THX

THX is a commercial quality seal of George Lucas group of companies. It was originally intended for movie theater, now it is but for a variety of applications that have to do with some form of sound and picture playback, forgive.

A common misconception is that THX is a sound system similar to Dolby Surround, SDDS or DTS.

THX for movie theater

Origin

The company THX Ltd.. was founded in 1983 by George Lucas as a certification body for cinema. The driving force was Tomlinson Holman, who realized in his work as a sound engineer and over again that the film sound, which he had mixed in the studio, often did not arrive in the same form in the cinema.

The origin of the name is unclear. Three possible explanations are:

• " Tomlinson Holman Experiment",
• " Tomlinson Holman Crossover", according to the THX Ltd.. crossover manufactured ( THX monitor).
• " THX 1138 ", according to Lucas ' first feature film.

Holman has developed a standard system that unifies the acoustics of the recording studio to the movie theater. Must subjecting themselves to these standards not only the technology used, but also the premises, since the nature of which has a decisive influence on the perception of sounds. Obvious reference for Holman's standards was a movie theater in Hollywood, were demonstrated in the films for the Academy Awards.

THX is only one standard for the exercise; the means by which sound ( and picture) are reproduced, is completely irrelevant for THX, as long as the result of the THX standard equivalent.

The company even sells accordingly no devices. The THX Monitor ( currently the THX Monitor D1138 ), at its core a crossover and monitoring amplifier, which is part of THX Ltd.. license issued and owned by THX Ltd.. This crossover is adjusted by a THX engineers, depending on the built, THX - certified speakers. After that, playback is adapted to the current standards using the equalizer in the cinema processor. Once installed, the presenter can ( individually or as a sum ) the sound on all channels listen to before and after the final stages to control the fly, if all function properly.

Today's meaning

For cinemas extensive requirements concerning not only the sound but also the image, as well as foreign influences apply to THX standards currently in force ( for example, the noise of the air conditioner ) involve. THX Ltd.. certified to not only technical devices and reviewed existing cinema halls, but also provides consulting services for new buildings to.

Meets a movie theater all the requirements, it is given on request ( and pay) by the company THX Ltd.. a THX license, compliance with which is reviewed annually even after the award.

In March 2008, according to THX.com world over 2000 cinemas in 30 countries THX - certified. The website reported in June 2007, also from over 2000 cinemas.

Dissemination in German cinemas

THX loses in the German cinema market of growing importance. Since 2003/2004, for example, has the Cinemax chain does not have certificates for their rooms more because they cost reasons, the contracts with THX Ltd.. announced.

In May 2009, existed in Germany 19 THX-certified cinemas.

For comparison:

• March 2006: 44 certified movie theaters
• June 2006: 40 certified movie theaters
• January 2007: 35 certified movie theaters
• April 2007: 32 certified movie theaters
• June 2007: 31 certified movie theaters
• August 2007: 26 certified movie theaters
• December 2007: 22 certified movie theaters
• February 2008: 20 certified movie theaters
• April 2008: 23 certified movie theaters
• June 2008: 23 certified movie theaters
• March 2009: 20 certified movie theaters

(Source:, accessed in the corresponding month )

The main reason is the uncertain relationship between the high license costs on the one hand that are just difficult to cope in times of declining visitor numbers for the movie theater, and the difficult to measure THX advertising effect for the cinema the other.

THX Ltd.. itself does in the Home THX a large number of licenses ( and Others for sound cards, DVD or VHS purchase cassettes). At least for parts of the movie theater industry is this inflationary emergence of THX seals in everyday life no convincing strategy to reward only the highest quality. There is also a sometimes lack of control of the conditions for a theater license and the use of the THX trailer (switched before the main program THX commercials ) in rooms that are not THX - certified, which means that the "THX - experience " is not always the promised high demands. Complaints from the public via a toll free number ( in the U.S. ) directly to THX Ltd.. to judge, is not possible in Germany.

Furthermore argue parts of the movie theater industry in that THX brings no benefit since the digital record of the cinema sound ( DTS, SDDS, Dolby Digital). It is generally believed that digital recording has, in conjunction with the technical possibilities in recent movie theaters will actually lead to quality improvement. However, the digital recording does not specify how the audience perceives the sound. An optimally abgemischter, high-quality, digital audio can be played back only deficient in movie theaters with inferior components or poor acoustics.

In many movie theaters, especially in the multiplexes, but THX - licensed components are installed, because their quality is unquestionable. Should be saved, as in the above example Cinemax, but the cost of the prescribed annual review and related annual recertification of the cinema as a whole. Without certification by THX Ltd.. is the use of the THX - monitor, the essential building block, not possible. The THX monitor is THX Ltd.. not sold, but is part of the license.

THX outside the cinema

THX seal there since advent of the home theater market for this area in the variations THX Select 1 and 2, THX Ultra 1 and 2 and THX Certified Multimedia. Are Certified all devices, amplifiers over loudspeakers to sound cards.

THX Ultra represents in each case the increase in the THX Select dar. From THX is often the room size is used as a benchmark. Consequently, should a THX Ultra Certified device ( such as a speaker) afford at least the same thing that has to make a THX -Select unit in a smaller space.

In addition, apply to specific device groups rules for the certification:

THX -certified amplifiers and preamplifiers also various electronic circuits and EQ programs are prescribed, the appropriate way of doing a sound improvement in the sense of THX. Examples are speaker systems with Dipollautsprechern ( in two directions beaming - one of which phase- twisted ) called, but they are not provided in all THX standards.

