Referencing is a critical part of mixing. It allows you to compare your song against well-mixed music in a similar style. In addition to giving you a reality check and ideas for treating various mix elements, it helps mitigate the acoustical issues often found in untreated studios, by providing you with a baseline to compare your mix with. There’s a lot to discuss about this subject, and Fab Dupont covers it thoroughly in the Puremix video, “How to Listen-Reference Mixes.” The full video is available to Puremix Pro Members, but in this free excerpt, Fab talks about using plug-ins that are specifically designed to help you reference more effectively.
COMPARED TO WHAT?
Fab mentions several available referencing plug-ins, including Magic AB from Sample Magic, Reference by Mastering the Mix and MCompare by Melda. He says he’ll demonstrate with MCompare. He starts by opening the plug-in and loading in a reference song. He explains that the essential operation is simple. When the plug-in is active, you hear the reference track, and when it’s bypassed, you hear your mix. MCompare has slots for multiple reference tracks to be loaded and switched between.
Melda MCompare is one of several referencing plug-ins on the market.
Fab points out that you can synchronize your reference to your own song so that the former doesn’t always start at the point it was stopped, but follows the transport of your mix. (This is particularly useful if you’re using the plug-in to compare an older mix of the song you’re working on with its current mix.)
MCompare has a feature called Set, which attempts to balance the level of the reference to match that of your mix. It checks your mix at the point in time you press the Set button and adjusts the reference mix to match.
The plug-in has a related feature called Automatic Loudness Compensation (ALC), which looks at the level of the reference track in real time and adjusts your mix to match it.
The ALC control on MCompare (circled) adjusts the audio from your mix in real-time to match the reference.
Fab says he doesn’t like the ALC feature because it tends to reduce the dynamic range of your track when you’re referencing. He says he prefers to find a representative spot in the reference song and then compare. When he says “representative,” he means one that is similar in intensity to the section of his mix he’s comparing it to. For example, you wouldn’t want to compare a breakdown section where the drums drop out with a full-out chorus section where all the instruments are in and playing hard.
THE POWER OF SAMENESS
Why is gain-matching so crucial when referencing? Because if there is a mismatch in level, the louder one will almost always sound better. This phenomenon will distort your perception of the differences between your mix and the reference, and defeat the purpose of referencing in the first place.
Why does this happen? The human hearing system perceives frequency differently at different volume levels. If you’ve taken any formal audio classes, you will undoubtedly have heard of the Fletcher-Munson Curves (also known as Equal Loudness Contours). Back in 1933, a couple of audio researchers named Fletcher and Munson discovered that the human ear is more sensitive to low and high frequencies as volume increases, and more to midrange frequencies as it gets lower.
Imagine how this impacts the process of referencing if either the reference track or the mix is significantly louder. When that happens, you’ll mostly be comparing apples to oranges, because you’ll perceive the frequency response differently between the louder and quieter audio. This will make your referencing useless, at least regarding frequency.
CHECK IT OUT
The following examples demonstrate the “louder sounds better” effect by comparing a mix with and without processing using iZotope Ozone 8 mastering software, which has built-in referencing and gain-matching capabilities.
Here’s iZotope Ozone 8 with its referencing and gain-match features activated.
Example 1. The first four bars are unprocessed, the second four have Ozone processing that includes EQ, compression and limiting. The processed version is a lot louder, so it sounds significantly better, even though the EQ changes are pretty subtle.
Example 2: Here’s the same comparison, except this time Ozone’s Gain Match feature has been activated. The first four measures are still without the processing and the second four with, but the differences sound much less dramatic because the volume is the same both without and with the processing. This is not to say that Ozone isn’t helping the mix, it is. But when you compare, the processed version doesn’t have the unfair advantage of being a lot louder.
So, whether you’re using a plug-in or some other method for referencing your mix, matching up the levels as much as possible, whether manually or with an automatic feature, is a critical part of the process.