Using Immersive Sound in Steinert 213

Overview

Steinert 213 is newly equipped with a 10-speaker surround sound system designed for spatial audio playback, using a Behringer UMC1820 audio interface.

This system is currently in a prototype mode using gear we already have available, with the plan to upgrade things over the summer. So, there are some limitations to know about. We are using fairly inexpensive speakers at the moment, and we have not yet included a subwoofer in the system. Still, the system sounds pretty good and we are learning a lot about what we can do in this room. Users will get an informative playback of immersive work in progress, but the fidelity is not perfect. In particular, the system lacks deep bass at the moment. Also, the 'sweet spot' for spatial balance is about arms distance or so from the desk (which we haven't moved yet).

Audio is routed through amps to 10 speakers placed around the room, including two overhead speakers. The routing is configured for Dolby 7.1.4 ITU Default - see the routing table for this arrangement. We have an IEM ambisonics decoder configuration that is compatible and will be working on others.

This page will go through surround sound setup for Reaper, Logic, and Ableton.

Here is a link to a google folder with helpful items.

Routing Table

Channel Speaker Position

1 Left

2 Right

3 Center

4 Rear Center

5 Rear Left

6 Rear Right

7 Mid Left

8 Mid Right

9 Upper Left

10 Upper Right

Setup

Power On the Equipment
1. Power Strip: Ensure the main power strip supplying the audio equipment is turned on. This is the white power strip pictured below, in front of the amplifiers.
2. Amplifiers: If necessary, switch on all the amplifiers connected to the speakers, on the right of the desk. The gains have been set, by ear for now, for good balance and should be left alone. You can see our settings in the image below.
3. Audio Interface: If necessary, power on the Behringer UMC1820 audio interface. Note: The "Main Out" and the "Monitoring" knobs should be all the up as shown below. (The main out controls outputs 1 and 2 and needs to be at full volume to match other channels, and the 'monitoring' control mixes between interface inputs and computer playback and should typically be all the way toward 'PB')

Connect the Audio Interface to Your Computer
1. Use a USB cable to connect the UMC1820 to your computer.
2. For Windows users: Behringer UMC1820 Manual

- - Download and install the latest UMC1820 USB driver from Behringer's official website.
  - After installation, set the UMC1820 as the default playback and recording device in your system's sound settings.
- For Mac users:
  - The UMC1820 is class-compliant; no additional drivers are needed.
  - Set the UMC1820 as the default audio device in your system preferences.
- Monitoring level control:
  - Unfortunately, the prototype system does not have a main/master monitor control knob. You will need to use your master fader in software. You'll want to adjust that before mastering/rendering/bouncing.

Surround Sound in Reaper Using AIIRA Decoder

For Reaper, Ambisonic decoding is handled by the AIIRA Decoder from the IEM Plugin Suite, using a custom configuration file tailored to this room.

1. Create and Configure Tracks

Add Two Tracks
- Designate the first as the Ambisonic Bus and the second as the Audio Source.
Organize Tracks into a Folder (fig. 1.1):
- In the track control panel, click the folder icon at the bottom left of the Ambisonic Bus track to convert it into a folder.
- Ensure the Audio Source track is nested within this folder, indicating it's part of the bus.
Configure Ambisonics Bus track (fig. 1.2):
- Navigate to the mixer panel and click the routing button on your Ambisonics Bus track. The routing button looks like a series of parallel diagonal lines.
- In this routing window, ensure that the Master send tick box is disabled.
- Set Track Channels to 16. Note that we will not be using all 16 channels.
- Add a new hardware output and select Out 1 / Out 2
- In the dropdown menu on the bottom left corner of the routing window, select Multichannel Source > 10 channels > 1-10
Configure Audio Source track (fig. 1.3):
- Open the routing window for your Audio Source track.
- Set Track Channels to 10
- Ensure "Parent send channels from/to:" box is enabled, and that it is sending to "1-10"

2. Insert the AIIRA Decoder

Add AIIRA Decoder to the Ambisonic Bus:
- In the track control panel, locate the Ambisonic Bus track and click the FX button to open the effects window.
- Insert the AIIRA Decoder from the IEM Plug-in Suite.
Import Speaker Layout (fig. 1.4):
- Within the AIIRA Decoder interface, click "Import".
- Select and load the rm213-decoder-v2.json file, which contains the specific speaker configuration for the studio. You can download the file here (it is also saved on desktop of the studio computer).
Calculate the Decoder:
- After importing the layout, click "Calculate Decoder" to generate the appropriate decoding matrix tailored to the studio's speaker setup. Ensure the Decoder Order is "3rd".
- Use the available "Noise" buttons to test each speaker.

