THE THX FACTOR by Peter M. Bracke

One of the most recognizable pieces of film known to moviegoing audiences, the THX logo has been synonymous with high-quality theatrical and home-based presentation for over the past 15 years. Though there have certainly been other integral contributions made to the art of film exhibition during the past century, THX can legitimately claim to having made a most profound impact on the industry. In addition to the theatrical market, THX also helped usher in the era of the home theater, and introduced new certification programs for consumer products and components, as well as mastering programs for the VHS, Laserdisc and DVD formats. And now with the advent of digital projection technology and the Dolby Digital 5.1 surround sound system, THX continues its mission to help the industry ensure the best possible presentation possible.

However, though despite being so well-known by even the most casual viewer, what exactly it is THX does, and doesn't do, continues to remain largely mysterious to even ardent home theater enthusiasts and film buffs. The following three-part overview is designed to provide a thorough, but not overly-technical, look at the art, application and consumer benefits of THX.

Part One of this piece begins with a brief history of theatrical sound production and theatrical exhibition, and the beginnings of the THX Theater Alignment Program. After the early great success of the program in the world's movie houses, Part Two examines THX's entry in to the home theater and laserdisc markets, with a more in-depth look at the concepts and applied theories of the THX process. Finally, in Part Three, we will focus solely on the current THX DVD certification program and some of the changes THX has undergone since its inception.

In addition to extensive research into the history of THX for this piece, DVDFILE.COM sat down with THX's Senior Technical Director JC Mitchell and Head of Marketing Charles Busslinger to talk about THX's role in the DVD production process and how the work of THX benefits the consumer and the format. We also had the opportunity to speak to one of the creators of THX itself, Tomlinson Holman, allowing us to take a better look at its history and the founding vision. Additional resources are also provided at the end of this piece for those interested in further study.

A Briefest Of Histories Of Multi-Channel Surround Sound Post-1970

"The THX is not a recording process. It is a a set of technical standards that optimize equipment, room acoustics, background noise levels, and projection and viewing angles to ensure that moviegoers see and hear a film at optimum performance levels and as the director intended."

          -- Promotional excerpt from the THX Web Site

On the surface, THX may seem to warrant no more than a footnote in the history of motion picture sound for some. Certainly, the basics of sonic reproduction, such as speaker design, room acoustics and amplification, to name but a few, were already well established by the time THX arrived in early 1983. And in today's current marketplace, where high-quality and relatively inexpensive digital equipment is commonplace, the vast leaps and bounds made in sound reproduction over the years is often taken for granted.

Flashing back a few decades, the situation was almost entirely different. Throughout the "golden age" of the studio system then up until the late 50's, the studios more often than not owned outright the motion picture houses that exhibited their products. However, when this monopoly was disintegrated by the landmark "Paramount" case in the early 1950's, most of the internal enforcements of standards for motion picture presentation were effectively wiped out.

The major studios, Twentieth Century Fox, Universal and Warner among them, still continued to develop more extensive and elaborate modes of exhibition, including CinemaScope, 3-D and 70mm, amongst other processes. But, most newly-independent theater owners no longer had the same level of pressure placed upon them to provide the proper environments in which to view these advancements. Subsequently, they began to cut corners to control rising costs. And along with the large losses in attendance due to the advent of television, the entire motion picture industry thus rapidly retreated to mono or limited stereo presentations by the beginning of the 1970's. Though the quality of the films themselves was about to enter its own "golden age" creatively, the state of film presentation during this era was in dire need of repair.

Hiss, distortion and lousy frequency range common to the audio equipment of the time, and were often far worse than even today's cheapest home theater system. The few theatrical presentations that did utilize more extensive sound technologies were relegated to the rare theater capable of presenting them. The situation continued to worsen as few studios were encouraged to produce films with more sophisticated soundtracks, as there was no profit incentive with such a potentially limited audience. Consequently, with so few movies utilizing high-quality sound, there was no desire by theaters to upgrade their facilities to show them. Thus, the state of film sound was stuck in a rigid "chicken and the egg hegemony" that seemed to be unbreakable...

