Audio Mastering is the final stage of the audio production process where you polish your track and prepare it for distribution. In this article we’ll walk you through how to master a song from start to finish using Ozone and the updated Tonal Balance Control.
While there are many approaches to mastering music, we’ll focus on some of the most common steps to getting a great sound and how you can use Ozone’s features to improve your workflow. Here’s what we’ll be covering.
Feel free to download a free trial of Ozone to follow along.
Import your reference tracks
A reference track is a professionally produced song representative of how you want your own track to sound. Oftentimes, musicians will have songs, albums, or artists they want their music to sound like. Track referencing is a way for audio engineers to compare and contrast the song they are mixing or mastering to songs of a similar genre or style.
Add Ozone and Tonal Balance Control to the master bus
Ozone is the channel strip you’ll use to craft your mastering signal chain. Tonal Balance Control is a metering plug-in you’ll use to see how the frequency distribution of your track compares to your reference tracks. You can use any of iZotope’s reference targets—which were created by analyzing the tonal balance of thousands of professional masters—or you can upload your favorite references.
If you’re new to mastering, you may be wondering how to approach a mastering signal chain. In what order should those modules be? Should you add an EQ or compressor first? Do you need special processing to upload your track to a streaming service? To help give you a push in a helpful direction, we created Master Assistant. Powered by machine learning, Master Assistant is designed to give you a starting point that’s intelligently tailored to your music to help you create a professional sounding master regardless of your experience level.
Master Assistant Workflow
To get started with Master Assistant, open the Master Assistant panel. You’ll be presented with Vibe, Loudness, and Delivery options you can select from to customize the Master Assistant’s recommendations. Vintage mode is an option in Ozone that deploys the Vintage Compressor, Vintage EQ, and Vintage Limiter to give your track a warm, gritty sound.
Choose your loudness
If you select “Custom,” you can choose from three loudness options resulting in different integrated loudness targets. If you choose low, it’ll aim to make the overall level of the master -14 LUFS. At medium, -12 LUFS, and at high, -11 LUFS.
The “Reference” option determines the target loudness value of your track based on the loudness of a reference track. Select any reference track loaded in the Reference panel from the dropdown menu. If no reference tracks are loaded, click the “Load Reference Track” button to select a file in a system dialog.
Choose your destination
The Destination option determines the Ceiling value in the Maximizer to ensure appropriate headroom for the selected destination format. If you’re mastering for streaming platforms, Ozone will ensure the threshold ceiling on the Maximizer will be -1 dB, which will protect your track from jumps in gain. If you choose CD, it will set the threshold ceiling to -0.3 dB. For more on loudness standards, check out our article: How Loud Should My Master Be?
Run the module
Click ‘Next’ to proceed to the Master Assistant analysis step. Master Assistant requires audio input to perform analysis and adjust settings. Enable loop playback in your DAW and play the loudest part of your track for at least 30 seconds so that the Master Assistant has enough time to analyze the input audio. No need to wonder what Master Assistant is doing, it tells you exactly what processing it is applying as it does so. When the module is finished running, you can either Accept or Cancel the changes.
Tweak the result
Master Assistant provides you with a great starting point. With basic EQ, Dynamics, and Maximizer settings in place, we can take the time to make the master our own by tweaking these modules or adding new ones.
Maybe after applying basic loudness and EQ settings with Master Assistant, you notice your drums are a little quiet next to the rest of the mix. If you had the mix session open, you could easily reach for the drum channel and turn up the kit. But with only a stereo track, your options are limited.
With the Master Rebalance module, you can take advantage of Source Separation technology to correct and change instrument levels at the mastering stage without needing the original tracks. Strategically boost vocals for added presence without impacting the midrange, eliminate a muddy low end by lowering bass guitar, and correct weak-sounding drums with only one module to save you hours of EQ surgery.
Master rebalance workflow
To get started with Master Rebalance, place the module prior to any other processing. This allows later upstream processing to affect it, simulating a mix that had healthy levels all along. While you can place Master Rebalance anywhere in your chain, we recommend placing it at least before the Maximizer to protect against clipping or distortion.
From here, it’s as easy as boosting the gain of whatever element you want until you’re happy with the level. If you raise the drums, for instance, you might notice that the kick comes up, but the bass guitar doesn’t. The machine learning technology powering this module ensures clean identification and separation of those track elements, so only the source that you want will be boosted.
