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A Guide to Bipolar, Dipolar and Direct-Radiating Monopole Surround Speakers

A surround speaker is a speaker system that is made up of:

  • A center channel is a piece that sits either above or below the TV.
  • Two front speakers both right and left.
  • Two to seven surround speakers.
  •  Powered subwoofer(s).

There are three types of such speakers namely; bipolar, dipolar, and direct-radiating monopole speakers with each type producing unique surround sound effects as discussed below.

What is Bipolar  Speakers

Bipolar surround speakers as denoted by the prefix ‘bi’ which means two, consists of two speakers that produce sound from both ends of the speaker cabinet.

Bipolar speakers can be used as both side and rear surround speakers and each has different sound effects.

When used as side speakers, the sound is directed towards the front and back of the room.

On the other hand, when they are used as rear speakers sound is only directed along the back wall.

In bipolar speakers, the front speakers are ‘in-phase’ which means that they work simultaneously and output sound at the same time.

In addition, they diffuse the sound in a such way that the location of the speaker cannot be spotted.

Bipolar Speakers Installation

Most surround speakers are normally positioned at or above the ear level. However, for another set up like a movie setup they can be placed two to three feet above the ear level for maximum output.

Bipolar speakers are more flexible compared to dipolar speakers making their installation much easier and they can be installed on the rear or sidewalls.

For example, in some specific setup like  5. 1 setup, (here  5 means 5 surround speakers and 1 subwoofer hence 5.1) the speakers can be installed on:

  • Both sides of the wall are behind or above ear level.
  • Hanging from the ceiling behind or above ear level.
  • Above the ear level on the rear wall.

The same setup can apply for the 7.1 setups only that all the extra speakers are mounted on the back wall, above ear level.

car audio car speakers
Image credit: autost, Deposit Photos

What are Dipolar Speakers

Dipolar speakers work in a similar way to that bipolar only that they are ‘out of phase’. This means that the front speakers work one at a time. When one is outputting, the other one is not, and the other way round.

Dipolar Speakers Installation

Dipole speakers normally have an empty space in front of them and it is in this empty area that the listener is supposed to sit. This empty area intensifies sound diffusion.

Unlike in bipolar speakers where they are normally placed above or behind the listener’s ear level, dipolar speakers are installed on the same level as the listener, hanging from the ceiling or the side walls in the 5.1 setups. The empty space is placed directly in front of the listener.

Dipolar 7.1 setup has speakers which are labeled right and left so that the in-phase drivers will be pointing towards the front of the room when placed on the sides. This is to prevent cancellation problems that that might occur by ensuring that they are in phase with the front speakers when out of phase drivers are facing each other.

What is Direct-Radiating Monopole Speakers

As the word suggests, they directly output sound in the direction of the listener. These speakers enable the sound effects in music, movies, and games to be heard. They are normally placed at the back or sides of the room.

Installation of Direct-Radiating Monopole Speakers

When been used as either side or rear surround speakers, direct-radiating monopole speakers should be positioned either behind or on the sides of the room. If the speakers are too close to the listeners when placed on the sides, they should not go beyond the intended listening position.

Additionally, they shouldn’t be aimed directly at the listener’s head. On the same note, experimenting with speaker aiming should be done if they are placed several feet behind the listening position.

Things to consider when choosing bipolar, dipolar, or direct-radiating monopole surround speakers

Choosing one model over the other is solely an individual’s preference which is based on the experience expected. However, here are some key considerations to keep in mind.

  • For movie lovers, the surround speakers shouldn’t divert or distract their attention away from the movie instead should make them even more glued and attracted to the movie.
  • Additionally, both bipolar and dipolar speakers have the ability to diffuse sound in the entire room as such they are able to regenerate surrounding effects such as gunfights, explosions, or the sound of various animals at night in a way that the sound feels like it’s not just coming from where the speakers are positioned instead they should sound like they are coming from every part of the room.
  • Bipolar and Dipolar speakers have a more defined and sweet surround spot than direct-radiating ones.
  • If you are looking for movie theatre experience bipolar and dipolar speakers provide an almost match to the arrays of surround speakers that you will find in a movie theatre. This is not possible with direct-radiating ones.
  • A major advantage that direct-radiating models have over other models is that they have the ability to send sound directly towards the listener’s ears. They have a focused and clear diffusion pattern a characteristic that enables them to generate in a precise manner all sound effects in soundtracks.
Car speaker audio
Image credit: piggypa, Deposit Photos

Finally, how do you determine which surround speakers to use?

Dipole Speakers

As earlier stated, dipole speakers have the ability to turn everything into a spacious environment through their ability to diffuse sound effects irrespective of the original intended purpose.

As such they are not ideal for those who want to achieve a small room effect as they always disperse much sound around which means they always sound voluminous. With that in mind, the following situations are appropriate to use dipolar speakers.

  • When you want to achieve that voluminous and diffuse surrounding atmosphere and at the same time not able to easily identify where the sound is coming from.
  • It was earlier indicated that dipolar speakers have an empty area created through the diffusion of sound to the back and front of the room. It is in this empty space that the listener can get to enjoy the diffusion nature of the dipoles. As such dipoles should be used when you want to be enclosed fully in indirect sound.

Bipole Speakers

Bipolar speakers give you the ability to enjoy the sound effects of dipolar and direct-radiating speakers and of course without the shortcomings that come with the two models.

This means that it is possible to achieve the localized i.e. direct and close environment that comes with direct radiating monopole speakers and the wide, enclosing, and voluminous atmosphere of dipolar speakers at the same time.

Here the advantage of using bipoles over the other two models is that with bipolar speakers, they are not in your visibility as the direct radiating ones are and not as voluminous as dipolar speakers.

The installation of bipolar speakers is more flexible as compared to that of dipoles as they don’t have the base rolls found with the dipoles.

The bipole’s nature to work ‘in-phase’ makes them generate greater sound effects than the dipoles  ‘out-of-phase’ configuration. This is especially important if you want to place the surround speakers away from the listening position that could be anywhere on the sidewalls or at the back of the room behind you.

People who prefer distinct surround channels have the best choice in bipoles as their settings provide for channel separation as well as localization of the soundscape.

Direct-Radiating Monopole Surround Speakers

These surround speakers should be used when:

  • When you have the limitations to only install the surround speakers at the corners at the back of the room, then the direct-radiating speakers come in handy as both dipoles and bipoles, installing them too close to the sidewalls will interfere with their performance as they will shoot the sound directly into the walls.
  • Monopole speakers are more appropriate if the area where the listener is supposed to sit is about 10 feet from the side or back walls where the surround speakers are to be mounted. In order to achieve a more diffuse effect, the speakers should be placed in a direction that is more to the front than to the listening space.
  • If monopole speakers are to be used in larger rooms, then a number of surround speakers should be mounted on both the rear wall and sidewalls. The speakers should also be placed at a far distance from the listening area and apart from each other so as to achieve the highest degree of ‘directness’ i.e. more and more sound to be directed to the listening area.

Also Read: Differences Among Monophonic, Stereophonic and Surround Sound


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