On this episode of Ask The Expert, we're going to talk about speaker placement in surround setups, specifically when used with a television.
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Today, we're going to talk about speaker placement in surround setups, specifically the placement of the centre speaker. Contrary to the above question, you more often or not find the centre speaker placed beneath the TV screen in a surround setup.
If we were to speculate about the perfect placement for a centre speaker, then it would actually be behind the TV screen, in the middle of the image, or actually a little above the middle of the screen (see figure 1.)
Theoretically, this would be the very best placement of a centre speaker used in conjunction with a TV, but as we all know, theory and reality can oftentimes be two very different things and – with a flat screen TV at least – placing a speaker behind it is an impossibility. This might be possible with an acoustically transparent projection screen and a projector, but with a TV not so much.
figure 1.
So what can we do if we can't have the speaker behind the TV? What's the next best option? Well, as this episode's question suggests, placing the centre speaker above the screen is actually very often the best position in terms of sound, and in terms of acoustics. Let's discuss the reasons for that now.
By placing the centre speaker above the screen, the sound from the speaker is more freely dispersed from the speaker and is not impacted by any furniture that you may have below the screen. The sound is given the space to radiate more freely into the room, which can significantly improve imaging, but also integrates better with the picture on the screen, with the fact that the sound is not coming directly from the picture being less noticeable. (see figure 2.)
Psycho acoustically, if it's coming from above instead of below, the sound has an easier time integrating with the picture, and this all contributes to the reasons why you might opt to place your centre speaker above the screen.
figure 2.
As with anything, there are also disadvantages with placing a centre speaker above the TV screen. The biggest one is that – by having your centre channel raised above the TV – it's suddenly not horizontally aligned with the left and and right speakers. To elaborate, if you have left and right speakers that are fairly low – floorstanding speakers, for example – they are not all that tall, and so by putting the the centre speaker above the screen, you might perceive too big of a difference when when the sound is going across from side to side, due to the difference in speaker height. (see figure 3.)
If it's going from a low point in one side, then up to the centre speaker and then down again, then you might notice the sound changing as it moves along this horizontal plane, and this may cause some undesirable effects. In this case, it would be optimal to place the centre speaker below the screen to have a more even sound across the soundstage.
figure 3.
Another potential issue, is that it's not all that unusual for people to place their TVs quite high up on the wall – often a lot higher than what is optimal. If your TV is already hanging quite high up, then having the centre speaker above the screen is not a particularly good idea, because we risk the speaker being too close to the ceiling, resulting in a negatively impacted acoustic performance. (see figure 4 below). So, if your TV is placed high up on the wall, then the advice would most definitely be to put the centre speaker below the the TV.
Finally – and not necessarily a factor for everyone, but worth mentioning nevertheless – is that placing the centre speaker underneath your TV is often more visually pleasing. For some, the aesthetic aspect in itself is enough to choose placing the speaker down beneath the TV.
This can also be dependent of your furniture, of course, and if it's possible to integrate the centre speaker into the furniture below the TV. And this should be a consideration in itself – you really have to be careful about how you're placing that centre speaker in that piece of furniture and how that furniture is built, because it could well have a significant effect on how the speaker sounds, especially if the centre speaker ends up being recessed into the furniture, with some part of the furniture in front of the speaker's drivers.
Reflections from the furniture can harm the sound quite significantly so, when possible, be sure to move the speaker forward towards the front of the piece of the furniture.
In an attempt to summarise all of this, if your TV is placed correctly – meaning that your eye level is approximately one third up from the bottom of the screen – then having the centre speaker above the TV will give the best possible acoustic performance. While not "mandatory," and often far from pretty, it simply sounds the best.
figure 4.