Introduction

This case study describes the process of converting a home stereo mix room to Dolby Atmos. For more details about Dolby Atmos room design, see our Technical Guidelines and Knowledge Base. For general information about creating and delivering in Dolby Atmos, visit the content creation landing page on Dolby Professional.

Background

A mixer decided to set up a Dolby Atmos system in their home studio. 

The room dimensions were 13.5ft (approx. 4.1m) length x 12ft (approx. 3.7m) width x 8.8ft (approx. 2.7m) height, with a stereo mix position of 3.5ft (approx. 1.1m) from the front wall. The mix position faced a window, and there was a single entrance on the rear wall. The room was treated with absorptive panels purchased from a reseller. 

Existing equipment included a Macbook Pro M1 Max with 32 GB of RAM, a mid-range 4-channel audio interface, two pairs of professional mixing headphones, and a stereo pair of Kali Audio LP-6 monitors. The mixer's Digital Audio Workstation (DAW) of choice was Avid Pro Tools.

The maximum budget allocated to the project was $6,900.

Using the DARDT

The exploration process started with reviewing Dolby's 'How to Design a Dolby Atmos Mix Room' document, downloading the free Dolby Atmos Room Design Tool (DARDT), and watching the step-by-step DARDT Quick Start tutorial.

The mixer decided to include the stereo pair of Kali Audio LP-6 monitors in the Dolby Atmos system. To determine a good starting point, they set the DARDT to 'Default' mode and input their room dimensions. The DARDT automatically populated speaker positions for a 7.1.4 system. 

Next, they opened the speaker model drop-down menu and selected Kali Audio LP-6 for the ear-level and overhead speakers. 

The 7.1.4 system was capable of the recommended 20 dB of headroom over a 79 dB monitoring level; however, they noticed a number of Design Feedback Messages. After reviewing the contents, they determined that most of the messages related to their existing mix position. The messages were resolved by adjusting the mix position from 3.5ft to 5ft (approx. 1.1m to 1.5m).

The remaining feedback message indicated that the Floor to Overheads distance was 0.08ft (approx. 25mm) below the minimum recommendation. They were not sure whether this would impact system performance, and decided to leave the decision until they could consult with an expert.

Finally, they opened the subwoofer model drop-down menu to select a unit for LFE and bass management.

The only Kali Audio model in the DARDT database was the WS-12; however, the mixer was hoping to use a pair of the smaller WS-6.2 to save space at the front of their room. Since they were not sure how to add the new model to their DARDT, they decided to seek support from Dolby.

Visiting the Professional Support Forum

The mixer posted the following question in the Room Design and Calibration section of the Dolby Atmos Music & Post Forum:

I am looking to use a subwoofer model that is not in the DARDT database. Is there a way to add new models to the drop-down menu? For reference, I am using the DARDT in default mode.

Dolby's engineering team responded with the following:

Yes! Navigate back to the Room Information tab and switch to Advanced or Music-Advanced mode. Next, navigate to the Design Creation tab and select the 'Enable Alternate Speaker and Amp Entry Sheet' tickbox in the View Options menu. Finally, open the Alternate Speaker and Amp Entry tab, click "Add Active/Passive Subwoofer," and enter the manufacturer specifications as directed. The model will populate in the subwoofer model drop-down menu, which is sorted alphabetically.

If you would like help creating/reviewing your DARDT, we recommend contacting a Dolby Certified Service Partner.

Using these instructions, the mixer was able to add the Kali Audio WS-6.2 subwoofer to their DARDT.

Engaging a Certified Service Partner

Following Dolby’s recommendation, the mixer contacted a Dolby Certified Service Partner for their expert opinion and assistance. The CSP engineer reviewed the DARDT file and confirmed that the Kali Audio system looked good. They also affirmed the mixer’s decision to adjust the mix position, and advised that the >1in (approx. 25mm) discrepancy in the ‘Floor to Overhead’ speaker distance would not negatively impact system performance.

Next, the CSP provided guidance on the hardware and software needed to mix in Dolby Atmos. They advised that the mixer had two options for rendering their Dolby Atmos mixes; the internal Pro Tools Renderer or the external Dolby Atmos Renderer application.

They advised that in order to connect their existing Macbook Pro to the 7.1.4 speaker system, they would need an audio interface with 12 main outputs as well as a dedicated headphone output to monitor the binaural Dolby Atmos mix. In addition to outputs, they informed the mixer that monitoring control functionality would be necessary to select playback sources, choose monitoring levels, and utilize dim/mute/solo functionality.

Lastly, they recommended utilizing dedicated DSP to control room equalization, speaker delays, and bass management.

The CSP advised the mixer that there are many suitable hardware and software devices on the market – some cover all of the functions in one box, while others are more specialized. After discussing the pros and cons of each option, the CSP recommended the following workflow based on the mixer’s needs, preferences, and existing equipment:

 

 

 

 

The mixer purchased the 12-channel audio interface, 7.1.4 Kali Audio speaker system, and appropriate cables from the CSP.

Installation

The mixer installed their ear-level speakers according to the DARDT. They used the Design Printout tab to easily view the speaker locations, and precisely placed them using a laser measurement device.

They engaged the Dolby Atmos Specialist from their CSP for assistance mounting and wiring the overhead speakers.

Room Calibration and Commissioning

While on-site, the Dolby Atmos Specialist from their CSP commissioned the room. First, they used a laser measurement device to confirm that all speaker placements were correct and completed the initial setup of routing and gain. The specialist then performed a basic room alignment by applying adjustments to level, equalization (EQ), and delay, and listened to reference material with the mixer to finalize.

During the calibration process, they discovered a resonant frequency at 65Hz. Through trial and error, the specialist determined that they could resolve the LF issue by simply adjusting the subwoofer’s position on the floor.

For more information about acoustics and room calibration, refer to the Room Calibration FAQs.