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Waldorf Quantum

Polyphonic Synthesizer
By Gordon Reid

Waldorf Quantum

Waldorf's new flagship synthesizer is complex, versatile and hugely ambitious.

Waldorf are a company with a patchy history. They have released unfinished products — most notably the Wave and the Q — and they even went bankrupt in 2004 only to reappear two years later with much the same product line as before. But they nevertheless retain a reputation for designing interesting products and, while recent developments have tended to be smaller and lower cost, the company are now aiming high again. I must admit to having had some trepidation when I agreed to review the Quantum. Would it fulfil its promise, or would it shower me with 'this feature is not yet implemented' messages as one Waldorf flagship did in the past? Let's find out.

Although the Quantum appears to be a conventional eight-voice analogue/digital hybrid polysynth I can almost guarantee that you'll fail to get the best from it if you plunge in without researching its capabilities. It's not that it's arcane, but there's a great deal going on within it and the 'I never read manuals, it shrinks my testicles' brigade is going to suffer in comparison with players who take the time to understand it. But don't fret about this. Once I had learned the Quantum, I found it to be quick and straightforward to use. But why the concern? After all, the control panel reveals that it's just a three-oscillator-per-voice polysynth with a couple of filter sections, three LFOs, three contour generators, something called a 'Komplex Modulator', and three effects sections, right? Wrong. Very wrong.

The Oscillators

Each of the three oscillators can host your choice from four sound generation methods and, depending upon the method chosen, all of the LEDs associated with its knobs will light up in a different colour — cyan to denote a wavetable oscillator, green for a waveform (virtual analogue) oscillator, and so on. You can control seven of the most useful parameters for each oscillator type using the large, friendly knobs on the front panel, while many more are accessible from the large touch-sensitive screen. And, to ice the cake, you can even save and recall individual oscillator setups.

Perhaps because of Waldorf's long-standing relationship with wavetable synthesis, this is the first oscillator type offered. The Quantum includes 85 factory wavetables, and these are real, 128-stage wavetables that you can travel through in meaningful ways. You can select the table used, its pitch, key tracking and pan, the position and brightness of its spectral envelope, the amount of noise applied to the steps in the table, and whether any drive or gain is applied. You can also determine how you move through the table, how quickly, and whether the steps are interpolated for smooth timbral changes or stepped with various quantisations for grainy transitions. In addition to using things such as LFOs and contour generators to sweep through the table you can use MIDI note numbers to determine the playback position as well as the resulting sound's noise level and brilliance, so each key can have a different but related timbre from the next. You can also create your own wavetables, either by typing a phrase into the Quantum for text-to-speech-to-wavetable conversion, or by analysing an audio file held in its flash memory. The results can then be saved to the internal memory or to an SD card. (Unfortunately, it doesn't seem possible to give your own wavetables meaningful names, and any that you generate are just called User X, where 'X' is a number, which is going to be a problem once you've created a large library of them.) If you like the glassy, sometimes fragile sounds of the type pioneered by the earliest PPGs, or the evolving sounds at which wavetable synthesis can excel, you'll love this oscillator type.

The next is called Waveform, and this generates the classic analogue waves — sine, triangle, sawtooth and square, with additional white and pink noise options. A Warp function then shapes these into intermediate waveforms and adds things such as pulse-width modulation. However, its apparent simplicity hides several advanced features. One of these is Sync. Nothing special here you might think, but there is; the sync oscillator isn't one of the other oscillators, it's part of the oscillator that you're programming. Taking this concept even further, each oscillator offers up to eight 'kernels' that share the same waveform but can have independent pitches for kernels 1 to 4 (which are duplicated for kernels 5 to 8 if used) and independent positions in a stereo spread. To test this type, I started with a single oscillator and used it as the basis of a simple eight-voice, single-oscillator-per-voice polysynth. This placed me firmly in Juno‑60 territory. Sure, the sound wasn't the same, but experimentation yielded sounds that I would have been happy to substitute for a Juno. Adding the second and third oscillators and selecting appropriate filter types (which we'll come to presently) took me into the realms occupied by Prophets, Oberheims, Jupiters and the Memorymoog. Even with its unusual PitchVar (pitch variation) parameter, the Quantum didn't ever sound quite like any of those synthesizers, but this isn't a criticism; I programmed many two- and three-oscillator-per-voice patches that I would have been proud to use, and one would have to be an analogue fanatic to deny their quality or musicality. Furthermore, in its monophonic mode, the Quantum also makes a fine virtual analogue monosynth.

