In This Issue
u-he Zebra3 – the Synth and Software Review
The latest version of the famous modular synth with no patch cables, combining wavetable/additive hybrid oscillators, FM, physical modeling… and that’s for openers
2026 is a good year for amazing new high-end synthesizer software. I could rattle off a list of five or six instruments that have been updated recently, and each of them has its own claims to fame, but it’s safe to say Zebra3 has two or three features that are going to leave the competition scrambling to catch up.
Zebra3 has been in development for a long time: Zebra2 was released back in 2017. I’ve used Zebra2 a lot. It’s a fine instrument. At first glance, Zebra3 looks quite a lot like Zebra2, to the point where you may be thinking, “Hey, looks like they just added a few features and tacked on a new number.” Foolish mortal, be not quick to judge! Zebra3 is way deep. It’s packed with unexpected goodness. So this is going to be a long review. Buckle up.
Overview
Most likely you’ll want to check out the factory presets before you delve into the sound programming, so let’s start there. With more than 1,200 factory presets to check out in more than a dozen different categories, that process alone will lead you through days of pleasant surprises, and will quite likely inspire a few new songs. Studying the presets is a good idea, as some of them, especially in the three folders of loop presets, use synthesis techniques that are not at all obvious.
The browser lets you set up ten different lists of Favorites; you could use one for basses, one for pads, a couple for current projects, and so on. There’s no way to rename the Favorites lists, though; maybe in a future update.
Two limitations need to be noted at the outset. First, Zebra3 does not do sample playback in any form: It’s strictly a synthesizer. There is no plan to add sample playback, I’m told. I don’t see this as a problem, because Zebra3 has some amazing resources in sound design; it’s just something to be aware of when comparing this instrument to others.
Second, Zebra3 has no dedicated step sequencer or arpeggiator. You can set up pitch and rhythm sequences using the Mapper modules and multisegment envelopes, but while this opens up some possibilities you won’t find in a conventional step sequencer, creating the patch is a bit more labor-intensive than if all of the tools were in one place.
Like its predecessor, Zebra3 is a patchcordless modular. Some signal routings are set up using dropdown menus, and others by clicking and dragging from a row of sources along the bottom of the main window. The modulation routings then show up in the Matrix panel, and a small dial for controlling the mod amount appears next to the knob you’re modulating. There’s no practical limit to the number of mod routings you can set up.
The number of modules of each type is fixed: four filters, four LFOs, four math modules, and so on. If four LFOs seems like not quite enough for complex patches, don’t fret: the multisegment envelopes can loop, and the math modules can run as LFOs.
Four signal paths are arrayed vertically in the central panel. These can be entirely independent, each with its own panning, amplitude envelope, and so on, but some of the audio modules have two or more inputs, so they can receive signals from modules in other columns. The control panels of audio modules show up in the left panel, the panels of modulation sources in the right panel. Once you understand how it’s set up, this whole system is quite easy to navigate.
The user interface is studded with convenience features: big editor windows, meters for monitoring the audio output or any modulation signal, and so on.
While auditioning the presets, be sure to try using MIDI control inputs A through D, not just the mod wheel. Most of the presets are set up to do things in response to these controllers, either for real-time expression or for subtly modifying the sound to suit your mix. You’ll be able to see at a glance whether the controls are active. To set your own preferred CCs, you’ll need to go to the upper right corner and click on the gear wheel followed by the wrench. This is a bit hidden, but it works. (Setting up the CC inputs in FL Studio requires a couple of extra steps, but this is not the place to go into that.)
Parameters can be locked. You can still edit a locked parameter manually, but it will retain its value when a new preset is selected. This is especially useful with the choice of microtuning tables, as it lets you audition various presets using the same tuning.
Oscillators
Zebra3 has three oscillator types: a wavetable/additive hybrid (four of them), FM (four), and physical modeling (two).
The basic oscillators are almost too feature-rich to be easily explained in a review, but let’s give it a try. A single oscillator can have from two to 16 different waveshapes, and a morph knob (modulatable from any mod source) allows you to scan through from one shape to another. You can edit the waveshapes graphically in a big editing window. Here you’ll find a variety of tools that makes oscillator editing look a bit like Photoshop. The documentation for the tools is not as thorough as it could be, but clicking on things and trying them got me oriented pretty quickly. A lot of thought clearly went into making this utility super-useful.
