Nugen Audio Halo Upmix Review – Stepping into Surround Pt.3

With the 3rd of our ‘Stepping into Surround’ series articles, I’ve got the chance to review Nugen Audio’s Halo Upmix plugin. I recently reviewed NuGen Audio Loudness Toolkit; a massively efficient set of tools for working with audio in Broadcast and Post – and this continues the trend of incredibly useful plugins for working in surround sound.

Halo is a recently released Upmix plugin – featuring in VST, AU RTAS and AAX formats, and can mix up or down from mono to 7.1; useful for all kinds of music and sound design, be it in film, television, video game, or standing by itself.

Mixing efficiently can be a real pain in multi-channel work, as there are a lot of phase issues and other technical matters that can leave you stranded. Halo is useful for bridging that gap of quality vs. efficiency – leaving you with a mix project that you’re proud of, without having cost you hours days or weeks of extra effort.

The GUI is one of the more beautiful ones I’ve seen – with a great balance of minimal design and useful graphic and numerical information.

The main aspect of the window is what looks like a radar encircled by the speaker positions you’ve chosen. As audio plays, Halo displays the material in directive light blue ‘clouds’ of audio information. As the audio gets more directional, the cloud becomes thicker, and slightly more narrowly aimed at the channel it’s coming from.

The more dispersed around the surround stage, the thinner and wider the cloud. For more clarity, you can change the colours of the speakers, and the clouds will reflect the colour of the speaker they’re playing through. This is a really clever way of getting a lot of information about the spread of the audio in a quick glance.


As I mentioned in a previous review of NuGen’s plugins; the presets are invaluable, providing all the necessary settings for different broadcast requirements. For Halo, it’s just as good, except slightly more subjective – as the presets are not necessarily prescribed by expected standards, but more by the most useful ways of converting the material into multi-channel. And as such, depending on whether you’re going 5.1 or 7.1, the preset list will change.

For example – say you want a track to be mainly effect ambience, whether it’s a reverb in a music track, or background chatter in a movie – you’re probably not going to want that in the center channel. There’s a 4.1 preset (6.1 for 7.1 presets) That automatically assigns just the stereo front and rear, and LFE channel for the audio material, muting the center channel.

This is a simple example, but it demonstrates how quickly and efficiently you can set up a process that would have taken a lot longer by setting up the channels in the DAW directly. There are presets for television/film, and there are some aimed more at music, and these are clearly delineated in the preset folders. If you create settings you will be returning to, these can also be saved in a user folder.

Spreading the love
Around the outside of the ‘radar’ screen are sliders that dictate how much signal is sent to the rear speakers. The more the sliders move around to the rear, the more signal will appear in the rear speakers. Simple as that. No phase issues, just movement of sound around the surround stage. Very effective.

If you want to remove the sound totally from specific speakers, clicking on the little circle around the outside will mute that particular speaker. So you can remove the signal from the centre channel by clicking on it. The LFE channel will automatically be sent the low-frequency information from the source material, at a cutoff of 80Hz, but if you wish, you can have more control, separate the LFE channel, and decide what the crossover range is for the LFE channel to activate.

All these parameter controls are so effective, yet so simple. Excellent work by Nugen here.


Center Channel control
Most of the time, you can just set the Halo and go, but in certain situations you need more control over certain channels. In TV in particular, the center channel is very important. If you get, for example, a stereo mix, and the requirement is a full 5.1 upmix, having more control over what goes to the center channel; being able to separate out mono material such as dialogue and send it directly to the centre channel, is vital.

Halo accomplishes this with aplomb using proprietary algorithms that use neural networking concepts to isolate the material that is vocal from the rest of the material. I found it to work surprisingly well at separating out the dialogue from effects or background noise. There is an aggression percentage which will remove more or less information around the dialogue depending on how much background material there is.

As with all of these algorithms, there is only so much magic that can be applied before artifacts start appearing, but you can automate the aggression factor throughout different sections to get the best possible results. Really useful if you’re converting stereo to 5.1 and you don’t have separate stems.

Clicking the I/O button swaps the surround scope and the monitoring levels in the bottom right corner of the GUI. Here you get more precise monitoring of levels, and to an extent, adjustment of levels in separate channels. You can link channels to avoid steering, and still keep an eye on the placement of audio, as the surround scope view gets minimized to the bottom right-hand corner.


Exacting output
At the bottom of the window is the output module. There are level meters, showing if you’re clipping or any other erroneous signals in the mix. There are various buttons to hear the original sound, the upmix, and the potential down mix if it’s converted back to stereo for television.

The EXACT button ensures that what you’re hearing in the source will sound identical when down mixed again. Very useful for ensuring phase compatibility and generally not having to worry about how the mix will sound if re-converted. The meters can be swapped with the radar, to take up the large proportion of the screen, giving more precise control over each of the channels, enabling trim, offset, mutes and solos for each channel, as well as more precise meter readings.

Here’s a video of me using Halo Upmix on a recent 5.1 nature documentary I did the music and sound design for. The left-hand window is for the sound design, the right hand for the music mix. It’s a demonstration of the effectiveness of the visual ‘radar’ of the sound in the surround stage. For this video it’s bounced to stereo, excellently and automatically, by the Halo plugin.


Halo Upmix is a fantastic plugin, one that as soon as you get a grip of, transforms the way you work in that particular medium. Working with multichannel audio, I found that it sped up the process immeasurably – taking a process that can be extremely complex and time-consuming, and cutting down hours and hours of work to make a product you can be proud of.

It’s designed for use by professionals on a time crunch, but the ergonomics of the design mean that anyone starting out in surround mixing will find this plugin a God send. Halo can be used in almost any field you wish to work with multi-channel audio in. Creating something different for a music project? This is definitely a plugin you want to invest in.

Halo is a great balance of efficiency and control – you can quickly set up sweeping changes to stereo audio to neatly fit in any multi-channel set up, and leave it there. However, if you want to have more control over specific channels, such as the LFE, or center channels, you can dive in and get creative.

I would highly recommend this as a plugin not only for efficient upmixing, with little need to worry about phase issues in the process, but also as an extremely creative tool to get you thinking outside the box when working with multichannel audio. As a side benefit, it’s extremely hypnotic to gaze at when you run out of inspiration!!

Halo is available for $499. More info here

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