But in the early 1970's, Dolby Laboratories posted the first dramatic improvements in film sound in years. The creation of noise-reduction technology greatly increased both the reproduction and recording of sound. The Dolby "A," "B" and "C" Type reduction systems were quickly adopted by the motion picture, professional recording and consumer electronics industries, with great success on all fronts. At around the same time, the move from mono to stereo was greatly aided by the new Stereo Variable Area (SVA) optical soundtrack process, developed by Eastman Kodak. Dolby championed this technology as well, and soon the motion picture industry would embrace SVA, which optically encoded (stored) multi-channel audio on 35mm film itself. Because the optical printing technology required for the SVA process was considerably cheaper than using the then-standard process of magnetic "striping" on 35mm or 70mm formats, the use of SVA gained wide acceptance in a relatively short period of time.

Building upon this foundation, a major breakthrough for multi-channel sound was made by Dolby with the creation of their MP (Motion Picture) matrixed surround sound system. Here, inverse sound frequencies are recorded in two track stereo, then are extracted by a decoder and sent to separate outputs. In simple terms, via a 2-channel stereo track optically printed via SVA on film, surround channel tracks could be embedded and then extracted, creating 4-channels out of 2. Though the frequencies of these matrixed signals was limited, it was a very convenient way to provide true multi-channel sound at cheaper costs, and laid the foundation for all recording and reproduction technology to follow. Rapid acceptance was ensured as existing theaters could more easily upgrade their current stereo equipment, and Dolby MP able to be "downconverted" (more channels combined into less channels) to stereo or mono.

Breaking Down The Barriers - The Spark Behind THX

It was on the heels of these advancements in film sound that a young filmmaker named George Lucas wrote, produced and directed a little film called Star Wars, which was to become a pioneering film in terms of the art of motion picture sound reproduction and the application of special effects. Though aside from being a genuine blockbuster and great technical leap forward, it would also be the birth of a new production empire, though many didn't realize it at the time...

While preparing Star Wars for theatrical release, Lucas was largely dissatisfied with the current state of theatrical exhibition. Given the vast amounts of work his team put into creating the aural and visual landscapes of the film, the generally poor reproduction of this work by the movie houses of the time (due mainly to differences in the recording stage versus the theatrical auditorium) was unacceptable to Lucas. It was here that the seed was planted for what would eventually become the THX program.

Lucas and his team (which would eventually become Lucasfilm) already had a close working relationship with Dolby Labs. Though during its original release Star Wars mostly played in stereo in the majority of theaters, a select few venues presented the film in 70mm, with a full six-track magnetic stereo soundtrack to accompany it (some SVA 35mm optical prints were also created). With no set code of standards in place within the industry, selection of the theatrical venues to show the 70mm prints were made by Lucas personnel, as well as the film's distributor, Twentieth Century Fox. Dolby also assisted on the technical end, helping to set at least some general specifications for projection and sound, as well as ensure the equipment of the venues was up to the high level of quality desired. Thus, the first cross-company, multiple-theater effort to set uniform standards of presentation was undertaken.

After the immense financial success of Star Wars and its pushing of the envelop on the technical level, George Lucas was now flush with the cash, wherewithal and vision to chart his own course. Work began on the next highly-successful chapter of his Star Wars saga, The Empire Strikes Back. In 1979, about the time the film was to begun the post production phase, Lucas made the decision to not only edit and mix the film outside the Hollywood system (it is worth noting that the second film was produced by Lucasfilm independently, and not by Fox, who had bankrolled the first picture), but also to set about improving the entire dubbing and mixing chain to help ensure a more consistent presentation of the film once it was exhibited. Though The Empire Strikes Back would ultimately not enjoy most of the fruits of this R&D, over the next year and a half, extensive work was done to set the stage for a rigorous and standardized system of film sound production. Thus, the research and development phase of what was to become THX began.

the Tomlinson Holman eXperiment

Without a doubt, planning, designing and executing such a vision would be a daunting task that few would be willing to take on, let alone pull off. But impressing Lucas enough to win the assignment was a young engineer by the name of Tomlinson Holman. Coming from a strong background in electronics and film production, Holman eagerly jumped into his assignment to realize Lucas' vision. With the aid of Lucasfilm personnel, what was to become THX would forever change the art of cinema production, presentation and the spectorial experience.

