Expanding your sound system beyong 5 / 7 channels - Audyssey DSX, DTS Neo-X, Prologic IIz

As more get HT systems with more than the usual 5.1 channels, those with deeper pockets and a greater than average interest will venture into the realm of > 7.1 channels, one can look forward to the various options to expand the soundfield beyond what is the typical 5 or 7 channel system.

Bear in mind, as of now, 99% or more of discs are only encoded with a maximum of 7 channels and more than 60% are only 5.1 channels. So don't lose too much sleep if you don't have > 5 channels.

This is a discussion thread to talk about moving beyond 5 / 7 channels.

What you will need:

  • Enough amplification for all the channels you wish to playback.
  • Decoding for each format.
  • Discs / software encoded for playback of DTS-Neo X
  • You can't add Wide AND Heights from a single preout.

The current choices are:

Audyssey DSX

Dolby Prologic IIz


 Audyssey DSX:

This is the oldest to get 11 channels, and allows any source with 5 channels of decoding to be matrixed into 11, and you use it concurrently with Dolby Prologic IIx Cinema typical.

Some links:

First listen:

Audyssey DSX Highlights

  • More enveloping surround sound. 7.1, 9.1 and 11.1 surround sound produces amazingly detailed and immersive experiences. The Height and Wide channels make movies sound three-dimensional. With Audyssey DSX, explosions, storms and battle scenes come to life.
  • Scalable setup. DSX-enabled AVRs can deliver content to 7, 9 or 11 speakers, allowing you to build a surround sound system with the appropriate number of speakers for your space and budget.
  • A key component in your AVR. Audyssey DSX comes standard on many premium home theater receivers – be sure yours has it.

Audyssey’s Surround Sound Solution

Today, movies are mixed with five discreet channels and nearly every home and movie theater in the world uses the 5.1 standard: five speakers and one subwoofer (read blog). But after years of research, Audyssey scientists discovered that by adding more channels in the right places surround sound could be even better. Audyssey DSX not only creates new Wide and Height channels, but also provides Surround Envelopment Processing to enhance Front and Back channels. This technology processes the standard surround signals in the time and frequency domains to improve the perceived sense of envelopment and blending with the other speakers in the surround system.
By expanding 5.1 sound, Audyssey DSX technology delivers true 7.1, 9.1 and 11.1 surround sound. The result isn’t just the most immersive, realistic home theater sound on the market, but a new standard in surround sound.

Technical Details

Why use more speakers?

Research in human hearing shows that we can hear many more directions than what current systems provide. We use the direct sound to localize the direction of sources and the reflected sound to perceive the size of the soundstage.
Experiments have shown that human localization is better in front than to the sides or behind. This means that for front-weighted content such as movies and most music, good engineering dictates that we employ more channels in the front hemisphere than the back. Imaging is also better horizontally than vertically and so good engineering also dictates that channels must first be added in the same plane as our ears before going to higher elevations.
Perception is not the only factor. The physics of room acoustics for music have been well studied, and their correlation with subjective impression increasingly understood over the last 30 years. This research has shown that we have strong built-in preferences for the direction, frequency response, and time of arrival of reflected sound. Additional channels and surround sound processing are needed to properly render these components.

Audyssey DSX Configurations

7.1 SURROUND: A B  |  9.1 SURROUND: A B C  |  11.1 SURROUND: A

Wides Before Heights

One key finding from the research is that first side wall reflections play a great role in determining subjective impression. The most important direction of reflected sound was found to be ±60° relative to the front. Audyssey DSX provides a pair of Wide channels (LW and RW) at ±60° with appropriate frequency response and perceptual processing to match these requirements of human hearing. These Wide channels are much more critical in the presentation of a realistic soundstage than the Back Surround channels found in traditional 7.1 systems. Adding surround channels behind the listener has a very small impact compared to the increase in envelopment and soundstage width that the Wide channels provide.
The next most important acoustical and perceptual cues come from reflections above the front stage. Audyssey DSX provides a pair of Height channels (LH and RH) that should be ideally positioned at a 45° elevation angle.

DTS Neo X is the latest on the market to offer a 11 channel system, but for now, there are only a few movies and even then it's matrixed from 7.1 channels.

