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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K. Reid's picture

Scott, this is good read. I am glad that THX offers such classes. I think anyone considering a formal installation of a home theater via a custom installer should verify licenses, CEDIA certification and references. There are so many bad installers out there and uninformed consumers being incorrectly advised. I can't tell you how annoyed I get when I go to a big box store and hear customers complaining that they cannot get adequate bass from their speakers only to have the store salesperson tell them to press the bass boost button on the receiver. Most who go to the big box stores just do not have the knowledge to even know what questions to ask, let alone awareness of custom installers. If you ask an average person in a big box shop if they know an installer or who Bowers & Wilkins or Dynaudio are, they would likely give you a blank stare. Bottomline: We readers appreciate you, TJN and the crew going the extra mile to stay educated and, in turn, educating we readers.

Joe's picture

Hi Scott - great article. You forgot to add where you go to sign up (thx.com, I think). I had researched taking an ISF class a few years back, so I hopped over to their site to see what their upcoming schedule looked like, and could not help but notice that their times and locations are pretty much identical to THX's. Have they joined up, or are they just hitting the same trade shows to go where their audience is? Thanks, Joe

The Aduio Dufus's picture

I agree with K.Reid. I have asked the big box stores who Altec and Lansing and Fisher are and who Symphonic and Funai are for years and got blank stares. Once they started pointing at me and laughing. I admit I don't know what you are talking about as I have never heard of either this Wilkins or Bowens fella. Dynaudio though, I have one of there big accelerometric subwoofers. I thought THX meant that the theater was thanking me for coming to the show. Home theater rocks.

The Audio Dufus's picture

One other thought regarding these classes. If you get the chance, see fi the ISF can rename itself becuase I tried to go to a class and signed up for FTD by mistake and now I like arranging flowers, very relaxing. Tahnks.

Scott Wilkinson's picture

How silly of me to forget to include a link to the THX website! My brain is mush after CES and the THX course. The main THX website is www.thx.com, and the training page is www.thx.com/training/index.html. I'll add a link to the main article. Thanks for pointing this out, Joe! BTW, ISF and THX have not joined together; I think you're right that they both offer classes when and where the audience is. I was interested to learn that ISF has now added a Level 2 course, which includes some hands-on practice at video calibration. The THX course has always included this, but from what I've heard, ISF Level 1 does not.

Oscar Worthy, DDS's picture

Scott, I have aquestion for you regarding THX processing; and seeing you are the most recently educated here it is. One function of the THX home processing is re-equalization. I understand at the inception of the home program that with laserdisc the soundtrack was identical to the studio master and in the home setting required the re-eq application. But now, I am told that the Bluray/DVD tracks have been re-equalized for home release. Is this true in general, and if so by using the THX mode am I double equalizing and thus killing the top end of the presentation? I like the other concepts of the THX processing, but the re-eq may do it in. What's THX's take on its use? Also, are the THX training open to home theater afficiandos like myself? Thank you for your time.

Scott Wilkinson's picture

Oscar, you are correct in your analysis. In general, movie soundtracks are mixed with a bit of boost above 6kHz to compensate for putting the front speakers behind a cinema-perf screen, which tends to cut the highs. In the early days of laserdisc, the soundtrack was not re-mastered, so THX ReEQ cuts the highs a bit because most home users do not put their speakers behind an acoustically transparent screen. With DVD and Blu-ray, some soundtracks are re-mastered without the HF emphasis, but not all. Therefore, ReEQ is useful in some cases but detrimental in others. Some equipment manufacturers allow you to defeat ReEQ without disengaging the other parts of THX processing, but others do not. Ultimately, it's up to you to use ReEQ or not according to your own ears, but in any event, the effect is not dramatic. THX training courses are absolutely open to afficianados; go to thx.com for more info.

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