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Review: Mastering Reference Tools

New Mastering Tools


MasterCheck is a powerful, multifunction toolkit designed to be the last plug-in in your mastering chain. It is basically a digital crystal ball that lets you hear what your master will sound like when standing up to other content, as it’s streamed on a variety of platforms. The marquee feature, only available in the Pro version, is the codec preview, which allows real-time encoding and auditioning of lossy data compression algorithms used by different services. That said, both the Pro and standard versions offer a good number of handy meters and utilities that help to contextualize your track better in the streaming universe.

In its simplest view mode, MasterCheck Pro looks identical to the standard version, displaying three vertical, bar graph–style meters, plus large PLR and LKFS values at the top of the display. The first bar graph is an LKFS meter. As with most Nugen plug-ins, the level of customizability throughout the interface is deluxe. With the LKFS meter, six different ranges can be defined by the user and color-coded with a choice of more than 100 colors. This allows the ability to define your own desired nominal value, while also painting a tolerable range around it The second meter is a PLR meter, which again is fully customizable in terms of color per value. PLR stands for “peak to loudness ratio.”

Like the TT Dynamic Range meter, the PLR in MasterCheck could be anchored to the top of the bar graph, extending down in a way that looks similar to gain reduction in a plug-in compressor. Alternatively, the stretchy PLR blob could ride beside the LKFS meter and extend up from that meter’s value position. I liked this option because it kept my eyes in the same place on the display. It also did a nice job of illustrating when my average LKFS value was smashing into the headroom. Directly above the meter, there is a long-term PLR measurement, while a box at the top of the plug-in interface shows the momentary PLR value.

The last bar graph is a dBTP (True-Peak) meter. Traditional peak metering measures the value of the loudest digital sample. True-Peak measurements oversample the audio to reconstruct pieces of the waveform that exist between samples, which may exceed the value of the loudest sample. One concern is that these inter-sample peaks, even in the original PCM version of a master, can potentially overdrive consumer DA converters. An even larger concern is that lossy compression codecs are likely to misrepresent these peaks, causing noticeable distortion or artifacts. Accurate True-Peak metering is a must when preparing masters for downstream lossy encoding. MasterCheck’s dBTP metering can follow either the universal ITU-R BS.1770 standard, or Apple’s proprietary “afclip” algorithm.

While the LKFS bar graph and its accompanying numeric display show short-term or “sliding” loudness levels, a large box toward the top of the GUI shows the long-term loudness as a single numeric value. A second, smaller number displays the target loudness, which can be set to reflect the standards used by different streaming services. With a click of the “Offset to match” button, the plug-in will automatically boost or attenuate the level of the master to match the target playback level. Alternatively, a reference track can be fed from another DAW track and this function will offset the loudness of the work track to match the reference. In either case, removing the “louder is better” factor allows more accurate judgment of what is really going on in the track.

Finally, the Pro version of MasterCheck offers the ability to monitor in real time through the codecs used by Spotify (Vorbis), Apple Music/iTunes (AACLC) and TIDAL (AAC-LC), as well as the FLAC and the new up-and-comer, Opus. Five codec slots are available, and each can be loaded with a different codec, or a redundant codec with alternate settings. This provides the ability to quickly switch between codecs and compare each to the uncompressed original version.

MasterCheck turned out to be the missing piece to my mastering workflow. I typically master at 24-bit/96 kHz using Studio One Pro. I wish I could say that I typically buy reference materials from HD Tracks, but more often than not I’ll have a playlist of songs prepared by the client in Apple Music or iTunes. In other cases, I’ll put together my own Spotify playlist of reference materials. That plays at 44.1 kHz through a separate converter, routed back to my monitor controller.

When flipping back and forth between the two sources, I have always had to manually and continually compensate for the differences in playback level between the two sources. With MasterCheck I could easily match my master to the Spotify or Apple Music LKFS standard and immediately level-match with my guide tracks. When I could start to feel my loudness level drifting from the references, due to compression or EQ changes, a quick click of the refresh button in MasterCheck tweaked the compensation. Even when the plug-in was set to compensate level, it continued to read and meter the true loudness level in the background, so it always had an adequate sample upon which to base the refresh.

The codec preview was also really handy for a couple of reasons. For one, the AAC-LC with Apple Music settings really colored the sound. The bottom end would frequently shrink, the lower midrange backed off, and the upper-mids would sound a little crisper and harsher. Unfortunately, most people don’t want to juggle different versions of the project for different services, but a case could be made for doing so. Overreacting to compensate for these codec-borne changes had an adverse effect when switching to a different codec, so creating multiple versions to cater to different services seemed to be a plausible approach.

