Dipole loudspeaker: the right setup

There are a number of things to consider when installing dipole speakers. We first explain what a dipole is. In the cinema, a large number of speakers create an immersive sound impression. Dipole loudspeakers are generally used to precisely reflect this spatial, enveloping sound impression of cinema audio systems in the home. On this basis, we explain how you should set up your dipole speakers.

What is a dipole?

To understand what needs to be considered when installing dipole speakers, it is helpful to understand the dipole in more detail.

• In the case of a monopoly, a wave spreads in all spatial directions.
• Many speakers behave approximately like a monopoly. They sound almost the same from the front, left, right and back.
• The picture shows a dipole. This resembles two polar monopoles that are very close together.
• The two clubs point in opposite directions and are reversed.
• If an overpressure spreads as a wave in one direction, an underpressure spreads in the opposite direction.
• There is an acoustic short circuit perpendicular to this main axis: air particles flow from the overpressure region into the zone of the underpressure.
• Due to this pressure equalization, no wave propagates in this direction. It is referred to as the "neutral axis"
• A dipole sounds almost the same at the front and back, even if there is overpressure in the front and a vacuum in the back. Nothing can be heard on the left and right.
• If there is a reflecting wall behind one of these dipole lobes, the reflection is superimposed with the overpressure and the vacuum wave. The reflection pattern is therefore much more diffuse than with a monopoly.

How does surround sound work in cinemas?

In cinemas, spatial sound environments are created through the use of many loudspeakers. In home theaters, dipole speakers should produce a similarly enveloping sound impression:

• The rear or back channel, i.e. the audio channels for the rear speakers, are used in the cinema for soundscapes, atmospheric sounds, sound effects and reverberation.
• Cinema sound formats such as DTS, Dolby Surround, Dolby Digital or SDDS are reproduced in the cinema via a large number of loudspeakers. A particularly large number of rear-channel speakers are used.
• If there are 20 rear speakers in the cinema, depending on the format, you can only reproduce one or two, sometimes three or four, different signals.
• But: Since each loudspeaker signal covers different distances depending on the position of the viewer, the waves arrive at different times and with different amplitudes.
• The overlay is quasi diffuse and thus increases the spatial impression of the cinema audience.
• The home theater version of most audio systems, however, only provides for the use of one rear speaker per rear channel. In order for a spatial, enveloping sound impression to be created, the sound field must be made more diffuse.
• Dipole loudspeakers are used for this.

You should take this into account when installing dipole speakers

Dipole loudspeakers should therefore make the sound field of the listener more diffuse in order to bring the spaciousness and the enveloping, reverberant effect from the cinema into the home:

• As described above, a dipole speaker creates a more complex reflection pattern than a monopole speaker.
• So be sure to place your dipole effect speakers in front of a large, soundproof area. Room walls are of course ideally suited.
• The reflection pattern is very complicated, especially along all axes beyond the skin axis and the neutral axis.
• For a diffuse sound field with dipole effect speakers, do not place them in a row with your couch. Place them in a line, but offset from the listening position.
• Ideally one meter behind and half a meter above the position of your head.
• Do not place the dipole speakers directly on the back wall of the room, but leave a distance of half a meter here, so that the sound field becomes even more diffuse.
• Do not point the speakers at your listening position, but around 45 ° next to them.