In this article, community member Chris Testa is going to share his recent transition from using Pro Tools natively with the Dolby Audio Bridge, to a Dolby Atmos HDX Hybrid Engine system. This new system allows him to utilise the power of the HDX DSP with the Hybrid Engine along with the computer’s native power while mixing in Atmos all on the same computer with the most recent version of ProTools Ultimate. Over to you Chris…

Introduction And Acknowledgements

Pro Tools 2021.6.0 finally brought us the Hybrid engine. I would imagine that most of us have always wished for the day when Native and DSP power can be used together and with just a software update Avid have done that.

I’ve had a lot of help along the way (shoutout to my friend Michael Keeley who was an immense help) but everyone at one point or another are faced with these tiny details that usually never get discussed. When you’re working with something new and a setup that basically no one else has it can be difficult to find out the exact details about how to make all of this work. Mostly because no one exactly knows because no one has ever done it.

A lot of this was figured out with a lot of questions, a lot of trial and error and a lot of help. My hope with this article is to share with you the final solution that works with every detail I can think of, every detail I wish I had when I was trying to figure it all out. So hopefully this will get you working quickly and not have to spend nights pulling your hair out and cursing at the internet as I did :)

My Initial ‘Native’ Setup 

I’ll get into more specific details later, but my initial setup was a 2019 Mac Pro used natively with a MTRX Studio, DADman, Dante Virtual Soundcard (DVS), Dante Controller and the Dolby Atmos Production Suite.

I ran Pro Tools Ultimate without any HD Native or HDX cards, used the Dolby Audio Bridge as my Playback Engine in Pro Tools to feed the audio from Pro Tools into the Dolby Atmos Production Suite (DAPS) software. Then I used Dante Virtual Soundcard (DVS) to take the audio out of DAPS via Dante to my Avid MTRX Studio.

This was the first time I was using anything Dante and as a result, it was quite a steep learning curve for me. Even though I consider myself to be pretty good at managing my home network, getting the Dante working correctly presented its own challenges. If I couldn’t get the Dante working then I couldn’t get sound so it’s a good place to start. 

There were three main mistakes that I made in the initial Dante setup. 

1. I bought an “un-approved” Ethernet switch

I first bought an HP managed switch, assuming it would work for my entire setup, Dante and local peripherals. When it didn’t work I did some research and realized that there seemed to be one main switch that was Avid “approved”. The Cisco SG350-28 managed switch is what they recommended so I got that. Programming a switch was not something I felt confident doing so I hired my first IT tech to come in and help me. He was able to program 4 ports for my Dante network and the rest were left for my local network. That seemed to get it all working. 

Since then, I have had friends use other switches that have worked so honestly I’m not sure why one managed switch would work and one wouldn’t.  My advice is to check with someone who has a working one and use one of those.

2. The new Mac Pro 10GHz Ethernet ports don’t work with Dante

For whatever reason, the Ethernet ports on the Mac Pro 2019 don’t seem to be able to talk to the Dante network. Honestly, I can’t give you the technical reasons why this does not work, but it doesn’t and Avid has confirmed this. It took some searching to find that Avid recommended a Belkin USB-C to Ethernet adaptor, because Apple doesn’t make a USB-C to Ethernet adaptor. With this adaptor in place, my Mac, via the Dante Virtual Soundcard (DVS), was seen by the Dante Controller.

3. I assigned static IPs to everything

I initially had the IT tech set up my network and networked peripherals with static IPs. For some reason, I thought that might make everything more stable but in the long run, it appears to have over complicated things. 

*I’m not saying static IPs won’t work it’s just that things seem to run better for me with DHCP all around. If you’re good at networking you can create static IPs for everything but it’s not necessary.

So after addressing these three main issues, I was pretty much up and running with a Native Atmos system. The MTRX Studio and the Mac were seen by the Dante Controller and synching and everything worked well for a while.