Mixing and mastering the low end can be complex. With lots of instruments competing in this space, the overall tone of your low end can become muddy and unfocused. The bass frequencies can contain the body of an acoustic guitar, the growl of saxophones, the weight of the bass guitar, and the punch of a kick drum.
You can add articulation and clarity to the overall low end with the Low End Focus module. Low End Focus gives you control of what’s in focus in your low end (between 20Hz-300Hz) by either preserving the most prominent spectral content and lowering the less prominent content, or by bringing both extremes closer together for your low end.
There are two modes in Low End Focus, Punchy and Smooth. Use Punchy if you’re aiming for an aggressive and exaggerated low end. Use Smooth for a more subtle and rich sharpening of your low end.
Adjust the contrast slider up and you’ll increase the contrast between prominent and less prominent frequencies, down and you’ll decrease this contrast.
A good rule of thumb is to place Low End Focus before multiband compressors––also called the Dynamics module in Ozone. This ensures that the module’s processing will be properly ‘framed’ and controlled via the compressor and Dynamic EQ modules ahead of it.
Next you want to listen to your track and analyze the stereo image to determine whether you need to apply stereo widening. If the track sounds narrow, add the Imager module to Ozone’s signal chain.
Ozone Imager allows you to adjust the stereo width of your mix, using multiband stereo imaging. Stereo imaging, when applied with a light touch, can help your master breathe and give it an impactful, wide panoramic quality.
Imager offers a new mode in Ozone, Mode II. This is an alternative to the classic Stereoize mode that imparts a slightly different tonal quality from the original, and helps to preserve transients at higher settings.
Should you EQ or compress first? The answer to this depends on the needs of your song, but you generally want to focus on making corrections before making any enhancements. If you hear problematic frequencies, for instance, then you’ll need to use subtractive EQ to correct them. The reason being, processing like compression, additive EQ, limiting, and saturation can amplify problematic frequencies making them harder to tame later on. This includes but is not limited to harsh sibilance, excessive low end, and any resonances that distract from the enjoyability of the song.
Stereo, Mid/Side, and Left/Right Processing modes
Ozone’s EQ has different channel processing modes that allow you to EQ the left, right, mid, or side signals in a different way. This makes it easy to surgically attenuate problematic frequencies or add stereo widening effects.
The following options are available in the dropdown menu and determines how processing is applied by the Equalizer: Stereo, Left/Right, Mid/Side
Stereo mode applies processing to the entire stereo channel. When selected, EQ adjustments will apply to both the Left and Right channels.
Left/Right mode separates the left and right channels so you can EQ each independently of one another. For example, if your guitar is panned hard left and you hear the unpleasant scraping sound as the guitarist’s fingers slide across the fretboard, you should isolate the frequency on the left channel and attenuate it. If you use Stereo mode (instead of Left/Right mode), attenuating that frequency will affect the entire mix rather than the left channel where the problematic frequency lies.
Mid/Side mode separates the center from the sides. Mid is all the mono information at the center of the stereo image (audio that’s equally present in both channels). The side, on the other hand, contains information that is only present in the left and right channels.
Mid/side EQ is typically used to control what’s at the center of the stereo image. Elements at the center are usually perceived to be louder and more prominent, so you can apply EQ to the center in order to bring something forward or backward in the mix. For instance, in the course of mastering a track, you may start to change the relationship between the vocal and the rest of the mix and you may find that it's not popping out enough.
With mid/side, instead of focusing on the sides, you can focus on the center in order to bring the vocal forward. Simply identify the frequency ranges of the vocals (say they’re anywhere between 500 Hz and 2.5 kHz), and slightly boost them in the mid channel to bring them out a little more. You can also try adding a high pass filter to Side channels to attenuate bass frequencies that make their way to the left and right channels. Doing so narrows your low-end (makes it mono) and ensures it doesn’t compete with elements you have panned to the sides.
Another application of mid/side EQ is to add a bit of stereo widening and control things on the sides. For example, you can create a sense of stereo width by applying a slight boost to the Sides focused on the high frequency information.
A useful feature you can use to identify frequencies you want to boost or cut is the Alt-Solo function. You can click the ‘solo’ button or use the alt/option key when clicking on a node or anywhere in the spectrum to momentarily solo a specific frequency region. When you release the mouse click, alt-solo will be disabled.
While you generally want to start with corrections before moving on to making enhancements, make sure you’re using subtractive EQ intentionally to avoid cutting important frequencies.
