How should multi-channel speakers be placed?

Nowadays, many game or HDTV enthusiasts have selected multi-channel speakers for their systems in order to obtain a more realistic sound field effect. So, compared with ordinary stereo, what are the advantages and disadvantages of surround sound? This is to start with stereo recording. Strictly speaking, stereo recording has high requirements for the placement angle of the microphone. Generally, it is required that the sound directly entering the microphone and the sound reflected by the room should reach a suitable ratio, so that the spatial sense of the recorded sound will be stronger. However, in actual stereo recording, it is very difficult to achieve a suitable ratio between the sound directly entering the microphone and the sound reflected by the room. The main problem is that various signals are mixed together in the later mixing. In fact, various sounds only have the effect of mixing after entering the ear canal. In stereo recording, the sound reflected by the room is the easiest to lose, and it just determines the spatial sense of the sound. Therefore, when people studied surround sound, they decided to set up rear channels to compensate for these mixing. This requires more microphones during the recording process, which means more speakers are needed to restore the sound during playback, which involves the placement of multi-channel speakers.

The placement of multi-channel speakers is directly related to the listening quality. Even a slight difference will cause a big change in the sound field. Although desktop theaters are near-field listening, they are not very sensitive to the shape and volume of the space, as well as the diffraction and absorption of furniture and other objects, and the placement of speakers is relatively free. Below we take the 5.1 speaker system as an example to explain the placement of multi-channel speakers.

Front speaker placement

The front left and right main channel speakers are placed in an isosceles triangle, with a bottom side length of 1.5m to 2.0m. If the two front speakers are too close to each other, the human ear can only hear the direct sound field effect of the speaker, without hearing the rendering effect of the reflection through the wall and the surrounding space, and the sound is inevitably dry and mixed. Even if it is reflected by the wall, because you are too close to the sound field, the diffracted sound is also covered, and it is difficult for you to hear it. Generally speaking, the two main speakers are best at a 45° angle to the listener. If the speakers are too close to the listener, the sound range positioning is not accurate, and there is a phase difference between the high and low frequency units, and the sound is not synchronized; if the distance is too far, the sound field will become narrow, and the sense of space and presence will be lost.

Center speaker placement

The principle of center speaker placement is very simple: place it directly in front, that is, on the vertical bisector of the left and right speakers, in the same plane as the left and right channel boxes, and usually above the monitor (Figure 2).

Rear surround speaker placement

The rear left and right surround speakers should be placed on the back walls on both sides. If possible, use speaker stands to place the surround speakers at the same height as the left and right main speakers. The placement should also be in an isosceles triangle, with the bottom edge being the same length or slightly longer than the main speakers. The rear speakers should preferably be placed at an angle of 110°. The reason for this placement is that the angle of the human ear is approximately 110°, and the rear speakers mainly play back sounds coming from the back, so a 110° placement is closer to the real effect.

For many computer gamers, the space behind is limited and it is unlikely to be used to place rear speakers. Even if there is space, whether it can be placed at 110 degrees is also a big problem. For this reason, you can adopt the following "compromise" solution.

1. For those who don't have space at the back, the rear speakers can be "inverted" to the front, that is, placed in a place in front that is mirror-symmetrical to their original rear positions.
2. If there is space at the back but it cannot be placed at 110°, you can ignore the 110° standard and place it somewhere at the back.
3. If the rear speakers cannot be placed in the same plane, the rear surround speakers can be placed about 60 to 90 cm above the listener, but try to avoid placing them below the human ear.

Subwoofer placement

The placement of the subwoofer is much more flexible, because the bass has a weaker directionality, so you don't need to consider the position when placing the subwoofer, but not considering the position does not mean you can place it randomly. Generally speaking, placing the subwoofer close to the wall will have a more even bass performance. It is recommended to place the subwoofer in the center of the table with the box facing backwards, which will have a better effect. Because the bass needs to be reflected twice before reaching the human ear, this can make people feel that the sound field is stretched, and the sense of presence is stronger.