Waldorf Quantum left side panel controls.

The Particle synthesis engine is based upon stereo multi-samples, allowing you to replay them in conventional fashion or in short snippets called grains. The Quantum comes with a sample library of around 1GB within its 4GB internal memory, but you can also import WAV, AIFF and AIFC samples from SD cards, record the synth's own output for resampling, or use its in-built recorder to capture external sounds. I thought that it would be long-winded and brain-twisty to create a multi-sample patch, but this proved to be wrong. I recorded myself singing 'aahhh' at multiple pitches and then selected the Particle option in oscillator 1 and positioned each of the samples across an appropriate region of the keyboard. (I could also have sung at multiple loudnesses and distributed the additional samples across different MIDI velocity ranges, but I didn't.) Next, I chose suitable start and end points for each sample, looped them, fine-tuned them, shaped the results using a filter and the audio signal amplifier, and added chorus, delay and reverb to obscure my awful singing. The results were remarkable and the whole operation had taken no longer than 10 minutes. In fairness, the Quantum isn't a substitute for a dedicated sampler but, if you're happy to work within its limitations, it can yield great results. In addition, if you fancy inflicting a bit of gratuitous violence upon your samples, you can extract grains from them, determining the position from which the first grains are generated, their lengths, the attack/decay amplitude contour applied to each, and the way in which the point of generation wanders through the sample. There are also pitch parameters that allow you to distribute the grains in various ways. Oh yes, and each oscillator can again generate up to eight kernels, so all but the spikiest sounds can be made to sound smoother and more musical. If you're interested in a bit of sonic mayhem and want to derive unlikely sounds from interesting starting points, this is one way to do it.

Unfortunately, Waldorf supply very little information to explain the Resonator oscillator. To quote: "For a better understanding on how the Resonator works, we recommend initialising a sound program and starting with a default Resonator. Try out all the parameters to become familiar with the functionality of this powerful sound creation tool." In other words, they don't tell you what's going on, and even the limited information supplied is confused in places. For example, the manual talks about the partials "fading out exponentially" when it means that their amplitudes are an inverse function of their frequency. Waldorf could do much better because the underlying concept isn't that complex: an Exciter — things such as clicks, noise bursts and samples — energises a Resonator, causing it to emit sound according to the various parameters on offer. You can control the attack and decay of the Exciter and whether it's applied once or whether it repeats, as well as the spread, structure, response and damping of the partials generated by the Resonator, and these parameters allow you to create a wide range of sounds that would be difficult to synthesize by any other method. When excited by an impulse, the Resonator excels at things such as plucked strings and hammered sounds including bells, chimes, and electro-mechanical pianos, while experimenting with extended Exciters offers very different results; with the decay of the resonators set to maximum, I obtained some weird and wonderful sustained sounds. I suspect that this is the oscillator type that offers the greatest hope of creating something new and interesting, although it might also be the one that causes you the greatest frustration as it attempts to do what it wants rather than what you want.

Filters, Amplifier & Effects

Let's assume that you're generating the initial sounds that you want — whether using a single type for all three oscillators or combining different types to create all manner of complex timbres, and with or without ring modulation (which I haven't yet had a chance to mention). If you now access the Filter/Routing page, you'll be presented with a display that shows which sound is going where, with the colours of each synthesis block corresponding to choices made elsewhere in the system. Following the oscillators, the Quantum offers three filters in two blocks — a parallel 'dual analogue' filter block, and something called the Digital Former — and you can choose to place these in parallel, or feed the output from the analogue filters into the Former, or vice versa. Oscillators can then be injected into these in any proportion or directly into the amplifier further down the signal path.