During the mastering stage of audio production, the goal is to get your entire mix to sound as dynamically cohesive as possible. You don’t want to have instruments or frequencies sounding out of place and distracting from the song because they’re suddenly spiking in level compared to other elements in the mix.
While mastering a song, you may need to control three different types of levels:
The level of your song
The level of specific frequency bands (i.e., a low end that needs to be controlled or a harsh high end that needs taming)
The levels of specific frequencies which require a surgical approach (i.e., sibilance, resonances, noise, etc.)
There are a few different tools you can use to apply dynamics processing based on the needs of your song: compression, multi-band compression, spectral shaping, and dynamic EQ.
Compression is used to achieve a consistent loudness level by reducing the difference between the loudest and quietest signal in your mix. This helps to glue individual elements of your track together. Compression controls the dynamics of your entire song and is applied to the entire frequency spectrum.
Multiband compression allows you to apply separate compression settings to different frequency ranges. Instead of applying compression to the entire signal like a normal compressor, you can separate the frequency spectrum into different frequency bands and apply separate compression settings to each of them. This is ideal for controlling broad frequency ranges such as the low end, mids, or the high end.
Dynamic EQ attenuates frequencies once they exceed a threshold. Dynamic EQ’s are different from multiband compressors in that they allow for narrower bandwidth settings which make them ideal for surgical processing such as taming resonances or sibilance. With a dynamic EQ, you’re attenuating frequencies with a filter (which have adjustable Q factors) rather than applying gain reduction with a compressor.
Spectral Shaping is low-ratio compression that is employed individually across dozens of frequency bands. You could imagine spectral shaping as a 32-band dynamic equalizer, with individual band shelf filters for every band, each automatically setting thresholds, time constants, and reduction amounts based on tuned models for each sound source. The result is a more transparent and surgical form of dynamic control that is constantly aware of the frequency content present in the incoming signal, and adjusting its processing accordingly.
While you’re free to use these tools as you see fit, it’s sometimes best to stick to the essentials. Sometimes, all you need is a compressor to get the job done.
Setting up Ozone’s compressor
If you’ve determined your mix needs more punch or dynamic control, use the Vintage Compressor module or the compressor in the Dynamics module. The goal is subtle compression. You want to avoid completely squashing your transients—the initial impact of your sound that contains all the punch. Too much compression and you run the risk of ending up with a song that sounds lifeless and lacks impact.
Set your threshold and ratio
Aim for subtle gain reduction of about 1 to 3 dB. Try experimenting with a high threshold (just enough to tame the highest peaks) and a low ratio between 1:25 and 2:1.
Attack and Release
Aim for a longer attack time to preserve the transients before compression kicks in. An attack time that is too short will apply gain reduction to your transients. Set a release time that’s long enough for notes to ring out properly and short enough that compression stops before the next transients kick in.
Do you need compression in mastering?
It’s important to note, however, that not every master requires compression since the original mix could have already been compressed effectively. Just by looking at the waveform, you should be able to tell whether there are too many peaks that need to be tamed. But most importantly, use your ears to determine whether compression is necessary.
By specifically comparing things like frequency response and dynamic range, using reference tracks in a mastering session can ensure that a track you’re working on is headed in the right direction. For this step, the goal is to make EQ moves that match the spectral profile of a reference track whose spectral profile you admire.
The three main tools you can use for this are Ozone’s Reference panel, Ozone’s Match EQ module, and Tonal Balance Control.
Ozone has a built-in track referencing feature that can load, manage, and audition reference tracks without any additional set up in your DAW. Referencing in Ozone 9 helps you compare and contrast audio in your DAW by allowing you to import up to 10 reference tracks, visualize differences in your music with overlaid spectrum metering, and quickly A/B your audio right in the audition panel.
Access the Referencing panel by clicking on the Reference button below the I/O meters. Enable/Disable Referencing by clicking Reference’s power button.
With Ozone, you can match any reference track to an extreme degree with an EQ that uses over 8,000 separate bands of frequencies for very precise reference matching. So if there’s an EQ profile out there that you love, Ozone will learn it and let you transfer it onto the track that you’re working with.
To get started with Match EQ, make sure the reference track whose spectral profile you want to match is already loaded in your session.
Step 1: Open the referencing panel by clicking “Reference.” Load the song you want to capture and enable reference playback with the power button.
Step 2: Switch back to the Match EQ module, press play in your DAW, and press the “Capture” button to enable Ozone to extract the spectral profile of your reference. Try capturing the part of the song with the most energy. Once the spectrum settles, press Stop in the Reference capture panel, stop your DAW, and turn off the reference panel.