Function

As the requirements for THX Ultra can be met by hardly a home theater system, comes in the home usually THX Select to use.

The THX - circuit includes the following functions:

• Re-Equalization

The original soundtrack is designed to be played back in large movie theaters with special Klangvorausetzungen. The speakers are positioned far from the audience, or behind the screen. To ensure good speech intelligibility even in the last row, the high frequencies must be played louder than the bass. If this soundtrack played on a home theater system, to a bright, unnatural sound image would be the result of over-emphasis of the middle and high frequencies. By Re-Equalization, the treble boost is compensated. Music and language are reproduced naturally and realistically.

• Timbre Matching

In the cinema surround effects can be realized by a variety of speakers to ensure a real sound as possible without sound holes. Here, the sound of all speakers used must match. In the home theater but there are only two, at best, four surround speakers available, the sound will be adjusted by the tone adjustment Timbre Matching to the sound of the three front speakers.

• Decorrelation

Dolby Pro Logic works with three front speakers and a mono FX channel, which is transmitted from two speakers. THX improved by Decorrelation the impression that the effects are not emitted from two speakers, but for the spectators can not be pinpointed to come out of the room. Here the mono channel is separated into two channels whose frequency and phase position just far differ, that they are perceived as different.

Through digital technology two more functions are added:

• Bass Peak Management

The loudest part of a movie soundtrack is the amount of bass, which is connected to the via the LFE ( Low Frequency Effects) subwoofer output. Due to the extremely wide dynamic range of a Dolby Digital sound track it is therefore possible that the subwoofer has to transmit signals that exceed its performance. Would lead to significant interference by sound distortion and penetration of the bass system. By Bass Peak Management, the bass signal is limited to a peak, so that the performance profile of the subwoofer is not exceeded.

• Loudspeaker Position Time Synchronization

Ideally all the speakers of a multi-channel system to be equidistant from the listening position, but this usually looks different in practice. The Loudspeaker Position Time Synchronization compensates for these differences by digital setting of the delay time of each speaker to the listening position.

• Loudness Plus

The Loudness Plus function ensures that movies even at a playback volume below the reference mix level nearly as sound like in the movies, as the reference level for most living rooms, based in relation is not to recommend to the size of a cinema hall. An example would be the playback of a movie in the living room of a Blu -ray disc, the sound technology was mixed for a movie theater. Playing the Kinofilmtonspur with the reference level provided for the cinema hall at the screening, and due to the high dynamic range of the recording, would have in the living room means that extremely high sound pressure levels would be achieved ( in the worst case up to about 120 dB (C)) because the small room size, in which the sound pressure can not distribute, but even multiplied by sound reflection on walls, room resonance and wave superpositions in extreme cases at the listening position. A playback of the recording below the reference level, at low volume would lead to a loss of momentum to compensate for this and to get the dynamic range at low sound pressure levels, and to come to the acoustic impression of the original on the next, you need a loudness compensation.

In addition to THX SELECT for home theater systems in smaller living spaces are available for high-end components since 1999 THX ULTRA, which was replaced by the broader Standard THX ULTRA 2 2002. For speakers THX Ultra 2 has a wider dispersion in the vertical direction and improved treble response, which should lead to greater " musicality " of the speakers in the first place ( in the scene but also slight skepticism caused because some thereby vs. slight losses in the Fimltonwiedergabe. THX Ultra feared ). For amplifiers and receivers Ultra 2 includes, in addition to mandatory 7.1 - channel number and THX Surround EX " Adaptive Speaker Array " (ASA ) DSP circuit that allows a more variable formation of the two " back surround " speakers, be what also no longer dipolar nature allowed. When the subwoofer " Boundary Gain Compensation" was added, which is used to prune lowest frequencies when playing in activation and thereby counteract possibly occurring excessive subwoofer rumble near walls. Ultimately provide both THX Select 2, as well as Ultra 2 certified amplifiers and receivers various THX listening modes, which serve the purpose, on the one hand the sound impression adequately the corresponding source material (movies, music, games) adapt, and on the other 5.1 material acoustically correctly on divide the 7.1 speaker layout. The presets in detail are:

• THX Games Mode ( Re-Equalization off, Side and Back Surrounds are connected acoustically in parallel, with a slight focus on the lateral Surrounds - ideal for video games in the 5.1 format )
• THX Music Mode ( Re-Equalization off, Side and Back Surrounds are connected acoustically in parallel to create between them a phantom sound source and thus to simulate a setup with 5 identical speakers - ideal for music in the 5.1 format )
• THX Ultra 2 Cinema ( Re-Equalization on, Side and Back Surrounds are connected acoustically in parallel, with a slight focus on the lateral Surrounds. Thereby, the sound of a large movie theater with each L- shaped arranged side or rear speaker arrays on the right and left side created - great for watching movies in 5.1 format )
• THX Surround EX is turned on ( Re-Equalization, from the two rear channels of the 5.1 signal ( which are reproduced on the respective side Surrounds ) is by analog matrix circuit extracted an additional rear center channel equally among the two back surround speakers is divided. in this way, film soundtracks in the so-called "Matrix 5.1" (also called " matrix 6.1 " ) given process. )

THX in the future

THX Ltd.. currently trying with the argument that the increasingly widespread in home cinema components for multichannel systems require a unified and perfect match to each other to make the THX Standard to the international standard in multi-channel recording technique for music and film sound.