Turning first to the analogue filters, you'll find the expected cutoff frequency and resonance controls for each of these on the top panel together with buttons labelled Type and Mode. The four filter Types are 12dB/oct and 24dB/oct low-pass filters with or without a light overdrive. The actions of the eight filter Modes — Single, Boost, Twin Peaks, Escaping, Opposition, Endless, Independent and Linked — are less obvious, and there isn't space to discuss each of them here, but it should be obvious that there are lots of possibilities. The filters will oscillate at high resonance, but when I tried to create a patch that used them as sound sources I discovered that they were all tuned to different pitches, which made it impossible to play them polyphonically. Filter calibration was introduced in OS v1.2.2, so hopefully this will sort things out. Unfortunately, the output from the analogue filter block is single-channel even when you feed it stereo signals from the oscillators, so it also includes a stereo simulator. It's not the same as retaining the panorama of the oscillators that you feed into it, but it can provide a pleasing spread.

Despite having just three controls on the control panel, the Digital Former offers 23 processing Types, including comb filters, a decimator, a wide selection of 12dB/oct and 24dB/oct low-pass, high-pass, band-pass and band-reject filters, overdrive and gain, all of which provide huge potential for further modifying the signal.

The outputs from these blocks and any oscillators that bypass them then pass to the amplifier section. There are no physical controls for this, although one of the contour generators is labelled Amp and is hardwired to it even though it can be directed elsewhere if desired.

The signal is then passed to the five effects blocks. These lie in series and each offers the same selection of effects: phaser, chorus, flanger, delay, reverb, a four-band EQ, an overdrive and a compressor. Strangely, you can only have one instance of any given effect inserted at any given time. You can control the amount and the depth of the first three effects units using the physical controls on the top panel, while deeper programming can be undertaken using the screen. The range of parameters available for each effect type can be impressive, and you can design and save your own preset effects if desired. I was able to create effects chains that I would be happy to use and, to make them sound a bit more vintage, I could always add a bit of noise from an unused oscillator (if one was available) to emulate the swirly noise of analogue stompboxes. Interestingly, this was where I found my only bug in the Quantum's GUI; the Bypass and Presets buttons didn't appear on screen in the flanger, although if I tapped where they should have been, things worked correctly.

Finally, the signal reaches the output section, which boasts a global compressor plus a volume control that affects the levels at the main audio outputs and the headphones output, but not the auxiliary outputs. (See 'Rear Panel' box.) In the routing page, you can determine whether the post-effects sound is directed to the main stereo outputs, the auxiliary outputs or both, but there's no single-channel option; at its outputs, the Quantum is steadfastly stereo.

Waldorf Quantum righthand front panel controls.


The Quantum's DADSR contour generators (of which three are revealed on the control panel, while another three are accessible via the screen) are velocity sensitive and can be assigned in the modulation matrix. The maximum lengths of the attack, decay and release stages are of the order of one minute, which is excellent, and an EnvelopeVar parameter imitates the inconsistencies of analogue contour generation. Their attack stages can independently take one of three forms — exponential, linear and logarithmic — while each of their decay and release stages can take linear or two types of exponential forms. In addition, you can loop the contours, and a Single Trig mode allows you to recreate a paraphonic response. Another nice touch is how the contours are displayed on the screen, which shows each note as a dot moving along the curve as you play, although not always accurately! If I have a complaint (well... a suggestion), it would be nice if there were a control to switch the top‑panel knobs between envelopes 1, 2 and 3 (ostensibly filter 1, filter 2, and amplifier) and envelopes 4, 5 and 6. But there isn't. Furthermore, I think that the Quantum deserves more powerful shaping capabilities: six-stage contours would at least allow me to create my favourite sforzando brass patches.

