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Surround formats

There are different surround formats and it is difficult to know what exactly they do. Although It is important to know which are the most important.
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Surround formats: Dolby and DTS

There are many different surround formats and it is very difficult to know what exactly they can do for you. It is important that you know which are the most important formats, so that you can be sure that your receiver can handle these formats. A DVD or Blu-Ray disc often contains different formats, such as Dolby Digital or DTS, and it is important that you know whether your receiver can play these formats. Your receiver has to convert these signals into sound and forward them to your speakers.

Surround formats

So let’s not make it too difficult. There are two main formats;

  • Dolby Digital
    Dolby Digital is a format that is used on almost all DVDs and (HD) TV broadcasts. This format processes the signals digitally on your 5.1 surround setup.
  • DTS
    DTS is a format that is also available on 70 percent of all Blu-ray discs and DVDs, usually in addition to Dolby Digital. This format also processes the signals digitally on your 5.1 surround setup.

Both formats are available on almost all Blu-ray discs and DVDs that are available today and 99% of all receivers can simply handle these formats.

More audio formats

If you still want or have a 6.1 or 7.1 home cinema system, then you should look at Dolby Digital Surround-EX and DTS ES . These additions ensure that you can also reproduce sound on more than 5 channels. Incidentally, both formats (DTS & Dolby) also have the option of reproducing sound from stereo sources over 5 channels and thus simulating surround sound. Dolby Pro Logic is one of these formats. Dolby Pro Logic cannot be found on sources such as DVDs and Blu-ray discs, but is often a setting of the receiver.

Dolby Pro Logic IIz
This setting, which can be found on receivers and not on sources such as DVDs and Blu-ray discs, ensures that the receiver sends extra surround information to two ‘effect speakers’ placed above the two front speakers. The reproduction of the sound thus comes even closer to reality. People are generally more sensitive to sound reproduced in this way, via two raised / hanging speakers in front of the listening position. Certain sound effects such as wind or rain are reproduced by these speakers and create a more realistic picture. Thanks to the two extra speakers, a 5.1 setup can become a 7.1 setup and a 7.1 setup can even become a 9.1 setup. All you need are two extra speakers and a receiver that supports the Pro Logic IIz technology.

Dolby Volume and Audyssey Dynamic Volume
There is quite a difference in volume between TV programs (also within programs), films and commercials. This can mean that you have to manually adjust the volume whenever there is a commercial break, for example. With Dolby Volume and Audyssey Dynamic Volume these differences are automatically corrected. Audio levels are continuously monitored and adjusted where necessary.

HD audio formats

In the HD era, some new additions have been added that are important, namely Dolby True HD and DTS-HD Master Audio. These two formats also come from the normal Dolby and DTS formats, only the difference here is that they have a much lower compression and therefore a much better sound. These new formats are on Blu-ray discs and not on normal DVDs. If you want to be able to play this higher audio quality, you must have a Blu-ray player, but also a receiver with a decoder (a chip that makes it possible to play surround formats) for Dolby True HD and DTS-HD Master Audio. The latest receivers have this decoder, but older receivers do not yet.

Pay attention; If you have an older receiver, but have a Blu-ray player, it is still possible to play HD surround formats. You then have to set the Blu-Ray player to decode the signal to PCM. This may be a bit complicated, but you will probably get there via the manual. You can also purchase a Blu-Ray player which has 5.1 analog audio outputs (6 separate audio outputs). In this way, the Blu-Ray player also converts your HD surround format and sends it to the receiver.

Surround formats for more speakers

Although 5.1-channel and 7.1-channel setups are most commonly used, more and more audio formats appear that use multiple speakers in the setup. In recent years, new surround formats such as  Audyssey DSX ,  DTS Neo: X  and  Dolby Atmos have been  released with which extra speakers are placed in the setup, for example above the listening position or at the top of the front of the listening room.


If you have ever been to the cinema, you have certainly encountered THX on the screen, but nowadays you can also find the THX logo on the better home cinema products. Many people think THX is a sound format like so many others (DTS, Dolby Surround, etc.), but nothing could be further from the truth. THX is a hallmark of audio and video quality issued by Lucasfilm. Lucasfilm has conducted all kinds of tests and set rules from which a package of requirements has been filtered that home cinema equipment must meet in order to create the most realistic possible reproduction of the cinema sound. THX aims to reproduce the cinema sound as convincingly as possible in a living room.