Step 3: Now you have to capture the spectrum of the track you’re working on. Go to a part of your track that is representative of the overall energy (like the chorus), press play in your DAW, and click on “Capture” in the “Apply to” section of the Reference panel. When the spectrum settles, press Stop in the Reference capture panel and stop your DAW.
In orange you have the spectral profile of your reference and in blue, you have the spectral profile of your track. The white line line represents the filter response of the matched curve.
There are two main parameters you’ll work with to make EQ moves to match your reference.
Smoothing: determines the amount of precision to apply to the matched curve. Higher smoothing is less precise. Lower smoothing is more precise.
Amount: Determines the amount of processing (intensity) to use when matching the Reference curve to the Apply To curve.
A Matched Curve amount of 100% and a Smoothing amount of 0% might be technically the closest match to your “reference” mix, but in reality it’s probably not the most effective combination of the settings. Those settings will try to capture every peak, valley, and level, which can result in extreme, unnatural EQs.
We suggest working with the Matched Curve amount under 50%. If your Matching EQ curve has narrow peaks and valleys, increase the Smoothing parameter to smooth them out. Your goal is to capture the overall tonal shape of the Reference as opposed to an exact match.
Another important feature in Match EQ are the cutoff handles. These can be useful when you want to concentrate on matching a particular region of the frequency spectrum. For example: apply the matched curve to the low end without affecting the high end.
Once you capture a reference from a track in your session, or a reference file loaded into Ozone, you can save your favorite results as presets for easy access.
Verify with Tonal Balance Control
To make sure you’re not overusing Match EQ, create a custom target in Tonal Balance Control. You can use the same track you used to create your reference snapshot preset in Match EQ, but the more tracks you feed Tonal Balance Control, the better it will be able to create a smooth average response. By using Match EQ and Tonal Balance Control in tandem, you give yourself both broad and detailed views of how your song’s spectral profile compares to that of your reference. If you notice your track having too much or too little of a particular frequency compared to your reference, you can address it by controlling Ozone’s EQ module directly from Tonal Balance Control.
Limiting is the final and perhaps most essential step in mastering a song. A limiter allows you to increase the overall level of your song to commercial loudness while ‘limiting’ the peaks from exceeding the clipping point of 0 dBfs.
There’s two limiters in Ozone, the Vintage Limiter and the Maximizer.
The vintage limiter in Ozone is modeled after the Farichild 670 and comes with three different modes: Analog for a tight bass response, Tube for a smooth feedback limiter with modern precision, and Modern for increased clarity and presence.
Ozone’s acclaimed IRC (Intelligent Release Control) technology lets you boost the overall level of your mixes without sacrificing dynamics and clarity.
Setting up a limiter
The main parameters you’ll be working with:
- Ceiling: The level your audio signal can’t exceed. In practice, you want your ceiling to stay below 0 dBFS to prevent any digital clipping. Begin by setting your ceiling before tweaking other settings. It is generally recommended to use a setting of -0.3 dB when dithering, or a more dramatic setting (-0.6 dB to -0.8 dB) when mastering audio to be converted to .mp3 or .aac later, in order to prevent clipping in the future.
- Input Gain: the amount of gain you’re feeding into the limiter. The more gain, the more gain reduction, and the louder your song will be. Start by slowly increasing the input gain until you reach your desired level
- Threshold: The level at which the audio signal gets compressed by the limiter. The appropriate range for the Threshold depends on the levels of your mix. For a subtle bit of limiting, bring the Threshold down to the level where just the highest peaks are being processed.
- Gain reduction meter: shows the amount of gain reduction applied to peaks that exceed the threshold. You’ll notice you need around 1 to 5 dB of gain reduction on the master bus to reach your target level.
- Transient Emphasis: preserves transients while optimizing loudness. Enable Transient Emphasis adjustment by clicking the Transient Emphasis power button. Adjusting the Amount control allows you to fine-tune the shaping of transients before limiting takes place.
Start Mastering With Ozone
Whether you’re a pro mastering engineer or mastering your own track for the first time, mastering can be a complex process––but it doesn’t need to be. Hopefully the intelligent tools and ways to use them outlined above offer some guidance on an initial mastering workflow. Please be sure to check out more articles about audio mastering for more helpful techniques.
BONUS: Learn how to get wider mixes in Ozone in the video below.