Superposition: Getting Speaker Placement Right

Superposition: Getting Speaker Placement Right

Written by Russ Welton

In Issue 130, Russ noted that he’s been reappraising his audio system and went over some basic ideas about speaker setup. The series continues here.

When placing your speakers in any given room, you may initially be concerned with all the factors you can’t control: the size of the room, its orientation, what furniture must go in there, if there is a hard wooden floor or large exposed glass surfaces that will cause unwanted sonic reflections, and so on. Although each of these individual issues can be examined and dealt with separately, let’s look at one of the factors we can readily control, so that we can happily say, “I’ve found a super position for my speakers! They sound great here.”

In quantum mechanics, particles can be in two or more states at the same time. (I wish I could work and sleep at the same time! Wouldn’t that be cool?) This is known as superposition. “But what has this got to do with our speaker positioning?” I hear you holler.

It may not be a precise analogy but if our speakers are placed optimally, they can be in two “states” at the same time: occupying the physical locations where we set them down, and at the same time, sonically “disappear.” Like our subatomic particles, they could be thought of as having two states or properties.

How do we get our speakers to be both “there” and “not there?”

When we get the soundstage correct, we can look and still know where the speakers are, but according to our ears, the sound produced will seem as if the speakers aren’t even there. Instead, we hear the band or artists as an event, and are immersed in the performance. The speakers become exciting.

By making fine adjustments we can perhaps even suspend disbelief entirely.

So how can we improve our listening experience? What I’m going to suggest is a bit different from the usual setup articles. First, a tip on what to listen for.

Do you close your eyes when you listen to music? Depriving yourself of sight may enhance your sense of hearing and listening. As you listen, think about how significant the vocals are in the mix, and how the song may have been produced with the intention of drawing you in as the listener, by getting you to engage with the emotion of the piece.

Close your eyes and these Magneplanar 3.7i speakers will disappear into a seamless sonic presentation. Courtesy of Magnepan.

Now consider the fact that vocals are one of our first natural references for communicating, and using our own voice can help us in setting up our speakers.

You are likely most familiar with the sound of your own voice, and its natural properties are firmly imprinted in your mind. You know what you sound like. This can assist you in determining how far from the rear wall you should place your main speakers. If you stand with your back against that wall and speak out loud at normal talking volume, pay attention to the tone of your voice. You may notice more reverb and/or delay than usual. Your voice may sound closed and less open. Move slightly forward away from the wall and repeat your recital. Again, notice if there’s a change in your voice. Does it sound less “slappy,” slightly warmer and less echoey? Keep gradually advancing forward until you like the tone of your voice, where it sounds most natural and familiar to you without that excessive reverb and hardness from being too close to the walls. Then, try placing your speakers at this same distance from the wall and listen to their tonal balance, and make further adjustments from there. You’ll likely notice they also sound more natural and develop more openness and breadth in their tone; literally sounding less hard and closed-in. They say that talking to yourself is the first sign of madness but perhaps it’s worth it in this case!

In the previous article I mentioned the importance of reading the manufacturers’ guidelines for speaker placement, both in relation to their distance from each other and from the back wall. (Remember, these are guidelines, not absolute requirements.) But what if there is no such information? Many manufacturers will not state a specific optimal distance from the rear wall, because this can vary according to the dimensions of the room itself. The room will heavily dictate the overall sound, because its dimensions will determine the areas of bass reinforcement and cancellation and the behaviour of standing waves in the room. If you place the speakers in an area of cancellation or reinforcement, the tonal balance can suffer greatly.

You may discover that a good starting point for your main speakers is to place them one fifth of the total room length into the room and one fifth in from the side walls. Alternatively, you can try the famous “rule of thirds” you’ve probably heard of before. If that’s not possible, try placing them one fifth of the room away from the side walls. Measure your distances from the front and center of the speaker as this is the acoustic source of your sound. If you measure from the rear of the speaker you could end up placing them further into the room than is necessary. Save yourself some space – measure from the front. Also, measure precisely – it’s important to get the speakers as accurately and symmetrically placed as possible. Even fractions of an inch can make a difference.

Placing the speakers as far apart from each other as possible will allow for a wide soundstage. However, if they’re too far apart you’ll get a “hole in the middle” rather than a seamless spread of sound with a focused center image, which is what you want. To get your sweet spot, angle the speakers in toward your listening position, which will increase the focus of the image, making it more solid. Toeing in your speakers increases the ratio of direct to reflected sound. Check for increased brightness and adjust to taste as you make these incremental adjustments.

Here’s a suggested speaker setup starting point, from Audiophile’s Guide: The Stereo by Paul McGowan. Illustration by James Whitworth.

Be aware though that some speakers are specifically designed to be positioned without any toe in, as their responses are very even both on and widely off axis. This is great for consistency of sound in a wider seating area and toeing in these speakers may yield no improvement at all. Some speakers actually sound better with no toe in purely as a characteristic of their “personality” and may well be bright enough already.

If the sound is still too boomy, it may be that your speakers are still too close to the wall. Gradually bring the speakers away from the walls until that boominess is gone. Also, the depth of the sound field can suffer if the speakers are too close to the wall, and moving them further out into the room can really get the sound to open up.

A guide for 7.1 surround-sound speaker setup. Courtesy of Sound & Vision.

Similarly, a good starting position for your listening chair is about one fifth of the length of the room in from the rear wall because, again, you won’t be located typically where standing waves peaks and troughs occur. Again, experiment. Moving the chair even a few inches forward or back can have a big effect. I realize that for many of us, however, we simply don’t have the freedom to put our listening chair in the ideal spot, or we may just decide against it because we don’t like the way it looks. If you can, it’s good to give yourself a reference of how good it sounds there and then you can aim for this within the compromises or further decisions you make afterwards. But at the least, try moving the listening position to different places, if at all possible.

What else can you try? Given that you want to avoid sitting where standing waves build up, you can experiment with placing your seating at a point that is not in a location where this problem is compounded, such as in the middle of the room. Measure the width of the wall behind your front speakers. Multiply this by 1.25 and place your seating this far back from that wall, in the middle of the room’s width. So, let’s say your room is 12 feet wide. Take your 12 feet width and multiply it by 1.25 = 15 feet. Place your chair at 15 feet from the rear wall behind the speakers and test drive your music from here.

But what if you find yourself competing with furniture or general access through the room? If this is the case, you may choose to reduce the distance between your main speakers so that your seat can be placed equidistant from them in a simple equilateral triangle. (In fact, many speaker setup articles will recommend such a triangle configuration between you and the speakers as a starting point, and it’s a tried-and-true method for many listening situations.) You may compromise some of the spaciousness of the soundstage – but not necessarily – as you place yourself in a more intimate position closer to the speakers. If you find this to be too focussed and direct sounding, experiment with toeing your speakers out a few degrees for your personalised room super position.

We think they’ve got it! From Audiophile’s Guide: The Stereo by Paul McGowan. Illustration by James Whitworth.

Header image: Klipsch Forte IV loudspeakers.

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