Review: Krotos Audio Reformer Pro - Sound Designers Dream?

This unique tool for turning your own sounds into foley effects - and much more - is capable of some amazing things. Joe Albano put it to the test and here's what he discovered...  

Reformer Pro from Krotos is a plug-in that offers sound designers a way to perform effects and foley in realtime, for a more efficient and creative approach to the sometimes tedious task of sound design for video. But it can also be used for musical purposes, like adding interesting organic or electronic tones and noises to spice up, say, a musical beat. Reformer Pro is the latest iteration of the software—there’s also a free version, called simply Reformer, that lacks some features, and doesn’t provide full library access; for this piece I’ll be looking at the Pro version.

Krotos’ Reformer Pro

Krotos’ Reformer Pro

Reformer Pro comes with a modest set of libraries, including collections of animals noises, food-related sounds, different materials, and electronic boops and beeps. Krotos offers additional libraries for sale—these range widely in price—including many other types of sounds suitable for sound design and foley work. And there’s also a utility included, the Analysis Tool, to help users create their own sound libraries (more on that below).

What It Does

Reformer Pro basically takes a collection of audio files of related sounds/sound effects, which is loaded as a library, and allows them to be triggered—played, really—in realtime by an input signal. That signal can be a live mic, with the user making mouth sounds into it, or a virtual (or real) instrument audio signal, and there’s also a mode called Dynamic Input where the user can “play” the library sounds simply by moving sliders in the interface, which in turn can be MIDI-controlled or Automated to create a performance.

Initially, this may appear similar to what a traditional envelope follower does, but it’s much more advanced. Reformer Pro takes into account not only the dynamics of the input (trigger) signal, but also frequency. Each library has been analyzed to match the different samples in it to the varying level and frequency content of the input trigger signal. Now, this doesn’t mean it follows pitch—it doesn’t—but differing frequency content in the input will play different sounds in the library. So modulating the tone/pitch of your voice or playing different notes on an instrument—whichever you’re using as the input—won’t give you correspondingly pitched results from the sounds in the library, but it will vary those sounds. If the library is made up of a well-chosen group of related sounds, then you can manipulate them in realtime to generate a sound design performance. It's much more efficient and a lot more fun than cutting up bits of a sound effect library and positioning them on a timeline by the usual editing techniques.

A typical library collection

A typical library collection

Performing Sound Design

While it’s easy to get the plug-in up and running, it may take a little practice to master controlling the variations available in a particular library, but once you begin to understand how the software is translating your input trigger sounds into library sound effects, then it’s pretty easy to generate, say, a realtime foley performance. Here’s a very simple example, using one of the supplied factory libraries—Black Leopard Pro. I recorded myself making a series of simple mouth sounds into a mic feeding the input in Reformer Pro, triggering in realtime the collection of growls, chuffs, and roars assembled in that particular library. I quickly got used to manipulating that group of sounds, and it would have been very easy to match my performance up with video of a leopard (or any animal, for that matter), reacting to the visuals to create a convincing soundtrack on the fly.

The Black Leopard factory library “played” in realtime via a vocal mic

Once the input signal—the mic—was recorded, I could switch to a different library, like the included Bengal Tiger collection, and use the same “performance” to trigger that library instead.

The same input signal “playing” the Bengal Tiger factory library

For that matter I could use my recorded vocalizations to trigger any sound library—that might result in some surprising or unexpected results, but for situations where you’re not trying to match the audio to specific video, it can be a good way to come up with some interesting sound effects. My Black Leopard trigger track set to play a library of electronic noises produced what could sound like some weird but interesting robotic vocalizations.

The same input signal “playing” the Electronic Pro factory library

Basic Settings

But Reformer Pro has more to offer than just the ability to perform a single sound effect—in fact, you could do that with the free Reformer version. In addition to access to (and the inclusion of) more sound libraries, Reformer Pro lets the user load up to four libraries at the same time, and blend them dynamically via the XY pad in the plug-in window. This can also be done simultaneously in realtime, with the XY pads controlled by an external/MIDI signal, allowing for layering and crossfading between sounds, for much greater flexibility in playing sound effects.