My Hybrid Setup Starts…

A few gigs and a few months later I had heard inklings of some Pro Tools updates that would allow you to use HDX DSP and native computer power together. At that point, I had done a few Atmos sessions via the Dolby Atmos Playback Engine and things had been fine but even with the power of my Mac Pro 2019 computer, I could see there would be a limit to working fully natively, especially when I realized the additional load that the Dolby Atmos Renderer was putting on my CPU. For me trying to work within one computer, I saw a wall in my future.

By now, I had invested a lot of money but I really wanted to have a complete system where I could open any session and still be able to work on one computer. I could have chosen to get another computer, say a Mac mini, and connect that via Dante and have DAPS work on that computer but I wanted to keep things as simple as I could and keep it all on one machine. So at that point, I took a calculated gamble and bought an HDX card. Soon after that, the Hybrid Engine was announced and so when Pro Tools 2021.6.0 came out I installed it immediately.

Hitting The 64 Channels Of Dante Limit On The MTRX Studio

I believe I was one of the first people in Los Angeles to get a MTRX Studio. I was new to Dante and knew that it had a Dante channel limit of 64 channels per unit but at the time I didn’t realize how that would limit me in the future when it came to working with a full 128 channel Atmos session. I thought that maybe I would be fine with just 64 channels of I/O to the Renderer if I could at least access both the native power of the computer and the DSP on the HDX cards with the Hybrid Engine so I initially tried that.

Now I ran into another problem. How do I get my Pro Tools session to talk to the Renderer now that the playback engine was set to Hybrid and not to the Dolby Atmos Bridge?

Dante Overload? Focusrite Card To The Rescue

I spoke to few very helpful people on the Avid DUC and they suggested doing some Dante patching via DigiLink to Dante and Dante to Digilink. I tried all that and my computer basically froze up. What I realized was that the DVS couldn’t really handle all that traffic. Some people on the DUC had said that it should work but based on the latency and the errors I was getting in the Dante Controller, it seemed to not want to work. To resolve this I chose to purchase a Focusrite RedNet PCIeR card which would give me 128 channels of Dante routing power on the card itself. It did fix that problem but it also led to my next issue.

The Dante Controller Could Not See The Focusrite RedNet PCIeR card

When I installed the RedNet PCIeR card into my computer, the Dante Controller wouldn’t recognize it. There was an IP mismatch happening. I was told to download the latest RedNet software so that I could see the IP configuration of the RedNet card (which I did) but I didn’t wind up having to change anything.

No matter what I did I just couldn’t figure out how to resolve it on my own so I decided to order another network switch for everything that was not Dante, re-set my Cisco managed switch, use it exclusively for Dante and call in another IT tech to help set it up. Once the IT tech arrived, we decided to put everything back to DHCP;  the computer, the MTRX and everything else. Once we did that, every Dante peripheral showed up on the Dante Controller and started talking to each other.  

Progress - A Working System - But…

Now I had the Hybrid Engine working with the MTRX Studio and I was able to route 64 channels to the Renderer via the RedNet PCIeR card. At this point I was happy but honestly, I felt like I had half a Dolby Atmos system with only 64 channels to the Dolby Atmos Production Suite (DAPS) limited by the MTRX Studio. I wanted the ability to open full Atmos sessions without any limitations.

How About Two MTRX Studio Interfaces?

I started to price out a full MTRX and although it was tempting, it was really expensive. So I reached out to a few people about using two MTRX Studios together. Avid got back to me on the DUC saying it was possible but no one seemed to have done it. So I tried it.  

I bought another MTRX Studio and another HDX card. I plugged the Dante port into my switch and I plugged both DigiLink ports into my second HDX card. Dante Controller saw my second interface and so did DADMan but once I fired up DAPS was still only getting 64 channels.

It took me a minute to solve this. Back when I was having the issue with the DVS getting overloaded, before I got the RedNet PCIeR card, I had switched the number of Dante channels in the Audio Midi Setup from 128 down to 64, to try and get it to work with my initial 64 channel setup. Once I switched this back to 128 channels, 32 bit and switched over to DAPS, everything was good, and for the first time, I was hearing everything and getting 128 channels to DAPS working with the HDX Hybrid engine.     

