When we launched Audyssey DSX one year ago, I never expected the incredible response that we received from home theater enthusiasts.  It turns out that the much dreaded SAF was less of a factor than I thought, and people will actually put nine or eleven speakers in their house.  Who knew?

Audio systems today have already reached the limits of human perception in frequency response and dynamic range.  Yet 5.1 channel surround sound is not completely convincing.  It can easily be distinguished from the real thing because human perception can hear many more directions than what current systems provide.  This is what we set out to address with Audyssey DSX.

But, if the gods grant us more channels, where should we place them?  The answers come from research in acoustics and psychoacoustics.  Our sense of “being there” is enhanced when we hear not only the direct sounds from the front, but also sounds that arrive later from very specific directions.  When our hearing starts to provide cues that match what are our eyes are telling us about the space, something magical happens: immersion.

I have received several questions about Audyssey DSX so I thought it would be a good idea to provide some practical tips that can help you get the most out of your system.

Wides before Heights

For years Audyssey has been talking about reducing the effect of unwanted sound reflections in the room with MultEQ.  But with Audyssey DSX we are adding reflections?  What’s all this about?  The key word is “unwanted.”  Sound reflections from certain directions are desirable because they improve our perception of the soundstage.  But, in our home listening room, these reflections rarely come from the optimal directions.  As a result they degrade the playback quality and that’s why MultEQ tries to minimize their effect.

But, what if we could recreate the desirable reflections?  Then, we can really feel more immersed in the scene.  The most important direction for these reflections is from the sides and that’s what the Audyssey DSX Wide channels are designed to do.  The algorithm looks at the content in real time and extracts from it the cues that we perceive from optimal side wall reflections.  This information combines with the direct sound from the front and gives us an enhanced sense of soundstage width.

The second most important direction for reflections is the top of the stage.  That’s where the Audyssey DSX Height channels come in.  The information from these channels helps enhance the sense of soundstage depth.

Audyssey DSX also performs real-time processing to make sure that the sound from these new channels does not produce a stereo image that competes with the original stereo image rendered by the left and right speakers.  The combination of Audyssey DSX Wide and Height channels is a very compelling addition to any 5.1 system.

Angling for position

The ideal location for the Wide speakers is along the side walls at 60° out from the center channel.  To find the right spot, measure the distance from the center speaker to the left speaker.  Then double it.  That’s where the Left Wide speaker should be placed.  Repeat for the right side.  The idea is to separate the Wides from the main left and right speakers so that their content is clearly coming from a different (wider) direction.

To get the most out of the Audyssey DSX Height channels, they need to be separated vertically as much as possible from the front left and right speakers.  The best place for the Heights is on the front wall near the ceiling pointing towards the listener.

Distance

The astute reader will notice that the recommendations above result in the Wide speakers being closer to the center of the listening area than the fronts, and the Height speakers farther away.  Just like with all the other speakers in the surround system, it is the job of MultEQ to measure these distances and apply the proper delays to place all the speakers on a virtual sphere.  Make sure you run MultEQ first to set the proper levels and delays for all your speakers.

Speaker type

Audyssey DSX synthesizes both direct and ambient content for the Wide and Height speakers and so the speakers need to be direct radiators and not dipoles.

Content

Dynamic Surround Expansion (DSX) is a method to enhance the reproduction of surround content.  It is not designed to expand two channel content.  It works best with original, discrete, 5.1 surround content.  It can also be used in conjunction with one of the many available upmixing methods that produce 5.1 from 2-channel stereo.

This entry was posted on May 20, 2010 at 9:31 am and is filed under Sound Ideas. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.