but not stuffed.


The next pictures show the first frame stuffed with insulation. The first shows how the twine supports the layers and the second shows how I stapled the burlap to cover the sides. The third is a test fitting of the rear "double decker" trap.:


I cut and stapled a second piece of burlap across the front of each trap to finish them off. Here is a shot of the pair of finished bottom traps for the front wall, as well as the finished trap for the rear wall:


I mentioned during the wall build posts earlier that I'd added crown moulding above the front wall, but I didn't have a picture. Turns out I found that picture buried in with these, since I applied that moulding before hanging the front traps.


And finally, a shot of the front wall with all four traps in place. Next up I'll be building the surround and Atmos speakers, then getting everything wired up inside the walls. On the left next to the equipment rack you can see I'd already started some wiring at this point, but eventually that entire spool of cable (plus more) found its way inside the walls.
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post #19 of 34 Old 08-11-2018, 08:22 PM - Thread Starter
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Surround and Atmos Speakers

As usual, I'll start first with the design plans. I used the Dolby specified angles to lay out the speakres as optimally as I could in my room. The four bed channel surrounds are located just about perfectly for the two middle seats in the primary row. In the rear row the rear surrounds are just a little too far apart, but that's mainly due to proximity of the rear wall. In addition, I had no leeway on the right rear surround because of the window.


For the Atmos channels I did the design for six speakers, though I only plan to install four for now. I was pre-wiring for 9.2.6 and wanted to make sure the appropriate speaker locations were reserved. Unfortunately my middle height speakers were very constrained in their placement due to ceiling joists and can lights, so it's lucky that they're even close to within Dolby's specs. The front and rear heights are again just about perfect for the front row, while the rear height is a little too close to the rear row, again due to wall proximity.


For all 8 speakers I decided to go with Volt 10LX's from DIY Sound Group. I wanted speakers that would be resilient and future proof, able to run a respectably low crossover and handle reasonable power. Who knows what height content we'll get in the future, I didn't want wimpy little satellites in the ceiling that I'd have to baby. I also liked the idea of the wide dispersion pattern helping cover the seats, particularly for the rear row where some speakers aren't optimally positioned. Here's what it all looked like during unboxing:


You may have noticed there aren't nearly enough flat packs there for 8 speakers. This is because I decided to buy four of the thinner Atmos flat packs for my wall-mounted surrounds, and to run my four ceiling speakers in an infinite baffle configuration in the attic. This was the other reason I settled on the Volt 10's instead of the 8's. In an IB configuration the 10's can handle a crossover of 80Hz where the 8's would need to be protected with a lower crossover. Somehow I can only find two photos of building the flat packs, but as I said with the HTM-12's you can find those threads anywhere:

After paint those got stuffed with polyfill and that's about it. The only semi-unique thing I did with them was to install the banana plugs on the top surface, rather than on the rear. This allowed me to mount the speakers perfectly flush against the wall. Above each speaker I have a wall plate with two banana jacks and a few inches of cable to make the final connection. I could have gone full stealth and just left a hole in the back of the speaker and a hole in the wall to pass wire through, but the knowing would bother me, even if nobody could see it...

For the attic mounted speakers I first built U-shaped supports out of scrap plywood and lumber, sat them on the drywall in the attic where the speakers needed to be installed, then screwed them sideways into the joists:

This was the same technique I used in my previous theater to mount the projector, it's much better than relying on drywall alone or restricting yourself to having to hit the joists from below.