There are also six LFOs and, again, you can access three of these from the panel, while the full set can be programmed in depth from the screen. Each offers six waveforms, including S&H, and two additional parameters — Warp and Slew — allow you to mould these into a yet wider range of shapes. Their frequency ranges extend from one cycle every four minutes to 100Hz, and you can also synchronise them to clock. Each LFO also has an associated AR amplitude contour, so you can fade it in and out in pleasing ways. In addition, they can be locked together for global effects, or generated individually for each note played, whereupon they can be free-running or key-triggered with user-defined phase.

Next, we come to the Komplex Modulator. This generates two waveforms that you can select from the usual candidates or draw by dragging a finger across the screen. You can then blend them to create yet more complex curves. But that's not the end of it, because you can smooth the curves, warp the results, and even add jitter to extend things further. You can then determine the frequency and the depth of the resulting waveform, and an AR envelope allows you to fade it in and out. Three modes then allow you to apply the modulation globally, on a per-note basis, or as a one-shot curve in which it's nothing less than a 32‑step contour generator that you can control in sophisticated ways. Yet more parameters allow you to determine the phase of the waveform, and whether it's key-sync'ed or free-running. I like the Komplex Modulator and was pleased to find that you can save and recall setups in the usual Quantum fashion.

Waldorf Quantum screen.All of which brings us to the modulation matrix. This offers 40 slots that can draw upon 43 sources that include all of the contour generators and LFOs, the Komplex Modulator, the wheels and any connected pedals, various MIDI CCs, the screen when used as an X/Y pad, the sequencer's modulation rows... and more, including polyphonic aftertouch over MIDI. (While the Quantum's keyboard generates channel pressure, you can control the sound engine using PolyAT if you have a suitable controller. What's more, I understand that MPE is on the list for a future update, which should make owners of Seaboards and Continuums happy.) Your choice of destinations is even greater, with 158 options, and you have a choice of 43 controllers (again including polyphonic aftertouch) to control the amplitude of the modulation in each slot. Happily, a huge number of parameters will also respond to MIDI CCs, which means that you can automate the Quantum and, in addition to its MIDI Learn feature, there's a page that allows you to assign your own choice of parameters to MIDI CCs 0 and 2 to 120. You can save these maps for later recall, so you can even configure the synth for different projects, studios or whatever.


So that's it... except that it isn't. Within the limitations of its eight-note polyphony, the Quantum offers two such synthesizers (Layer 1 and Layer 2) that you can split or layer across the keyboard, and the split mode allows you to overlap Layers so that you can have, in effect, three zones. There's also a unison mode available for either Layer so you can allocate, say, five notes for a pad under your left hand while playing a huge three-voice unison lead with your right. More advanced uses allow you to direct the audio from the external signal inputs to either or both of the Layers for granular synthesis of incoming signals, or via the filters and effects if you want to process the audio in more conventional fashion. You can also use the Layers to create true stereo sounds by layering two appropriate patches and panning these left and right. However, this drops the polyphony to just four notes, so may not be worth the effort. Best of all, the two Layers can respond to different MIDI channels, they have independent effects sections, and you can direct them to separate output pairs, which makes the Quantum truly bi-timbral.

In Use

The Quantum is big, heavy, bold... and surprisingly stylish. It offers firm knobs, positive buttons, clear graphics, and a 61-note semi-weighted keyboard that — while not top of the range — is nonetheless pleasant to play. It also boots quickly, which is more important than you might think. Unfortunately, two minor faults were apparent on taking it out of its box: the Effect 1 Amount LED had been pushed a small way into the case (possibly by a previous reviewer or user) and the screen had a flaw that revealed itself as a blotch in the display. Happily, neither of these affected its operation.

The Quantum is a substantial instrument, measuring 1006 x 401 x 131mm and weighing in at an impressive 17.8kg.The Quantum is a substantial instrument, measuring 1006 x 401 x 131mm and weighing in at an impressive 17.8kg.

