iZotope Neutron Masking Meter Display

Designed to process individual audio tracks from mono to eight channels wide, its top features are an algorithmic analyzer called Track Assistant and the Masking Meter, a clever real-time display of frequency collisions and buildups between any two tracks in your mix with the goal of remediation of this potential problem.

Neutrino, Neutron, Neutron Advanced

Neutron has three versions. Neutrino is a spectral shaping plug-in that subtly increases separation between instruments and is available as a free download. It has four operating modes: Vocal/Dialog, Guitar/Related, Bass, and Drums/Percussive. It has controls for Detail (its frequency range) and Amount (its dynamic processing depth). Neutrino is for smoothing out resonances and harshness, and it becomes more effective when used on all tracks in a mix. Neutrino, as part of the Neutron plug-in, automatically selects one of those four modes in conjunction with every Track Assistant analysis.

The Standard and Advanced versions of Neutron are identical channel strips with both Input and Output sections, and five processor modules: EQ, Compressor 1, Compressor 2, Exciter and Transient Shaper. The modules can be placed in any order by clicking and dragging, and are followed by Neutrino and the Limiter.

The limiter has three algorithms: Hard, IRC LL, and IRC II--borrowed from the company's Ozone 7. There are also three modes: Mode 1 (Clear), Mode 2 (Smooth, a good starting place) and Mode 3 (Thick, useful for handling loud, low frequencies cleanly).

Neutron Advanced supports up to 7.1-channel surround and includes separate plug-in versions of Neutron's EQ, Compressor, Exciter and Transient Shaper modules that can be used anywhere in your mix.

EQ Learn Mode

I inserted Neutron Advanced on a lead vocal track and clicked on the Learn button. EQ Learn analyzes a short portion of audio wherever you start playback and places "nodes or points of interest" at response peaks caused by fundamentals, sibilance, rumble, P-pops and resonant buildups.

For this vocal track, I played a section of a quieter verse going into a louder chorus section to get a representative dynamic range and spectral picture of the nature of the singer's voice and the recording/production. I tried scanning other sections of the vocal track and essentially got the same results. I found EQ Learn to be an incredibly useful tool that's better than a spectrum analyzer for identifying problems requiring corrective EQ.

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The newly designed equalizer section has 12 adjustable bands with choices of vintage analog style, Baxandall, band shelf and proportional Q filters. In surround track instances of Neutron, there is an LFE bypass button so that the LFE channel passes through unprocessed and with the correct latency compensation.

I especially like that all these EQ bands (except for the high and low filters) can be switched between static and dynamic modes with adjustable threshold and a choice between compression and expansion. There are also side-chain facilities to control the dynamics of any EQ band from its own frequency, any of the other EQ bands in play, or from external sources using the plug-in's side-chain input.

Track Assistant

Next, I engaged Track Assistant on the same lead vocal track. The software's learning algorithm first identifies the nature of the audio it is processing and selects one of the four Neutrino spectral shaping algorithms, or Clean where Neutrino is bypassed. Neutrino's faders for Detail and Amount are set midway (50%) by default.

Track Assistant has a pull-down menu with three selectable Modes that govern its strength: Subtle, Medium (default) or Aggressive. Three Presets further define the precise processing goals: Broadband Clarity (default), Warm and Open, and Upfront Midrange, for a total of nine combinations of Types and Presets to consider.

Running and constrained by the nine processing directives and Neutrino, Track Assistant scans audio and, in about 10 seconds, configures the signal chain order, parameters for all five of the modules including any dynamic EQs. It also bypasses unused modules and sections to minimize CPU load. After a scan, a suggested chain position for the Transient Shaper is made (if deemed necessary) but not enabled, and the Limiter section must be manually turned on.

First Scan

For my first scan, I set Track Assistant mode to Subtle with the Warm and Open preset. Neutrino switched to Vocals/Dialog mode and the equalizer had a 108Hz -12dB/octave highpass filter set, a +3dB shelving boost at 247 Hz, a fairly high Q dynamic EQ cutting at 1095Hz, and +2dB of a proportional peaking EQ centered at 3,305 Hz.

Compressor 1, a multi­band compressor module, was set to wideband with a ratio of 8:1, fairly fast attack and 1.2-second release times. The lead vocal sounded hardly processed at all, with original dynamics intact and a warm and fuzzy tone ready for my automated mix moves. This initial starting preset was very close to what I wanted, save for a few refining tweaks.

