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UDO Audio Super 6

Polyphonic Synthesizer By Rory Dow
Published December 2020

UDO Audio Super 6

UDO Audio’s highly anticipated debut instrument is a synthesizer with a sound all of its own.

Anticipation for the Super 6 was palpable after its announcement at Superbooth 2019. It may be UDO’s first product but designer and company co‑founder George Hearn is not new to the industry, having previously been involved in the design of the Modal Electronics 008. Nevertheless, a flagship, 12‑voice polyphonic, binaural, analogue‑hybrid synthesizer is an audacious entrance for a start‑up company.

The Super 6 is designed with a firm philosophy. There are no screens and no menus. There is, mostly at least, a one‑knob‑per‑function design. It doesn’t do multitimbrality or have a software editor and it won’t connect to the internet. The design is proudly old school and more than a little inspired by early‑’80s Roland synthesizers like the Jupiter 6, with lots of vertical faders, tri‑position switches and clicky retro‑buttons.

The sound engine, however, is more modern. While it still follows many of the subtractive synthesis norms, there are a couple of headline features. The first is ‘binaural’ mode. Under the hood, the Super 6 has a true stereo signal path. When binaural mode is enabled, the 12 voices are paired to form six true stereo voices. Left and right signals get processed independently and this results in a wide, spacious, almost ‘record‑ready’ sound.

The second clear innovation is found in the two FPGA‑based oscillators. FPGA is fast becoming the norm in digital synthesis and replaces traditional DSP chips, which were often restricted to clock speeds of 48 or 96 kHz. FPGA can run clock speeds at magnitudes faster than these old chips, which means that the telltale aliasing heard in older digital synths is a thing of the past, even when performing complex audio‑rate frequency modulation. In short, these are digital oscillators with all the clarity and depth of analogue ones, and none of the instability.

In essence, the Super 6 represents a modern take on a classic polysynth format. There are two oscillators, two filters, two envelopes, two LFOs, a delay, chorus, arpeggiator and sequencer. There are presets too and even a mod‑matrix, but largely UDO have focused their modernisations on aspects that improve the sound.

Super Good Looks

The Super 6 is available in two colours; the blue exudes a casual demeanour, whereas the black (more of a medium grey in person) feels more business‑like. The 49‑key Fatar keybed transmits velocity and aftertouch and has a lightweight synth action with no annoying clacking sounds. The keys do overhang the main body by about a centimetre, so if you’re moving the keyboard a lot, you’ll need to take extra care not to chip or snap them. For playability, I think this might rank amongst the best synth‑action keybeds I’ve used. I’m less convinced by the combined modulation and pitchbend stick. It is of a similar design to those found in the Roland Juno series. The mod ‘wheel’ has a travel of just a few millimetres and is spring loaded, which means it has to be held in place to be active. Unlike the Roland versions which I’ve played (my SH‑101 has the same design), the resistance feels quite stiff. Occasionally the force needed to apply modulation would cause the stick to fly sideways, applying pitchbend when I didn’t want it. I’m sure, over time, the spring would relax and my playing technique would adapt, but I would have definitely preferred two wheels.

The Super 6 is also available in black (grey); appropriate for more formal settings.The Super 6 is also available in black (grey); appropriate for more formal settings.

The general layout of the front panel is logical and very well labelled. The raised top half of the panel is home to most synthesis parameters. The bottom half contains the voice setup, arpeggiator/sequencer, mod matrix, patch storage, and effects. The section above the pitch and modulation stick is home to LFO2 and routing options as well as portamento, the keyboard transpose switch and the ‘manual’ button. The manual button switches the Super 6 into a what‑you‑see‑is‑what‑you‑get mode where all the front panel control values are used at their current position; invaluable for learning, or for anyone who thinks patch storage is for wimps.

For everyone else, there are 128 patch storage slots, in 16 banks of eight. These are accessed with the two rows of white/black buttons found just above the keyboard. These buttons are also used for a multitude of other functions such as mod matrix, oscillator waveform selection, sequencer programming and a few setup options. By default, the synth comes loaded with 64 sounds, the second 64 are left empty for you to fill. Whilst 128 sounds doesn’t seem overly generous by the standards of many other modern synths, I think it’s fine. The Super 6 is a synth you’ll want to spend time actually programming, not browsing through thousands of presets. The lack of any screen does make finding specific presets a challenge, though, so anyone relying on presets to recall sounds for a gig will need either a good memory or a notebook and pen.

The star of the show has to be Binaural mode which, along with the buttery smooth DDS oscillators and the high‑class effects, helps to create a record‑ready sound.

Binaurally Yours

Normally, one might move to explaining the oscillators or some other synthesis parameters at this point in the review, but let’s take a small detour to look at Binaural mode. This is such an integral part of the Super 6 that it is worth understanding upfront.

With Binaural mode on, the synth is always processing in stereo. Each oscillator will produce two or more waveforms per voice, each of which travels down its own signal path, through separate twin filters, amplifiers and on to the stereo effects. On its own, this can create a subtle stereo image because the filter and amplifier stages are analogue, so each side of the stereo field comes out slightly different. More pronounced stereo sounds can be made by using Oscillator 1 in ‘Super’ mode, which creates unison sounds by adding six additional copies of the oscillator, detuning and panning them (Super mode is also where the synth gets its name). Furthermore, LFO1 can work in a stereo mode where left and right sides are phase‑shifted relative to each other and applied to the left and right signal paths separately. When you apply this to, for example, pitch or filter cutoff, the stereo image opens up even further.