At this point I did what was clearly the stupidest and most dangerous act of the entire build. Thankfully nothing went wrong, but I do want to say if you're considering a similar project, try to come up with a better method for this part. I can't condone my own actions here


What you're not seeing in those photos is me standing at the top of the ladder, router in one hand and shop vac hose in the other, with the shop vac precariously balanced on a Christmas Tree box so it could reach the 10' ceiling. I was using the circle jig to cut holes through the drywall and plywood. Here's what one looks like from the attic side once it's cut:


Assembling the speakers couldn't be easier. Simply screw the compression driver into the woofer and of course solder together the crossovers. I took the easy way out and purchased the PCBs with my kits, laid out the components, then had a friend of mine do the soldering:



Once the speakers and crossovers were ready the provided baffles were painted, then screwed up into the plywood supports with 2-4 screws. The woofers were awkwardly screwed into the baffles like any normal box installation, aside from the fact that you're holding them into the ceiling at the top of a ladder, holding a pointy power tool very close to them in your other hand. I'd really recommend getting a helper for this part just to ensure no accidents, but fortunately I made it through with everything in once piece. Here's what they looked like once all four were in, plus one closeup next to a can light for size comparison:


On the attic side I simply connected the crossovers and leaned them against the woofer basket. All of the connections were electrical taped and then some leftover pink fluffy insulation (not shown) was laid on top of the whole stack.


That essentially does it for the Atmos speakers. This one final shot shows the surrounds mounted to the walls as well, prior to the wallplates being installed. You might notice up near the wall, laying on the plastic is the fourth surround. That one I'm saving for later as it doesn't have a wall to mount to. I had to get extra creative with that one and that part of the build isn't quite finished yet. I'm hoping to get that done in the next month or so, then I'll come back here and document it.


You might also notice that the large spool of wire is gone from behind the equipment rack, and in its place is a new wallplate with a bunch of cables. All that cabling is what I'll go through next time.
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post #20 of 34 Old 09-07-2018, 04:33 PM
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Those Atmos speakers look clean up there: that’s exactly how I’ll do it. Going to borrow your spiderweb suspension for the corner bass traps too.
I keep seeing people harp on spacing the bass trap out from the corner for air space: what did you end up doing?


https://www.avsforum.com/forum/15-ge...topics/2958434
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post #21 of 34 Old 09-08-2018, 11:16 PM
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Hey Magius,

Very nice build you got going there and very interesting to read about your challenges and solutions. I always love a good thread with lots of pictures and some words on the thoughts going into the build. I’m definitely subscribed and looking forward to seeing how the end result turns out.

I also have an IB sub in a baffle wall in the front of my room with 4x Fi IB315v2, and that thing can really shake the house! I have a rather small theater, so I couldn’t squeeze in the 18” version, but I’m sure they’ll shake your room pretty well

Keep up the good work!

My Small Home Theater Build
JVC RS400 / 110" 2.40:1 Curved DIY AT Screen w. Masking / Prismasonic A-Lens / Marantz SR7011 / Emotiva XPA-5 / Behringer EP4000 / Oppo UDP-203 / PS4 Pro / Apple TV 4K / 7.2.2 Surround / DIY LCR's / 4xFI IB3 15" IB Sub
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post #22 of 34 Old 10-27-2018, 05:07 AM - Thread Starter
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Wow, I can't believe it's been almost 2 months since I posted here! I still have plenty more to share, but work and life seems to have gotten in the way these past couple months. The great news is the theater build (phase 1) is now complete! We enjoyed our first UHD movie in there around 2 weeks ago. I'd been saving Ready Player 1 for the occasion and it didn't disappoint.

I'll be sure to post another couple progress posts here this weekend, and I'll try not to let any more large delays sidetrack the thread. Hopefully some of you are still interested in how this turned out!
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Too close for comfort to your neighbors + no sound isolation + Florida exterior walls + sound coming from the second floor - they'll love the boom emanating throughout the neighborhood.
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post #24 of 34 Old 10-27-2018, 06:08 AM - Thread Starter
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Wiring
Wiring isn't the most exciting subject, so I'll try to keep this one short. I mostly wanted to give a closer look at the wall plate I installed behind the rack, and the challenges that went with it. In addition, this activity took place at the same time as installing the surround speakers, so you may notice some jumping back and forth in the timeline between the pictures...

