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Sonible Smart:Limit – A Real-World Review

Reviewer Mike Levine finds that Smart:Limit, Sonible has created a powerful plug-in that will simplify the workflow of audio pros everywhere.

Sonible Smart:Limit
Sonible Smart:Limit

Sonible has quietly become one of the leading developers of intelligent music production software, having previously released several impressive AI-powered plug-ins, including Smart:Comp, Smart:EQ and Smart:Reverb, among others.

The latest, Smart:Limit (Mac/Win), may just be the best yet. It has a deep feature set, but the design makes it easy to set a song’s audio level and dynamic range to meet the standards for major streaming music sites, broadcast outlets and more.

Most likely, you’d use Smart:Limit at the end of a mastering chain, but you could also put it on your mix bus if you’re self-mastering.


Considering how many controls, meters and displays are included, Sonible did an admirable job of user-interface design. Still, there’s a lot to look at in a relatively small space. Fortunately, you can freely enlarge the GUI up to about 35 percent.

The waveform display occupies the largest section, containing controls for the amount of limiting and input gain, marked by the horizontal white Limit and green Gain lines, which you can drag vertically to adjust. Above the Gain line are Attack and Release controls, with the option to choose Auto Release.

After analyzing your audio, Smart:Limit sets these parameters and others for you. To get the process going, you first choose a genre from a reasonably extensive list in a pull-down menu near the top left of the GUI. The category choices are based on the dynamic profiles Sonible created—presumably by incorporating machine learning-based analysis.

If you can’t find a category that fits your music, you have two choices. One is to select the Universal category. Alternatively, you can load your own track and Smart:Limit will use its dynamics as a reference. If you were mastering an album, for example, you could get the initial setting dialed in on one song, then load that as a reference for the others.

Next to the genre list is a green Record button, which you press with your music playing to initiate what Sonible calls the “learning process.” Using its intelligent features, the plug-in creates a custom setting based on an analysis of your audio and factoring in the genre choice you made (or your uploaded reference track). To get the most out of Smart:Limit, and to be able to access all of its adjustable parameters, it’s essential to go through the learning process, which only takes a few seconds.


Four of those parameters are controlled by dials in the Sound- Shaping Panel, located at the bottom of the waveform display. The first is called Style. It adjusts between hard- and soft-limiting. Changing its setting, says Sonible, is equivalent to switching sound-shaping algorithms in other limiters. Hard settings are less transparent but punchier, whereas soft does the opposite.

The Saturation dial creates more density when turned up. It increases the perceived loudness without affecting the True Peak level. On the far left, you can open a small window called Distortion Monitoring, which shows a waveform-style display to indicate the amount of distortion in your signal. If you see the inside of the waveform turn red, it indicates that you may be overdoing the added saturation or the amount of limiting.

It’s hard to describe what the Balance knob actually does. According to Sonible, it controls the “spectral polish” and can help with gluing a track. In my experiments, it sounded best when set somewhere in the middle range.

The final dial is the Bass Control, which offers subtle low-end enhancement and is worth playing around with once you get comfortable with all the functionality.

Smart:Limit makes it easy and convenient to store up to eight different settings, which Sonible calls “States.” Many plug-ins let you save one setting while trying another, but having eight gives a lot more freedom to experiment.

The plug-in offers even more helpful monitoring options. The Constant Gain feature matches the unprocessed and processed signal level so that you can compare them more accurately. The Delta button, when activated, lets you hear only the parts of the signal that the limiting process removes.


The Limiter’s control set is only part of Smart:Limit’s story. What makes it such a powerful plug-in is its Loudness Monitoring section (can be hidden), which helps you tailor the loudness of your music for specific Publishing Targets, available from a pull-down menu in the upper right of the meter area. Sonible sure managed to fit a lot of different meters and displays in this section. It’s a relatively small space and looks a bit jumbled visually, but there is a lot of helpful information.

Across the top are numerical readouts for Loudness (in LUFS), Loudness Range (in LU) and Dynamics (in dB). Sonible defines the latter as “the average difference between the peak level and shortterm loudness.” The Dynamics readings help you avoid limiter settings that overly reduce a song’s dynamic range. Just above the readouts are controls for choosing between Integrated, Short-Term and Momentary readings, and resetting the meters.

Unlike many Loudness Meters, you don’t have to reset each time you change a parameter. Smart:Limit features what Sonible terms “Instant Impact Prediction,” which means its meters reflect parameter changes in real-time.

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On the far right are numeric readouts for Gain Reduction and True Peak. Both sit above bar graph meters of matching type. At the bottom of the True Peak meter is a numeric control for Output Gain, which you can pull down to reduce the output level.

The rest of the visual metering includes a vertical, color-coded bar graph-style loudness meter that’s calibrated based on the chosen Publishing Target. The part of the meter in the target range lights up green, while the part below it is gray. If you overshoot your target range, that portion of the meter lights up yellow, then red, as you go further above the target.

Dynamics are displayed in a horizontal bar graph meter at the bottom of the screen. Just above that is a histogram that shows the Dynamics over time.

The Loudness and Dynamics Crosshairs provides another means of checking whether your song is in range of your loudness target. You’ll see a moving “x” for Loudness and another for Dynamics. When both are inside the crosshairs, you’ve met the target’s requirements.


Quality Check is yet another feature for ensuring that your loudness is compliant with the chosen Publishing Target. Once you have a limiter setting that you like, press the Quality Check button and hit Play on your DAW’s transport. See if you’re in range.

Dialog boxes will open for peak level, dynamics and output gain, and Smart:Limit takes only a couple of seconds to calculate the results. If an adjustment is needed, the plug-in advises you on how to change the settings. For example: “Raise the input gain to increase the loudness,” or, “The peak level is too loud for tracks on Spotify. Reduce the limit to -1 dB.”

There were a couple of occasions where the calculation went on and on without returning results. When that happened, I removed the plug-in from the session and reopened it, and then it worked fine.

I experimented with Smart:Limit on various finished mixes and found it easy to get good results. The intelligent settings were consistently useful, and the plentiful monitoring and metering features made it easy to meet the requirements of whichever Publishing Target I was aiming for.

I loved Smart:Limit’s States feature, which allowed me to compare multiple approaches for each song. I also liked being able to upload tracks to use as Dynamics profiles. Finally, I was surprised and pleased by the price. I expected a product with these capabilities to be more expensive.

With Smart:Limit, Sonible has created a powerful plug-in that will simplify the workflow of mastering engineers, post-production engineers and music producers.