December 2018


Building A Sound Room
Philip Gold describes how he put together a listening room in an apartment block.
Article By Phil Gold Of HIFICRITIC

  After 30 years of living in a two-storey suburban house, my wife and I decided to move into a downtown apartment. We each had specific requirements, mine including a dedicated listening space. (That was one of her requirements too – that I should have a dedicated listening space, so she should not be disturbed while I was listening to music.)

We spent over a year checking out building after building. Eventually we found one we both liked: walking distance to the center of town, close to all amenities and transit, on a quiet cul-de-sac and backing onto a large park. A den could be converted into a room to suit my listening and reviewing requirements, just over 17 x 14 foot with a high tiered ceiling. I thought this could work, and will explain what it took to transform it into a decent listening space.

Before doing any work, I sent two rough sketches to Yoav Geva (founder of YG Acoustics), who designed my current reference Carmel 2 speakers, and knows a thing or two about setting up a room. One picture showed the speakers along the shorter wall, the conventional configuration, and the other along the longer wall.

"Positioning along the long wall is definitely the better option." He replied without hesitation, confirming my own thoughts. My strategy has the objective of providing great acoustics alongside good sound isolation, bearing in mind that the room must double as an occasional guest room.

Unusable as it stands, since the only door is just behind one speaker, and heavy built-in shelving was biting into the limited space available, my contractor needed to remove the built-ins and then the sliding door. The wall would be rebuilt, and a new and more conventional door would be fitted well away from the audio system. An exterior door might have best sound insulation properties, but we settled for a solid wooden door with a bottom seal, realizing that some soundproofing compromise was acceptable, as long as most of the sound spillover was reduced, and we could not introduce an ugly exterior door opening into the living room. The door was designed to open outwards to maximize the available space in the sound room.

At this point I shared my plans with a Texas-based company that specializes in treating studios and sound-rooms, that featured a testimonial from The Absolute Sound's Robert Harley in their advertising. Having contacted Harley for his opinion, he wasn't aware he was being quoted in the ads, and cautioned me against too much treatment which can over-damp a room. The recommended treatment price tag also seemed rather high, so we decided to start with the soundproofing, and worry about the acoustics later.

The treatment involved painting a layer of Green Glue Noiseproofing Material over the first layer of half-inch drywall, then applying a second layer of drywall on top. A complication was that the previous owners had applied stucco to the walls, and you cannot soundproof with Green Glue over stucco walls. We wanted to get rid of it throughout the apartment anyway, but it proved murder to remove, creating a ton of dust. (Fortunately, we were living in our old house at the time, so didn't have to breath the air on a daily basis, but did need to bring in industrial cleaners to clean up after the stucco was gone.)

We only had to apply the Green Glue on the two interior walls of course, but also had to make sure sound would not leak through the electrical sockets. You can still hear music through the interior walls, but the level is so low it's no problem for my wife (unless I'm doing high level testing). In a building with concrete floors, we have not heard any complaint from the neighbors, so I think the objectives are met here.

I'm not sure how much difference a dedicated power line provides, but wasn't taking any chances. I asked the electrician to install two Furutech GTX-D NCF duplex outputs with GTX wall plates and 105D duplex cover plates, and run two dedicated lines to the main building power supply, bypassing my power panel completely.

However, getting excellent room sound is rather different. The basic shape is good – if not quite the golden ratio that some consider ideal. Some minor asymmetry may be seen at the windows around one corner and the beveled corner facing it, but one's own voice also sounds unnatural at certain parts of the room, as it bounces between the two bare long walls, so these reflections need to be broken up a little.

We created an uneven surface on these two side walls by building two enormous CD racks, with a total capacity of around 5,000 discs. Such items can't be purchased in the normal way, but a friend called Gene makes beautiful furniture in his spare time, and he relished the challenge. Now, nearly filled with CDs and other objects, the walls need no further treatment.

I used one of the best floor covering stores in Toronto to select the best carpet and underlay for a busy reviewer – something that would not be beaten up by the frequently repositioned spikes under the speakers, and something that would provide additional sound insulation while not introducing static. We selected Dura Pad High Density Rubber underlay, and Montreal color Misty Morn acrylic carpet: a low pile that was soft under the feet and neutral in tone.

Instead of a conventional sofa, we would buy a sofa bed (and if you haven't seen what America Leather has to offer, you haven't lived). Supremely comfortable as sofa or bed, the mechanism doesn't cause a risk of injury every time it's opened or closed. We lined up the center of the sofa to the center of the equipment rack, and set-up the speakers, using the exacting techniques espoused by Sumiko in a training session I recently attended. This builds the sound from the bass up and makes the best of any room.

At this point I was ready to bring in some acoustic experts – a local team this time. A man arrived with a starter pistol and proceeded to fire shots from a couple of locations in the room, mapping the results with a microphone and iPhone software. He generated a seventeen-page report which recommended particular size acoustic panels on each of the long walls, with the option of applying some ceiling treatment. The current ceiling is beautiful, so I was reluctant to touch it, but was open to some acoustical paneling, especially if it looked good.

The acoustician offered a choice of 1, 2 or 4 inch thick panels, and told me I could use one panel on front and back wall or a number of smaller ones of the same area. The panels come in a wide variety of finishes and can be cut to any size, and the company could put artwork onto the panel surface instead of a cloth finish for an additional cost.

This was music to my ears. My wife and I researched which galleries offer royalty-free hi-res downloads of their art, a list that included the Metropolitan Museum of Art and the Getty Museum. We searched through the catalogues and narrowed down our choices to around a dozen images. We then chose three landscapes for the rear wall and three portraits for the front.

We worked out how large each would be, and wanted those on the rear to have the same height. To get the desired effectiveness, the three images on the rear wall would be 1in thick; the other three would be two inches thick. We specified a paint color for the edge of the panels, selecting a match with the sofa bed.

The company tasked with printing the selected images onto fabric managed to get four images to the exact size, but one was too large and one too small. It took another two weeks to ready all six of the panels. The installers returned to mount the finished panels in the room. The three on the front wall aligned perfectly, centered to the listening position and the stereo system. One panel, covering a junction box on the wall, stuck out a little, but removing its front panel allowed the acoustic panel to lie flat against the wall and act as the junction box cover.

The rear pictures would all have fit nicely if we hadn't meanwhile ordered a tall chest of drawers for the beveled corner. Since this would obstruct the view of the left image, we positioned that panel on the side wall instead. One day we may have the acoustician with his starter pistol back in, but my ears tell me the treatments are doing a fine job: the slight echo is gone, and music sounds great.

I've never suffered bass problems in this room, so probably won't have to explore tube traps to tame low frequencies. This is partly due to luck, but partly due to the judgment of selecting sealed box speakers in the first place, and the positioning them along the long wall and far from the corners. The bass comes directly from the front mounted woofers without benefit of corner reinforcement or a bass port. It loads the room naturally without overwhelming it.

The biggest expense for the project was removing the stucco, moving the door, and the sound-proofing. Next was the dedicated wiring while the sound treatment itself worked out less than £1500.

Occupying the room we now have a Krolo rack, EMM Labs XDS1 V3 CD player, EMM Labs PRE pre-amplifier, ModWright KWA 150 SE power amp driving YG Acoustics Carmel 2 speakers, all hooked up with Nordost Valhalla 2 cabling.

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