Eventually becoming Chief Engineer of Production in 1980, Holman recently remembered that upon accepting the job, "I got about a year to look at the entire audio chain - from microphones on the set through reproduction in dubbing stages and theaters. What I found was very uneven quality among the parts of the chain: some parts were quite modern and up to quality standards of the rest of the audio industry, while other parts seemed in the dark ages for the time." In the course of researching what would eventually become the basis for the entire THX program, Holman also managed to break the chicken-and-the-egg hegemony that had plagued film sound since the studio days.

It is here that the notion of an "A" and "B" chain becomes important and a bedrock of the THX approach. The "A" chain is the core of sound and vision capture; namely, the projection, lenses, sound heads and the film stock itself. These areas are primarily the realm of equipment manufacturers, film stock developers and audio companies such as Dolby Labs. Thus, THX would instead focus on the "B" chain: issues such as room acoustics, equalization, panning, and electronic alteration, as well as the physical equipment itself, including loudspeakers, amplifiers and recording apparatus.

By recognizing that the acoustics of a dubbing stage (the place where movie sound is recorded, mixed and augmented with additional dialogue and effects) was often vastly different than the eventual theater where it will be reproduced, Holman built upon the fundamental concept of working from the top down, which was a relatively unusual concept at the time. As Holman explained in an article in Sound Professional(1), "What I decided to do was to produce the best possible sound that we knew how to make, but then to provide electronic methods of downgrading that sound to that of the average cinema, so the mixers could have the choice" of hearing a variety of responses.

Thus, instead of trying to turn the dubbing stage into an estimation of what the theatrical space might be, the best possible environment was created with user-controlled alternation enabled to recreate other acoustical environments. This refusal to "dumb down" recording standards to make up for inferior exhibition environment was a key turning point for film sound. The creation by THX of a consistently high standard of theater sound (which, importantly, could be consistently implemented) did eventually help encourage the exhibition side of the industry to improve itself all areas of presentation. It is perhaps this accomplishment more than any other that has cemented the importance of THX in the annuals of film history.

However, there was more to do beyond "just" fixing the weak links in the audio chain. In an intense period of study, Holman and his crew built upon the foundations of prior pioneering work in audio done by Bell Labs, the Society of Motion Picture And Television Engineers (SMPTE), the International Standards Organization (ISO), and the Audio engineering Society (AES), amongst others. Along with this vast knowledge base and the substantial advances in sound technology made by Dolby Labs, Holman "sorted through these developments, picked the right one, and added some things." The result of this extensive research was patented technology that would greatly improve the quality of sound in theaters and new speaker technology. Frequency range was extended, sound was made more uniform with less distortion that greatly increased intelligibility of dialogue, and the localization and directionality of surround sound was vastly improved.

