Dolby Atmos Music, the technical guidelines

After having introduced the Dolby Atmos in a previous post, we have collected here the information and the procedures needed to realize a Dolby Atmos Music studio capable of being included in the official list. This list is managed, directly in its website, by Dolby Digital.

It is worthwhile to mention that we are not talking about a certification. We only can have the public listingof the qualified studios.

We would like to thank Donato Masci and Cecilia Torracchi from Studio Sound Service for the valuable collaboration in providing us with such detailed information.

The post’s objective is to clear the doubts up and provide the fundamentals to understand how to proceed to support the Dolby Atmos Music in your very own studios.

The main reason is to work in order to ensure a good listening compatibility among different facilities so that the final products behave homogeneously.

The physical features of the listening rooms

The first set of checks to be done are about the listening room features starting from physical dimensions and acoustic response.

The minimal room’s dimensions deend by those of the speaker layout. The lattes has to comply with following figures:

• minimum height at 2,4m
• minimum width at 3m
• minimum length at 3,5m
• minimal recommended volume at 50m³
• maximum listening distance at 5m (recommended value less than 4m)

From the acoustic point of view, following figures have to be verified:

• noise level within the NC25 curve
• first reflections under control
• RT60 within the Dolby tolerance
• Dimension ratios under specified limits (as per following picture)

The audio system

Once that dimensions and room acoustic are compliant we have to make sure that speakers have the proper positioning and layout and their audio performance are consistent with the requirements.

Looking at the system from above we can have a symmetrical layout or an orthogonal layout.

In the first case the orientation angles of the speakers must fall within the intervals specified in following picture:

In the second case the specs are:

Both pictures refer to a 7.1.4 system where the ear height speakers are identified by cone shaped icons and the overhead speakers are indicated with squares with circles inside.

The side views are also relevant to define the proper speaker layout orientation. Looking at the longitude the following picture helps to understand:

And, for the lateral perspective, we have:

The just installed speaker will also have to comply with following audio specifications:

• Every speaker must be capable of delivering 85dB(A) in terms of SPL with a +20dB headroom. That’s up to 105dB!
• The Subwoofer has to be able to supply further 10dB still with a 20dB headroom
• If non full range speaker are used a bass management system must be in place
• he speaker must comply with the ISO 2969 SMPTE 202 standard so that they have an audio response curve within ± 3dB da 40Hz a 18KHz. The subwoofer must guarantee the same range within 31,5 to 150Hz
• It is strongly recommended to have all speakers of the same brand
• The surround speakers must have a directivity of ±45° from 100Hz to 10KHz

So, a system capable of complying with the Dolby Atmos Music in the production phase is quite a big one.

The software components

Also the software system needs to be updated with added components (some of them are already available within selected DAWs). Dolby has released two main sets of applications:

• Dolby Atmos Production Suite
• Dolby Atmos Mastering Suite

The terms Production and Mastering can be misleading. The two application suites don’t have to be used sequentially to apply different processes. They are both capable of generating Dolby Atmos signal flows.

The Dolby Atmos Production Suite has the following features:

• It is not compatible with Avid HDX cards
• Does not support external plugins as insert for the tracks (the signal is catched before the delay compensation)
• Implements an Atmos rendering process quite heavy since both the DAW as well as the renderer runs on the same hardware
• Is is cheaper than the other

The Dolby Atmos Mastering Suite has the following features

• Allows for the utilization of Avid HDX cards
• Supports external plugins
• Runs on a different computer than the one used for the DAW (so we have two computers connected via MADI or Dante interface) enabling, in this way, faster processes.
• The price is higher

Several DAW have already implemented their native support to Dolby Atmos, in detail (as of the date of publication):

• Avid - Pro Tools
• BlackMagic Design - DaVinci Resolve
• Steinberg - Nuendo
• Merging Technology - Pyramix
• Apple - Logic
• Ableton - Live

Steinberg has just announced the upcoming Dolby Atmos support for the last release of Cubase. We are sure many other software houses will follow.

Conclusion

As it should be clear now, being compliant with the Dolby Atmos specs needs a professional level investment. We do believe, indeed, that the investment is worth because is a sort of coming back of a certain way of producing music contents. The market trends will have to be analyzed but, as alway happens, being able to anticipate the market can be a source of competitive advantages. We already had the chance to talk about the topic here but we believe we shall come back on it. Stay with us!