Room acoustics

Light acoustics in the listening room can improve the sound quality of the audio system. The acoustics are positively affected by e.g. a sound-absorbing material such as a long-pile carpet placed between the listening position and the sound reproduction. The starting point for dampening wall surfaces is that there is no exposed wall surface at opposite points.

Equilateral triangle rule

As a general guideline for speaker placement, the so-called equilateral triangle rule, where the listening distance is at least as large as the distance between the speakers.

In two-channel stereo listening, it has been found that in terms of the stereo image, it is better if the listening distance is greater than the distance between the speakers, for example 4:3, and the directional beam of the speakers crosses in front of the listening position.

This instruction also applies to the front speakers (left-right) of the multi-channel system. There should be no obstacles between the speaker and the listening position that could adversely affect the radiation. A direct line of sight from the listening position to the speaker is the most recommended. The main speakers should be placed in an acoustically similar environment to each other in order to achieve the best and most balanced sound image. The distance to the side and back wall should be at least 40 – 100 cm. Corner placement, where the speaker is close to the back and side walls, is not recommended due to excessive emphasis on the bass area. In the case of a subwoofer, the reinforcing effect of interfaces is often useful. You can also reduce this accent with the included damper by installing it on the reflex element. In order to achieve the best listening pleasure in the listening room, you should try different placement options.

The distance of the speaker from the back wall clearly affects the final sound. The closer the speaker is placed to the back wall, the more damping the effect is at higher frequencies, but at the same time the bass level is higher.

If the speaker is 30 cm from the back wall, the center frequency of the attenuation is 287 Hz, if the distance of the speaker to the back wall is 1 m, the attenuation is 86 Hz.

In a home theater, with a crossover frequency of 85 Hz, the speaker can be placed up to 1 m away from the back wall, and the lowest frequencies are handled by a subwoofer.

Bookshelf and pedestal speakers

The speakers can be placed on a stand, a shelf or a shelf, so that the listening height is correct. The most suitable listening height is on the axis of the tweeter or slightly upward (less than 5º). The speaker can also be placed on a shelf, in which case the distances to the side and back walls should preferably be kept above 40 cm. If the amount of bass starts to feel too large when placed on a shelf, an optional attenuator can be installed in the reflex tube. When placing on a table or shelf, it is recommended to lift the speakers off the shelf to achieve the best listening pleasure. Do not place the speaker near the floor, as the floor reflections will mess up the sound. The speakers can be kept in a horizontal position if necessary, although the best result is often achieved with the speaker in a vertical position. The recommended listening distance is approx. 3 meters.

Floor speakers

With floor speakers, the listening height is basically correct. The distance of the floor speaker from the back or side wall is at least 50 cm, preferably more. Approx. 3 meters can be considered a suitable listening distance. If the amount of bass, due to the location, starts to feel too high, the level can be dampened with the attenuator available in the reflex tube and or by moving the speakers further away from the interfaces.

Subwoofers (active)

The placement of the subwoofer in the listening room is of great importance in terms of the end result. In order to achieve the best result, it is necessary to make listening comparisons. Placing the subwoofer close to the main speakers is recommended. The place of the subwoofer can be either in the corner of the room behind the main speakers or between them. In this way, playback can be integrated more easily with the main speakers. A corner placement is usually well suited for a subwoofer, because the interfaces amplify the sound.

When placing active subwoofers, the following safety factors must be taken into account in order to ensure sufficient air circulation for the amplifier unit. Incorrect placement may cause the amplifier unit to overheat and cause a fire hazard.

The amplifier unit must not be placed 10 cm closer to any interface (sofa, wall, curtain...)

50 cm of free space must be left on the sides and top of the case

Active speakers

The active speaker can be placed on a table, shelf or stand, so that the listening height is correct. The location is ideal when there are no obstacles between the speaker and the listening position that could adversely affect sound radiation. If several active loudspeakers are used, they should be placed in an acoustically similar environment. The distance to the side and back walls should be at least 40 cm. A corner placement where the speaker is close to both the back and side walls is not recommended due to excessive emphasis on the bass area.

When placing an active speaker, the following safety factors must be taken into account in order to ensure sufficient air circulation for the amplifier unit. Incorrect placement can cause the amplifier unit to overheat and cause a fire hazard.

The amplifier unit must not be placed closer than 10 cm to any interface

50 cm of free space must be left on the sides and top of the case

Placing a home theater in a normal room

Home theater can consist of combinations of several speakers, even a two-channel stereo system. Just improving the TV's own sound with a separate amplifier and high-quality speakers often changes the sound quality dramatically. By adding an active subwoofer to the system, even the lowest sounds can be heard. Often, adding an active subwoofer to the system also makes it possible to use smaller main speakers.

In a multi-channel system, it is recommended to use speakers that create a similar sound image in all channels and place them in similar acoustic environments.

The same applies to the placement of the main speakers as in the two-channel system. The center speaker should be placed in the immediate vicinity of the image. When the center speaker is placed close to the TV in relation to the main speakers (e.g. on top of the TV), its signal is delayed, typically approx. 1 ms when the viewing/listening distance is 2.5 m.

The rear speakers (surround) are placed slightly behind the listening/viewing position (DD5.1) higher than the main speakers. Speakers that are placed directly on the floor and where the elements are directed upwards can also be used as rear speakers. By placing such speakers close to the back wall, the reflective effect of the wall is used, the back channels do not sound too pointy when they have to be placed close to the listening/viewing position.

Building a home theater for your own room

Dolby's instructions for room dimensions are, width 1.00, height 0.67, depth 1.55. That is, if the width of the room was 4.00 m, then the height would be 0.67 ⋅ 4.00 m = 2.68 m and the depth would be 1.55 ⋅ 4.00 m = 6.20 m, the floor area would be approx. 25 m².