Reformer Pro’s per-library controls

Reformer Pro’s per-library controls

There are four sets of per-library controls, including Response, which has a significant effect on the response time of the audio to the input signal, from slow to medium to fast attacks, depending on the library. There’s also a control for Playback Speed, which pitches the samples up or down tape-machine-style for even more variety, and finally there’s a Volume knob with independent control for each of the four libraries.

The Transient Controls tab accesses a new feature, the Transient Engine. This has user settings to optimize Reformer Pro’s response to sharp transient input signals. If you choose to use an input signal like a drum or percussion track or loop, you can improve the library’s handling of that kind of input signal. Since Reformer Pro is doing behind-the-scenes processing to ensure smooth transition between library elements, this is important to help it adapt to more percussive input signals, rather than, say, more typical mouth noises.

Reformer Pro’s Global controls

Reformer Pro’s Global controls

Global controls include Master Volume and a blend knob, to balance the input and library signals when appropriate. A Master Dynamics tab has controls for the built-in compression, which I found very useful to control the dynamic swings of the library effects, making them easier to “play”.

Above the Master section is the Visualizer, which displays information about the input and output audio signals.

The Visualizer display

The Visualizer display

The yellow outer ring indicates the frequency content of the output signal—the library sounds being played. The red middle ring shows the amplitude of that same output signal, and the orange inner ring shows the amplitude of the input signal from the live mic or audio track.

Dynamic Input

Besides playing Reformer Pro’s libraries from a live mic or audio recording, you can also perform sound design in realtime by moving the sliders in the Dynamic Input panel. This is accessed with a click on the little audio plug icon at the right.

The Dynamic Input control panel

The Dynamic Input control panel

The Amplitude slider at the top is the main control—when grabbed, sounds are triggered, just as they would be from an incoming audio signal: let go and the sound stops. Dragging this slider varies the effect, just as changes in level from an incoming mic signal would. Naturally, this can be controlled via MIDI—depending on the host DAW’s MIDI access features—and Automated to record the performance.

The Frequency and Bandwidth sliders let the user hone in on different elements of the library collection, based on frequency content of that particular library. Variation provides additional variety among the library sounds, and the Continuous button is good for libraries that lend themselves to the creation of sustaining, evolving textures.

Roll Your Own

The included Analysis Tool which pops up from a click on the button just to the left of the Dynamic Input button allows users to create their own libraries.

The Analysis Tool, for creating user libraries

The Analysis Tool, for creating user libraries

The process itself is simple—just select a collection of audio samples, let the application analyze them, and save the result. Of course, the real work is done in preparing the samples, and Krotos offers a set of guidelines to ensure that a group of samples will work well together, blending smoothly in performance—these include both instructions regarding technical aspects like sample length, sample rate and normalization, and suggestions on miking and content. Those who don’t have the time or inclination to create or adapt their own library material can always visit the Krotos website and choose from the large selection of libraries available there.

Final Word

Krotos’ Reformer Pro offers a new way to approach the post-production tasks of foley and sound design, as well as other creative possibilities for musicians and producers who want to add a little audio spice to their productions. I’m confident that once users get accustomed to and adept at performing their sound effects rather than utilizing the usual editing approaches, they won’t want to go back. For the curious there’s a fully-functional 10-day demo, which, like the full purchase, requires an iLok account, and this plug-in is well worth the time spent getting to know it.

Price: $399.99 via the Krotos website

Pros: Realtime performance of sound effects for foley, sound design, and other creative applications

Cons: Included sound library is a bit heavy on fruit & vegetable sound effects


Learn more about audio post production in the Ask.Audio Academy:

Joe is a musician, engineer, and producer in NYC. Over the years, as a small studio operator and freelance engineer, he's made recordings of all types from music & album production to v/o & post. He's also taught all aspects of recording and music technology at several NY audio schools, and has been writing articles for Recording magaz... Read More


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