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NUGEN Audio MasterCheck

Loudness Metering Plug–in For Mac OS & Windows By Hugh Robjohns
Published April 2015

It’s becoming ever more important to monitor the loudness of music mixes, and NUGEN Audio’s MasterCheck makes it easy.

While HDTV broadcasters all around the world have embraced the concept and practice of loudness normalisation — a method of ensuring a more consistent listening experience for the end user (see our feature in February 2014: — the music industry is taking a rather more leisurely approach. This is not surprising: whereas the major international standards bodies managed the adoption throughout the TV broadcasting industry, and similar progress is increasingly evident in digital radio in many countries, there is no similar organisational drive for the music industry. The appallingly misplaced concept of ‘louder is better’ is so deeply ingrained here that we must rely on a slow process of osmosis, as music producers and artists start to respond to the gradual evolving appreciation of audiences using loudness–normalised music services like iTunes Radio (and iTunes Souncheck on iPods and iPhones), Spotify, Windows 8 Media and others.

However, it could be argued that another potential impediment for the music industry is that most of the available loudness–metering tools are geared exclusively towards broadcast applications rather than the specific needs of music mixing and mastering. Thankfully, this aspect has now been addressed very nicely by NUGEN Audio’s latest plug–in, MasterCheck.

Check It Out

MasterCheck is available in AAX, VST, VST3, AU and AudioSuite formats, in both 32– and 64–bit versions, as well as in RTAS (32–bit only). It is compatible with Mac OS 10.6 and above, and Windows XP and above, and is secured either with a licence code for a specific computer, or a second–generation iLok licence to make it portable.

Nugen Audio MasterCheckAt the simplest level, MasterCheck is a very neat, three–way bar–graph meter. It provides a standard (ITU–R BS.1770) ‘Short–term’ Loudness meter on the left, a peak–to–loudness ratio (PLR) indicator bar in the middle (similar to that of the ever–popular TT Dynamic Range meter), and a stereo True Peak meter (capable of revealing inter–sample peaks) on the right. In addition, two numerical displays at the top indicate the integrated PLR and Loudness values over the full duration of the audio material. Usefully, a button converts all three meters to show the equivalent Mid and Sides signals, instead of the default left–right (on the true–peak meter) and mono sum (on the loudness and PLR) displays.

As you would expect from NUGEN, there are plenty of options for user configuration, too. For example, the level thresholds at which the different meters change colour can be customised — although the defaults work very well — and the peak meter scale, segment intervals, loudness target value, loudness units, and even the label text colour can all be changed, if required.

Out Of The Blocks

Usefully, MasterCheck ships with 10 factory presets. These include settings conforming to the established loudness–normalisation standards for HDTV in Europe, America and Japan, as well as for the current DAB radio trials. More importantly for music mixing and mastering applications, though, there are two variations optimised for music streaming outlets such as Spotify, and three for iTunes. Most of these presets employ the standard BS.1770 loudness and true–peak algorithms, but the iTunes options use a slightly different true–peak calculation called ‘afclip’, which is specified for Apple’s ‘Mastered For iTunes’ (MFiT) process.

The inclusion of the PLR indicator is the most obvious sign of this product’s optimisation for music mix/mastering applications. This display comprises a bar of variable length and colour that indicates the audio programme’s dynamic range. It works in much the same way as the classic TT meter, and is a helpful guide for adjusting mix or mastering compression/limiting: anything less than about 8 is starting to get pretty heavily squashed, and more than about 15 is impracticably dynamic. It is also a great tool for making objective comparisons of the dynamic range of same–genre reference tracks. In fact I think it works so well that I have already switched entirely to using MasterCheck instead of my old favourite TT meter.

MasterCheck is highly configurable.MasterCheck is highly configurable.The integration of this dynamic range meter with so many other useful meters and tools also considerably furthers its appeal and usefulness in a music–specific context. The Short–term and Integrated loudness metering displays are invaluable when trying to mix material to hit a specific target loudness value — as we will probably all have to sooner or later. The iTunes Soundcheck and iTunes Radio services work with a target level of –16LUFS, while Spotify is closer to –14LUFS, for example. Material mixed to the historic convention of ‘as loud as possible all the time’ simply gets turned down when replayed through a loudness–normalised system, and inevitably end up sounding quiet, flat and boring to the end listener. Mixing to the required loudness target, and building in dynamics, delivers dramatically more appealing material!

