Blogs

Around 15 years ago, my wife and I upgraded from a condo to a large duplex. During our search for our next home, I had but three criteria: a two-car garage, space for a wine cellar, and a decent-sized spare room that I could convert into a modest home theater. At the time, I never would have called myself an audiophile, and I knew diddly-squat about room acoustics or how to treat them. All I knew was I wanted a big screen, a high-quality projector, and a half-decent 7.2 surround-sound system.

Because our duplex was the last unit to be built within our strata complex, I was able to negotiate a few subtle upgrades that would give me a decent head start when building my theater, such as changing the location of an exterior door to accommodate a stage for theater seating, installing an additional 20A circuit for audio equipment, adding some additional lighting, and gaining the ability to string my low-voltage wiring for all the home-theater equipment before the drywall went up. In exchange for being unable to delete or move either of the room’s 4′ × 6′ windows, my general contractor offered to double up the party wall between us and our adjoined neighbor, so I was off to a respectable start.

Not long before completing my theater, I started writing for the SoundStage! Network, and this, quite quickly, precipitated an unanticipated wave of desire to incorporate a dedicated two-channel music system. As I grew increasingly exposed to better equipment through reviewing, the upgrade bug bit me hard, which inevitably snowballed into me selling my beloved Jeep to free up cash for my first high-end stereo system.

Fast-forward through 15 years of continued reviewing, and my feet remain firmly planted at the bottom of the rabbit hole. I’ve learned a thing or two about how a room’s dimensions, volume, and boundary treatments can shape sound, and with that knowledge, I found myself wanting—no, needing—a new room. So, in July 2022, I opened my laptop, double-clicked the AutoCAD shortcut, and got to work.

Designing from scratch

My listening room is essentially two boxes of unequal dimensions sewn together by a hallway offshoot. The wider half measures 12′4″ × 12′, while the narrower half measures 11′4″ × 11′.

When I originally built my stage for the tiered theater seating, I installed it on the broader side of the room to allow enough space between my back row of seating and an adjacent floor-to-ceiling movie rack.

What I did not appreciate at the time was that the layout would place my speakers on the narrower side of the room and my front row of seating inches away from the center, which was about the worst place, acoustically, I could sit. Later measurements would show that bass response was not ideal at my listening position, particularly at 37Hz and 57Hz.

Frequency response in my old room (1/12 smoothing)

I tried moving my speakers within the space I had, but only saw 1–2dB improvements at best. Ergo, to achieve any appreciable improvements in sound, particularly in the bottom end, I knew I would have to move the listening position, and the only way to do that was to swap the room around. Unfortunately, that meant gutting the room, because the stage was previously installed with drywall terminating over it—and if I was going to go to the lengths of removing drywall, I might as well strip the room to the studs and start from scratch.

Fully renovating the room meant that I was free to consider all manner of design criteria, and these were my top ten:

1. Move the primary listening position outside of the center room void.
2. Incorporate an equilateral listening triangle while increasing the distance between my main speakers.
3. Build a quieter listening environment.
4. Design for ideal placement of speakers and acoustic treatments.
5. Improve electrical capacity while eliminating ground-loop potential.
6. Improve home-theater sound without limiting two-channel performance.
7. Upgrade from a 7.2 to 7.4.4 Dolby Atmos surround-sound system.
8. Move the center channel behind the screen.
9. Hide all non-essential audio equipment while simplifying equipment access and cable routing.
10. Improve room aesthetics and lighting.

With the above in mind and haunted by myriad ideas of how I wanted the room to look, I spent about two months planning and preparing AutoCAD drawings outlining the room layout, lighting, electrical, low-voltage cable routing, listening position, and speaker placements for both two-channel and multichannel listening.

With 15 channels in total, the latter pursuit required a separate drawing. I wanted to ensure all six theater chairs resided inside the ideal off-axis performance window of each surround and height-effects speaker, which meant figuring out which speakers I wanted to go with prior to design (more on these later). Drawings for cabinetry, millwork, and a new bulkhead that would double as a quasi–bass trap spanning the entire upper perimeter of the room were also completed.

While laying everything out, I was in touch with Grant Samuelson, Shunyata Research’s marketing and sales manager. Grant has been down the path of designing and building a few high-end listening rooms during his time, and he was kind enough to share a host of suggestions to help minimize line noise and potential ground loops within my room. I incorporated several of these recommendations, including using a semi-dedicated sub panel (shared with our heat pump and hot water tank), installing equal line lengths of 10AWG Romex power cable for my 20A lines, and, of course, utilizing Shunyata’s robust 20A power outlets and ultra-handy cable cradles, which Samuelson kindly donated to my cause. Grant, if you are reading this, thank you again for all your invaluable help!

Time to build

I initially estimated this project would take about nine months; it took 19. Reasons for this varied, but the most significant factor was my failure to leave time for the unexpected. If you plan to undertake a project of a similar scope, please learn from this village idiot and give yourself plenty of time. Demolition of my old room took almost three weeks as opposed to the week I had budgeted, as I forgot that I had used glue and screws everywhere I could—particularly in building the stage.