As you can see in the following photo, there's a narrow wall that separates my AV rack on the left from the AC closet and bathroom on the right. My plan was to run all of my cables up this wall, into the attic, then down to wherever they needed to go. The first problem I ran into was a firebreak (horizontal stud) halfway up the wall. I had to open up the backside of the wall and drill several holes through the firebreak to accomodate the large quantity of cables being run. The second problem I ran into was the narrowness of the wall itself. The back of my low voltage box butted right up against the backside of the drywall, leaving no room to get cables in or out. In order to resolve that problem, I cut the entire back off the box, leaving just the front wings to hold it in place and allow screwing a faceplate to:


As far as the box and faceplate go I'd decided on a 4-gang design, using three Monoprice inserts with 5 sets of binding posts each. Unfortunately the Monoprice inserts are a little larger than standard Decora size, so the slots in the 4-gang faceplate had to be dremeled out a bit to fit. For the fourth slot I used a standard Decora insert with keystone jacks that I had leftover from the previous theater build. This contained two more sets of binding posts and a 12V trigger pass-through. It was a little extra work making the Monoprice inserts fit, but it was the only way I could find to get 17 speaker runs for 9.2.6 all in a 4-gang box. Here's the design I'd sketched out:


With the preparation of the wall done, running cables could begin. I'm hoping to never replace the cables, so I bought a 500ft spool of 12ga speaker wire from Monoprice to run everywhere. 12ga is overkill for most (all?) of these runs, but for the extra few bucks over 14ga it seemed silly not to use it. I ran seven cables behind the baffle wall first, to test out the front three channels and subs, plus two more for a future upgrade to wides. It was nice being able to just poke a hole in the ceiling and tack the cables to the wall without worrying about aesthetics. Nobody will ever see back there anyway

Each pair of subs is wired in series, using a small jumper of speaker wire between them. Anyone confused about series/parallel wiring can follow the colors. Red wire from the wall to the red post on the unseen sub. Black post on the unseen sub jumpered to the red post you can see, and black post on the sub you can see back to the black wire from the wall to complete the circuit.

Next up I ran the wiring for the Atmos speakers and the projector. For the projector I ran three cables, an 18gbps HDMI, a Cat6 Ethernet, and a 12V trigger cable. Only the trigger is shown in the photos. That trigger is actually unused as well, since I misunderstood what it was for, but at least it's there for future use. Additionally I ran two extra cables for 5th and 6th Atmos mid channels in the future. Ideally with a future processor I'll be able to jump from 7.2.4 to 9.2.6 (or Auro 3D, using the 5/6 as VOG) and everything is already wired.


Finally came the wiring for the three surround speakers which will be wall-mounted. Thankfully I was able to cut these holes above the firebreaks and not have to cut open more wall than necessary. For the fourth (left) surround, I left a bunch of cable coiled in the attic, as that would be a project tackled much later.


By this time the holes I'd made to pass wires through the firebreak were pretty full! I was glad I cut one hole per "gang" in the box below, as five 12ga speaker wire pairs through each hole was just about perfect. In addition, in the final photo you can see the finished wall plate, including the roughness around the three Monoprice inserts where I had to dremel them out. I'm happy with how it turned out, and I'm looking forward to some day populating those last 4 channels :
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post #25 of 34 Old 10-27-2018, 07:00 AM
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Jeff is waaaay too nice of a guy, so he's not going to call you out on some of this stuff - I'm just a so-so nice guy too, so I'm allowed to point out mistakes so that others don't make them.

1) you're connecting 14 gauge Romex to a box that has 12 gauge Romex coming out - the confusion now or, more importantly, when you sell your house, is that the outlets the 12 guage wires run to are 20A circuits, when they're only 15A. How is the 14 gauge coming out of the floor under the riser - if it doesn't run directly to the breaker, then you can't have a hidden junction box (or existing outlet) for it to tap into. Also, your plug is running from the outlet to behind the riser's face, which is a no-no, along with the covered transformer for the riser lip lighting.

