When I started freelancing in the summer of 2013, I built my Pro Tools 11 HD system, iZotope’s RX3 software was near the top of my plug-in wish list. I’d been exposed to the original RX plugin package and even used RX2 a fair bit. I was headed into my fledgeling business’s first TV series, which was a reality-based prank show; each show had as many as 17 mic’s. These mics were located on the host, hidden on the pranksters and surreptitiously around the location. I knew I’d need to be able to dig out the ‘prankee’ from whatever mic I could; mic hiss, cloth moves, buzz, hum, plosives and all. So RX3 was a purchase, well justified. 

It would be nearly a year until I upgraded to RX4 and when I did, one of my favourite plug-ins, “Spectral Repair,” had been dropped as an AudioSuite option. I still have the anxious email chain in my archives and it appears I have a helpful man named Joel from iZotope to thank for pointing me to what RX is actually all about: The Standalone software. With this paradigm-shifting revelation, I learned very quickly that the real power of iZotope’s restoration software is contained in a vital, omnipotent package outside the Pro Tools experience.  

The quality and power of processing using the stand-alone iZotope RX, rather than the plugin versions are much greater, plus there are many things that iZotope RX can do that there aren’t plugins for, so it’s well worth learning how to get audio to and from iZotope RX from your DAW cleanly.

In this article, I will take you through the seemingly rudimentary process of sending to and printing back to Pro Tools from RX using the RX Connect plugin in the AudioSuite menu. But note that in other DAWs RX Connect is an AU or VST plugin in your DAW’s effects menu.

The process may seem basic but there are some tips and tricks that I have learnt that could help you. To begin, you’ll need an Aux track somewhere, that is Solo Safed, for the RX Monitor real-time plugin. This is how you can route the output from iZotope RX back into your DAW monitoring. This plugin acts as an output portal from RX to whatever hardware is being used by Pro Tools. It can be implemented on a variety of track widths from mono to 7.1, depending on what you need in your session and how recent your version of RX is.

Since TV dialogue is what I mainly use RX for, I have my RX Monitor on a 5.1 track inside my template, because the output of this track directly feeds my 5.1 dialogue sub-master bus. You can instantiate the plugin on a mono or stereo track instead if you’d like and it can be routed straight to your main output. In any case, It should look something like this until we launch RX. Note the Disconnected Status.

Having successfully engaged the Pro Tools end of the monitoring path, we need to set up the ‘send’ next. This is done via an AudioSuite plugin in Pro Tools. Note that in other DAWs RX Connect is an AU or VST plugin in your DAW’s effects menu.

RX Connect’s simple interface belies its power. 

There are two ways to send audio from your DAW to iZtope RX using the RX Connect plugin.

Reference is a one-way example that can be sent to RX to profile ambience, or sample EQ and level, or to reference reverberation content. I use reference files a lot to help me match ADR or dialogue outtakes but I also occasionally use it to send a stereo piece of music over to EQ Match a stereo music track I’m working with. There are lots of uses for Reference files, tonnes actually!

Repair is the default mode of this window and the little arrows are emblematic of the round trip between Pro Tools and RX. The plugin defaults to ‘round trip’ because after all, you probably want your repaired audio back in the timeline where and when it came from.

Hitting ‘Send’ starts the round trip and hitting ‘Render’ prints our final RX output back on the DAW timeline. 

What’s less obvious about this plug-in is the fact we can pull down that ‘create continuous file’ button to expose some other options. Most AudioSuite plugins have these options but for RX, they’re especially handy.

Today, I want to send 4 voiceover files to RX and print 4 voiceover files back, so I’ll choose ‘create individual files’.

This setting, along with ‘entire selection’ will take all my selected clips on a given track and send and return them, without any additional handles or ‘pad’ at the tops and tails of the clips. Typically, this is how I work with VO tracks.

If I want 2.00 seconds of handles for each file, I need to ‘create individual files’ and also select ‘clip by clip’. For fun, let’s briefly do this because it’s not the default and might teach us something we didn’t already know.

I now have my RX 8 Connect window configured the way I want and my four voiceover clips selected on the timeline, to send to RX. I’ll click SEND on the RX Connect window. RX opens up and takes in the audio from Pro Tools.

This is pretty funky and not very user friendly. The blue tabs are all things we can send back to Pro Tools at the same time. With things tabbed, I can’t work on them all at once! I need to collapse these tabs to a single view. If I click on the little arrow just to the right of the blue “SEND BACK” button at the top, we go into “Composite View” in iZotope RX.

Now, had I just sent over the entire selection instead of multiple clips, the timeline would have looked like this without having to ‘collapse to composite’.

In Composite View, I can work on as many as 32 clips at once. Sometimes, I have 80-90 voiceover clips I send over for processing so I certainly want to see them all as one timeline in the Spectrogram. In those cases, I have to send them over as an ‘entire selection’, not ‘clip by clip’. 

