Building Monitor Controller for Dolby Atmos Studio

Takumi Amano
5 min readNov 17, 2023

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Monitor controller for Dolby Atmos Studio
Monitor controller — on top of the rack

Monitoring at Dolby Atmos Studio

Abstract

  • The project: Trying to build a monitor controller for a Dolby Atmos studio, which is a music format that creates a spatial and immersive audio experience.
  • The challenge: Those who want to build own Dolby Atmos studio faces difficulty in finding suitable equipment for monitoring Dolby Atmos music, especially an audio interface that can output at least 12 individual channels for the required speaker configuration.
  • The solution: This proposes to design and build a custom monitor controller that can meet the key requirements of input, output, and connection to other equipment. This article would also shows a prototype of the controller and a plan for the project.

What Dolby Atmos Music is

Music Like Never Before — Dolby Atmos Music — Dolby

Dolby Atmos goes beyond the ordinary listening experience and puts you inside the song in a spatial way, revealing every detail of the music with unparalleled clarity and depth.

It’s one of audio/music format, introduced by Dolby Laboratories, Inc, as one for immersive audio environment for theater and movie initially. They extended it to just music area, mainly for subscription service. Recently Apple music, Amazon Music unlimited and Tidal started streaming Dolby Atmos enabled tracks for their subscribers. It’s called as Dolby Atmos Music.

Please visit the Dolby’s website above if you’re not familiar with the technologies.

The difficulty on monitoring

Our studio, with “7.1.4” speakers

The Dolby Atmos format provides various options for playing back its contents, but it requires a strict production environment for monitoring. This includes at least 7 surface-level speakers, 1 low-frequency effect (or sub-woofer), and 4 ceiling speakers. Recently, many artists have been composing and recording music with digital-native musical instruments or software, and they are producing music creations using just a PC with 2-channel speakers or headphones. However, Dolby Atmos still requires a much larger investment for both speakers and audio interfaces.

During my trial for building my own Dolby Atmos-enabled studio, I found that there are too few options to choose from when it comes to equipment, especially audio interfaces. It’s mandatory to output at least 12 individual channels (7+1+4) from a DAW on a PC, but audio interface products that have more than 12 channel line outputs are sometimes too expensive. Professional artists may be able to invest in them, but beginners cannot.

But I found an inexpensive option — it’s to use an audio interface which has 4 line outputs, and 1 ADAT output. The later one is legacy digital and optical interface with multiplexed 8 channel audio. It was introduced by multitrack “tape” recorder in 1991 but still used in some case. Some inexpensive audio interface has ADAT interface for input and/or output. So, if we provide ADAT audio decoder, it can be attached the interface and number of output is extended.

However, most of such inexpensive audio interface doesn’t have output volume control — it can control line outputs, but for ADAT output. That’s the reason why I decided to build this product — “12 channel monitor controller with ADAT input.”

Additional Requirements

Typically, artists need to setup one more playback system for Dolby Atmos with “AV Receiver”, because there is no reasonable way to decode and playback existing Dolby Atmos music track, delivered by such as Apple Music or Amazon Music. So, in addition to the main monitoring audio path (12 outputs to 12 speakers, at least), one more set of line-level inputs for such equipment.

In most case AV Receiver provide consumer audio level (0.3Vrms) as output, we would need level conversion to match with pro-audio level (1.25Vrms), otherwise speakers may have damage by too high level input on switching between the sources.

What we need?

Input

  • 4 balanced line inputs plus optional 4 inputs with XLR connector
    1.25Vrms standard, +24dBu max
  • 1 ADAT input with optical connector
  • 12 unbalance line inputs with RCA/pin connector, for AV receiver
    0.3Vrms standard

Output

  • 12 balanced line output with XLR connector
    1.25Vrms standard
  • 2 balanced line output with XLR connector for headphone amplifier

Control

  • OLED indicator for current volume level (-∞ to 0dB, 1dB step)
  • Volume potentiometer
  • Mute switch with red mute indicator
  • (external control interface and firmware update terminal — not available on prototype model)

Connections to other equipment

How it works between audio interface and speakers

8 balanced line input and output requires 8 XLR to DB25 cable — typically called as “TASCAM snake cable”. It can be found at music equipment store/shop.

For input —
Hosa DTF-803 — Thomann

For output -
Hosa DTM-803 — Thomann

12 unbalanced line input is also integrated DB25 connector, but the pin layout is original, so I built original conversion cable from RCA plug to DB25.

Inside — prototype

Audio and control signal flow
Inside — some circuit board is made by hand-soldering
Originally designed balanced line output board
Front and backside panel
Confirming output signal — low distortion and noise

The Plan

I’m still brushing up the internal component structure and its design, and also trying to reflect the issue I found (power-on pop noise, etc.) to the circuit/internal signal flow, but in general it could be rolled out to the market after one or two more prototype, as very small number of productions, maybe through eBay or something.

Since the product is to be built for casual and/or beginner artists, I will try to keep the price lower than other major products.

If you’re interpreted in this project/product and/or you want to participate early beta program, please contact to me, and check the project website.

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Takumi Amano
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Startup in Estonia for Audio/Visual hardware and service