2) building on existing carpet - over time some of the carpet, assuming there's padding underneath, will give way more than other spots - always build on a solid, non-dynamic surface.

3) The dozen bass trap vents are sonically and aesthetically (in number and ornateness) overkill. As you know, the greatest amount of standing waves will be in the corner, yet there aren't any vents there. I know you're trying to use the corner baffles as bass traps, but if you had just used two 24" linear bar grilles extending out from the corners then you wouldn't need the baffles in the first place - you're not pumping 20,000 peak RMS that you need that much LFE attenuation, especially since you've skipped out on all other forms of sound isolation in that room and those windows are the proverbial elephant in the room.

May Jeebus have mercy on your neighbors - yes, you've said you've tested it with dance music, but LFE booms are still annoying even more so if they're sporadic (again, those windows on three sides aren't going to help).
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post #26 of 34 Old 10-27-2018, 12:30 PM - Thread Starter
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@theaterofpain thank you for the feedback. You bring up some great points, a couple of which I don't fully agree with, but yes it's always good to make sure people don't blindly follow the mistakes of others. I believe I said early in the thread that *almost* everything was being done to code, with a few calculated exceptions, but maybe I forgot to mention that. Even still, I should have pointed out along the way where those exceptions were being made, specifically. In any case, I'll try to respond to each of your points so you can see where I was coming from.

1.) You bring up three distinct concerns here so I'll take them separately:
a.) Connecting 12ga romex to 14ga romex. I agree with you 100% that the smarter thing to do would be using 14ga romex inside the riser. That said, my understanding of the electrical code is that while 20a breakers may never connect to 14ga wire, it's perfectly acceptable for 15a breakers to connect to 14ga, 12ga, or even a mix of the two, which is what I have created here. I agree if someone cut into my riser and saw yellow romex they might assume the circuit was capable of higher current, however both the breaker in the panel and the receptacles in the riser are 15a only. So I'm sure we can agree there's no actual safety risk here (running 12ga wire on a 15a circuit), and as far as I know, though I wouldn't object to being corrected, no code violation either. There is definitely potential for confusion from mixing wire colors, so I could have been smarter about the wire I bought, lesson learned for the next guy. The only way this could go wrong for someone is if they somehow upgraded the breaker in the panel with a 20a breaker, connecting it to the existing white 14ga romex the builder installed, which would be 100% against code. In that case I can't really say I'd feel bad for them, or that anything I did led them down that path of bad decisions.
b.) Hidden junction box. Here again you're 100% correct. As shown so far in the build thread I've created a hidden junction box under the riser which is a code violation. In the final design this box will actually be accessible via trap door underneath the Cinebar, which would make it code compliant. Just like burying a junction box inside a cabinet in your kitchen is OK, you just can't embed it in the wall. I just haven't done that part of the design and build yet, so I made the decision to live with the illegal junction box in the meantime until I correct it. It's a good thing to point out for people who might follow this thread though, since a lot of folks don't think twice about burying boxes like this.
c.) Hidden transformer / plug under riser. Technically I'll give you this one too, however this is only this way for aesthetic purposes. There's nothing wrong with my electrical, it's a standard receptacle on the side of the riser. I plugged the DC transformer into it, and if I left the transformer laying there on the floor, outside the riser, it would be 100% A-OK. For aesthetic reasons I didn't want the transformer sitting there on the floor, so I tucked it in under the riser behind a flap of carpet next to the receptacle. I can actually pull it back through to the front side if I need to, so it's more of a temporary/aesthetic thing, but yes, it's technically another no-no to bury a transformer inside a wall/floor. This was just one of those areas I decided to ignore the code. Whether the transformer is sitting on the carpet "inside" the riser or "outside", it's no more or less likely to start a fire, so it's a calculated acceptance of the risk of ignoring code. No hard feelings with you pointing it out though!

