New Software Review: MasterCheck Pro by NUGEN Audio

Gain invaluable insight into your levels with NUGEN Audio’s MasterCheck Pro.

I’ve been using NUGEN Audio’s original MasterCheck as my main level monitor for a couple of years—most notably as part of my music mastering process, where pinpoint accuracy is critical.

Before I settled on MasterCheck, the TT Dynamic Range Meter had been the centerpiece of my metering. Although I felt totally comfortable with that one, it was stuck in 32-bit mode, and when Logic went to 64-bit only, I felt it was time to move on.

The winning feature on the TT Dynamic Range Meter’s was its RMS metering display, and several other companies expanded upon this design to varying degrees of accuracy. Then, I discovered MasterCheck.

MasterCheck is among a select group of plugins that the mastering community deems accurate. All the measurements reference “ITU-R BS.1770”. That is to say that this is a  Loudness Unit meter, not a conventional dB or RMS meter.

More recently, NUGEN has released the MasterCheck Pro update, which expands the existing set of tools, enabling you to work directly with the codecs and volume levels used by popular streaming services such as Spotify and Apple Music.

Note that the MasterCheck plugins aren’t designed for the audio-post community. NUGEN has its own surround-capable solution for this market in its VisLM 2 plugin.

If you’re not familiar with the terrain of modern mastering, here’s a very brief summary: In the past, when we used to cut masters for CD, the main measurement devices we used were Peak and RMS (average) level meters. Master levels for CD grew very high because the CD itself embodied a fixed end-level for the product. Record labels and artists kept pushing for the maximum because, “louder sounds better,” which resulted in the average level of rock or pop CDs coming in at about -8RMS. Loud, but potentially, grating and lifeless.

Various agencies then moved to provide guidelines for loudness, as the general perception of producers and mastering engineers was such that the quality of music production was being stymied by excessive compression in order to achieve ear-shattering levels. So, the ITU and EBU both developed industry standards which has produced a new measure of loudness: The Loudness Unit.

The idea is that if we have a common unit of measurement, we can all work to that standard. The measure of loudness over the entire length of the program material is its “Integrated Loudness” level.

Many of the major streaming services (Spotify, Apple Music, Tidal, etc.,) have implemented systems to keep the user experience as even and seamless as possible in terms of playback level. Loud tracks are turned down to a nominal LU (Loudness Unit) level for playback and quiet tracks are turned up to match that level. This process is known as “Loudness Normalization”, or “Replay Gain”.

What this means for your master is that concerns over achieving maximum relative loudness are no longer as important, because any attempts to increase the level of your tracks beyond a certain point could be overridden downstream. No longer is the final level of the track’s playback embodied in the file as it was with CD. Although the relative level of your tracks may change from platform to platform, the element that is far less likely to change is the dynamic range within the track.

That’s where MasterCheck Pro comes in. Let’s see what it has to offer.

Features and Use

Available for $199, MasterCheck Pro is compatible with Mac OS X and Windows in VST2, VST3, AU, AAX and RTAS plug-in formats. It gives you an accurate ITU 3-second “Short Term” measurement of Loudness Units (LU), which to me, is reminiscent of VU metering.

Note that there is no “Momentary” reading on this plugin, but I don’t find this to be an issue as that is almost akin to reading a Peak dBFS meter and not very helpful when setting relative song levels in mastering.

MasterCheck Pro also shows you the Peak to Loudness Ratio (PLR). This is the difference between the loudest signal and overall average, measured over 3 seconds. By carefully monitoring the PLR, you can see how much the mix is being compressed, irrespective of the output level. For me, if you can keep the PLR between 8-12 LU you will have a modern punchy mix that retains dynamics and will suit both downloads and streaming.

Visually, MasterCheck Pro is easy on the eyes…and rightfully so! When mastering, my eyes tend to reference the PLR and LU meter every 10 seconds or so. MasterCheck Pro’s GUI is uncluttered: PLR at the top, Integrated Level beneath, and Short Term meter to the left. NUGEN gives you the option of fine-tuning the color scheme of the volume gradations for LU level, PLR and True Peak (more on True Peak later).

In my mastering process, there will typically be several meters open, such as MeterPlugs’ Dynameter and LCAST, TT Dynamic Range Meter, and Wavelab’s meters. There is really very little that needs adjusting if you are only monitoring level, other than refreshing the Integrated Loudness level. Loudness can be viewed in LUFS or LKFS, and shown in L/R or M/S format.

MasterCheck Pro also allows you to monitor clipping in detail. One of the by-products of codecs is that the level can sum at the output to greater than it was at the input, due to signal modulation. A file normalised to 0dBFS will almost certainly show clipping if it has been changed into an MP3 or AAC file. Similarly, files played through streaming codecs could clip. True Peak metering (displayed large and clear on the right of the GUI) provides you with an adjusted level to help avoid clipping.