In order to achieve Binaural mode each note needs two voices, which halves the total voice count to six. In mono modes, Binaural mode is always active. For a more detailed rundown of the various mono and poly modes, see the ‘Voice Assign’ box.


UDO describe the Super 6’s oscillators as DDS — Direct Digital Synthesis. Oscillator 1 (DDS1) offers ‘Super’ mode, which gives you six additional unison voices at the oscillator level. Waveforms include sine, sawtooth, square, triangle, noise or one of 16 single‑cycle waveforms, selected using the 16 patch buttons. These are not wavetables, more’s the pity, but single static waveforms. The Range control allows you to change the octave of the oscillator through six different octaves.

DDS2, the second oscillator, has no Super mode, but offers some different features instead. The same waveforms are available with the exception of the 16 single‑cycle waveforms, which are replaced by a square wave with pulse‑width modulation. There is an additional tuning control which offers +/‑6 semitones. Again, a Range control offers octave‑switching, but the lowest octave is replaced by an LFO mode, where the oscillator is tuned down to subsonic levels and can be used to modulate other parameters using the modulation matrix. LFO mode can also be replaced by a sub oscillator mode which outputs a phase‑locked square wave one octave below DDS1.

The ‘DDS Modulator’ section offers dedicated controls for oscillator modulation. A common theme here, and in many sections of the front panel, are the tri‑position switches which allow you to select a modulation source or destination for the associated slider. It’s worth remembering that you can use the modulation matrix for more esoteric modulations, but these dedicated controls offer a quick way to adjust commonly used modulations. The two left‑most sliders in the DDS Modulator section adjust oscillator pitch with LFO1 and Envelope 1 and there’s a switch to choose between destinations of either or both oscillators.

The Super 6’s panel design — classic with some distinctly modern touches — seems to sum up the whole ethos of the instrument.The Super 6’s panel design — classic with some distinctly modern touches — seems to sum up the whole ethos of the instrument.

Moving to the right we find controls for DDS1 Super Mode. Another switch offers off, half or full mode. Full mode means all six additional oscillator unison voices are at equal volume and half mode means the six voices taper off in volume, giving the central voice more presence. There are sliders for detune amount and modulation amount (from either Envelope 1, LFO1 or both). These two sliders also function as PWM controls for DDS2, with the Detune slider controlling Pulse Width and the modulation slider controlling Pulse Width Modulation. It’s a shame that these features had to share controls because it means that you cannot combine DDS1’s Super features with DDS2’s PWM without controlling them both simultaneously. Happily, this seems to be the only place on the front panel where physical controls are shared in this way.

Another nod to those classic ’80s synths is Cross Mod. This offers exponential FM where DDS2 modulates DDS1. This is real FM, as opposed to Yamaha’s DX‑style FM (which is actually phase modulation), and that means that the pitch of DDS1 will move as more FM is applied, which can be annoying. At the moment, there is no preset‑level tuning that can be used to counter this tuning drift, so it’s difficult to use cross mod to alter the timbre of a melodic sound without the whole patch ending up out of tune. The folks at UDO acknowledge this and are considering solutions, so fingers crossed this might be solved in a future firmware update. Nonetheless, Cross Mod is a fantastic source of harsher, clangourous, metallic and inharmonic sounds, plus it can be modulated via the modulation matrix.

The mixer section is quite straightforward. A single knob, by default, adjusts the mix between the two oscillators. It can be switched into a couple of other modes. First is a crossfade mode, which crossfades the two oscillators over a two octave range — DDS1 will play on the left side of the keyboard, and DDS2 on the right, with the crossfade midpoint being moved by the Mix knob. The third Mixer mode is Sync, which forces DDS2 to hard‑sync to DDS1. Sync sounds great, and I found some beautifully monstrous sounds by combining Sync, Unison and Cross Mod together.

Filters & Envelopes

The filter is an analogue, four‑pole 24dB‑per‑octave, low‑pass filter from SSI (Sound Semiconductor). These filter chips are new versions of the SSM2044 chip, designed by Dave Rossum and used in classics like the PPG Wave 2.3, Korg Polysix and Emu SP1200. It is an excellent‑sounding filter with a sharp but stable resonance. It does lose quite a lot of bottom end when pushing the resonance up, but you can use the Filter drive to combat this. The Drive has three settings which overdrive the signal going into the filter by varying degrees. My favourite was the middle position, which mitigated any bass loss due to resonance without losing too much of the resonance character.

There is also a high‑pass filter. It has just one control on the front panel, which switches between off, fixed (at 500Hz) or tracking. When tracking, the high‑pass will track the low‑pass cutoff frequency, effectively turning the low‑pass into a fixed bandwidth band‑pass filter. The 500Hz fixed option is useful for removing muddy low end on patches where it’s less desirable.

A few more front panel controls round off the filter section, with dedicated switches for key‑tracking (off, half and on) and modulation sliders for envelope, LFO1 and DDS2. The audio‑rate modulation of filter frequency from Oscillator 2, I must say, sounds fantastic.

The Filter section flows into the VCA section. There is an envelope level slider, which can be used to overdrive the VCA at its higher position. For amp level, there are options to use either Envelope 2 (the default amp envelope), or a simple gate, or a third option which I like a lot, a gate with release time of around 2 seconds. The latter two settings are useful for freeing up Envelope 2 for other uses. There’s also a switch for enabling velocity sensitivity (off, half or full) and a dedicated slider for LFO modulation of amplitude.