I also didn’t account for how many trips to the dump I would have to make, nor did I account for scope creep. Building a bulkhead to house a perimeter bass trap, re-insulating the entire room, installing a new vapor barrier, and properly sound-deadening the room took months—not weeks, as I had anticipated. I also decided to remove all, not just some, of the pre-existing electrical. In doing so, I discovered that I needed to reroute both HVAC plenums feeding the room so that they coordinated with the layout of the forthcoming coffered ceiling and allowed for the ideal placement of my height-effects speakers.

Once I stripped the room to its studs, the next step was completing the electrical work, which involved the installation of six new dedicated circuits (CCTs). My electrician installed two 20A CCTs, one dedicated to two-channel equipment and another to home-theater equipment, using the equal-length 10AWG Romex. He then ran circuits 3 through 6, each 15A, with CCT 3 allocated for a pair of JL Audio F112 subwoofers in the front of the room and CCT 4 earmarked for the same in the back of the room, plus my new JVC DLA-NZ7 laser projector.

CCT 5 feeds an in-wall cabinet housing noisy equipment such as my router, NUC, lighting controller, ethernet switch, cable box, Control4 box, and Apple TV. These first five circuits all trace back to the dedicated secondary panel. CCT 6 was reserved for lighting, powering six Lutron dimmer switches and controlling 24 LED light fixtures throughout the room. My electrician pulled this feed directly from my main electrical panel in the garage because I wanted to eradicate any chance of ground-loop noise being induced by the dimmer switches, a problem I struggled with in my previous room.

With the electrical work completed, I framed up the perimeter bulkhead. Then, I installed the remaining in-wall low-voltage wiring, including ethernet, speaker, HDMI, and subwoofer cabling, ensuring each was sufficiently isolated from any of the power line paths. A quick tip: make sure to test all low-voltage wiring before drywalling. I found a faulty trigger cable that would have been a nightmare to replace later.

The next step was to frame in both large windows and fill the voids with Rockwool Safe’n’Sound insulation, followed by the new vapor barrier. I then got to work sound deadening the room. One can deaden a room in numerous ways, but based on my budget and space constraints, I chose to use a product called SONOpan, as it was readily available at my local Home Depot and quite economical. It is, however, very messy to work with because of its fibrous composition, so be sure to wear a mask, glasses, and gloves. Due to supply challenges during the pandemic, I didn’t have access to any sound putty, so for any objects penetrating a SONOpan panel, such as electrical boxes and switches, I built little SONOpan boxes and sealed them with acoustic glue to ensure a consistent envelope. Once the panel work was complete, I sealed all the panel gaps with acoustic glue and installed a second layer of SONOpan over the shared party wall with a ½″ air gap between layers.

With my room resembling a green special-effects background on a movie set, it was ready for its finish layer of ¾″ veneered plywood. I chose plywood over drywall because it is more robust, slightly better damped, and provides a significantly more rigid surface to attach things to. The ceiling construction was the same, but with one additional layer of glued-and-screwed cross-thatched ½″ plywood to add strength and rigidity to the room and a bit of depth for all the intended millwork and eventual sound-absorbing panels (a sound cloud) to mount to. (Be sure to check your local building code for fire-rating requirements if using a substrate other than drywall.) The only area I didn’t plywood over was the bottom of the bulkhead, as this would be the absorbing surface. Instead, I used a 1/8″ layer of permeated corkboard to let sound pass through this surface more efficiently, instead of amplifying in the corner. Above the corkboard forming this pseudo–bass trap is a layer of ¾″ SONOpan, a 1″ air gap, 3.5″ of Safe’n’Sound, a 3.5″ air gap, and a final layer of 3.5″ Safe’n’Sound. Because the bulkhead is over 12″ deep but only 6″ is exposed, the top 3.5″ air gap also vents directly into the ceiling joist voids, which themselves are damped with ¾″ SONOpan on the bottom and 3.5″ of Safe’n’Sound at the top. This allows sound that enters this void to dissipate effectively. Does it work? More on that later.

Once the room was fully encased in wood and almost airtight, I was ready to procure all the finishing materials, carpet, audio and video equipment, and speakers. All planning needed to be done in the evenings so I could spend weekends building, and with the room boarded up and gaps sealed, I turned my attention to creating the new stage for my theater chairs. I repurposed most of the 2 × 12s I had from my previous stage, but this time, I spaced them 12″ apart instead of 16″. Once built, I wired in stage lighting and a couple of outlets for the power recliners and finally insulated the stage for additional sound absorption. Again, I glued and screwed everything together.

Building the new stage took far less time than removing the old one, but once complete, it was time to measure for carpet and underlay. While I waited for the carpet to be installed, I got to work mounting the back blocking for the custom baseboards I had yet to mill and finish. The millwork in this room was easily the most challenging part of this build, as over two thousand pieces of wood needed to be milled, sanded, treated, stained, and clear-coated before being installed. Ordinarily, the finishing work is completed after the millwork is installed. However, because I had fabric on the walls and faux leather behind the wainscoting and ceiling millwork, sanding, staining, and clear coating in place was not an option.

All that’s left is everything else

In the second part of this series, you’ll read about the steps taken to finish the space, how and why I selected some new home-theater and two-channel products, my thoughts about choosing acoustic treatments, and an overview of how my new room performs both quantitatively and qualitatively through a series of measurements and some final listening impressions.

Aron Garrecht
Contributor, SoundStage!