Home Theatre Recommended Practices

It's time for an update! The global Recommended Practice guides for home theatre design are being updated to allow installers in the entry level and ultra high-end markets to deliver better systems for their clients. Paul Skelton reports.

The professional home theatre sector is redeveloping its global Recommended Practice guides for audio and video design.

CTA/CEDIA-CEB22 Home Theatre Recommended Practice: Audio Design is expected to be available in the coming weeks, and CTA/CEDIA-CEB23 Home Theatre Recommended Practice: Video Design is due for a launch later this year.

Both guides are expected to fundamentally change the way the residential AV industry operates.

“When we first released CEB22 in 2009, immersive audio didn’t exist,” CEDIA senior director of technology and standards Walt Zerbe says. “We had Dolby Digital Plus and Dolby TrueHD, but that was all we had to work with at the time.

“Today, audio installations can feature lots of speakers and lots of channels. We also have Dolby Atmos, DTS and Auro-3D.”

CEB22: Not just a ‘how-to’ guide

Developed as part of a partnership between CEDIA and the Consumer Technology Association (CTA), the new CEB22 focuses on audio system design rather than being a prescriptive ‘how to’ guide.

“It’s important to note that CEB22 is not a replacement for learning and studying. You still need to know your fundamentals. You still need to understand acoustics and Ohm’s Law,” Walt says.

UK-based Peter Aylett is a prolific volunteer and educator who sits on the CEDIA global board of directors.

“If you ask a client if they would like a home theatre, home cinema, media room or any one of the other descriptors that we use to describe these high-performance entertainment spaces, most will look at you and say ‘I have no idea what you’re talking about’.

“As a result, we’ve removed the concept of ‘use modes’ from CEB22. We don’t need to talk about home cinemas versus media rooms anymore. We only want to discuss raw performance.

“Besides, there’s no reason why a multipurpose room cannot perform to the highest possible standards.”

Peter says it is important to note that none of the recommendations in CEB22 go against the current format providers’ recommendations.

“We are simply trying to unify everything,” he says. “Rather than having to choose between an Atmos layout or a DTS:X Pro layout or, if you’re thinking about the future, one that is compatible with MPEG-H, following these recommendations will allow you to cross all of those different formats.”

He reiterates that the Recommended Practice guides are a discussion about objective performance.

“These documents are about making rooms work on paper from an engineering perspective, so that when you build it, your technical crew has a baseline to work towards. If the room doesn’t work on paper, it’s an absolute lottery when you get to measuring the final results.

“When CEB23 is launched, reading it in conjunction with CEB22 will give you a complete story on the design of rooms.”

Changes in CEB22

Big changes in CEB22 include a new focus on room seating layout and the introduction of performance levels, which Peter calls ‘transformational’.

“Nowadays, you have to design a room in three dimensions. The relationship between the listening area and the room is of utmost importance. It’s no longer enough to look at where the seats are, and the proportions of the room. You’ve got to look at those in conjunction with each other.

“But the most transformational change in CEB22 is the introduction of ‘performance levels’. Level 1, for example, defines the base level of objective performance that we would consider an acceptable level of performance.

“Level 1 systems do not have to be expensive; we think they could be achieved in a small to medium sized room using a $1,000 AV receiver and $3,000 speaker package.

“We also appreciate that with Level 1 systems you probably won’t have a lot of time in that room. You’ll want to get in and out quickly. Commercially, it wouldn’t make sense to be in that room for two days, performing detailed measurements.

“On the other end of the spectrum, Level 4 systems will probably be the domain of Silicon Valley tech entrepreneur billionaires. The guidelines for a Level 4 system are really, really draconian.”

Reintroducing integrity into the market

The primary reasoning behind the introduction of performance levels, Peter says, is to reintroduce engineering integrity into the market.

“All too often, as an industry, we go straight from sales to specification. But specification should happen after design.

“A bill of materials tells you nothing about how a system’s going to perform. It is not a functional performance specification; it’s just a list of products.”

Another important feature of the new Recommended Practice is clarification of the x.x.x syntax.

“When most people think of Dolby Atmos, for example, they think 7.1.4. But it could also be 9.1.6, or even 11.1.6. Well, we are now saying that those numbers should represent discreetly decoded or rendered channels, which means that that number might not correlate with the number of speakers.

“If you have three pairs of speakers being fed by a single decoded or rendered channel, you can’t just add the extra two sets of speakers to your channel count because those are not being discretely decoded.

“Further, in a 9.1.6 system, for example, that number ‘1’ does not refer to the number of subwoofers in the room; rather, it refers to the low frequency affects channel, of which there is only going to be one.

“Even if you have four subwoofers in a room you do not have a 9.4.6 system because those four subs are all being fed by one single low-frequency effects channel.”

Keeping the end-user in mind

Ultimately, these documents are designed with end-users in mind.

“Home owners just want to walk into a room, press one button and have the most incredible experience that is as close to the artistic intent of the content creators as they possibly can,” Peter says.

“Content creators spend huge amounts of money to deliver something that tells a story, and the AV systems you install need to facilitate that.

“Your rooms need to be high-performance entertainment spaces that, regardless of the content, will deliver as close to the artistic intent as the space and budget allow.”

To find out more information about the new CEB22 Recommended Practice, you can watch the Sneak Peek! – Home Cinema Audio: CEDIA Recommended Practice Gets an Overhaul webinar at https://www.youtube.com/watch?v=9BrgNAykxsw&t=1s

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