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Issue #028 - What's new
22nd December 2006

The Practical HT Guide Update  brings you the latest additions in a series of informative home theater design articles, unbiased system reviews, practical guidelines and free advice. If you like this e-zine, please do a friend and me a BIG favor and "pay it forward."

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Welcome to the December 2006 issue of
Practical HT Guide Update

In this issue:

  • Speaker Placement and Delay Settings in Surround Sound systems:

Home Theater Speaker Placement:

Time Delay Settings in Surround Sound Systems:

  • Sound formats and THX:

Home Theater Surround Sound Formats

THX Home Cinema - An Overview


Speaker Placement in Surround Sound Systems

Home theater is not just watching movies - it is the experience of being immersed into the movie action itself. This would not be possible without the enveloping atmosphere created by surround sound.

Home theater sound systems require at least five main speakers plus and a sub woofer, hence the reference to a 5.1 speaker playback setup. More advanced audio playback systems may feature six (6.1 setup) or seven (7.1 setup) full-range audio channels for greater realism.

speaker placementSurround sound requires that the various sounds produced by the different speakers originate from specific positions within your home theater room. Knowing these requirements will help re-create the sound producers intended it to be.

Further more, very few are aware of the fact that there are distinct differences in speaker placement requirements between multi-channel music listening and watching movies.

More on correct speaker placement can be found in our Home Theater Speaker Placement article at our site. This article takes a detailed look at the role of the individual speakers in a surround sound setup. This should lead to a better understanding of the different speaker placement requirements in multi-channel audio. We also explain the different speaker placement requirements between home theater sound and multi-channel music. More info here.


Time delay settings in Surround Sound

A correct home theater speaker placement is just one aspect of home theater sound, or in that case of any multi-channel audio set-up. 

For a correctly set home theater surround sound system, the sound from the different speakers should reach the listener's ears exactly at the same instant. This also explains why the main front left and right speakers, and the center speaker, should all be set at exactly the same distance from the listening position.

Surround speakers in home theater systems are usually closer to the viewer than the front speakers.

For this purpose, Dolby Digital and Dolby Surround Pro Logic playback based systems apply a split-second delay in the order of a few milliseconds for the surround sound channels.

Setting the time delay in a surround sound system would effectively adjust the soundfield between the front and rear channels to ensure that simultaneous sounds from each speaker arrive at the listener's ear at about the same time.

Dolby Pro-Logic surround sound systems have a second reason for applying this split-second delay, namely to reduce the so-called 'Haas' effect, and therefore improve the channel separation between the front speakers and the surround.

It is true that some of the latest A/V receivers incorporate a smart and easy-to-use user interface that would either make use of an auto calibration process, or require that the user simple key in the distances between the different speakers.

Unfortunately, not all surround sound systems do provide such a friendly user interface as detailed above. Some systems still require that the user will have to key directly the delay settings in milliseconds. So how do you arrive at the right values for these delay settings? More info can be found in our article on Time Delays setting in Multi-channel Audio Systems


Surrounding Yourself with Sound!

Up to the mid-50's, home audio was still the good old single channel - or mono - format. The first multi-channel audio appeared in the 60's with stereo sound. While this represented considerable improvement over monaural sound, yet it still lacked the ability to envelope the audience during movie watching or music listening.

In other words, it still lacked that surround soundfield so important to help you feel immersed into the middle of the movie action or concert.

The first surround sound playback systems appeared in the late 80's with the advent of Dolby Surround - a 4-channel matrix-encoded format that provided for the first time, a surround sound channel (in addition to an extra front speaker)  encoded over the two main left and right channels.

It is the addition of this single rear surround channel played over two identical speakers placed on either side of the listener that made it possible for this format to surround the audience with sound.

7.1 speaker setupDolby Surround was eventually to mark the first of a never ending list of home theater surround sound formats that soon followed in the process.

Most of today's surround formats incorporate a minimum of six discrete rather than matrix channels, meaning that each channel is unique and independent of the rest.

Extended surround sound formats make use of additional speakers e.g. 8 speaker channels in a 7.1 audio playback setup.

Unfortunately, the world of surround sound has become a bit too complicated for the end user, with a never ending list of terms and brands - DTS, Dolby, THX, etc.

Help is on the way! Our guide to Surround Sound Formats should help clear up the confusion by bringing out the main differences and characteristics. It also discusses the latest high definition audio formats designed to match the video quality on HD-DVD and Blu0ray discs. More info here.


THX Home Cinema - An Overview

THX logo

Not a standard by itself, THX Home Cinema aims at delivering cinema-quality picture and sound to the home.

THX. Ltd was established in 1983 by George Lucas company. It started out as a program to correct inadequacies in film playback, ensuring that surround sound in theaters meets the standards set by filmmakers. It then expanded into the home theater arena through its THX Home Cinema with product certification that makes it possible to implement Dolby and other surround sound formats in a uniform manner in the home.

The THX Home Cinema program, like its cinematic counterpart, ensures that the home entertainment consumer, experience movies as the director intended.

In other words, THX Home Cinema is not some surround sound format, but a quality assurance program that works in conjunction with the different surround sound formats, to deliver superior-cinema experience via quality picture and sound presentation, in the home.

Many home theater enthusiasts do not have a true understanding of what the THX certification system and related technology is all about, nor what the different logos found on home theater THX certified gear really mean, yet to the 'everyday consumer', the 'THX' label signifies that the highest standards have been used.

More information is available in our article on THX Home Cinema. There you will find an easy-to-follow explanation of the THX certification system and related technology as well details on the different THX logos that you may encounter on THX certified gear. More info here.

Hope you will enjoy and profit from these additions to our site. More new content will follow soon, so...

Finally, this news letter would not be complete without...


Christmas greetings

I wish you all a Blessed Christmas and all the best for the New Year 2007. May God shower on you health, happiness, and abundant happiness.

Baby Jesus: May God Bless YOU Always.


Take care and stay tuned! 



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