ISL 2 True Peak Limiter by NUGEN Review

  • By: Thorsten Meyer
  • Date: Thursday, 27 January 2022
  • Time to read: 5 min.

The ISL 2 True Peak Limiter is a simple plugin that can be used on individual channels or on busses. It has the ability to add loudness and punch to tracks, while protecting them from clipping. Its interface offers three modes of operation: Gain, Limit and Loudness. Each mode offers the user different options for processing.

ISL 2 True Peak Limiter by NUGEN Review

ISL 2 is on the review table today, NUGEN tools are used by professionals in countless studios and production houses. As there are many professional limiters to select from when you deliver the final mix. I did use ISL 2 in the past two months to learn more about its features and to prepare this review.

I can tell you early that there is not a clear winner and that you would need more than one limiter to work in the professional space as you want to be able to select the result that sounds best to your customers. ISL 2 is one of the tools you need to have in your toolbox. NUGEN did send a review copy with no strings attached.


The plugins work as AAX, VST, VST3, AU, and AudioSuite. The AAX DSP version supports 7.1 audio up to 48Khz and 4 channels at 96kHz.


ISL 2 is an essential investment if you are a mixing or mastering engineer, you need another limiter besides it to have options available, I would recommend a combination of FabFilter’s Pro L2 and ISL 2 by NUGEN.

ISL 2 True Peak Limiter in FL Studio

NUGEN’s ISL2 is an inter-sample true-peak Limiter and follows many of the ITU. The sound quality of ISL2 is honest. One of the key features of this tool is its transparent look-ahead limiting. Features like it prevent further distortion that could be introduced by compression and audio codecs. ISL2 can not only prevent inter-sample clipping, but it also restores the original quality of the audio signal. I would recommend ISL2 to anyone working with content that could benefit from a true peak limiter.

ISL 2 True Peak Limiter Small UI

ISL 2 should be used as final limiter just before tools like MasterCheck Pro, the tool also works as a broadcast limiter. The limiter works for scores ranging from mono through 7.1 surrounds mixes. It is compatible with ITU-R BS. 1770.

ISL 2 Modes

ISL 2 gives the user three different modes to choose from depending on how they want their track to sound. The three modes are Gain, Limit, and Loudness. A description of each mode is as follows:

  • Gain mode allows users to adjust peak reduction without adding loudness.
  • Limit mode offers the ability for further peak reduction and the option of adding subtle loudness.
  • Loudness mode is very similar to Limit mode, but it offers more options for fine tuning output levels.-It’s important to note that ISL 2 always processes audio according to its current sampling rate and bit depth.

Gain Mode

The Gain Mode allows users to adjust peak reduction without adding loudness. In Gain mode, the user can adjust Threshold, Ratio, and Output Gain controls. The Threshold control sets where the reduction will begin.

The Ratio control determines how much gain is reduced from the signal once it crosses over this threshold point. Reducing gain at a 2:1 ratio means that for every 2 decibels of input end gain, the output signal will lose 1 decibel of gain. For example: If the input level is at 0dB and goes up 3dB, it will only go up by 1dB after passing through this plugin. This mode offers the user a quick way to attenuate peaks without making any other adjustments, but it doesn’t add loudness.

Limit Mode

The Limit Mode offers the ability for further peak reduction and the option of adding subtle loudness. This mode gives users variable true peak limiting, with additional options for adjusting processing behavior. The Threshold control sets where the gain reduction begins.

The Ratio control determines how much gain is reduced from the signal once it crosses over this threshold point. Upper and lower threshold controls allow users to set different loudness targets for the upper and lower signal levels. The Output Gain control allows users to adjust overall output gain on a per-channel basis without changing the dynamic behavior of the limiter. This mode also provides two additional meters: one that displays true peak levels and another that shows how much limiting.

Brings Music to Life

The ISL 2 used correctly can improve the audio quality of anyone who has access to this plugin. It can also bring music more to life in video game design, it works excellent on cinematic scores, and its threshold is perfect for use with dialog. However, I do not recommend using this tool for any source with frequencies lower than 100Hzes

  • Dialog
  • Mixing & Mastering
  • Cinematic scores
  • Video game design

If you are mixing, mastering, or even doing some video game design you need another limiter besides it to have options available. I would recommend a combination of FabFilter’s Pro L2 and ISL 2 True Peak Limiter.

ISL 2 can be used as a true peak limiter and it is easy to use. It has only the necessary parameters, and one will need less than 5 minutes to understand how this plugin works. That makes it perfect for beginners or people that want a quick solution to their loudness problem.

User interface & Usability

When it comes to presets NUGEN did include the ones to cover all the standard industry ones you need to deliver against for the different platforms,  broadcast, and even the good old DVD mastering.

ISL 2 True Peak Limiter Presets

The UI has the NUGEN standard professional look and feels that is geared towards results. There is also a small UI available to reduce the real estate used by the plugin.


The ISL 2 True Peak Limiter by NUGEN is an excellent tool for anyone who wants to improve their audio quality. This plugin is easy to use, and it offers a variety of options for peak reduction and loudness. The ISL 2 is perfect for mixing, mastering, or video game design.

Pros & Cons

+ Easy to use

+ Great preset library

+ UI is clean and intuitive

+ Good value for the price

– It has a very good tool, and the price is much lower than a lot of other plugins for this job. However, it may not be powerful enough to meet all your needs at once, so you will need another one as well to use alongside it.

ISL 2 True Peak Limiter UI

Rating:  Five out of five stars

ISL 2 True Peak Limiter by NUGEN is a look-ahead brick-wall limiter that helps you to prepare your mono,  stereo and surround mixes for various streaming platforms or when you deliver scores to picture. Even in the YouTube days you need and should add a limiter at the end of your chain before you load up a new video to Google’s sharing platform.

ISL 2 sits as the final limiter on a master bus it is perfect for broadcast and post-production. Combine this limiter with tools like MasterCheck Pro and you are ready to enter and compete in the loudness wars.

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