A Full Breakdown Of All The Hardware, Software And Configurations

Let me stress this. This all works. I bought a switch initially that should have worked but didn’t. I tried different USB-C adaptors that should have worked but didn’t.  For whatever reason everything listed below works, but be aware, if you want to substitute things there is a chance they won’t work.

Also, I am not endorsing any of these companies. This just happens to be what works for me. And finally, there might be some better ways to do some of this. I’m constantly improving the setup and finding out new things myself.

My aim in writing this article was to enable someone considering a similar solution to be able to jump to a fully working system and avoid the pitfalls and setbacks I have experienced, so here is a detailed list of everything I have used…

Hardware

Computer:

Mac Pro 2019 3.2GHz 16 core, 1TB internal, 128 Gigs of RAM, W5700X graphic card

• 4 x 4k monitors off the graphics card. 3 for my desk and 1 TV for video playback.

• A Sonnet Fusion Flex J3i adaptor, which has two 7200RPM 16TB drives for sounds

• Sonnet M.2 4x4 PCIe card with 16TB of Sabrent SB RKTQ 4TB drives set to RAID5 in slot 1

• RedNet PCIe Dante card in slot 3

• HDX1 in slot 5

• HDX2 in slot 6

• OWC Accelsior 8TB PCIe card set to RAID5 in slot 7

• UA Octo PCIe card in slot 8

Peripherals:

• OWC Thunderbolt 2 docking station

Switches:

• Cisco SG350-28 managed switch for DANTE peripherals ONLY.

• Cisco SG112-24 unmanaged switch for local ethernet peripherals.

Interfaces:  

• 2 x MTRX Studio

Software

• OS 10.15.7 Catalina (I believe I can move to Big Sur on everything but I haven’t yet)

• PT 2021.6.0 (current version)

• Dolby Atmos Renderer v 3.5.0 (current version)

• EuControl v 2021.6.0.181 (current version)

• Avid Control v 2021.6.0.90 (current version)

• Latest HD drivers (current version)

• Audinate Dante Virtual Soundcard v 4.1.2.3 (this was for when I was running Natively before the Hybrid engine.)

• Audinate Dante Controller v 4.4.0.8 (current version)

• DADman v5.4.5.1 build1 (current version)

• MTRX Firmware 1.0.3.2 on both units (current version)

• RedNet Control2 v2.8.0 (current version)

Hardware Connections

Mac Pro

• Belkin USB-C to Ethernet adaptor plugged from my OWC dock directly into the Cisco SG350.  The dock is connected to the Mac Pro via USB-C.

MTRX Studio 1

• Dante out on bottom ethernet port into Cisco SG350 (the port shouldn’t matter)

• Digilink Port1 into HDX1 card port 1

• Digilink Port2 into HDX1 card port 2

MTRX Studio 2

• Dante out on bottom ethernet port into Cisco SG350 (the port shouldn’t matter)

• Digilink Port1 into HDX2 card port 1

• Digilink Port2 into HDX2 card port 2

RedNet PCIeR Card

• Primary port out into Cisco SG350 (port shouldn’t matter)

Cisco

• There was no need to get into the managed switch. The default settings work fine with the Dante network. But definitely run two networks each with their own switch, one exclusively for Dante and a separate switch for everything else.

Software Settings

Network Settings

• The Mac Pro Dante network should be set to DHCP. Everything that is networked via Dante (both MTRX Studios and/or anything else), all set to DHCP. Everything is going to have a 169.xxx.xx.xx address. They all need to be on the same subnet as well. I’m by no means an IT tech but I think this should all work itself out if you’re using DHCP.

Audio MIDI Setup

• RedNet card is set to 128 channels. (I have 32 bit, 48kHz selected as well for the work I do.)

