Also read: Rebuilding My Music Room, Part 1
This is the second of a 2-part article describing the process and results of rebuilding my music room. The first part described the goals I had when I started. This part will describe issues that arose during the process, the choices I made, several unexpected problems and opportunities and the final result.
Controlling Bass Response Is the Most Difficult Part of Room Acoustics. It is almost impossible to have too much bass trapping in a room. Unless you have a very unique room with “ideal” dimensions (and it’s not very easy to get ideal dimensions even when building from scratch with a big budget – witness the various symphony halls in the world that struggle to get it right), you’re going to have some bass boom unless you use a lot of trapping or work with some type of room correction. However, there are two big problems with using a lot of bass traps: 1) they can look really lousy and 2) most bass traps absorb the full range of the audio spectrum. This second problem means that you might correct for all the bass boom in the room, but end up with a room where the music sounds lifeless (try listening in an anechoic chamber and see how it sounds). Most of the reputable acoustic treatment companies that make bass traps include materials that reflect the mid and upper octaves so that the absorption is concentrated in the lower frequencies. One way to do this is to put a layer of such reflective material over part of the trap. For example, some traps have reflective material on half of the round or on 2 sides of a column trap. This allows you to turn the trap so that the reflective material faces a direction that sounds best in the room. The problem with this is that the trap still looks like a bass trap, especially if it’s a column that is fully round or squared. Some of the visual effect can be minimized by use of triangular bass traps or the creation of ceiling soffits that look more like they’re part of the room.
In the past my listening room made use of the “deadwall/live wall” model. This involves a front wall (behind the speakers) that is absorptive and a rear wall that is reflective. Of course, this doesn’t mean that you want your front wall to be totally absorptive or your rear wall to be totally reflective. Room dimensions can affect the degree of reflectiveness and absorption needed, so you have to experiment. One of the reasons that it helps to put absorptive materials, especially bass absorption, at the front wall is that the front wall generally has the greatest amount of bass energy. Bass energy tends to build up in the corners, so it is very typical to see bass traps in the four corners of the room. However, the front two corners are usually more critical than the rear corners.
After the four corners of the room are addressed, you’ll most likely get the most bang for the buck by installing bass trapping soffits on the front wall, followed by soffits on the side walls. Two advantages of soffits are (1) they tend to be a bit less visually obtrusive and (2) they don’t take up floor space. Bass trapping also works in the floor, but usually you have limitations that prevent you from having openings in the floor (things fall in), and a floor-standing “soffit” would take up too much room.
I addressed these issues in four ways: 1) I refurbished my existing bass traps and installed them as soffits; 2) I built some bass trapping into the room walls and floors; 3) I used triangular corner bass traps that employed an attractive external wood finish; and 4) I had all of the traps built and stained with one consistent design and the same stain colors.
Refurbish Existing Bass Traps and Mount Them As A Soffit. I didn’t want to simply toss the ASC bass traps I already owned, so I decided to reupholster them and use them to make a soffit for the front wall of the listening room. The simplest and cheapest way to do that was to put a new acoustically-transparent fabric over the existing fabric, and then create new endcaps that would also operate as mounting brackets. I decided that the endcaps should be wood and match the other wood in the acoustic treatments I would be installing. I was lucky enough to have a creative carpenter/handyman who built and/or stained all of the acoustic and anti-vibration treatments that are in the room, as well as the custom shelving and rack. Here are pictures of the original ASC Cube Traps, how they looked after being recovered with the acoustic fabric, and how they ended up looking after being mounted as soffits with the new endcaps. This soffit was clearly the trickiest thing to accomplish in a visually appealing manner, but I was pretty happy with the outcome. More importantly for the audiophile in me, the soffit provides significant front-to-back and floor-to-ceiling bass control without taking up any floor space.
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