In addition, MasterCheck Pro boasts a wealth of additional features, such as Codec View, which (although not scaleable in its rather large display) allows you to flip between Compact and Codec in the settings shown below. This incorporates an Encode section showing up to five streaming profiles (consisting of Codec and Data Rate).

With MasterCheck Pro, you can stay up-to-date with the industry’s latest specs for streaming—and preview how they will sound in real-time.

Something I hadn’t really thought about before is the effect of data quality on clipping. Spotify for instance has three different codecs for mobile, desktop and premium. What MasterCheck Pro will tell you is how close you are to clipping across all of the output options simultaneously. Up to five mini meters can monitor clipping directly below the main True Peak meters.

In the above picture, the streaming profile for iPlayer is loaded. You will see in the bottom center four “Profiles.” These go from high bit rate streaming to low bit rate at the bottom. Notice that as the data rate drops, the clipping increases—this is useful information in establishing the sweet spot for a maximized but safe level.

The codec is the engine that compresses the data, and each codec removes different elements of the frequency spectrum and stereo field. If you want to actually monitor the audio quality, you can flick between Meter and Monitor mode. Meter will give you the visual data but with the unprocessed audio. Monitor will output the sound after the codec.

A lovely extra is a Delta button, which allows you to monitor the differential pre and post processing. With this button engaged, you can flick though the various data rates and codecs to hear what each will remove, and the results are quite shocking. This feature could easily lead you back to tweaking your mix to compensate.

The original MasterCheck had presets such as YouTube, Spotify, Tidal, and TV levels for Europe, Japan, and the US. These presets combine the service loudness normalization level and the currently used codec. There are newly added presets for BBC iPlayer and Apple streaming, as well as updates for the Youtube presets and other streaming services. This is an ever-changing terrain.

In July, NUGEN released an update for MasterCheck Pro due to Spotify changing their playback loudness setting to -14LUFS from the previous -12LUFS standard. It’s easy to “Offset to Match” your mix with US or Japan TV presets, and MasterCheck will drop the output to the expected operating level. This is very useful when outputting to multiple formats.

Another important feature is the ability to reference other material. The bundled NUGEN “Send” plugin allows you to directly compare your current mix with a reference mix. Put Send across your reference track and the PLR and Integrated LU level will be visible. You can also use MasterCheck Pro to monitor the pre and post processing feed by inserting Send at the start of your chain, and MasterCheck Pro at the end.

Send can sync to offset any latency in your chain, and by engaging Offset to Match, you can level-match the results. Using Offset to Match was pretty accurate when I tested it, but the visible levels are still useful. This is such a great tool to check the mastering lore of ”Do no harm”—the notion that you are maintaining the clarity and coherence of the original mix, and are able to see (hear) through the artifacts of limiting.

To Be Critical

One thing to note is that MasterCheck Pro does not provide a history of loudness over an album or multiple-part program (though NUGEN Audio’s VisLM 2 Loudness Meter does). Because of this, I had to use MasteCheck Pro as part of a suite of other plugins such as Meterplugs’ Dynameter and LCAST, who have made this aspect their central feature. Although this isn’t available in MasterCheck Pro, NUGEN has still provided us with one of the best tools for providing rock solid, super clear and customizable real-time readouts.

I also experienced some lag on both the Latency Sync and Offset To Match features, an issue made more annoying by the level refresh being on one page and the Latency Sync being on another. At one point, Send lost the ability to sync and I had to restart Wavelab in order to solve the issue. I was testing the AU and VST2 version in Wavelab and Logic, but I have heard that in some instances the VST3 was inaccurately monitoring level at higher sample rates. NUGEN assured me they will soon release an update that will fix this. I made my own comparisons against the Wavelab Loudness meter at sample rates up to 192 kHz and did not experience any issues myself.

Summing it Up

NUGEN Audio’s MasterCheck and MasterCheck Pro will give you reliable ITU-R BS.1770 measurements for Program, Short Term Loudness and True Peak material. The excellent PLR meter gives instant insight into the dynamic punch of your mix. The interface is customisable in colour which makes it really easy on the eyes, especially over the course of a long session.

The Pro extension gives you access to real-time audio codec processing including HE-AAC v1 & v2, Ogg Vorbis and AAC-LC, and service presets for Spotify, Apple, YouTube, AES, BBC and more. Lastly, MasterCheck Pro gives you a loudness matching tool when outputting to multiple platforms, as well as for A/B and Pre/Post processing.

At a well-justified price point of $199, MasterCheck Pro would be an invaluable addition to any mastering engineer’s arsenal.

Julian Tardo is a producer/engineer and music lecturer working at Church Road Studios in Brighton, U.K.

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