If you go to the movies frequently , you ’ve in all probability encounteredTHXat some power point . The lights dim , the screen door dismount up and you see the THX logotype , accompanied by earthshaking strait . The phrase " The audience is listening " appear and you get it on you are in for an aural , as well as visual , experience .

The rough-cut assumption is that THX is but another moviesound data formatting , but it sour out THX is not a sound format at all but something else wholly . In this article , you will take just what THX is , how it figure out and how dramatics acquire it .

Short History

THX , identify afterTHX 1138(George Lucas’first feature film ) , was developed atLucasfilmin the early 1980s . George Lucas wanted a agency to assure a movie would look and sound on the button the same no matter where it was played . Tomlinson Holman , former collective proficient conductor for Lucasfilm , and a team of THX engineers took on the challenge of recrudesce abaselineset of standards .

They noted several theater shortcomings that might negatively affect an consultation ’s enjoyment of a film :

The nub of THX is a band of guideline that solve these problem . To expose the THX logotype , a theater must adopt this set of standards and then becertifiedby Lucasfilm’sTHX naval division . The first movie to be shown in a THX - certified auditorium wasReturn of the Jediin 1983 . There are now more than 2,000 auditoriums around the populace that have been certified .

THX written in a comic speech bubble.

Before a theater can be certified , a number of thing must happen :

We ’ll take a look at these steps in the following sections .

Licensing & Evaluation

The first step in the process is for the theater owner and THX to take care of thelicensing accord . The theater possessor agrees to let the THXcrossover equipmentand pay off for the right to use the THX logo . Once the field of operations possessor signs the concord , THX review either the architectural plan of the auditorium or , in the slip of subsist auditoriums , a survey of the current conditions .

The theater owner and a THX team then develop a design for carry out the substructure needed to get together THX specification . After the theater owner has incorporate the intent changes , THX will help him or her in take equipment from the THX equipment listing . The final intention and equipment tilt is relegate to THX for blessing . Once THX approves the list , the owner can begin real construction or renovation . CES : TXH Tech Pagesshows some of the architectural design details involved in fabricate a THX theater .

Certification

Let ’s take a tone at the THXcertificationprocess . THX looks at a number of theater qualities , which come down into four basic group :

The auditorium in many theatre of operations do not furnish adequate roadblock to keep out unwanted noise . How many times have you posture in an auditorium listening to the gunfire and explosions from the pic next - door ? You may also have been distracted by the unceasing Movement of Holy Warriors of HVAC equipment . THX - attest auditorium can not surmount anoise criterialevel ofNC-30per musical octave . disturbance criteria is a mensuration of background noise in a way – in this vitrine , noise from external rootage . NC-30 is comparable to the level of external noise you would get a line from inside a Christian church .

The THX team also measuresreverberationandechoingin the auditorium . They do this by counting the number of seconds it takes for a 60 - decibel(dB ) tone to completely fleet off . For THX certification , this time must return within a certain boundary determined by the auditorium ’s size of it . You should not find out any reverberation in a THX field .

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Theprojection systemand thescreen’sbrightness levelmust meet guidelines established by theSociety of Motion Picture and Television Engineers(SMPTE ) . The projector must align with the center of the screen within five percent , and sooner three percent , of the silver screen ’s breadth and superlative .

When watching a movie with a stock 2.35:1aspect ratio , masses sitting in the remnant seats on the back dustup must have aviewing angleof at least 26 stage ( 36 degrees is considered optimal ) .

No rear end can have a partially stymie survey . to boot , the movie ’s strait must be clear-cut and discrete from any tail .

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Sound

Certainly , high - quality sound is at the spirit of the THX outgrowth . In developing the criteria for THX strait , THX engineers look at two distinct character of a sound system :

TheA - chaincomprises the component part that decrypt the sound from whateverformatit is in and action that signal to remove stochasticity . This includes the audio pickup on theprojectorand the cinema sound processor . Digital sound formats , such as DTS , Dolby Digital and SDDS , and noise - decrease system , such asDolby AandDolby SR , are systems that improve the A - chain .

TheB - chainis essentially the rest period of the sound organisation ( THX crossover voter , poweramplifiersandspeakers ) . The THX engine driver agnise that no matter how good the phone come out of the celluloid processor was , a weak B - chain sound system could bankrupt it . To prevent this problem , THXpatented a sound organisation designconsisting of a specialcrossoverand components from alist of THX - approved equipment . The engineers at THX subject field all of the professional audio equipment on the inclination to a assault and battery of trial to ensure that it come across the spec they have established .

The THX crossing over is a proprietary auditory sensation processor that separates the down and high frequencies to supply blank sound over the theater ’s sound system . theater of operations owner do not corrupt the crossover , but instead lease it as part of the THX licensing system . The crossover uses 24 - dB - per - octavehigh - passandlow - passfilters . The filters keep all of the highfrequenciesfrom sound to the subwoofer ( grim - pass ) and all of the low frequency from get going to the main utterer ( mellow - pass).This pagedemonstrates a high-pitched - base on balls filter , andthis pagedemonstrates a low - pass filter .

During the 1990s , THX spread tohome dramatics . VHSandDVDmovies that bear the well - known logotype have go through the THX Digital Mastering Program . This is a professional services group that works with studio and post - production facilities to ascertain that the highest standard are apply for sound , video , compression , and reverberation . Check outTHX.com : evidence Productsfor a list of manufacturer that offer THX - approved menage theater component . Just remember , unless you set up your dwelling theater in a elbow room that meets the same demanding spec ask for theaters , abode THX belike wo n’t fathom the same as it does at the movies .

For more entropy on THX and related to matter , check out the links on the next page .

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THX and Lucasfilm are trademarked right of first publication of Lucasfilm Ltd. All right reserve . Used under authority .