2.) I agree that the best approach would have been pulling up my existing carpet and building the riser directly on the subfloor. I have no defense for that other than laziness. I considered that approach and simply decided not to do it. What I ended up with works fine, and the riser weighs hundreds of pounds so any variation in the compression of the half-inch of carpet and pad underneath it will be minuscule. It's worth pointing out that it could have been done better, as you have, but in all practicality I don't believe what I did will negatively impact me.

3.) Here again you have two main concerns, and this is where I begin to disagree with some of them:
a.) Register quantity and placement. While aesthetics and ornateness are subjective, I believe that what I've done with the registers, while definitely overkill in quantity, is still optimal for treating the room. As you said, bass builds up at room boundaries, ie walls, and in particular in corners, where two walls meet. That said, there's nothing special about a corner where two vertical walls meet, as compared to a corner where a horizontal wall meets a vertical wall. Bass traps laid down on the floor straddling the floor's corner with the wall are just as effective as vertical traps straddling a corner the traditional way we all use them. So by placing my registers against the two side walls of the riser they're effectively in the corners between those two walls and the floor. The location you suggested, where all three boundaries meet, is definitely an ideal location for registers as well, however I chose to make use of that space with a 9' tall and 3' wide bass trap instead. So basically I have a traditional corner bass trap straddling Wall X and Wall Y, then the registers open up the riser to be used as a trap for the two corners between Wall X and Floor Z, and Wall Y and Floor Z, respectively. I've treated all three of the corners this way, and just in case the riser trap isn't effective (it's hard to find controlled experimental results) I have the traditional trap to fall back on. Certainly I didn't need to install 12x 14" registers, but again without much experimental evidence to know how much is enough I'm prone to going with overkill and no regrets
b.) Skipped other acoustic treatments. Technically you're correct according to what I've posted to date, however I wanted to add that I've actually treated a large section of the room, those photos just haven't been posted yet. While I'm not running a ton of power into the subs, not everything is about power. If a system can reach reference level it really doesn't matter how much power you use to get there. IB subs are extremely efficient and even with only a few hundred watts they go very low and very loud. All I can say is that there is a ton of low frequency reverberation in my room that needed to be tamed according to REW, and I've done a lot of treatment in addition to the traps and riser to assist with that. Stay tuned in the thread and you'll see those in the near future!

Thanks again for the feedback and like I said I agree with most of it, even where I've made conscious decisions to go against certain electrical codes. It's always good to point that stuff out for others that might just be following blindly, and I'll try to make an effort to do so myself in my future updates. I'd hate to think that I'd unintentionally misled someone or caused them to do something that in my situation was fine but in their situation could be dangerous!
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post #27 of 34 Old 10-27-2018, 12:49 PM - Thread Starter
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Equipment Rack & Gear

There's really only one photo necessary for this, so I'll get right to it (pardon the dust!):


The rack itself is an Omnimount RE-27. I was lucky and found it locally on Craigslist from a guy who was getting out of the home theater hobby and reselling all of his gear. Only cost me $250 and it just barely fit in my Acura RSX hatchback to get it home I like the rack a lot and would recommend it for those on a budget. It's very sturdy and reasonably priced, plus it comes with several shelves and blanking plates that would cost extra on higher end racks. I did swap out the top fan tray, however. It comes with two 80mm fans up top that aren't what I'd consider quiet. I cut a larger hole in the fan tray and mounted a 240mm fan which is essentially silent.

Starting from the bottom, I'll go through each slot in the rack and any relevant story behind how I acquired it:

Emotiva XPA-5 (4U) I use this to power my primary five bed channels, LCR and the two surrounds. I don't own the rack ears conversion kit, so I have it sitting on one of the 2U shelves that came with the rack. I bought this almost 10 years ago off Craigslist from a guy in Las Vegas who lost his job and was selling all his AV gear. It cost me $400 plus $90 for shipping, and it's been an absolute beast of an amp. Paired with my previous Infinity speakers and now the DIYSG speakers, both very sensitive, it can drive them insanely loud very cleanly. A year or two after I bought it an internal fuse blew and I had to ship it back to Emotiva, who repaired it free under the original 5-year warranty. Nothing but positive things to say about Emotiva and their equipment, especially with that transferable warranty.

