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Keepforest – AizerX Trailer SFX Designer Toolkit (Review)

keepforest aizer x trailer sfx designer

With their new AizerX line of products, Keepforest presents two collections of cutting-edge cinematic sound design toolkits powered by a sample engine that is built around layering and randomization. The AizerX Trailer SFX Designer Toolkit was created for trailer music producers and editors who want to come up with powerful and complex sound effects fast and easily.

After releasing their first two very successful trailer sound design libraries Evolution: Dragon and Evolution: Atlantica, Keepforest decided to open up new sonic possibilites by designing their own, brand-new sample layering engine: AizerX.

AizerX Trailer SFX Designer Toolkit focuses on the impressive, earth-shaking sound design you can hear all over today’s movie and video game trailers. The library contains a huge number of hybrid sound design elements like impacts, whooshes, risers and transitions. Centerpiece of the product is the brand’s newly designed AizerX engine, which allows for comprehensive layering and customization options. The large amount of samples paired with Keepforest’s new layering engine leads to literally endless combinations of expressive sound effects.

We were given a review copy of Keepforest’s AizerX Trailer SFX Designer Toolkit and want to check out together with you which sonic possibilites the library has to offer.


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AizerX Trailer SFX Designer Toolkit is a sample library for Native Instruments’ KONTAKT sampler. The product comes with roughly 4.1GB of samples and well over 1,000 sound design elements which can be layered and randomized using the new AizerX engine. Here’s a quick rundown of the library’s most important facts:

  • Trailer SFX creation toolkit
  • Powerful 6-layer sound design engine “AizerX”
  • Almost 1,200 individual sound design elements
  • 4.1 GB of samples
  • 12 categories of cinematic sound effects (Hits, Whooshes, Braaams, Transitions, etc.)
  • over 40 pre-configured preset banks
  • Comprehensive customization possibilites
  • Literally unlimited randomization options
  • Full version of KONTAKT 5.7.3 and above required


The heart and centerpiece of both the Trailer SFX Designer Toolkit and the Modern Designer Toolkit is their sophisticated AizerX engine. In essence, this engine offers 6 sample slots that can be loaded with any of the library’s 1,200 sound design elements. By layering, filtering and modulating the samples, you can generate unique and complex sound effects with just a few clicks. Let’s have a more detailed look at Keepforest’s new AizerX engine:

keepforest aizer x trailer sfx designer toolkit interface
AizerX Trailer SFX Designer Toolkit Interface

The 6 sample slots can be found on the left and right side of the interface. Although you can load any of the sound pool’s samples into any slot desired, there’s a certain structure the engine was designed for. The bottom left and bottom right represent the core parts of any sound. They are used to load up a pre-whoosh or lead-in sample (left side) and a hit or impact sample (right side). To spice up and customize this whoosh-hit combo, you can load more sounds into the four upper slots (labeled A,B,C & D). This allows you to create not only complex trailer hits, but also interesting transitions and motions. Most of the library’s preset banks are configured this exact way.

Sounds you create are linked to a pair of keys in the range between C3-B4. One of the keys plays back the whole Whoosh-Hit while the other one triggers just the impact portion of the sound, without the lead-in. The key switches located at the lower range of the keyboard allow you to change the root key of the tonal samples you loaded.

keepforest aizer x trailer sfx designer keyboard layout
AizerX Trailer SFX Designer Keyboard Layout

Each sample slot has its own controls for volume, tuning and filtering of the sample loaded. To further customize and modulate a sound, the sample slots also offer individual access to their own LFOs and ADSR envelopes.


The big square in the middle of the interface represents AizerX’s XY pad. Its corners represent the four sample slots A, B, C and D. By moving the XY pad’s cursor towards any of the four edges, you increase the volume of that sample slot and turn down the other three modules respectively. Moving the cursor around therefore fades between the four sound layers which can add a sense of movement and interest to an otherwise static sound. Many of the libaries presets come with an automated XY control. You can however record and play back your own XY movements if you want to.


