Room Layout Principles
TAXI is the leading independent A&R company helping unsigned bands, artists and songwriters get record deals, publishing deals and placement in films and TV shows. WSDG is creating a series of articles on small listening / production room design and acoustics.
Article 4: "Room Layout Principles"
In the past few articles we have discussed a number of general acoustic principles as well as specific materials that can be applied to room surfaces in your rooms in order to solve fundamental acoustic problems. All of this has been towards the goal of having your work spaces sound as good and as accurate as possible.
Often (in fact, usually) the best and simplest solutions may be to position all of the equipment, furniture, speakers, etc. in the room in an optimum fashion. There are usually several options in laying out a room, with one of them clearly delivering superior acoustic response in the primary listening (work) position. By choosing the best layout, the amount of added surfaced applied treatments may often be reduced -- or in some instances even eliminated.
There are a number of factors that will contribute to an optimal room layout. Organizing the decision making progress for dealing with these factors is not linear -- in other words there is no easy list of factors to deal with in order. Often one decision will affect another Having said that, let's try to list a few:
1. Length vs. Width
I generally do not like to give hard and fast rules, but for a "one person audio suite" (usually set up like an airplane cockpit, with lots of equipment surrounding a single person in the listening position) I recommend organizing the room with the shorter dimension being on the front to back axis (see figure 1). This axis is called the primary acoustic axis of the room or "acoustic centerline." By definition it should be in the center of the room, or as much on the true centerline of the room as possible.
Figure 1: Typical room - choose between long and short axis
There is really no argument for not having the primary equipment and listening position being symmetrical on the "acoustic centerline" of the room (see figure 2). The symmetry that we are discussing pertains to the room boundaries (walls) but also can be affected by any large pieces of furniture, such as a bookcase. In one of our recent design projects, by simply removing a lager bookcase we had a very positive effect on the audio response at the listening position.
Figure 2: Same room with listening position and acoustic centerline in a symmetric condition
Symmetry and width / length room set-up is mostly about mid and high frequency control and more specifically about the organized effect of early reflections. This was discussed in some detail in a prior article. Basically, when early high level reflections arrive at the listening position only a few milliseconds later than the direct sound, an acoustic condition called a comb filter results: a harsh frequency response that will alter what you are hearing. This is not what you want!
The best way to avoid this is to design so you do not get early reflections. One of the most common sources of an early reflections is a side wall that is two close to the listening position. (Remember that one millisecond of delay is about one foot in additional travel distance.) By organizing the room with the side walls further to the side (which is what we have suggested above), you have already reduced the level and extended the time of an early reflection, without adding any absorption to the wall -- and spending no extra money! (see figure 3). This one single solution will go a long way toward creating better room audio response.
Figure 3: Long and Short Axis Orientation and early reflection organization
The days of the dark basement project studio are happily ending, and I see more and more studios in rooms with windows. Organizing your room with respect to windows is an early room layout decision that should be made wisely. Try not to lay out the room with windows ending up on one of the "side" walls and not the other. Remember the symmetry discussion from above. Windows could be on the side walls, but I would try to not have them end up on the front portions of the side walls. The best location for windows is actually in the front of the room. This will have the least effect on first order reflections as well as the least effect on visual glare. Today's audio production rooms usually always have computer screens or video monitors - things that do not like daylight glare. So, respect for symmetry and attention to glare is important.(see figure 4).
Figure 4: Windows - usually best in front of control room - less glare on video monitors
5. Doors (room entrance)
Try not to lay out the room so that the door(s) are in the front of the room. Same with what would become the rear wall and in particular the center of the rear wall. This location is where you might need some surface applied acoustic treatments. Having a door in the center of the rear wall would make that more difficult to apply. I like to have the entrance to an audio room be on a side wall, slightly behind the listening position. If possible, try to make a symmetrical door or acoustic treatment opposite the door. Sometimes this could end up being a small storage closet or machine room (see figure 5).
Figure 5: Project Studio Shaping Example - "make a closet"
These are a few easy tips on room layout. In a future article we will discuss speaker placement as well as some simple computerized programs that might assist even more accurate room layout and design.
Good luck, Have fun.