Blank plate (1U) Even though the Emotiva is always cool to the touch, I like to keep one slot free above it for ventilation. The EP2500 runs really hot so I didn't want it sitting directly on top of the Emo.

Behringer EP2500 (2U) Another great Craigslist find, this one cost me $150 from a local band who was splitting up and getting rid of their gear. It took almost a year of searching to find one at that price, but it was well worth it. I use this to power the subwoofers, and it puts out ~650W per channel in stereo mode. With two subs in series hanging off each side, they see ~325W each, which is more than enough for an IB. Any more and I'd be afraid of them ripping themselves apart! A few months after buying this amp it started shutting down on me in the middle of listening to music, and I realized it was getting *very* hot. It turns out the fan has siezed up so it was getting no ventilation. Fortunately, doing a fan swap on this amp is a pretty common thing to do anyway, so I bought a quieter fan and fixed it right up. The only downside now is that it dumps a ton of heat into the rack, which causes the AVR to run even hotter than it would normally. I'm currently working on a solution to duct the hot air out the bottom of the rack so I can close the rear door without spiking the AVR temps.

Behringer DSP1124p (1U) The good old MiniDSP of yesteryear, aka Feedback Destroyer Pro. To be honest I don't even use this anymore, but in the old days it was an essential component to getting good LFE. Nowadays I'd recommend folks pick up a MiniDSP instead, but you can still find these for $20-30 on Ebay if you want to save some cash. Somehow I got extremely lucky and the Audyssey XT32 with subEQ does a fantastic job with my subwoofers, leaving next to nothing for this unit to correct. I've considered pulling it from the rack, maybe even selling it, but for now it's there in bypass mode, essentially being used as a VU meter. When the LFE gets really heavy I can glance over and see the LED meter blipping yellow and know that things aren't clipping. Old habits die hard I guess.

Denon AVR-X4300H (4U) No real explanation needed here. It was the cheapest AVR available that could run 7.2.4 and also contained a decent room EQ solution. Not to start a flame war but in my opinion only Dirac, ARC and Audyssey XT32 constitute "decent" room EQ solutions, though I'd have been willing to give MCACC a shot if Pioneer had a comparable unit to try. YPAO and whatever Onkyo calls their solution after they dumped Audyssey do not impress me. I bought this AVR brand new as soon as the next-gen X4400H was announced, which is typically how I buy anything that I can't find used. At $799 I think it was a total steal. Since the unit isn't rack mountable it sits on another 2U shelf which came with the rack. The internal amps are used to drive my rear surrounds as well as all 4 Atmos channels, but as sensitive as they are it has no trouble taking them to reference levels.

AC Infinity Aircom T8 (1U) This is a cooling unit containing 3 blowers that suck air from the bottom and blow it out the rear. They make other models that blow it out the top, front or sides, but for my rack the rear exit seemed ideal. I noticed that my Denon was running quite warm to the touch, especially when the rack doors were closed and the EP2500 was cranking out hot air. I got this unit on sale but even at the retail price of $99 I feel it's worth it for a little peace of mind. It has a digital readout for the intake air temperature, which is the air coming out the top of the AVR. It's also programmable with 6 different blower speeds that can be engaged to stay below a temperature setpoint. If nothing else it's a little bling for the rack, and maybe if you're lucky a little life extension for the AVR due to running with less heat.

Blank plate (1U) Before I bought the Aircom unit I had a 2U blank plate here to leave 3.5" of space for ventilation above the AVR. After adding the Aircom I wanted to be able to see the LCD readout, so I swapped for a 1U blank.