Fig 1.1 Track 2 should be nested within track 1

Fig 1.2 Routing window settings for Ambisonics Bus track

Fig 1.3 Routing window settings for Audio Source track

Fig 1.4 The AIIRA Decoder should look like this once you've imported rm213-decoder-v2.json

3. Encode Stereo Audio Sources

To convert mono/stereo audio source tracks into a multichannel Ambisonics format:

Insert StereoEncoder on the Audio Source Track:
- On the Audio Source track, click the FX button.
- Add the StereoEncoder from the IEM Plug-in Suite.
- Other ambisonic tools (Sparta, ATK) can also be used with the IEM decoder.
Configure the StereoEncoder or other panning and transform tools:
- Within the StereoEncoder interface:
  - If using IEM tools, they should automatically detect the Ambisonic 'order' based on the number of channels in your output track.
  - Adjust the Azimuth and Elevation to position the audio source within the 3D sound field as desired. Adjust width as desired.
- Reaper is now ready for spatial audio.

Other Useful IEM Plugins

BinauralDecoder

If you're working with headphones or a stereo speaker setup, you can monitor the Ambisonic mix binaurally:

Add BinauralDecoder to the output track:
- On your output track (Ambisonics Bus or Master track depending on how you configured your project), click the FX button.
- Insert the BinauralDecoder from the IEM Plug-in Suite.
Configure the BinauralDecoder:
- Within the BinauralDecoder interface, ensure the Ambisonic order matches that of your project.

This configuration allows you to experience the spatial mix through headphones, simulating a 3D auditory environment.

EnergyVisualizer

To gain visual insights into the spatial distribution of your audio:

Insert EnergyVisualizer on the Ambisonic Bus:
- On the Ambisonic Bus track, click the FX button.
- Add the EnergyVisualizer from the IEM Plug-in Suite.
Monitor Spatial Distribution:
- The EnergyVisualizer provides a real-time visual representation of the energy distribution within the Ambisonic field. It can be useful to visually track your outputs, especially for troubleshooting purposes

Surround Sound in Logic Pro using Dolby Atmos 7.1.4

For Logic, spatial audio will be monitored as a Dolby 7.1.4 system. Note that since we have 2 overheads, the other 2 in the 7.1.4 configuration will be empty outputs.

Set Up 7.1.2 Surround Project
- When starting a new project, ensure that it is configured under the "Details>Spatial audio" dropdown for Dolby Atmos 7.1.4. If 7.1.4 doesn't show up as an option, selecting 7.1.2 also works.
- Existing projects can be switched to Dolby Atmos mode by going to File>Project Settings>Audio.
Set Up Input/Output Assignments
- Under Logic Pro>Settings>Audio> I/O Assignments, configure the assignments to match fig 2.1. You can do so by selecting "7.1.4" then "ITU", then changing the assignment for "LFE" to some unused output 16 (or any above 11). [Note: we are not currently implementing an LFE channel in this system, and we are not currently utilizing a subwoofer, though this is planned.]

Fig 2.1 I/O Assignments

Configure Atmos Settings
- Under the channel strip for "Master", open the "Atmos" plugin window.
- Under "Monitoring Format", select 7.1.4 to use the studio speakers.
  - (For binaural headphone monitoring, select an option under "Binaural". )
Add a Surround Track
- Create an audio/instrument track. In the channel strip, ensure the output format is set to either "3D Object Panner" or "Surround". Access the panning window by double clicking the panner.
  - The 3D Object Panner has a different control for elevation, which may be more intuitive in this setup.
- Logic Pro is now ready for spatial audio

Surround Sound in Ableton using Envelop for Live

For Ableton, spatial audio will be monitored as a Dolby 7.1.4 system, with decoding handled by Envelop for Live (E4L) plugins.

Set Up Audio Outputs
- Navigate to your audio device settings, select UMC1820 as the device, and click on "Output Config". Ensure that all mono and stereo outputs from 1-10 are selected, and colored orange (fig 3.1)

Create the Master Bus
- Add a new audio track and insert "E4L Master Bus" effect under the Max for Live category. This track will handle the decoding and routing of your spatial audio.
- By default, the E4L Master Bus uses a binaural decoder, allowing you to monitor your spatial audio through headphones/stereo speakers. Select "7.1.4" in the decoder dropdown menu and turn off "Monitor 1+2" to use the studio speakers.
- Route the outputs in the "Output Routing" menu according to fig 3.2
Create Audio Tracks
- Add new audio source tracks. For each track you wish to spatialize, insert "E4L Source Panner". You could also use other panners, such as "E4L Stereo Panner" or "E4L Mono Panner" depending on your preference.
- E4L panners are automatically routed to the E4L Master Bus. Double check that your audio track outputs to "Sends only", and that your E4L Master Bus outputs to "Master".
- Ableton is now ready for spatial audio

Fig 3.1 Output configuration

Fig 3.2 Output routing in the E4L Master Bus

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