If you choose additive for an oscillator rather than wavetable, you have the same 16 waveshapes to work with, but the partials can be detuned in various ways. Beyond which, there are 20 different shaping effects, any two of which can be applied to the oscillator’s signal. This is a separate business from the FX section; there’s no connection between these effects and the audio processing effects.
Each FM oscillator has its own sine modulator built in, so you can easily do 2-operator FM with a single module. There’s also an external audio input, so stacking two FM modules or using something else as an input will be easy to set up. Both DX-style FM (which I believe is actually phase modulation) and through-zero FM are provided.
Even the two noise oscillators are more versatile than you might expect. There are nine different noise types and several internal envelope types, including multi-bump, which has three of its own knobs. Plenty here to explore.
The physical modeling setup adds a whole new sound palette to Zebra3’s tool kit. Each of the modal oscillators can use two different models (from among the 18 available choices, including such things as gong, hard tines, and chaotic bell) and blend between them. The position and decay knobs are also essential.
Zebra 3’s modal oscillator takes a brief input that is normally from an exciter module, where you can set parameters like stiffness, colour, bounce, and noise amount. The output can then be routed through a resonant comb filter, which can shift or distort it in various ways. A cautionary note: you don’t have to use an exciter as the input for the modal oscillator; you can use an ordinary oscillator. However, a continuous input will totally overload the model, resulting in a very loud sound!
Filters
It’s widely believed that the filter is the soul of a synthesizer, so it’s great to see Zebra3 offering a wide variety of filter models. The differences between some of them are subtle. They may sound the same until you turn the Drive knob, for instance. The screen shot shows the filter selector grid. Clicking on a button here will change the active filter to that type.
You can include up to four standard filters in your patch, plus two more in the effects section, plus four comb filters (more useful for physical modeling), plus two multiband equalizers. The standard filters have a second audio input, so they can be modulated at audio rate for various traditional filter sweep effects. The comb filters lack this second input, but they have some extra knobs for controlling things like damping, tone, and distortion.
The EQ modules can be switched to run as resonators instead, and they can track the note number (pitch) coming from the keyboard, exactly as a filter does. Running a basic sawtooth wave through this module can produce quite a variety of tone colors. The parameters of the various bands can be modulated, so really an EQ module can function nicely as an extra filter.
I was confused by the filter types labeled SVF in the selector grid. The state-variable filters I’ve seen in the past have a knob with which to blend between lowpass, bandpass, and highpass response on a single output, but the Zebra3 SVF filters simply don’t have such a knob. If you want that type of filter behavior, you’ll need to use one of the mixer modules and set up some type of modulation to suit your needs. And if you do that, you can use any filter module at all, not just the SVF models.
Envelopes
Going the extra mile, Zebra3 features four ADSR envelopes and also four multisegment envelopes. Both types have unexpected features.
The ADSRs can operate either normally (that is, with a sustain segment that remains for as long as the gate is high) or in one-shot mode. They don’t have parameters for segment curvature (you’ll need the multiseg envelopes for that), but they do have two Vary knobs, which allow you to set parameters like delay or hold time, key scaling, overall time-stretching, and a few other things. Best of all, they can be activated not by your MIDI notes but by any of the LFOs, mappers (more about mappers below), or several other sources.
The multisegment envelopes (MSEGs) lack the inputs for alternate trigger sources, but they have quite a lot of other features. As with the oscillator waveform editing, you can specify up to 16 entirely different envelope shapes and morph between them using a modulation input. In effect, this gives you a lot more than four MSEGs, as you could use a Mapper or an external MIDI signal to switch from one contour to another while the music plays. Each of the shapes can have its own loop start and end points within the contour.
LFOs
Do you crave an LFO that’s both synced to the DAW clock and not synced at the same time? Zebra3’s four LFOs will do that: The time base is always set in increments (eighth-note, quarter-note, whatever), but the Rate knob lets you deviate from that setting, and of course the rate knob can be modulated. The usual waveforms are on offer, but a Symmetry knob can reshape them. When the Spice knob is set to Wiggle and the Slew knob is turned up, a square wave acquires a bounce at the transition moments, as if the waveform were being sent through a resonant lowpass filter to make it “ring.”
Mappers
u-he has used mapping generators in a couple of their other synths. There was one in ACE and two in Bazille. Zebra3 has four. Each mapper can have from two to 128 steps, and there are several modes for choosing which step will be output, including external triggers and MIDI note number. Map tables can be edited manually or with commands like Soften, Invert, and Randomize.