There’s one issue worth pointing out with Composite View before we go any further and that’s the fact that the gain line, akin to Pro Tools volume automation, won’t show up in this mode. I hope they fix this but for now, we’re going back to Pro Tools to resend as ‘entire selection’ to move on with this tutorial because we’re going to need the gain line later.

Now back in Pro Tools, we can still create individual files, just without handles. The upside is we can send many more than 32 files since they’re effectively being treated by RX as a single file. ‘Create individual files’ will just print back to Pro Tools as multiple clips so I can keep the timeline edits I’ve defined.

This is great. I have all my material in RX  but I can’t hear anything when I hit the spacebar. In RX Preferences (use the menu access or Command+Comma on macOS) the first tab is ‘Audio.’

I set my Driver Type and Output Device to RX Monitor and all of a sudden, I can hear my audio through the real-time plugin in my DAW, in this case, Pro Tools on my 5.1 Aux track. On this page, I can set my multichannel layout and even trim my output gain.

If you have read my Pro Tools Preferences - Why So Many Choices? you might deduce, I spent a lot of time here on each tab, learning what the various functions do. Hit OK and we’re done for now.

Checking back in on the RX Monitor plugin I instantiated on an Aux Track, I now see my monitor path is connected and happy. 

To maintain the focus of this article, I’ll forgo the various processing stages I typically take. What I really want is clean audio going back to Pro Tools.

This is where a tiny bit of knowledge can help a great deal.

My Pro Tools session is 48 kHz, 24 bit. RX derives its sample rate from the materials I send it; auto-switching when sample rates change in different sessions. For example, when I switch to a 192 kHz, 24-bit session, RX will switch over to 192 kHz mode to faithfully output the sound, without noise or distortion. But what is RX’s bit depth?

RX is a 32-bit floating-point audio processor. Floating-point math means I can assign numerical values to audio levels that peak above 0dBFS (decibels full scale). It means I can’t clip audio in RX very easily at all because peak clipping occurs when anything above full scale is assigned a static peak value (0dbFS) and these peaks occur long enough for us to mentally process the flatlining of levels.

Before I return my audio to my 24 bit Pro Tools session, I need to ensure my peaks don’t rise above 0dB before I send it back. Why? Because once clipping distortion is consolidated into a freshly printed audio file, the distortion is now part of the sound. And this, my friends, is where a lot of operators run foul of their software.

To prevent this, I present your gatekeeper, the “Waveform Statistics” window in RX. As any power user of RX might tell you, this is possibly the one window you want to keep open all of the time; occasionally opening and closing it to ensure the information refreshes. OPTION+W will open and close this vital tool. 

My levels in my demo files are all fine for Pro Tools, as it turns out. At least, the levels are below clipping. The dialnorm in the integrated loudness box second from the bottom isn’t at my mix target of -24 dBFS so I am going to turn the whole thing up at least 5dB to illustrate another couple of ideas.

Command+G (on macOS) gets me the gain line view on the Spectrogram. This is akin to volume automation in Pro Tools. If I Shift+Click in the middle of the gain line, I can move the entire thing up or down at once. I’ll bring everything up until Waveform Statistics tells me I’m at -24 LUFS, integrated loudness. It turns out I had to boost everything by 5.1 dB. I am now peaking above 0dB by 1.71 dB. But where? 

It turns out, those little amber bubbles to the right of the numerical boxes in the Waveform Statistics window can be clicked on. Click on the one to the right of True Peak Level and we’ll be taken to the loudest point in our Spectrogram.

Now at the loudest peak, by Command-clicking on the gain line, I can create breakpoints, to bring the level down just at this peak, and prevent 1.7 dB of clipping when I return to Pro Tools.

I just had the one peak to worry about but thanks to the dynamic Waveform Statistics, I could keep clicking that same amber bubble to move along and trim any other peaks on my spectrogram’s timeline. 

Once I'm happy with my work in RX, I can SEND BACK with a single click.  In DAW, the RX 8 Connect window now shows me there’s audio waiting to be rendered. I’ll RENDER now.

Having rendered my clean audio to the timeline, I can see the waveform is now bigger than before, thanks to the level increase I made. The names of the clips have been appended by Pro Tools with ‘RX8Cnct_’ and a number. The clip boundaries are all intact though, exactly as they were when I started.

I have cleaner, louder clips in my timeline, with no fear of added peak distortion. As a popular character might say of our excursion to and from RX, “This is the way.”

If I don’t like what Pro Tools has done to the clip names, I can use the Auto Rename function in the dropdown menu to the right of the word “CLIPS” in the Clips pane attached aside the Edit Window, to rename and renumber these newly created clips. 

There you have it. Some tips and tricks on how to get audio to and from your DAW into iZotope RX cleanly. Enjoy.