The other thing that the Quantum is, is deep: there's been no opportunity here to go into detail (and there's a lot of detail!) and it has myriad other facilities that I've had no room to discuss. For example, there's its capacious internal memory, its definable knob responses and colour schemes, its waveform displays, oscilloscope and spectrum analysers, its multiple editing modes, its multiple tuning scales, and much more. As a consequence of this, I think that I may have spent more time learning the Quantum before starting to type than any other instrument since the Korg OASYS. But, once I had grasped it, everything soon fell to hand. Sure, Waldorf's programmers didn't get everything right — for example, it's far too easy to hit the wrong option in many of the lists, especially when scrolling — but in general I found myself performing all of my programming via the module selection buttons, screen and editing system rather than using the equivalent knobs.

Sound-wise, it's hard to summarise something that combines the souls of a PPG, a virtual analogue synth, a dedicated sampler, a granular synth and a physical modelling synth... but it's not impossible. If I had to characterise the Quantum, I would say that it sounds 'European'; clean and precise whether it's producing sounds that are simple or deep or complex. This may or may not be to your taste, but I like it because it allows the Quantum to sit in a mix without drawing attention to itself when you don't want it to. I also have to compliment Waldorf on the Quantum's lack of aliasing. I had to work hard to try to create any, and it never interfered with any musical sounds that I created. Nonetheless, I did discover some pitch instability at high frequencies, most easily heard when using the ring modulator. I checked that nothing in my patches was creating this, but couldn't find anything to explain it. Would this matter in the real world? Probably not... I was pushing the synth beyond reasonable extremes. It's interesting, but nothing to worry about.

So, where does the Quantum go from here? We already know about the next oscillator model (see 'Kernel Synthesis' box) and Waldorf have admitted that there are a number of other updates in the pipeline. This is good, because I can think of a few things that could be improved. For example, I would like to see the scrolling of long lists improved because you can't flick a long list nor can you use the knobs to scroll quickly. Then there are the six sets of 20 'favourite' patches for live performance. These should be good news, but a given sound can reside in only one location in any given set, which precludes stepping through a set sequentially unless you save multiple copies of any patch that you need more than once. I also dislike the way that the arpeggio, latch and mono buttons interact. Oh yes, and I hope the company will add a screensaver. Waldorf claim that the screen won't burn but a screensaver would be a source of reassurance if nothing else. I also think that this is a synth that would have benefitted from a ribbon controller, but that's not something that can be added in a firmware update.

Unfortunately, the review unit suffered from a problem that I gather has already been identified elsewhere. I connected it to my MacBook Pro via USB and recorded a short MIDI piece. All seemed fine until I tried to replay this and play along with it. After a few seconds the Quantum started glitching and creating very loud high-pitched notes. It then crashed. Pressing the panic buttons did nothing, and even turning the Master Volume control to zero did nothing to abate the noise — only a power cycle restored sanity. Further tests showed that the problem is related to the use of the USB interface and, until Waldorf fix this, the Quantum will be unusable by some potential purchasers. Hopefully, it will have been resolved by the time that you read this.


Very soon we'll have at least three flagship analogue/digital hybrid polysynths from which to choose — the largely analogue Moog One, the largely digital Waldorf Quantum, and the Prophet X, which sits somewhere between the two. All three are mighty powerful beasties that nod toward earlier synthesizers, but I'm not going to try to compare them because, despite superficial similarities, I view them as very different. If you are wealthy and suffer from unrelenting gear lust, you could make an argument for owning all three. If you have to choose just one, and if we assume that the sound quality of each (which is excellent in all three cases) is equally appealing, then your choice will possibly be determined by the balance between immediacy and flexibility. If you lean toward the latter, the Quantum is undoubtedly the winner, and I can't see anyone exhausting its capabilities. And, to answer the question that I posed at the start of this review, it's the most 'finished' flagship polysynth that Waldorf have ever released; there's a delightful absence of messages to tell you of features not yet implemented. When the USB/MIDI problem is fixed it will be a superb sound design and performance tool. Lest you be under any illusions, I like it a lot.