The mappers can be used for various things. You could simulate the slight differences from note to note in filter cutoff or envelope decay time, thus emulating a vintage analog instrument. They can also be used as step sequencers, and with the aid of the Pitch page (see below), four oscillators can be playing four different step patterns. Bear in mind, though: the Mapper is not a dedicated step sequencer. Tied steps don’t seem to be possible. It’s possible to create a pattern with a few silent notes (rests), but you’ll have to be a certified ninja to get it working.
The Pitch Page
All synthesizers (well, most of them) have controls for pitch-bend depth, glide, and some sort of pitch envelope. Zebra 3 takes this concept in a radically new direction. For starters, there are four different pitch programming panels on the Pitch page, and each oscillator and filter can be assigned to any of them. This makes it easy to do effects like having the pitch-bend wheel mutate a three-oscillator unison into a triad, for example.
Beyond this, you can set a pitch panel to a different amount of key tracking, a different transposition, a fixed pitch, a different type of glide (equal time vs. equal rate, for instance), and a different scale quantization. The quantization can be set to post-modulation, which lets you set up an LFO to give an oscillator a stepping pattern within your chosen scale.
You can have a pitch panel track the lowest or highest note in a chord, or the oldest note, and so on. When the Calibration parameter is set to Hypercalibrate and the amount is turned up, Zebra3 will adjust the pitches in a triad so as to fine-tune the pitches toward a perfect just intonation sound, with little or no beating. This doesn’t work with dominant 7th chords, but it sounds quite nice with triads.
Rather conspicuously missing from the Pitch panels is a keyboard zone setup. You can set up key zones by using a mapper to control the output amplitude of different signal paths, but that’s a bit of a workaround.
Other modules
The four Math modules are relatively simple devices for contouring control signals. Fifteen different modes of operation are available: sum, multiply, scale, crossfade, slew, and so on. They have two inputs, which are selected from dropdown menus. This type of device is very useful for tricks like crossfading between two different inputs for filter cutoff modulation.
If the oscillators themselves don’t give you enough resources for tone control (not likely, that) you can patch in two wavefolders, two distortion modules, and/or two ring modulators. One odd detail I noted: if an oscillator is set to use additive rendering and the starting phase is set to random, a wavefolder will produce a rather different timbre on each new note. I don’t know why this happens, but it’s cool.
The 4-in, 1-out mixer module can run in vector mode if desired, with its own loop settings to blend among the inputs and also X and Y modulation inputs. Here again, a lot of sound design possibilities open up.
Effects
Like the audio signal routing in the main voice signal path, the effects section has four parallel routings, each with six slots for effects. Thus it’s easy to set up patches with several different sound sources routed through their own effects. The modules here include two reverbs, a granular processor called TextureVerb, two delays, a more sophisticated 8-tap delay, four modulation effects that handle the chorus/flanging/phasing, a couple of filters, two each of equalizers, distortion, wavefolders, and ring modulators, and even some mixers so you can route signals from one lane to another.
Unlike a standard reverb, TextureVerb never responds immediately. It has to fill its buffer with audio input before it starts generating output. It can freeze its buffer in response to an input signal such as a MIDI control, so you could set up an endless wash of droning sound and solo over it using a different sound, all within one patch.
The verdict
Zebra3 will be a paradise for sound designers, whether they’re experienced or just eager to learn more. On the other hand, if you’re the kind of musician who just wants to play the presets and maybe once in a while edit the filter cutoff, this synth might be slightly less desirable, because the sheer number of possibilities in sound design could make it a bit harder to find the parameters you want to tweak. It’s not hard to find a filter cutoff knob, but you get the idea. Zebra3 is certainly not as hard to wrangle as UVI Falcon, but for the novice it won’t be exactly a stroll in the park. Even after a week exploring it, I’m still discovering things. Also, unlike Falcon and the Arturia Augmented synths, Zebra3 doesn’t have a convenient “easy parameters” page with four or five useful macro knobs. When it comes to customizing the presets, you’ll be tossed straight into the deep end of the pool.
I’m certain that as time goes on, Zebra3 will find an important place in my music production. And since I have a few dozen software synthesizers that I almost never touch, that qualifies as a firm recommendation. In spite of the quibbles mentioned in this review, it’s a terrific instrument.
Price: €249