New Software Review: RX 6 Noise Reducer from iZotope

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With the addition of several new and powerful modules, RX 6 is surely the most expansive and comprehensive iteration of the RX series iZotope has yet to offer.

iZotope is an undisputed champion of creative audio tools for music and post-production. Their products allow users of every skill level to tackle the most challenging sonic obstacles with relative ease and speed, and always produce spectacular-sounding results.

I’ve written extensively in the past about many of iZotope’s offerings. Today, we’re going to be focusing specifically on RX 6 and its wealth of new features and additions.

If you are new to RX, I would recommend you start by reading my reviews of RX 3 and RX 5. These detail some of the groundbreaking modules that debuted in the earlier versions of the RX suite, such as Dialogue De-Noiser (now improved and re-named Voice De-Noise), Leveler, De-Plosive, Module Chain and many more.


iZotope has added several new modules and features to RX 6, making it an even more comprehensive and impressive suite of tools than its earlier iterations. Some of these new additions include De-Rustle, De-WindDialogue IsolateDe-BleedMouth De-Click and Breath Control.

RX 6 can be used as a standalone audio editor connected to your host via RX Connect, or as a suite of plugins. Information on system requirements, supported operating systems, plugin hosts, and plugin formats can be found here on iZotope’s website.

RX 6 is available in four different tiers, each of which is designed to accommodate the unique needs of musicians and post production professionals of all levels. RX Elements is the most bare-bones of the four, available for $129, RX Standard for $399, and RX Advanced for $1,199. RX 6 is also available as part of RX Post Production Suite 2 for $1,499.

The tools in the RX line are without question the ones that I use most often on audio-post projects. Lately, I’ve been splitting my time between documentary and film work, as well as editing and mixing podcasts like Here’s The Thing and The West Wing Weekly.

As I did for my RX 5 review, we’ll be talking with L.A.-based audio-post mixer Lawrence Everson to get his take on some of the new modules in RX 6. Lawrence recently mixed the spectacular feature documentary “A River Below,” which I had the pleasure of screening at the Tribeca Film Fest. (I highly recommend you check this film out if you get the chance.)

Before we begin, one note on connectivity and efficiency: the relationship between RX and your DAW is made possible by the Connect plugin, which allows you to select one or many audio clips in your DAW and send it to and from the standalone RX app for maximum processing ability and ease of use. Connect first debuted in RX 4 and has really become the cornerstone of the relationship between RX and my DAW.

Note: All modules labeled “(ADV)” indicate that it is an advanced version feature only.

As for all of the new features found in RX 6, let’s dig in!

In Use

De-Rustle (ADV): This is easily one of the most asked-for additions to the RX module set by its user base. Simply enough, De-Rustle is designed to snipe out rustle noises typically created by lavalier mics rubbing against clothing. The noise profile for a rustle sound is often very complex and can run the spectrum from top end crackle to low end rumble, making it one of the most challenging and frustrating types of noise to deal with.

As with many of the RX tools, the De-Rustle module is very simple to use. Two sliders for Reduction Strength and Ambience Preservation make up the entire GUI, along with some general presets. Ambience Preservation incorporates elements of the Ambience Match module to help preserve clean background noise while removing unwanted rustle noise. How does this work? iZotope’s preview video for De-Rustle explains:

“We collected lots of isolated [noises] rustle which we then used to corrupt clean speech and feed to a machine learning algorithm trained to recover the clean speech. When processing, the trained machine learning algorithm separates the clean speech from the background rustle.”

All this to say, De-Rustle works. And it works very well.

De-Wind (ADV): De-Wind is another brilliant addition to the RX 6 toolkit for tackling one of the most common production audio issues—wind noise.

De-Wind accomplishes with a single click what was once a tedious task in the Spectral Repair module, saving me tons of precious time over the course of a given project.

Sliders for Crossover Frequency, Fundamental Recovery and Artifact Recovery (as well as a General Reduction slider) make up the main controls.

Overall, De-Wind performs exactly as you would expect. The module quickly and easily removes low end subharmonic wind rumble from dialogue and production tracks while retaining the structure and integrity of the original recording.

That said, De-Wind does require a bit of experimentation to find the sweet spot. There’s a threshold in terms of reduction level where the processed audio can begin to sound too filtered or thin. By and large, De-Wind performed perfectly and saved me lots of time when processing complex outdoor audio for the feature documentary “Not a War Story” that I’ve been mixing for director Tim O’ Donnell. Take a listen to De-Wind in action here.

Dialogue Isolate (ADV): Dialogue Isolate is a beast. As described by iZotope, “[It is] is designed to separate spoken dialogue from non-stationary background noise such as crowds, traffic, footsteps, weather, or other noise with highly variable characteristics.”

This is a truly remarkable plugin that I’m constantly finding new uses for. Again, very simple parameters for Dialogue Gain, Noise Gain and Separation Strength give you clear and simple control over this extremely powerful module.

My colleague Lawrence Everson was also able to put Dialogue Isolate to the test. Lawrence notes, “One common documentary problem I often face is voices recorded in crowds, conventions, protests, or other issues where a human voice is within a sea of other human voices. This is something very tricky to tame.

“While it’s not a miracle worker, I was impressed more often than not at what Dialogue Isolate could do, especially versus the previous broadband noise reduction modules. I found gentle passes had surprisingly helpful separation, and even intense passes would be helpful for forensic or translation situations where you simply need to hear what is being said in a noisy space.”

Check out iZotope’s breakdown of Dialogue Isolate here.

Mouth De-Click: This is bar-none one of my most-used modules in podcasting work, and anything else where dialogue and voice are crucial elements of the production. Mouth De-Click improves upon what I used to use De-Crackle for; it utilizes a completely separate algorithm from De-Crackle for processing specifically the tiny cracks and clicks created by mouth noises from dialogue.

I had some questions about the differences between De-Crackle and Mouth De-Click, which iZotope engineers happily answered for me. Most notably, Mouth De-Click is optimized for standalone mouth noises (with short or long intervals in between), versus De-Crackle, which is optimized for continuous noise. It is designed to handle mouth noises that range from clicks to smacks to watery sounds, and works many times faster than De-Crackle. It is lower latency, and caters specifically to frequencies in the voice/vocal range.

While De-Crackle and Mouth De-Click can often provide similar results, I’ve found Mouth De-Click to be faster overall and a better, more focused module for making close mic dialogue sound spectacularly clean and polished.

De-Bleed: De-Bleed is used to reduce bleed from one track or one mic to another. The release of this module was practically a jump-up-and-down, happy-cry moment for me and likely many other engineers who have dealt with these issues before.

While iZotope has made great progress with regard to bleed issues in their Spectral Repair tool, De-Bleed creates an entirely new purpose-built solution to one of the most detrimental tracking problems in music production.

The most obvious use for De-Bleed is click track bleed from a vocalist’s headphones into their vocal mic or perhaps an acoustic guitar mic. It requires two sync’d tracks: the bleed source and the active track.

With a bit of “learning,” RX 6 can then process the unwanted bleed sound completely out of the active track with truly stunning results. I wasn’t able to put De-Bleed to the test on any of my current projects, but take a look at this full length demo of the De-Bleed module and see for yourself just how remarkable this tool is.

Two other modules worth mentioning that have been extremely useful to me in the podcast world are De-Ess and Breath Control. Both of these perform just as you would expect, and provide surgical control over two of the most problematic areas of voice recordings.

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