The Grotto

Welcome to Joe’s Bar and Theater

Category Archives: A/V


atmosIn order to further separate our theater from a typical commercial theater, I installed transducers in the furniture. I did this with the sectional in our last house, which were a nice addition, and always got a surprised response from guests. I used Aura Bass Shaker Pros for my previous install, powered by a subwoofer plate amp that I installed in a custom box that sat behind the sectional.

Doors FramingI wanted a cleaner look for the new room, with no gear at all inside the room, with the obvious exception of the projector, so the amp will be in the rack in the billiard room. Parts Express had also come out with their own transducer under their Dayton line. Not only are the Dayton transducers cheaper than the Auras, but they also show a lower resonant frequency (30 hz vs. 40 hz), with the same power handling capability (50 watts).

The structure of this furniture is much more robust than the old sectional, so I didn’t feel the need to beef it up. When I opened it up, the old sectional looked like it would fall apart rather quickly once I started shaking it. The wood looked like miscellaneous scraps left over from other projects, and everything had been fastened with staples—no screws or glue. I sistered a number of new members, glueing and screwing them in place.

atmosI’m powering these using the rear center channel amp of my old Pioneer VSX-D850S AVR. I figured these wouldn’t need the same power as my subwoofers, so I adjusted the trim down as far as it would go. Even so, they were still shaking too much, and at higher frequencies than I wanted. So, I’ve pulled an EQ out of my studio rack, and am using it as a low pass filter, and also pulling the gain down further.

Compared to the Aura Bass Shaker Pros that I used to have, these seem to reach deeper, as I feel some very low shaking that I don’t hear. And my twin 15″ subwoofers dig far deeper than the single 10″ sub I previously used.

Category Archives: A/V


atmosAtmos is finally in our house!


Seven identical speakers around the room, two independent subwoofers, and four identical overhead speakers for a 7.2.4 setup. Mary’s response upon hearing a Dolby Atmos demo trailer— “Oh wow!”

Then we watched Mad Max: Fury Road in 3D and Atmos, which I had been saving as the inaugural film.

Category Archives: A/V


Because my theater is small, I’ve got to be creative in hiding all the gear. The electronics are all outside the room, but that doesn’t work for speakers. For the seven surround speakers, I’m using identical MTM in-wall speakers that will all be hidden by either the screen, or fabric panels that will cover the walls. For the four overhead Atmos speakers, I’m using four identical in-ceiling speakers that’ll also be covered by fabric. You won’t see any of them. However, it’s a little more difficult when it comes to subwoofers.

Like my last house, I could’ve put a store-bought subwoofer in a front corner of the room and been happy with the sound. But I didn’t want a typical black box that stood out in an otherwise clean room. I also wanted bass that was loud, low and clean—which isn’t cheap when it comes to subwoofers. And I’m cheap thrifty.


Many people who build dedicated home theater rooms in their houses who have larger rooms, are able to build false walls for their screens, and are able to hide large ported subwoofers behind these walls, keeping the decor of the room clean. As my space is only 12′ 2″ x 16′ 6″, I don’t have that luxury.

So I decided to build my own subwoofers that I can build into my front stage. Parts Express had 15″ Community subwoofer drivers on sale, which would be perfect for a pair of sealed subwoofers in my room. These drivers are normally used for pro-audio subwoofers that cost well above what I’m willing to spend, but because I’m building these myself, I’ll be enjoying quite a cost savings.

The math said that with these drivers, a box size between five and seven cubic feet of volume would give me the best performance. So I designed a box two feet high, one and a half feet deep, three feet wide in the back, and two feet wide in the front. Taking into account insetting the back and front, driver volume, and bracing volume, final interior box volume is just under six cubic feet.


While I previously build a bass amp out of baltic birch plywood, for this project I decided on using MDF due to its higer density and weight. It also mills and cuts very easily. Unfortunately, It does not hold screws or nails well. Because of this, I decided to assemble the boxes with traditional joinery via dados and rabbets with wood cleats to hold screws. Adding glue, caulk, and bracing, these will be very strong boxes. I filled them with five pounds of poly-fill each.

The math also says that with taking room gain into account, I’ll be able to hit 110db from 23hz to 120hz ±3db at the front row. We’ll find out how well practice hits theory later.

To fit the design of the room, the tops of the subwoofers will be covered in the same bamboo flooring that I used in the rest of this project, and the front and angled side will be covered in the same navy fabric that’ll cover the walls. The stage piece between them will also be finished the same, after being stuffed with insulation to keep from becoming a resonant cavity.


Once assembled, I tested by powering ’em with an old Pioneer VSX-D850S whose preamp stage had been fried by lightning. I wasn’t sure if the amp section would work at all, and I also wasn’t sure if the rated 110 watts to each sub would be powerful enough, but to my happiness, it did, and it is. And holy moly do these subs deliver. I still need to buy a measurement microphone to see if I’ve hit my mathematical goals, but in several weeks of music and movies so far, my ears (and body) say success.


Category Archives: A/V

Running the Audio

Back of the RackThe plan for the basement is to have speakers wired from the rack to the family room, the deck, the bar, and the theater:

• Family Room – Two Speakers
• Deck – Two Speakers
• Bar – Five Speakers and One Subwoofer
• Theater – Seven Wall Speakers, Four Overhead Speakers, Two Subwoofers, Two Sets of Transducers

All total, that’s 24 channels of audio going to the rack. In this pic of the back of the rack, the bottom two rows are the connections to all 24 channels, with the four at the right already connected to the family room and deck.

Family Room SpeakersBefore the basement ceiling can be drywalled and closed, I have to install the speakers in the family room and the deck. I’m running these with as the same zone, so what’s playing on one will play on the other. My thought is that if we want to listen to something on the deck, we’ll use the tv in the family room to view/control it. Or, we’ll use a phone app to control it while out on the deck.

Installing the family room speakers involved cutting a couple of rather large holes in one wall of the room, making a bunch of drywall dust in the process. While the initial mess had the wife a bit nervous, the final result had her rather pleased. Eventually, these will be painted to match the wall.

deckspeakerOur deck isn’t very big—12’x16′. We decided on a smaller deck with the thought that we’ll eventually have a very large patio below on to which our entertainment level (i.e., the basement) will open. Because we don’t want to disturb our neighbors (at least too much), I put the speakers on the outside corners of the deck, aimed up at the seating area. This way, sound is aimed away from the surrounding houses, and reflections off the house will be aimed up and away, instead of directed at our neighbors. When the wife is at ground level in the backyard, which is 14 feet below the deck, I have to get the system uncomfortably loud before she can hear anything.

The bar speakers will all be in-ceiling speakers, with the three front LCR speakers being angled at the TV, so that primary sound should be heard as reflections from the TV and wall, instead of the listener hearing the sound coming from the ceiling. I’m still not sure how effective this’ll be, but as the primary purpose of these speakers will be watching sports at the bar, I’m not too concerned.

Front of Bracket

Back of BracketFor the speakers in the theater, all of them will be in-wall and in-ceiling speakers, so that when the room is finished, they’ll all be invisible. Normally, in-wall and in-ceiling speakers fasten directly to the drywall, which works well; however, I wanted the theater speakers to be more solidly attached, so I made brackets out of OSB and 2x3s. They’re solidly attached to the framing using deck screws.

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