Overall diagram of 5.1 speaker system placement:

6.1 speaker placement

Compared with the 5.1 sound system, the 6.1 sound system has an additional rear center speaker, and the placement requirements of this speaker are the same as those of the center speaker. Therefore, the placement of the 6.1 speaker is relatively simple, which is to add a rear center speaker on the basis of the 5.1 sound system placement method.

It should be noted that the addition of the rear center speaker strengthens the sound from the rear. Therefore, the placement of the rear speakers of the 6.1 sound system will not affect the effect too much. Therefore, the effects of various "compromise" solutions are strengthened and closer to the ideal solution. This is also the biggest advantage of the 6.1 sound system over the 5.1 sound system.

7.1 speaker placement

Compared with the 5.1 sound system, the 7.1 sound system retains the original front and rear speakers while adding two side center speakers, which are mainly responsible for the playback of side sounds, while the original rear speakers can focus more on the playback of rear sounds. Therefore, the 7.1 sound system can have speakers on all four sides responsible for sound playback, and the surround effect is further enhanced.

2.0 speaker system placement principles

For many music lovers, a high-quality 2.0 speaker system is still the best choice for music appreciation. For music playback, 2.0 bookshelf speakers do have considerable advantages, and many people like to use 2.0 bookshelf speakers to listen to music. However, if the placement is not appropriate, the advantages of 2.0 speakers will not be brought into play. Proper placement can maximize the perfect sound quality of 2.0 speakers. Next, let's take a look at how to place 2.0 speakers.

Don't use bass boost randomly

If the room is not very large, it is not recommended to use bass gain, otherwise the sound will be low and muddy. Some 2.0 speakers have a bass control knob with no gain at the minimum scale, not at the 12 o'clock position, so you need to pay attention to this.

Keep a certain distance between speakers

Since 2.0 speakers have high power and can create a larger sound field, it is recommended to keep the two speakers at a certain distance, preferably 80 to 120 cm (Figure 1). Do not pile up large objects in front of or behind the speakers. Things that are prone to vibration, such as CD boxes, should be kept away from 2.0 speakers. CD boxes will also produce slight noise when vibrating. It may be difficult to place 2.0 speakers on some uneven desktops. It is recommended to use soft rubber pads to raise the speakers to achieve the purpose of stable placement.

The distance from the wall is greater than 30 cm

Many 2.0 speakers are rear-inverted speakers, with the inverted holes pointing to the rear. When the speakers are working, they will discharge air through the inverted holes, especially when the output is high. When the airflow hits the wall behind, the bass will become turbid and unpleasant. To get a better listening experience, it is recommended to keep the rear panel of the speaker at least 30 cm away from the wall. If you are limited by space and cannot place it at a very suitable distance, you may wish to hang a tapestry on the wall, which can also help improve the bass quality.

Place the speakers as far forward as possible

Like other waves, sound waves can be reflected, diffracted, and combined with other waves. When the speakers are placed at the back of the desktop, the sound waves emitted are easily reflected by the desktop, which will also make the bass muddy, the sense of speed worse, and the overall layering worse. Putting the speakers forward can greatly improve the sound quality, because there are fewer reflections from the desktop and the sound is much clearer.

Keep a certain angle in the near sound field

The human ear can easily hear the direction of the treble sound source and the direction of the treble. When the speakers are placed in parallel, it is suitable for far-field listening (more than 1 meter), while most computer users listen in the near field. At this time, the speakers need to be slightly turned inwards, with the speakers roughly pointing towards the user. This way, more treble can be heard, which can help improve the sound resolution and make the bass sound stronger, and the sound quality will be greatly improved.

Pay attention to the above points, and you may find that the speakers you always thought had unsatisfactory sound quality are actually very good, but you just haven't brought out their potential. After readjustment, you can make your 2.0 speakers perform better and get more enjoyment of listening to music.