Dante Controller

• REDNet PCIe channels 1-64 transmitting to MTRX1 channels 1-64 receivers

• REDNet PCIe channels 65-128 transmitting to MTRX2 channels 65- 128 receivers

• MTRX1 channels 1-64 transmitting to REDNet channels 1-64 receivers

• MTRX2 channels 65-128 transmitting to REDNet channels 65-128 receivers

• REDNet PCIe latency set to 1.0 msec

• MTRX1 and MTRX2 latency set to 1.0 msec

• MTRX1 is the Primary v1 Multicast Leader (Main Leader.  This should happen automatically.)

• MTRX2 is the Primary v2 Multicast Leader (Follower.  Again, this should happen automatically.)

• RedNet PCIeR (Follower. And again, this should happen automatically.)

DADman

• MTRX1 Digilink1 1-32 patched to Dante 1-32

• MTRX1 Digilink2 33-64 patched to Dante 33-64

• MTRX2 Digilink1 1-32 patched to Dante 1-32 (I relabeled these 65-96)

• MTRX2 Digilink2 1-32 patched to Dante 33-64 (I relabeled these 97-128)

Pro Tools 2021.6.0

• Playback Engine:  HDX with Hybrid Engine selected

Dolby Atmos Production Suite (Renderer)

• Audio Driver: Core Audio

• Input Device: Focusrite RedNet PCIe

• Output Device: Focusrite RedNet PCIe

RedNet Control2

• no changes to the default

2 Small Issues

Two small issues have cropped up more recently. I have tried to suss them out as best as possible but it’s such a new workflow it is still a work-in-progress. Both of these issues pertain to the dual MTRX setup and not to any other part of the overall setup.

The first issue is an occasional random disconnection. Sometimes if I leave the session open and step away for an hour and come back the second MTRX Studio seems to lose its signal. It’s still showing in DADMan, it’s still locked in Dante Controller and showing up in ProTools but I get no sound coming out of its channels. 

We getting into deeper Dante territory and I do not by any means claim to be a Dante expert. The workaround is to go to Dante Controller, click on MTRX2, go to Device Config and Reboot that unit.  Then you will hear the sound again.  I do have both units and the card set to the lowest latency so maybe turning those latency times up will help.  It may be as simple as some deeper settings.

Secondly, sometimes when DADman starts up it will put the MTRX Studio 1 on the right side of the DADman window and the MTRX Studio 2 on the left side of the window. They seem to get flipped.  When this happens the second MTRX will not pass any signal. The fix for this is to make sure you have the first unit labelled “1” in the top left-hand corner of the DADMan DA section and the second unit labelled “2” and then they will be in the correct order.

Conclusion

As I am using the Hybrid engine for mixing power, not recording, I wasn’t really sure what the benefit would ultimately be. I did a test, which technically wasn’t a totally accurate A/B test but it was close. I used a small film I had mixed in Dolby Atmos natively using the Dolby Atmos Bridge as my Playback Engine. At one particular demanding point in the film, my system usage was up to about 35%.

Then I opened up the same session with the HDX and Hybrid Engine engaged with no tracks in DSP mode and played back in the same spot and my system usage was at 8%.

In a recent article, Pro Tools HDX Hybrid Engine - Is It Really A Game Changer? Jamey Scott had mentioned, “the mysterious optimized CPU usage factor” of the new Hybrid Engine in Pro Tools 2021.6 and he wasn’t exaggerating at all. It’s really quite incredible what this software update is doing. It’s basically putting an almost “no limit” on mixing in the box which is a dream.

There are a lot that people still figuring things out, when it comes to having a Dolby Atmos mixing room at home, but I believe you have to have an idea of what you’re going to be doing with it and possibly what might be required of you in the future before you start any setup. The very first thing to do is to reach out to Dolby and speak to them. They were essential for the initial planning at the beginning and for the tuning at the end.

Honestly, it’s an amazing time for audio mixing. Between Dante, DADman, EuControl integration, the Hybrid engine, room tuning and the Dolby Atmos Production Suite the sky really is the limit.  (Especially when you throw in SoundFlow!)

So in the end I hope this helps get you to a point where you’re getting the technical things out of the way and mixing and being creative a lot faster. It’s quite a bit of work to get it all together but once it’s all up and running it’s an amazingly creative place to be.