My only complaint about MasterCheck Pro was that it is a bit of a CPU hog. I started playing with it on projects that were already loaded up with plug-ins, and MasterCheck Pro would break the camel’s back, so to speak. This was true in Studio One Pro and Pro Tools|HD (no HD card), running on an i7 Mac Mini with 16 GB of RAM. When inserting the MasterCheck plug-in first and building a processing chain afterwards, particularly when leaning toward more UAD processing, this was not an issue.

When working with MasterCheck, I challenged myself to conform my masters to the Spotify standard of -14dB LKFS, rather than just making them loud. It proved a rewarding experience, as I achieved what, to me, were better-sounding results. On top of that, it took less processing to arrive at a final product. Not going loud is still a tough sell, but I’m hoping that with MasterCheck helping to illustrate benefits of dynamic mixes, and the knowledge that Spotify and Apple Music are no longer rewarding over-compression, there is light at the end of the tunnel.


COMPANY: Nugen Audio
PRODUCT: MasterCheck Pro
PRICE: MasterCheck $129 / MasterCheck Pro $199
PROS: Allows real-time preview of codecs and loudness normalization
CONS: CPU-intensive, which can lead to overload errors


Reference is the second plug-in from newcomers Mastering the Mix. The company’s first effort, Levels, is more of an LKFS loudness meter, with some cool features for analyzing masters. Reference is designed for comparing a master to existing source material or to the unmastered version of the same track. Altogether, the plug-in provides some very unique and useful visual feedback, all while easing the process of A-B’ing tracks.

Operation of the Reference plug-in begins with loading in reference tracks by drag-and-drop or browsing. I was able to load tracks at different sample rates, encoded with different codecs, as well as PCM, and everything was quickly converted to play correctly within the plug-in without issues. Multiple tracks could be loaded, with tabs to switch between them. Each was displayed with a large and detailed waveform view.

If referencing the unmastered version of the current track, a handy “mirror” function can be enabled, which automatically aligns the two versions and syncs Reference’s transport to the DAW’s transport. Even when moving the cursor around the Pro Tools timeline, the plug-in’s transport kept up. This allowed the timing to match perfectly when flipping back and forth between the two versions.

The bottom half of the GUI features a set of peak and LUFS meters for both the Original song that is being mastered and the selected reference track. A level-match function attenuates the Reference to match the loudness of the Original, making for more honest judgment of effects being applied. This process continues to track and adjust the level-matching as LUFS data is updated, without the need to refresh manually. Toggling between the two tracks is done by clicking on Original and Reference buttons, or on a single customizable quick-key. This made it easy to A-B, even with my eyes closed.

Along the bottom of the GUI is an interesting part of the software, the Trinity Display. This area can split the frequency spectrum into a choice of up to five frequency bands, each of which can be soloed when A-B’ing against reference material. Each band shows a level bar, indicating whether that band is louder, quieter or equal to the same range in the selected Reference. Waves of purple dots moving toward or away from that bar indicates whether that band is more or less dynamic than the Reference, with their density indicating the difference. Horizontal bar graphs for each frequency band compare the stereo width of two sources. Relative gain, dynamic range, and stereo width can also be displayed numerically in a box inside each band.

I found the frequency-dependent level and compression metrics to be really useful when comparing my master to a third-party reference track. If a particular range was much more compressed in the Reference, I could address that range in a multiband compressor while watching feedback from Reference. With a combination of soloing, A-B’ing and watching the visuals start to match up, I was often able to emulate the texture of the other track quickly. At that point I could decide whether that sound truly fit.

The width displays gave me somewhat mixed results. These were accurate when comparing the mastered track to the unmastered version. Places where I had deliberately widened or narrowed the image were generally reflected accurately. In some cases, however, after clearing mud out of a certain frequency range, other details were able to shine through, effectively widening the perceived image.

If you’re looking for a quick way to match sample rate and loudness between your masters and reference tracks, this a solid tool. The extra level and compression metering are handy for grasping the direction in which you need to start your work. Keep in mind that you can only import songs that are downloaded or ripped from CDs. I’d love it if they could integrate a streaming service, but for now you’ll have to rely on your personal library or buy the songs on the client’s reference list from iTunes or HD Tracks.


COMPANY: Mastering the Mix
PRODUCT: Reference
PRICE: $65.62
PROS: Great-looking graphics, useful insight into masters
CONS: No streaming integration