Panamax M5400-EX I'm not a big believer in power conditioning, but I got this cheap many years ago for the old theater when it was first discontinued. It was $250 at the time and I've used it for nearly a decade to sequence power in the rack. Unfortunately the DSP1124 doesn't have soft start circuitry, so if everything is powered on together the subs produce a terrible thump. Using this Panamax the AVR turns on first, then the DSP1124, and finally the EP2500, so there is no thump. A lot to spend to avoid thumping your subs, but maybe I'm getting some benefit from the power conditioning too. To be honest I think the VA meters add great bling to the rack so I'm not too upset about the money spent.

Panamax M5500-EX In the new theater I had the builder run two dedicated 20A circuits to the wall behind the rack. As such, I thought I should keep my eye out for a second Panamax unit to plug into the second circuit and add more outlets in the rack. I scoured Ebay for months and finally found one for $200 that included the rack ears. Seems like most people no longer had the ears so I considered that a good find, and it's a bit more bling for the rack now.

At the top of the rack I installed the three remaining 2U shelves with the intent of using them to support various sources. Streaming boxes, gaming consoles, BR players, etc. For now they're mostly empty or holding media we intend to watch soon, but the bottom shelf does have two devices on it:

Sony UBP-x800 (1U) I couldn't justify spending what the OPPO cost after it was discontinued, and this seemed to be one of the better UHD players out there at a reasonable price. Panasonic players weren't out yet, and even if they were I don't think I'd have jumped on one at launch price. I ended up getting this open box unit from Best Buy for $99, so it won't hurt so bad if I end up upgrading to something higher end down the road. For now though, I have absolutely zero complaints. It seems to be a great player.

Logitech Harmony Home Hub I've always been a fan of the Harmony line of remotes, and this one is no exception. I own one for the theater and a second for the living room.

As you can see, between DIY construction, second hand and closeout gear, I'm very much a budget shopper. This is an expensive hobby but I feel like I've cobbled together a more than respectable system at a reasonable cost. It just takes a lot of persistence on Ebay and Craigslist, and a willingness to always buy last-year's toys instead of the newest oh-shiny

Last edited by Magius; 10-27-2018 at 12:49 PM. Reason: Picture was grossly large, resized it a bit
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post #28 of 34 Old 10-28-2018, 02:19 AM - Thread Starter
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Acoustic Treatment

In the previous posts I detailed my three corner wedge bass traps, each approximately 9' tall and 3' wide, as well as the ~140 sqft seating riser which I hope will act as a trap as well. That's a pretty generous amount of trapping, however I wanted to significantly treat the wall surfaces as well. My primary objective was to completely deaden the area behind the screen, as well as the rear wall directly across from the screen. On the side wall I planned to add a few panels around the surround speaker and hope for the best, and then I'd take in-room measurements to determine whether additional treatment (ie: ceiling or additional wall coverage) was necessary. The below three drawings show my overall treatment plans:




I decided that all my wall panels would be 4" thick to maximize their contribution in the low frequency range. My early REW measurements showed a lot of reverberation, so I might as well do what I can to help with that. In addition, the floor registers in the riser come out around 5" from the wall, so having 4" panels lining most of the wall would provide encouragement against people inadvertantly steeping on the registers.

I also decided to construct my panels the less common way, using a flat back frame only, as opposed to a full side frame. If you're not sure what I'm talking about, here are two pictures to demonstrate, first a "normal" frame, then my "flat" frame:


With a normal frame you cut the acoustic material down to fit inside the frame, while with the flat frame you simply lay the material on top and wrap it. I'm not going to say that either style is better than the other, though there are pros and cons to each. Primarily the normal frames are simpler to build and give a cleaner look with tighter corners and straighter edges. The flat frames are difficult to build since you can't just screw them together, they can have sloppy looking edges and coners, and they can sag a bit due to gravity with no support from the frame when hung. The only reason you might even consider a flat frame is to squeeze that last little bit of absorption out of it due to the exposed material on the sides. With a normal frame, higher frequencies approaching from the side will bounce off the wood frame, which is why many people go even fancier and cut holes or slots in their frames. My original plan was to put these flat frames behind the screen where nobody could see them and normal frames elsewhere, but the first ones behind the screen turned out well enough I just continued that process throughout the room. If I had it to do over again, I might do normal frames for the cleaner finish, but I'm not unhappy with how mine turned out.

