Drinking From a Fire Hose

I must be a glutton for punishment. After spending five grueling days at CES, I decided to stick around Las Vegas for THX's Home Theater 2 training course. I've already taken the Home Theater 1 and Video Calibration courses, so I figured why not complete the training offered by THX? At least I'd be sitting most of the time.

As expected, I already know much of what John Dahl, THX's Director of Education, was teaching—in fact, I couldn't help kibitzing from the back of the room, which probably didn't endear me to him. Like the other two courses, my purpose in taking this one is to see what is being taught and how it's being taught so I can recommend it—or not—to those who would like a foundation in home-theater design and audio calibration according to THX.

Also like the other two courses, students in this one must drink from a fire hose. The accompanying 184-page book is a reprint of the PowerPoint slides used in class, which Dahl supplements with a lot more detail and many illustrative stories from his 35+ years in the A/V business, almost half of which has been spent at THX.

The course is organized into four main sections—designing the room, the audio system, the video system, and system control—all designed to answer the question, "How do you create a system that transports the client out of the theater and into the story created by the artist? The answer is, "Replicate the critical elements of the studio environment and keep it free from distractions and sources of fatigue."

Of course, the devil is in the details, and there are tons of details in fulfilling this mission. The first section is a discussion of room acoustics and control (including room dimensions, wall construction, and acoustic treatments), sound isolation, background-noise control, lighting, and interior design. In the photo above, Dahl is demonstrating how to locate sources of acoustic noise in the room.

Next is how to select and place audio and video equipment—that is, after determining the best seating positions for the viewers—as well as what to look for in each type of component, with an extensive treatment of speaker directivity and projection-screen size and gain. Finally, system control includes information on automation with systems such as Crestron, AMX, and Control4 as well as universal remotes, though this is the least detailed part of the curriculum.

After a full day of theory, the second half of the course is more hands-on. THX provides A/V receivers, DVD players, and various speakers and subwoofers, which allowed Dahl to demonstrate how speaker placement affects the sound. This was especially dramatic with a signal generator and subwoofer—walking around the room while the sub played some of the room's resonant frequencies made the concept of room modes perfectly clear. In addition, Dahl put the sub on a rolling cart and moved it around the room, illustrating the importance of placing it correctly.

Also on hand was test equipment such as real-time analyzers, SPL meters, voltmeters, impedance meters, and polarity checkers so students could practice evaluating and calibrating audio systems. Unfortunately, some of the AVRs were not functioning properly, which took time to figure out, forcing Dahl to rush through some of the material at the end of the day. Learning how to troubleshoot such problems is valuable in and of itself, but that's not the subject of this course, so I was disappointed that the equipment was not working reliably. In fact, an argument could be made that the systems should be pre-assembled and working properly so the students can concentrate on testing and calibration in the very short time they have. Speaking of time, with so much information to impart, I wish the course was three days instead of two.

The most important take away for me is that fully calibrating a multichannel audio system is orders of magnitude more complex than calibrating a video display. As a result, the course is really an introduction to the subject—no one should expect to start working as an audio calibrator after taking it. Organizations such as CEDIA and the Home Acoustics Alliance offer more advanced courses, but if the equipment problems are solved, THX Home Theater 1 and 2 provide a solid foundation on which to build a potential career as a home-theater designer and calibrator. For more info, go to the THX website.

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