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November 12, 2019

Joel Hamilton syncing multiple computers




Did you ever consider the idea of using two computers simultaneously in one session? In the video, "Joel Hamilton Mixing Highly Suspect," Hamilton does just that, linking two Macs—each running a Pro Tools system with MIDI timecode over Ethernet. In this excerpt, he describes his dual Pro Tools setup and explains how it helps his production process.

Slaving Away

Hamilton, working in his Brooklyn-based studio, is using a hybrid system for this session, which includes not only two Macs with Pro Tools systems but also an analog console and a collection of outboard gear.

The individual tracks from the multitrack Pro Tools system are routed out to individual channels on his SSL console. From the console's main output, his mix goes into his "print path," where it gets recorded in the second Pro Tools rig.

Hamilton's setup is conceptually similar to that of an old-style analog studio where you'd record on a multitrack tape machine, send the individual tracks to channels on the console, and then mix them down to a two-track recorder. In Hamilton's rig, the primary Pro Tools system replaces the multitrack tape machine, and the second system replaces the 2-track recorder.

Hamilton uses a second Pro Tools system, this one on his laptop, as his mixdown deck.

This setup is quite different than mixing "in the box," where the multitrack mix is summed inside of Pro Tools and mixed down to a digital file, without ever leaving the computer. It's also different from a typical "analog summing" setup, where individual DAW tracks or stems are converted to analog and sent to the summing amplifier, which combines them in the analog domain. Then, they're re-digitized by an analog-to-digital converter and recorded to a stereo track in the DAW.

Locked and Loaded

Hamilton's print path starts with some outboard processors ("EQ and other tweaky things," is how he describes them), eventually feeding into a Burl analog-to-digital converter and then into the other Pro Tools system on a Mac laptop. The multitrack audio is converted from digital to analog on its way to the console. So, the print path, which is fed by the console, is receiving analog signals that must be converted back to digital.

The signal flow for Hamilton's two-computer setup.

Interestingly, he's running the multitrack rig at 24-bit, 48kHz, but he prints at 24-bit, 96kHz. Hamilton says he always mixes to 96kHz, no matter what the ultimate delivery format is.

His two Macs with their Pro Tools rigs are locked together with MIDI time code over Ethernet. The multitrack is the master, and the laptop he's mixing to is the slave. Because their transports are locked, all he has to do is put the slave Pro Tools rig into record, and it will start capturing as soon as he hits play on his multitrack session in Pro Tools.

He finds this configuration to be convenient in a mix session. Typically, he's asked to create alternate mixes such as acapella or instrumental ones. Having the print machine set to record automatically—when he hits play to start the mix—simplifies his workflow.

Hamilton uses the screen-sharing facilities built into the Mac OS to open the screen of the slaved laptop inside that of his master computer, so he can arm the record function of the Pro Tools system he's mixing to. With screen sharing on, you don't just see the display of one computer inside another; you can work inside of it as well.

In this example of screen sharing on a Mac, Digital Performer is running on the main computer, and Logic Pro (in the smaller window) on a networked laptop, but both can be controlled from within one screen.

You don't need to use screen sharing with a two-computer setup; you can operate each computer from its own screen, keyboard and mouse; but it's certainly more convenient when you can control everything from one machine.

Hamilton also points out that another application for a locked, two-computer system is to utilize one networked computer as a remote control for the DAW the other. Ethernet allows for long cable runs, so you could easily put the second computer into another room, and the machines wouldn't lose sync.

Why Use Two?

Hamilton says he originally started using timecode-locked devices back when he was still recording to tape. He'd stripe (record) timecode to one of the tracks of his 16-track tape machine and slave his computer to it, which he'd use as a sampler.

Later, after he'd switched over to digital, but before computers were as powerful as they are today, he'd lock two computers together over Ethernet so he could run more virtual instruments than he could on a single machine. In other words, he used it to give himself more processing power.

If you wanted to network two computers so that you could run virtual instruments on one to save CPU, you could set it up like this.

Another advantage of locking computers with MIDI time code is that you can have a different DAW on each machine. You could even lock and Mac and a PC together, although it might be a time-consuming to get everything correctly configured.

Getting Practical

With all of its potential, setting up a MIDI network to synchronize DAWS on separate computers can be tricky, particularly the first time you do it. But before you even start there are some practical matters to consider.

Do your computers have Ethernet ports? Contemporary Macs support Ethernet but some require you to purchase a Thunderbolt-to-Ethernet adapter. Windows machines are less standardized, so some may not offer Ethernet ports or options.

Then you have to consider whether your DAW's copy protection will allow you to run it on two networked computers simultaneously. If you use Pro Tools, which is iLok protected, you can only run one instance at a time. So, you'd need to own two Pro Tools licenses, and use two iLoks, to have systems running on two machines at the same time.

However, if you have Pro Tools on one computer and another DAW, say, Logic Pro X on the other, you can connect them through your MIDI network. The beauty of MIDI is that it's host and platform-agnostic, making it an excellent bridge between different DAWs or platforms. Logic Pro X and MOTU Digital Performer are two examples of DAWs that don't feature dongle-type authorization, so if you use of one of those applications, you can have two instances going simultaneously.

It’s a Lock

The step-by-step details of how to lock two computers using timecode-over-Ethernet is beyond the scope of this article and will vary somewhat depending on which computer and DAW you're using. You can find plenty of info online about how configure such a setup.

It's more straightforward to accomplish on Macs, because of the Mac OS's built-in virtual MIDI network (which you access through the Audio/MIDI setup application). Windows computers don't have built-in MIDI networking capability, but there is a freeware MIDI driver that's designed to enable it.

One place to read about how to network your computers is a post called "How to set up a virtual MIDI network" that's on the Ableton site. Although it's mainly about locking two computers running Ableton Live, it offers some good tips for how to set up a MIDI network on a Mac.