In case anyone is curious how to assemble this flat frame, I'll run through my construction process briefly. It essentially boils down to cutting half lap joints in the end of your boards and then glueing them together to form the frame:


In order to accomplish this I used my router and a jig I found plans for on the Internet. https://www.woodmagazine.com/woodwor...-lap-joint-jig. Using the jig I was able to route four boards at a time and ensure clean cuts. I ended up producing giant piles of sawdust like this one on at least three separate weekends:


Once the frames were assembled I stapled on a piece of burlap as the backing, set the Roxul on top, and wrapped it in Joann Black Speaker Cloth. I'd tested a few of the recommended materials available at Joann and preferred the look and feel of the speaker cloth.


The first panels went on the screen wall, along with some french cleats which would later be used to hang the screen:

I could have squeezed three more panels up top, though they could only be 2" thick to fit behind the cleats and the one on the left would partially cover the air vent. I decided not to bother at this point, as I'm hoping to end up with plenty of treatment elsewhere.

Next up was the rear wall. Some of you might have come this far wondering about the giant window on the rear wall, and how I was planning to hang acoustic panels over it? The answer, of course, is to first get rid of the window . I won't claim that my course of action was best in this regard, and I'm sure by covering over two of the three windows in this room I've violated some kind of fire code, so I don't recommend following this approach blindly. I'd actually be curious if anyone has a better idea of how to treat this window, as it wouldn't be too hard to take apart if there's a better option. First, I hung a curtain inside the window, so that from the outside it would retain the look of a normal window with curtains closed. Then I covered the window with plywood, and began hanging panels.


In retrospect I probably should have at least put pink fluffy behind the plywood, and the window cavity might have acted as a poorly tuned trap itself. Regardless, once the wood was up it was more hanging panels until the rear wall was covered:


I will point out that I was very happy with how the skinny panel in the center turned out. That one is 5' tall, so a single piece of fabric wasn't long enough to cover it. I had to overlap two pieces, so I was careful to put the seam in the same place as the gap between the other panels to the left and right. Visually I think it worked out well.

In between treating the rear and side walls I actually received my theater seats, but I'll go into that in a future post. For now just a couple more pictures of the side panels going up, in which you can catch a glimpse of the seats. For what it's worth, there is one more panel in that empty bottom slot, I just don't have a picture showing it.


So that wraps it up for the planned acoustic treatments. All in all I have around 105 sq ft of wall space treated with the 4" panels, plus the three corner traps covering around 100 sq ft, and the 140 sq ft riser which may or may not contribute much. Eventually I hope to come back and post data about the effects the different kinds of treatment had on in room measurements, but on first glance I believe I may have corrupted some of that data with other variables (like adding seats).
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post #29 of 34 Old 10-28-2018, 11:37 PM
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I’ve never seen anybody do the flat back panels before, and to be honest I thought the outcome would look much worse, but you’ve managed to make it look quite good - kudos!

Your plans doesn’t mention any diffusion. Do you plan on installing any of that later on?

My Small Home Theater Build
JVC RS400 / 110" 2.40:1 Curved DIY AT Screen w. Masking / Prismasonic A-Lens / Marantz SR7011 / Emotiva XPA-5 / Behringer EP4000 / Oppo UDP-203 / PS4 Pro / Apple TV 4K / 7.2.2 Surround / DIY LCR's / 4xFI IB3 15" IB Sub
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post #30 of 34 Old 10-29-2018, 08:18 AM
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This looks really good so far. I have questions for you about how you ran the speaker wires in-wall. I'll pm you!

And i agree, those panels look great. After spending a decent amount of change on GIK Acoustic panels, i am building my own for the remaining treatments.
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