The Rear Panel

Waldorf Quantum rear panel connections.

The Quantum's rear panel starts with a headphones output and its associated volume control, followed by unbalanced main and auxiliary output pairs. Next there are stereo audio inputs for real-time processing or 24-bit recording of external signals, followed by control inputs for a sustain pedal and a single expression pedal. The digital I/O starts with USB Type A (MIDI in from an external controller) and USB Type B (MIDI in/out). Unfortunately, the USB B interface doesn't carry audio, which is disappointing. These are followed by a slot for an SD card, and five-pin DIN sockets for MIDI in/out/thru. The power input is an IEC socket (hurray!) for the internal, universal power supply.

Updating The Quantum

Despite its MIDI and USB connections, the method for updating the Quantum is a pain in the arse because, once you've downloaded the file from the Waldorf website, you have to copy it to an SD card to perform the update. I use a MacBook Pro which, amongst other terrible design decisions by Apple, has only USB-C slots, so using an SD card means buying an adaptor as well as a suitable card. Why not stream the upgrade from the computer or use USB memory sticks? I have no idea, but I view it as a poor decision by Waldorf.

Quantum v2: Kernel Synthesis

The recently announced v2 firmware includes a new oscillator option called Kernel Synthesis. This will offer six kernels within each oscillator, with each kernel freely selectable from virtual analogue, wavetable, sample and noise sources. It will be possible to tune each kernel individually and each will also include a contour and a wide range of control options. It will then be possible to cross-modulate kernels, selecting from AM, FM, phase distortion (PD) and ring modulation options. The possibilities are immense but, unfortunately, this review was completed before the first beta version became available, so I was unable to try any of this.

The Arpeggiator & Sequencer

The Quantum's arpeggiator offers seven patterns; a range up to four octaves; tempo that can be synchronised to the LFOs, the Komplex Modulator and the delay effects; user-defined gate length; a selection of seven sorting orders to determine the pattern; three velocity interpretations within the arpeggio; and 31 factory programmed rhythm and accent patterns. In addition to this, there's a five-row, 32-step sequencer, with the first row containing the note data and the other four carrying control sequences that you can use as modulation sources. There are also five playback modes and three reset modes, and you can of course adjust the bpm, the clock ratio, the swing and the gate length. This is all good stuff, but it would be nice if Waldorf updated the sequencer so that it could run without outputting notes, allowing it to be used as a complex modulator.

The Performance Panel

To the left of the keyboard you'll find the performance panel, which is dominated by a pitch-bend wheel that you can assign to each oscillator individually, and a modulation wheel that you can assign to any parameter in the modulation matrix. Behind these, you'll find six buttons. These include octave up/down (which allow you to transpose the keyboard by ±2 octaves), the latch and chord buttons (which can hold the current notes with or without the arpeggiator playing), and the mono button that, depending upon contour settings, can provide single- and multi‑triggered operation for monosynth duties.


  • A PPG, a VA polysynth, a sampler/granular synth and physical modelling synth in one box... Wow!
  • It offers huge synthesis power, and the range of sounds is stunning.
  • Given its depth, the editing system — although not perfect — is quick and intuitive.
  • Version 2 will soon add FM synthesis and more to the sound generation already available.
  • It feels solid but it's also attractive — you'll look good standing behind one.


  • Until the MIDI/USB problem is fixed, it may be unusable for some potential owners.
  • When a sound passes through the analogue filters it's reduced to a single audio channel.
  • The use of SD cards rather than USB sticks was a poor decision.
  • The review model had a screen flaw.
  • It's not cheap (but I don't think that it's overpriced either).


The Quantum is a massively flexible polysynth. It lacks the polyphony of some of its competition, but it can sound superb and I have to admit that, during the review period, I found it to be quite inspiring at times. Once the teething problems are ironed out, it will be hard to ignore it.


Published April 2019