iZotope Neutron 5 — A Mix Real-World Review

Neutron 5 (Mac/Win) is the latest incarnation of iZotope’s integrated mixing-processor suite. It includes a modular “Mothership” plug-in incorporating all of its processors, plus individual plug-in versions of each and several separate utility plug-ins.

iZotope has also added three new processors, bringing the total to 10. The lineup includes: Compressor (multiband, up to two instances in a signal chain), Equalizer, Exciter (saturation), Gate, Sculptor (spectral shaping), Transient Shaper, Unmask and the three new modules: Density, Clipper and Phase.

THE STRUCTURE

Before getting deeper into the new modules and features, let me quickly review the structure of the Mothership plug-in. It offers two main work areas: Detailed View and Assistant View.

The former’s workflow resembles that of a standard modular plugin. You can open your desired modules, adjust their places in the signal order and edit all their available parameters. When you select a module in the signal chain area, its display and controls are visible underneath.

The other workspace, Assistant View, is where you access the AI-based Mix Assistant. After briefly analyzing your audio, Neutron chooses the appropriate modules and settings. Assistant View offers a simplified set of parameter adjustments, all in one screen, for tweaking the AI settings.

iZotope revamped the Assistant View controls in Neutron 5, rearranging and renaming the categories and changing the available controls to make them even more intuitive. From Assistant View, you can adjust EQ, dynamics, saturation and stereo width, mostly with “one-knob”-style controls.

Novice mixers will gravitate to Assistant View because it makes creating usable settings for any source easy. However, thanks to the deep parameter control available in Detailed View, Neutron 5 will also appeal to advanced users. I like to use Assistant View to create a basic setting, then switch to Detailed View for more precise tweaking. I suspect that most users, no matter their experience level, will use some combination of both Views.

DENSITY: GOING UP

The new Density module is an upward compressor, meaning that instead of attenuating any signal above a user-selectable threshold, it boosts any signal below a threshold.

Let’s say you have a vocal track where the singer maintained a good level most of the time but wasn’t loud enough in several intermittent spots. You could manually adjust the gain using automation in your DAW to compensate for each occurrence, but it’s faster and easier using Density to bring up those quiet moments so they are closer in level to the rest of the track, which increases intelligibility without having to raise the overall volume.

Like the Compressor module, Density’s Threshold control is a horizontal line that crosses the waveform display. You adjust it by dragging it up or down. Another line, called Gain Trace, indicates gain changes from Density’s processing. (This combination of graphic threshold control and waveform/gain trace displays is common throughout many of Neutron’s modules.)

In addition to the Threshold slider, Density provides three more knobs. Range controls the maximum gain range and can be set between 0 and 20 dB. Ratio controls the amount of boost for signals falling below the threshold. Speed governs how quickly the processor acts on sounds below the Threshold.

CLIP IT OFF

The new Clipper module affects dynamics using soft-clipping, which aggressively cuts off the tops of waveforms and makes it possible to increase a track’s average level significantly. It can add some distortion and make a track sound more energetic when applied heavily.

What makes Neutron’s Clipper especially powerful is its multiband capabilities. It supports up to three user-adjustable frequency zones, each with independent settings. In addition to Threshold sliders, each band has a Soft Clip Boost knob, which controls the Clipper’s knee. The higher you set it, the faster the clipping is applied to the waveform and the more squashed the track will sound.

The multiband capability provides great flexibility. For example, if you put Clipper on a drum bus or stereo drum loop, you could set up the frequency zones and thresholds to focus mainly on the kick, leaving the snare sounding less processed, or vice versa.

THE HEARTBREAK OF ASYMMETRY

The final new module, Phase, has two significant functions. First, it can detect and correct (through phase rotation) asymmetrical waveforms—a problem you may not have even realized you had. Such waveforms are sound waves, typically from vocals and certain instruments, that are unbalanced between positive and negative. Their peaks end up higher than their troughs, resulting in a loss of headroom and potentially leading to distortion when you turn up the track.

With the Phase module open and the DAW’s transport playing, hitting the Learn button will automatically adjust the Rotation parameter to reduce asymmetry. It’s easy to do and has no impact on a track’s average level.

The other main parameter in Phase is Delay. It applies a time shift to the track. You can set it manually, but if you want Phase to automatically time-align one track to another, you need to route a feed of the source track into the target track using your DAW’s sidechain feature.

The Phase module features an oscilloscope-style display with several view options. You can choose to see the signal from the Main track only, the Sidechain track only, the Main and Sidechain together (with the sidechain in a different color) or a single summed waveform of both. The Phase module works as advertised and provides functionality for which you’d generally need a separate alignment plug-in.

MULTIPLE MODALITIES

Those features are new, but one of the big “improvements” in Neutron 5 is called Channel Modes. Previously, each processor was limited to one operating mode, either stereo or mono, depending on the plug-in’s instantiation. Now, the Sculptor, Equalizer and Clipper modules offer the choice of three modes: Stereo, Mid-Side and Transient/Sustain. The Density, Transient Shaper and Unmask modules offer Stereo and Mid/Side.

With Mid-Side, you can address the mid and side sections of the signal with entirely different settings. This allows you to be more surgical with processing when needed and gives you additional control over the stereo image (e.g., boosting just the sides of a stereo image will make it sound wider).

Transient/Sustain mode lets you process the two aspects of a signal separately. For example, you could use the Equalizer to brighten and emphasize the attack portion of an acoustic guitar without affecting the body of the tone.

Also new are Delta solo buttons in every module. These buttons allow you to hear the difference between the processed and unprocessed audio, making it easy to grasp what the processing is doing to the source.

A BETTER ASSISTANT

Besides revamping Assistant View, iZotope also improved the Mix Assistant’s performance. I compared the Assistant’s automatic settings in Neutron 4 and Neutron 5 on various track types, including a drum kit, electric piano, vocals, electric bass and a full mix.

On the iZotope website, one article says that the new Mix Assistant is twice as fast as the one in Neutron 4. My (admittedly anecdotal) testing didn’t bear that out. Both versions took about six seconds to create a setting on my M2 Mac mini.

However, I found the results of Neutron 5’s Assistant to be better overall than those of Neutron 4. In the latter, the Mix Assistant sometimes guessed the wrong instrument (for example, guitar instead of bass). My only complaint—valid for Neutron 4 and 5—was that the Mix Assistant frequently added too much saturation for my taste when used on a clean source. However, dialing that back using the controls in Assistant View was easy enough.

Another way to use the Mix Assistant is to upload a custom reference file. For example, I found a clean and warm acoustic guitar recording and uploaded it to the Assistant View. It produced better-sounding results than the acoustic guitar reference built into Neutron.

It is rare for a plug-in to appeal to the full spectrum of users, from novices to experts, but Neutron 5 does just that. For the former, it offers the Mix Assistant and the simple-to-adjust Assistant View controls. It provides a comprehensive suite of mixing processors with extremely deep adjustability and a flexible architecture for the latter. The new features, particularly Density, Phase, Clipper and the Channel Modes, add additional control layers. Considering all you get, it’s an excellent value. If you already own a version of Neutron, the upgrade is well worth it.

iZotope sells Neutron 5 singly and includes it in the Music Production Bundle 7 and The Mix and Master Bundle Advanced. A stripped-down version, Neutron 5 Elements, is also available for significantly less. It offers fewer features and modules but includes the Mix Assistant.