Some useful websites:

DTS Neo:X™ is the world’s most comprehensive upmixing solution offering up to 11.1 channels of immersive surround with near discrete Front-Height and Wide imaging. From ambient/non-directional effects like raindrops to overhead effects like a low-flying jet, DTS Neo:X lets listeners track all the audio action. Sound arcs overhead to the Front-Height speakers, sideways to the Wide speakers, and back to the Rear speakers, creating a semi-spherical soundstage.
 DTS Neo:X Benefits
  • The most comprehensive matrix upmixing solution on the market that creates a semi-spherical sound field.
  • Ability to place near discrete vertical cues (especially with optimized content) for maximum immersive effect.
  • Flexible options to cover various products and usage cases (AVR, HTiB, automotive, headphones, etc.).
Unparalleled Immersion in Music, Cinema & Games Cinema mode: This mode offers a clear and enhanced Center channel that makes center stage action stand out in movie soundtracks, with a firm position for dialogue. It also enables listeners to experience the full audio effect across a wider range of audience seating.
  • Music mode (enhanced immersion for music): In this mode, use of the Center channel is more controlled to prevent narrowing of the front of the musical soundstage.
  • Game mode: This mode delivers enhanced directionality and immersion for an extremely interactive gaming experience. It offers the greatest degree of channel-to-channel separation, delivering discrete sound localization cues from Front-Height or Wide channels.

Pro Logic IIz: is a 9 channel system that allows a 5 channel source to be matrixed into 9 channels - not 11, and gives you Heights but it does not allow you to select WIDE unlike Audyssey or DTS-Neo X


Dolby Pro Logic IIz delivers these enhanced effects through the addition of front height channels. These added channels create a soundstage so lifelike, you'll think the rain in a movie is actually falling on your roof. Special effects will hit with an intensity you've never experienced before. And you'll feel like you're front and center when watching concert videos. Take your listening to the next level with Dolby Pro Logic IIz.
 Dolby Pro Logic IIz Benefits  Introduces front height channels for more spacious surround sound
 Delivers a compelling and enveloping listening experience
 Adds depth and dimension for a lifelike soundstage
 Provides you with a wide range of choices for speaker positioning to optimize sound in almost any room
  Works with existing soundtracks by identifying and decoding spatial cues that occur naturally in a soundtrack

Listening reviews:



Dolby Pro Logic IIz Details

Dolby Pro Logic IIz Details

Elevating Surround Sound to New Heights

A Lifelike Soundstage

Dolby Pro Logic IIz 7.1Conventional 5.1- and 7.1-channel surround sound systems deliver a horizontal soundfield—sound is directed at you from only one vertical plane. Dolby® Pro Logic® IIz takes surround to the next level by adding front height channels—an additional pair of speakers positioned above the front left and right speaker. What that means for you is a surround sound experience with incredible depth and dimension.
Most surround sound solutions use digital signal processing (DSP) to artificially model listening environments. Expanding on proven Dolby Pro Logic IIx technology, Dolby Pro Logic IIz stands apart by identifying and decoding spatial cues that occur naturally in all content—stereo and 5.1 broadcast, music CDs, DVDs, 5.1- and 7.1-channel Blu-ray Discs, and video games. It then processes ambient sound and certain amorphous effects such as rain or wind and directs them to the front height speakers.
Movie and game producers can even mix specific height channels into a soundtrack, and Dolby Pro Logic IIz will faithfully reproduce the vertical placement of those sounds. That means you’ll hear lifelike sound that comes at you from varying heights, compelling you to follow the action with your eyes and ears—above, below, and all around you—precisely as the producers intended.
Add it all up and the result is an incredibly spacious vertical soundfield that immerses you in richly detailed Dolby surround sound.

Flexibility Is Built In

By expanding the soundfield vertically Dolby Pro Logic IIz lets you create a 7.1-channel playback system from your 5.1 surround system, or a 9.1 system from your 7.1-channel setup. Dolby Pro Logic IIz even makes speaker positioning and wiring simple. And if it’s not practical to add rear surround speakers in your environment, Dolby Pro Logic IIz still lets you enjoy incredibly realistic surround sound.
Dolby Pro Logic IIz 9.1How flexible is Dolby Pro Logic IIz? If you already have a 5.1-channel system and buy a new 7.1 audio/video receiver with Dolby Pro Logic IIz, you can put the two additional speakers above your left and right front speakers for 7.1 height, or at the back for a traditional 7.1 setup. Or you can stay with 5.1 channels and use the extra amplifier channels for stereo speakers in another room. With a 9.1-channel setup, you have even more choices, including state-of-the-art 9.1 playback with both surround and back speakers and two front height speakers.
With Dolby Pro Logic IIz you’ll have the flexibility to experience startlingly realistic surround sound no matter how challenging your listening environment may be.

I have no financial interest or other interests in any of the items / events I write about.


  1. Note on Wide Speakers. I have added two wide speakers to my setup and you going to be blown away. Pioneer amps have a Wide Surround Music / Movie mode and it changes the way to listen to music and movies. From Stereo to Surround Sound to Wide Surround Sound makes such a difference. You just get surrounded in sound and it enhances standard stereo tracks.


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