CEDIA’s Walt Zerbe on the Importance of A/V Standards Page 2

Lastly, video calibration is super important. Calibrating a screen with appropriate software, like Calman’s Video Pro, to ensure white levels, black levels, and colors are correct is essential to realizing the director’s intent. For example, James Cameron likes to push blue color tones a bit in his movies. If a TV is adjusted to the cool (blue) side, everything will look extra blue!

While TV’s are definitely better out of the box today, there are still major benefits to calibration. One is matching light output to the space. A display can be too bright or too dark. Professional calibrators can create presets for proper day and night brightness while ensuring colors are properly represented along with black and white levels. It’s also worth knowing how to disable many of the default settings on today’s TVs or video projectors. Most of the time, these add undesirable artifacts that can cause the image to look unnatural.

S&V: Yep, these are issues our reviewers routinely address in TV reports. Let’s shift over to audio. I understand the R10 Committee has established a procedure for setting and achieving goals. Can you walk us through the highlights as they relate to home theater?
Zerbe: If I might toot my horn here, I’m super excited about RP22 (Multi-Channel Audio Room Design Recommended Practice). First off, note the name. We’ve removed nomenclature like home theater, cinema, and media room because this is about multichannel audio in a space, and that includes surround sound for movies, gaming, music — you name it. Who are we to make assumptions? We don’t care about the name of the space so we dropped that stuff. The point is, a traditional media, or multiuse, room may actually perform better than a dedicated home theater space.

Now, this recommended practice is a big undertaking so it’s still ongoing. We’re at 90 plus pages and going strong! We’re getting deep into system design and, for the first time, introducing four levels of performance to consider when designing a room for multichannel sound. Level 1 is the base line, Level 2 is a step up, Level 3 is a reference room, and Level 4 is a state-of-the-art, cost-no-object room. Level 1 and 2 spaces, as you might imagine, are most common.

The great thing about the Level 3 recommendations is that we can now tell you what a system needs to do to be considered “reference.” The other great thing about levels is that they will even out the sales process. In other words, systems will no longer be based on price but on performance, which helps integrators and consumers alike. This is super important but also potentially disruptive in that we’re saying if a system doesn’t meet Level 1 performance objectives, then it won’t effectively portray the director’s intentions. I should also note that while we don’t talk about pricing during standards work, a Level 1 system is achievable using an AV receiver and a set of speakers designed for surround sound.

Of course, we also get into a number of more technical issues such as speaker directivity and immersion, bass management, room acoustics, reflections and reverberation times. Our work also covers best practices for wall construction and speaker placement as well as subwoofer location, seating layout, sound isolation, and the effect different types of ‘acoustically transparent’ screens have on sound.

Building a system always involves compromises — it’s about learning which things to focus on.

S&V: Whether we’re talking about a basic 5.1-channel home theater or a Dolby Atmos/DTS:X setup with many more speakers, getting sound right in a multichannel audio setting is a complicated subject. We don’t have time to delve into them all so let’s focus on speakers. What are the key considerations for achieving a compelling experience with great sound? Let’s look at speaker selection first.
Zerbe: So, as I touched on earlier, there are a plethora of variables for good sound. We are still learning how speakers work in rooms, which is an extremely complex subject. The biggest consideration for good performance remains design. An installer can no longer just throw a few speakers in a room and call it a day. They need to understand how loud the homeowner expects the system to play and then “negotiate” how many seats are feasible to achieve a good presentation across the room; the customer may want more seats than is practical.

You also need to know the dispersion characteristics and power handling of the speakers you are using and where to put them for the best possible sound. The room will also need to be acoustically treated to avoid a major degradation in performance. And this needs to be done properly. Over dampening the room, for example, will yield a dull, uninviting presentation that lacks immersion. And if the room is too reverberant, or “live,” you will end up with a mess of a sonic presentation where listeners are unable to localize sounds as the director intended. So, this isn’t an easy thing to convey in a paragraph — it’s all about education and design. Building a system always involves a series of compromises — it’s about learning which things to focus on and where to make those compromises.

S&V: Let’s touch on speaker layout for a moment — what are the key considerations?
Zerbe: It’s important to know which surround format you’re designing the room for because that defines speaker placement. If the goal is to build a system around high-channel formats like Dolby Atmos, DTS:X, Auro-3D, or IMAX, you will need a much larger budget than, say, a basic 5.1 system to accommodate additional speakers, including the overhead speakers (or speakers that bounce sound off the ceiling) needed to add a vertical dimension to the presentation. Also, it’s worth noting that many of today’s audio processors can up-mix or re-map channels to accommodate listening in other formats.

S&V: As you touched on earlier, room acoustics is an important, yet often overlooked, piece of the audio equation. It’s also highly complex and the subject of many books. Can you share a couple nuggets of wisdom here — things people can do (or should at least be aware of) when building a home theater?
Zerbe: Sure! Here’s some of my top considerations. Drywall on studs can cause issues. Floating the dry wall on isolation channels can greatly assist here. As I previously mentioned, over damping a room is a bad thing to do. Diffusion, which scatters the sound, is just as important as absorption and helps keep the room lively sounding without being too reverberant. Treating the points of first reflection is also quite important and pertains to not only to side walls but to the ceiling and floor as well.


Traveler's picture

So this mostly effects people who sell to people with money to burn.