U-He Zebra2 needs no introduction. For years, it has wiped the floor with competing softsynths. It was one of the first of its kind: a fully hybridized semi-modular workstation the likes of which no one had ever seen before, and was also one of the first to popularize wavetable synthesis, sporting a highly sophisticated wavescanning oscillator with unprecedented power and flexibility. In every way, shape and form, it represents the high standard of excellence by which its peers are measured.

Of course, I won’t argue that its sterling reputation is earned by way of its superior routing capability, but it also has a unique character all it own. Zebra2 sounds like no other; it has a fullness, a richness in detail no other instrument possesses. In the years to come, when its successors enjoy their time in the sun, Zebra2 will be remembered as one of “the classics” in very much the same way that vintage hardware synths are honored and sought after to this day.

The Review

Holding center stage is arguably the most powerful oscillator on the planet. Each of the four oscillators have a dedicated Wave Editor in the lower panel wherein you can choose between four Waveform Modes, allowing you to morph between drawable geometric shapes or any combination of harmonic partials, making it a very special kind of additive synthesizer… if you need it to be that.

Also, there are options for phase inversion / pulse width modulation, sync effects and up to eleven stacked unison voices available in the main oscillator panel, which includes a long list of spectral effects, altering the frequency spectrum in a myriad of ways. I highly suggest you become familiar with these effects and how they manipulate the “spectra” to produce awe-inspiring harmonic overtones.

Amidst a formidable arsenal of interchangeable modules are four additional FMO (frequency modulation) oscillators capable of modulating themselves or each other. Also, they can work in tandem with the regular oscillators if need be. The “Key Scale” envelopes in the lower FMO panel let you control each oscillator’s amplitude and velocity levels in accordance with MIDI note pitch. Also, there’s a context menu near the bottom of the screen providing access to a small handful of alternative modulator waveforms.

I was especially impressed by the Ring Modulators, which are surprisingly musical. Here, ring modulation functions a bit differently than usual. Instead of multiplying one signal by a stationary oscillator’s output, which is actually very common, two signals are multiplied by each other, outputting the sum and difference. I find this ideal for using ring modulation as a nice alternative to frequency modulation, scaling the resultant signal with a mod envelope for shimmering bell tones and chimes.

Another hidden gem is the Comb Filter, which is perfect for physical modelling synthesis and experimental atmospheres. It has seven modes optimized for many different purposes and dynamic characteristics such as a “Dissonant” algorithm with a special feedback delay network enabling you to create percussive drum sounds in a matter of seconds, and the “Tone”, “Flavour” and “Distort” knobs add tons of personality and charm when you modulate them with envelopes and LFOs.

Of course, I could go on forever about the filters, of which there are a copious supply. In fact, there are so many to choose from, for obvious reasons I cannot list them all in this review. But I can tell you there are some real hidden treasures, such as the “LP Vintage 2”, which is slightly more CPU intensive than the regular “LP Vintage” algorithm, plus it’s also capable of self-oscillation. What I love most about this filter is the way the “Drive” sounds, so big and warm. My scope indicates a good deal of “soft-clipping” when the filter input exceeds a threshold of -16dB.

The XMF (cross-modulation) filters are especially cool, even though they are substantially more CPU intensive, but they are well worth the hit when you consider just how flexible they are. What is meant by “cross-modulation” is that you can route a second input via the “SideChain” list in the drop-down menu when you right-click on the XMF cell in order to modulate the filter cutoff with a side-chain input from another lane in the Main Grid.

Both XMF inputs are equipped with a whopping fifteen filter Types and four routing configurations: Single, Serial, Parallel and Diff’ed, which is a misleading label. At first, I thought this meant “diffused”, but what is actually happening here is that the first filter Type is subtracted by the second Type. Of course, if both Types are the same, they will cancel each other out, but if they are different, you can produce some really interesting filter sweeps; and then you have five options for the filter’s overall Character: XMF, Analogue, Biased, Eco and Folded. I’ve yet to completely understand how some of these algorithms behave, but I can at least say that I have a newfound appreciation for advanced filter topology due to the diverse palette of sounds I’ve been able to coax out of a wide variety of filter combinations.

At the center of the Synthesis window, the Main Grid has four vertical lanes where all of Zebra’s modules interact with each other. Any combination of modules can be mixed together, routed to the Master Bus or to Bus 1 & 2 within the FX Grid in the Global section, which is exactly the same as the Main Grid, but with effects modules instead of oscillators and filter modules.

A veritable ocean of modulation sources are available in the Modulation Matrix or in the dropdown menu that appears when you click on definable controls indicated by an ellipsis (…) underneath the knob. One very special feature is the “Via” parameter next to the Target windows in the Modulation Matrix, allowing you to scale the depth of modulation by another modulation source.

Speaking of modulation sources, Zebra2 has four Envelopes, another four Multi-Stage Envelopes, six LFOs (two being Global), four Mod Mixers, four Mod Mappers and two rows of bipolar faders in the Arp/Seq panel labeled ArpMod and ArpMod2… and those are just the native modulation sources, not even counting things like keyfollow, MIDI note velocity, breath controllers, aftertouch, expression pedal, mod-wheel and pitch wheel. You can also assign parameters to the X and Y axis for each of the four performance controls.

In the Performance section, you have four XY Pads with two rows of vertical lanes with assignable target windows in the lower “XY” panel – but those are just the local assignments for one XY Pad! Assignments for the other three pads are accessible via the square buttons at the top left-hand corner of the XY panel.

We now have drag-and-drop modulation within the Mod Matrix and the XY panel, which is enormously helpful and very conducive for a hassle-free workflow. Just left-click and hold on any of the Target windows (a light blue cross-hairs symbol should appear) and drag your mouse cursor over the target parameter of your choice. Now, release your left mouse button. Boom. Done.

Both the Arpeggiator / Sequencer and the Multi-Stage Envelopes are a bit cumbersome when you first start using them. Fortunately, Howard Scarr wrote a thorough manual, so kick back with a cup of something hot, you’re going to be spending some quality time with each other. Remember, a big part of being a good synthesist is being a good manual reader. So, get used to it if you haven’t already.

The Verdict

I could go into further detail about each and every module, listing off various parameters and what they do, but that’s not what I want the focus of this review to be on. What I really want to call attention to is what makes Zebra2 so special and why you should invest your hard-earned money and precious time becoming familiar with it, especially since it’s been on the market for quite some time. While it’s not exactly a “hot new item”, it has a lasting quality that other instruments or in short supply of.

“Flexibility” is the first thing that springs to mind. There are other hybrid synths that take on similar tasks, but they usually skim the surface, not really getting elbow-deep into any particular synthesis type or technique. With exception of granular synthesis, Zebra2 can be whatever you want it to be. As a wavetable synth, it might not be able to scan entire audio files, but it has one of the only wavescanning oscillators allowing you to create your own wavetables on the fly; not only can you design your own waveforms in real time, but you can seamlessly morph between them as you go.

Zebra2 is also lots of fun… once you’re no longer intimidated by it. I actually had to pry myself away from it just to finish writing this review! But seriously, If you’re looking for a superior quality commercial softsynth that you really want to pour yourself into and build a career with… trust me… this is the one.

More info: U-He Zebra2 ($199)