True–peak metering is essential for not only managing headroom, but also to warn of potential clipping problems in D–A and format converters caused by inter–sample peaks. These slip by completely unnoticed on standard DAW meters, but can cause real problems with the lossy data–reduction systems which are routinely employed in Internet music streaming, downloads and for MFiT. It is recommended, for example, when mastering for the MP3 format that true peaks should be kept below –3dBTP to avoid the risk of overload distortion from the codec.

Music–specific Applications

In addition to these critically important, but broadly familiar, metering functions, MasterCheck has some rather more specialised and extremely powerful features. First amongst these is the ability to audition the real–time effect of loudness normalisation on a mix in progress. Clicking on the ‘Offset to Match’ button introduces the required level cut (or boost) necessary to match the material to the current preset’s loudness target value. This replicates exactly how the track will sound on the equivalent loudness–normalised system, and it’s a very sobering thing to do when working with hyper–compressed material!

Cleverly, NUGEN have also incorporated a facility to use an external signal as the reference, rather than a fixed target level. The external signal is routed into the MasterCheck plug–in via a separate (supplied) ‘Send’ plug–in, and once this ‘side–chain’ input has been established the display is able to show the difference in PLR, Integrated loudness and true–peak values between the external reference and source tracks simply by clicking on the ‘delta’ button. It is also possible to audition the reference track directly through the MasterCheck plug–in in place of the normal source track.

This external reference input mode provides a remarkably powerful facility, and the most obvious way to use it is simply to get a handle on where a work–in–progress sits in relation to a reference track by instantly comparing their PLR, Integrated loudness and true–peak values, as described above. In this case, the reference track could be a commercial track from a similar genre, a previous mix attempt, or an alternative master version.

The inclusion of presets conforming to many widely used standards is very welcome.The inclusion of presets conforming to many widely used standards is very welcome.However, it can also be used to negate any loudness change imposed by upstream signal processing, such as compression, essentially by using the unprocessed track as the reference. This is achieved by placing the Send plug–in at the start of the processing chain and selecting its ‘audio pass through’ option. The MasterCheck meter is placed at the end of the same processing chain, and the ‘Offset to Match’ button clicked to restore the output signal to the same level as the source. Clicking on the speaker button toggles the audible output between the processed and original signals, at matched levels. Where the processing chain also involves some latency or delay, a ‘sync’ option in the MasterCheck settings menu can be used to time–align the source and output signals when A/B switching. This is a really useful and immensely powerful feature, especially for mastering applications, and one I had previously only found in the brilliant MeterPlugs Perception plug–in (reviewed last July:

Yet another clever application of this external reference facility is to assess the audibility of dialogue above background effects or music — something which is critically important when mixing for TV, for example, or when mixing podcasts and so on. In this situation the MasterCheck plug–in is inserted on the dialogue track and the Send plug–in on the effects or music track. When the ‘delta’ button is clicked, the numerical displays will show the loudness differential between the dialogue and music/effects tracks, as well as their individual values, making it very easy to adjust the mic as necessary to maintain a minimum positive dialogue offset of 3dB, or whatever is deemed appropriate for the material in hand.


I’ve yet to be disappointed with any of NUGEN Audio’s plug–ins; they all seem to be superbly designed and engineered to meet the precise needs of each well–defined application. The MasterCheck plug–in is no exception to that rule, and I am tremendously impressed with how easy it is to use, how much useful, relevant information it provides while still being very easy on the eye, and how amazingly flexible and powerful it is. It seems very well priced in comparison to other metering and loudness tools of similar capability and performance, and it has already become a default plug–in on the master bus of everything I now mix in the DAW — it really is a tool I couldn’t work without! Very highly recommended.


  • Comprehensive loudness–metering facilities that are, unusually, optimised for music production.
  • Good value for money.


  • None.


Sooner or later, we are all going to need tools to evaluate the loudness of our mixes, and Nugen Audio’s MasterCheck provides everything you’ll need.


£102 including VAT.

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