But not only were the technical specs covered, but also the physical design elements as well. A new mixing facility was created at what was to become Skywalker Ranch (the main Lucasfilm production complex) in 1982. Via this facility. Holman and company refined quad panning, ambient noise simulators, user-friendly automation and Dolby matrixing. Creatively, Lucas and Holman's desire to influence the industry to better their standards and production of film sound would make an important impact on multi-channel surround mixing. THX championed the idea of making the theatrical space relatively "dead" or reverberation-free. Thus, the sound can help combine with the visual elements seamlessly without distortion by the room acoustics. This allowed sound designers to better enhance an audience's sense of position of sound relative to what is on the screen without distraction, as well as further their art by allowing greater freedom in design of the motion, background and direction of sound in relation to the visuals. Building upon that, THX encouraged using the surrounds for ambient sounds and envelopment, rather that hard directional sounds. Speaker specifications were set to best serve this approach, with the surrounds designed for wide, unlocalizable dispersion, versus the more directionally-inclined front speakers. Such specifications thus sets up a paradigm whereby the creative mixing and sound design decisions are partially defined by the limits of the THX-approved speaker's capabilities. (This last issue of equipment dictating creative decisions has proven to be continually controversial in many circles, and probably always will be.)

Once the audio side was in place, the focus shifted to the exhibition side of the equation. Again working from the top down, THX also greatly improved the visual part of the theatrical experience. They eventually began reviewing release prints for image and soundtrack quality, helped educate theaters on the technical facts about film and proper equipment alignment and performed on-site equipment alignment. They also set strict standards for viewing angle, ensuring by architectural design and chair placement that viewers would not be stuck too far off axis (off center) from the screen in any direction. THX can also be credited with helping involving the audience with the technical process, establishing the first toll-free phone number and web site that theater patrons could contact to report presentation problems.

The combining of these technical developments, a continuing coalition with Dolby Labs, and George Lucas' continuing passion for standardizing these process and advancements on a consistent basis, all led to the formation of the basic THX concept. (The name THX, by the way, comes from the moniker Tomlinson Holman eXperiment, or as a play of words from Lucas' first film, THX-1138, depending on whom you ask. Perhaps it is an amalgam of both...) The fruits of all this labor was a smashing success. Upon the arrival of the first two THX-certified theaters for the premiere of Return Of The Jedi in 1983, it didn't take long for the Hollywood community to embrace Tom Holman and THX's realization of Lucas' vision. The then newly-instituted Theater Alignment Program (TAP) quickly established THX as a recognizable emblem for quality theatrical presentation. The THX trailer before a film often drew cheers from the audience, and by 1986, research had already begun towards a THX home theater program. With the total completion of Skywalker ranch in the mid-80's, Tom Holman would leave the company as a full-time employee and remain on a consultant basis, and TAP continued to be refined through the rest of the decade.

The THX TAP Program Today

Before concluding, let's take a brief look at the current THX guidelines for theaters wishing to earn the Theater Alignment Program seal of approval. In order to use the THX trademark and proprietary technology, any prospective client must submit the THX License Agreement as well as standard licensing fees, as well as lease fees for any THX equipment. Should the theater wish to renew a THX agreement, each year the theater must be recertified and pay the necessary renewal fees.

However, it is not enough just to apply for a licensing agreement. THX reviews the architectural plans during construction of the theater, or after it is built, to determine if the exhibition space is suitable for the program. Once the project has been accepted, THX is involved in every stage of the installation, and all elements of the system. THX does not sell or lease equipment. However, formal testing is done of all equipment to be used to ensure it meets with THX's performance specifications and standards. Again, all theaters are retested annually in order to achieve recertification.

Once certification is achieved, the THX logo can be used by the theater for promotion. THX also will consult on other services, such as the creation of screening rooms, dubbing stages and post-production facilities. As of this writing, there are thousands of THX certified facilities in world currently in operation.

The Next Phase

With the rapid success of THX in the theatrical arena, it was perhaps inevitable for them to begin to expand. Please join us for Part Two, where we examine THX's entrance into the home theater and Laserdisc markets. (Part two will follow shortly!)

Additional Resources: "The THX File" by Tomlinson Holman Sound Professional, Volume 1, Number 5. July 1999, Pg. 82. "InnerView: Tomlinson Holman" by Kimberly Jaynes. NetWorker, Summer 1996, Pg. 18. "The THX Story" by Gary Reber, Widescreen Review, Premiere Special Edition 1993. For further information, visit THX and Dolby Labs online.