At the bottom of the interface, you can find AizerX’s Global Menu which shows you a timeline of your samples. Here you can change the start points of the samples you loaded into slots A-D, allowing you to create cascading sound effects.

keepforest aizer x trailer sfx designer toolkit global menu
AizerX Trailer SFX Designer Global Menu


By clicking on the Mixer tab just below the interface’s XY Pad you are directed to the engines 6-channel mixer, which lets you adjust the volume of each sample module. Every slot can also be processed with up to 8 slots of internal FX like EQ, compression, distortion, reverb, etc.

keepforest aizer x trailer sfx designer toolkit mixer
AizerX Trailer SFX Designer Mixer

There’s also a dedicated FX Rack providing the same kind of FX but on a global level. These effects can be modulated and animated on the same tab by four dedicated LFOs and sequencers each.

keepforest aizer x trailer sfx designer toolkit fx rack
AizerX Trailer SFX Designer FX Rack


As you may have seen, Keepforest’s AizerX engine provides you with a plethora of layering and customization options, which might as well be the wet dream of every sound designer. However, in reality there are two sides of the same coin. The huge amount of controls and features leads to a rather steep learning curve and a somewhat cluttered interface. I found it a bit hard to get my head around all the available routes and functions and I can’t say I’ve discovered them all yet. Of course, I’m also notoriously ignorant to manuals, so if you take the time to have a look at it, you might even get along quicker than I did. For someone who is in the midst of a pressing project however, getting to know the engine quickly might turn out quite frustrating.

keepforest aizer x trailer sfx designer toolkit wav samples
All the library’s samples are also available as individual WAV files.

The good side of all of this is that you are by no means bound to use the AizerX engine. All of the samples are available as individual WAV files, too. So if you’re more into working with audio files, this is probably your way to go. As far as I understand, the engine is designed more as a tool to help you design your sounds more quickly and in one place. If you take the time and effort to learn the interface’s most important functions, you’re able to create oustanding sound effects very quickly.


Not only does the Trailer SFX Designer Toolkit offer a ton of versatile sound design elements, most of them are also very well-crafted and -produced. The percussive hits sound fat and punchy and the tonal elements cover a broad emotinal range from ethereal to downright disturbing. The majority of samples just sounds “ready” – allowing you to work them into your tracks without any additional processing needed.

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AizerX Trailer SFX Designer Toolkit Audio Demos

One of the absolute strenghts of the Trailer SFX Designer is the ease of creating so-called Signature Sounds. This is a term referring to recognizable and characterizing sound elements in a trailer cue that can stand on their own. These Signature Sounds are a staple of today’s trailer music as they really help to discern one cue from another. With just a few clicks and sample combinations, you can create hundreds of unique, recognizable effects.

I’d also like to mention the generous collection of great sounding preset banks designed by Keepforest. These offer lots of terrific sounding material and could as well be all you need for a long time.

keepforest aizer x trailer sfx designer toolkit preset browser
AizerX Trailer SFX Designer Preset Browser


Keepforest’s AizerX Trailer SFX Designer Toolkit provides you with a comprehensive set of powerful cinematic sound elements used in today’s trailer music.

Making use of the AizerX engine’s layering capabilites, its various modulation options and FX processors, leads you to a literally endless amount of sound options you can generate from this library. If you’re willing to make the effort to learn how to use the feature-packed engine, you’re able to create unique and recognizable sounds with just a few clicks.

If you’re a trailer music composer or editor looking for a way to quickly incorporate cinematic sound design into your cue, this library really is a safe bet.

Keepforest’s AizerX Trailer SFX Designer Toolkit is available on Best Service or the company’s own web store and sells for $399.


On occasion of Keepforest’s last product release, we had the chance to talk to Evgeny Emelyanov: co-founder and lead sound designer at Keepforest. In our 2017 interview, we had a chat about sound design, sampling and how to create your own, cutting-edge trailer sound effects.



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