I next set the Mode to Aggressive and used the Broadband Clarity preset and let Track Assistant rescan. Track Assistant applied corrective EQ settings at seven different frequencies, with two as dynamic EQs.

Compressor 1 was set at a 10:1 ratio and multiband Compressor 2 had crossovers at 360 Hz and 3.27 kHz, again in Vintage modes. There are Digital and the new Vintage compression styles with RMS, Peak and True (Envelope) level detection methods. iZotope's 3-band Exciter module also came onboard with crossovers at 82 Hz and 3.25 kHz, with joysticks for each band to blend any mix of Warm, Tube, Retro and Tape harmonic profiles.

Never Dreamt This!

I would not have dreamt of using this kind of processing for a vocal track, but it sounded great, especially within the mix. Even with aggressive settings, the lead vocal never got harsh or angry sounding. I like that each of the five modules has Wet/Dry Global faders that are automatable, as are all the 200+ parameters in Neutron.

Masking Meter

The Masking Meter shows auditory masking--the partial covering of one track's sound by another playing at about the same time and in the same frequency range.

The Masking Meter (pictured above right) has two parts: ghostly white lights behind the frequency EQ curve (the brighter the light, the more collisions) and the Frequency Collision Histogram bar chart that tallies collisions over an adjustable, resettable, three-second window.

Masking, termed "loudness loss" of one track's volume while colliding, is measured relative to another track in your mix. Multiple tracks instantiated with Neutron show up in a drop down window in each instance to compare them to the currently running track under scrutiny. You can name each instance with the track's name, but I think iZotope should update the software so the track's name automatically flows into each instance of Neutron.

On a pop ballad mix, kick drum and 5-string bass masked one another. I wanted good separation, though the kick was a big sounding 24-inch drum with a front head and the five-string bass played the low B string throughout.

I started by running Track Assistant on both tracks. With kick drum set to Aggressive and Upfront Mid­range, all five modules came into play with the Transient Shaper positioned right after the EQ but in bypass. On the bass track set to Medium and Broad­band Clarity, the Exciter module came up enabled right after the EQ. Later on during the mix, I adjusted the Exciter on the bass to give it more presence, and I enabled the Transient Shaper on the kick to dial in more attack.

Clicking the Masking button on the kick drum's Neutron instance and selecting the bass guitar track in the Masking drop-down window, the EQ window divided in half with the kick's EQ on top and the bass guitar EQ window on the bottom. I found this very helpful visually when setting slightly different EQs between a kick drum and the bass. You can elect to use the Inverse Link mode to automatically boost on one track and cut on the other at the same time on the same EQ band. That's a pretty awesome feature right there!

Neutron A New Game

I am impressed with Neutron's automatic analysis and preset generation. I use Neutron experimentally and for problematic sources, and I love it! However, it's not perfect--Neutrino Mode had some trouble identifying a drop-tuned stereo guitar track, causing Track Assistant to produce a thin-sounding preset. Using the Masking Meter information effectively is an acquired skill, and I find new uses all the time. Neutron is a powerful, advanced music mixing toolset that I'm thrilled to recommend.

Try This!  I used Neutron to check the masking between a lead vocal track and the 20 backing vocals--all sung by the same singer. As I would suspect, Track Assistant returned nearly the same preset when applied to both the lead and the vocals in the backing vocal stack. So for the lead vocal I set Track Assistant to Aggressive and Warm and Open and for the backing vocals, I set it to Medium and Broadband Clarity. This "trick" produced completely different results that "meshed" better in the mix. -- Barry Rudolph

Barry Rudolph  Barry Rudolph is a recording engineer/mixer who has worked on over 30 gold and platinum award-winning records. He has recorded and/or mixed Lynyrd Skynyrd, Hall & Oates, Pat Benatar, Rod Stewart, The Corrs, Mick Jagger and Rick Rubin. A three-time Grammy-nominated engineer, Barry has his own futuristic music mixing facility called Tones 4 $ Studios and also teaches at: Musician's Institute, Hollywood, CA.. He is a lifetime Grammy-voting member of NARAS, the 'New Toys' columnist for LA's Music Connection Magazine, and a contributing editor for Mix Magazine. www.barryrudolph.com   www.gearlust.com

iZotope Inc  Web Site: www.izotope.com/en/products/mix/neutron.html Product: Neutron Advanced Price: Neutron $249, Neutron Advanced $349 Pros: Remarkable mixing tool but not perfect. Cons: Track name should show up in plug-in.

Barry Rudolph is an L.A.-based recording engineer. Visit his Web site at: WWW.BARRYRUDOLPH.COM