Surround formats

Below you will find some THX regulations;

  • THX logo may only appear on equipment approved by Lucas film.
  • Decoders, amplifiers and loudspeakers must meet high requirements with regard to security and load capacity and also comply with all requirements set by Lucas film.
  • The sound reproduction (front and rear) should never distract from the image. The sound of an aircraft taking off above the viewer should only be audible as such, not as a locatable source of changing sound.
  • Because the living room is so much smaller than the cinema room, reflections are much more likely to be a nuisance, especially those through the floor or ceiling. In order to convey sound effects according to plan, THX-approved LMR speakers exhibit a very narrow vertical and a very wide horizontal dispersion.
  • The arrangement of the identical LMR loudspeakers in the front must match the position of the image. The subwoofer (s) can be placed more freely.
  • The 2 surround speakers are not placed against the back wall, but diagonally upwards on the side wall, at the level of the enjoyment area (hotspot). They should have a diffuse dipole radiation, so that you hear a really diffuse sound. Because you sit with your head between both surround speakers (which contain a mono signal). The Left rear speaker is presented with a signal that is slightly phase shifted relative to the Right rear speaker. THX calls this “de-correlation” and gives you the idea that you are listening to a kind of stereo.

A THX device for the living room is a good (but more expensive), solid and reliable product, which meets the highest requirements in terms of Lucasfilm’s package of requirements. Opinions are divided, but experts say that the difference is certainly noticeable. The sound is reproduced as intended and with the best cinema effect.

THX Select (2) & THX Ultra (2)
For receivers and speakers, the THX Select certification means that these components are certified to work at the highest level in a medium-sized home cinema room up to approximately 56 cubic meters. THX Ultra is just that little bit further. This certificate is awarded to components that can achieve THX performance standards in larger home cinema rooms up to 85 cubic meters. Theoretically, THX Select receivers and speakers in a room of 56 cubic meters or smaller should deliver the same performance as the higher THX Ultra components. There is no THX Select certificate for components such as preamps, DVD players and Blu-ray players. These components are only indicated with the THX Ultra certificate.


Speaker manufacturers design their speakers to reproduce sounds without distortion or discoloration. However, when you place the speakers in a certain room, the character of the sound changes. Walls, furniture and other objects reflect and absorb certain frequencies. This creates complex changes in the sound reproduction and these distortions are different in every room. A loudspeaker manufacturer simply cannot take this phenomenon into account. Audyssey is a company focused on optimizing the sound in any room. If certain Audyssey software is installed on a receiver, you can see this by the Audyssey logo below.

Surround formats

Audyssey MultEQ
This is a technique, developed by Audyssey, which can optimally adjust your speakers and receiver in every room. When you find this technique on a receiver, each speaker can be set precisely individually. You will often find a set-up microphone at receivers that contain this technique. You place this at different listening positions (often up to 5 or 8 different) and then the Audyssey MultEQ program optimally adjusts your speakers and receiver, taking into account all objects in the room and the distances from the listening position.

Audyssey Dynamic EQ
Audyssey Dynamic EQ is a loudness correction technology that solves the problem of sound quality degradation at low volume settings by taking into account the characteristics of human hearing and room acoustics. Film producers, musicians and audio engineers produce (film) music at a reference level that is much higher than is usually used in the living room. At a lower volume, voices change, bass diminishes and the overall sound experience diminishes. But with Dynaminc EQ you can experience the original sound at any volume. Note that Dynamic EQ only works well in combination with a well-adjusted room by means of MultEQ.

Audyssey Dynamic Volume
There is quite a difference in volume between TV programs (also within programs), films and commercials. This can mean that you have to manually adjust the volume whenever there is a commercial break, for example. With Audyssey Dynamic Volume these differences are automatically corrected. Audio levels are continuously monitored and adjusted where necessary.

Audyssey DSX
With this Dynamic Sound Expansion technology from Audyssey you can add more audio channels to a surround setup. For example, you can expand a 5.1 system to a 7.1, 9.1 or 11.1 system. Through Audyssey DSX can be at the front left and right speakers an extra wide locations channel or two additional height channels or two additional back surround kanalen.Volgens Audyssey will especially wide channels for additional effects ensure that the cinema experience yet intensify .

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