Page 2: Waldorf Iridium Keyboard

Effects

Each layer can have up to five effects chosen from a list of eight. They include phaser, chorus, flanger, delay, reverb, EQ, overdrive and compressor. Each can be used only once, so you can’t chain two choruses, for example. But they can be placed in any order.

The quality of the effects is excellent, and most parameters can be modulated for extra fun. Some effects even use the display to show helpful feedback, like the compressor, which shows a live waveform display with an overlay to show the amount of compression.

In addition to the layer effects, there is a global one‑knob compressor and bass‑boost option, both of which I preferred to leave off, but they could prove handy in a pinch.

Other Stuff

The Iridium is loaded with useful features to make operation more practical and fun, like the seven Macro buttons near the pitch and modulation wheels. They serve as programmable shortcuts. For example, I had one set up to enable glide (inexplicably, the Quantum had a dedicated button for this, but the Iridium doesn’t), another to begin sample recording, one to enable the arpeggiator, and one as a shortcut to the Favourites page. You can also use them to send a variety of MIDI messages.

The Favourites page is handy for quick access to your favourite presets — perfect for gigs. You can save up to six sets of 20 presets that can be loaded from the touch of a screen.

The Autoplay page houses the sequencer and arpeggiator. The sequencer can be up to 32 steps with lanes for pitch, note length, velocity and up to eight controller lanes for modulation. The sequencer can be used without note triggers simply as a modulation source or as a powerful SH‑101‑style sequencer. It can output MIDI, with extra options for swing, direction, and scale quantising. The arpeggiator offers the usual functions but adds 31 preset rhythm patterns, which can turn a basic arp into something much more complex.

The other Performance tabs are the X/Y pad (a modulation source that uses the touchscreen), and the Pads tab. The Pads tab is inherited from the Iridium desktop model, which has the 4x4 MPC‑style pad arrangement. The Iridium keyboard has no such pads, so these pages seem less useful. You can still use the on‑screen pads for triggering notes and chords, but there seems little point when the keyboard — in all its velocity‑sensitive, poly‑aftertouch glory — is right in front of you.

If ever there were a synthesis engine that deserves poly aftertouch, this is it. Fatar’s new TP/8SK keyboard plays like a dream. The aftertouch is responsive and highly controllable.

If ever there were a synthesis engine that deserves poly aftertouch, this is it. Fatar’s new TP/8SK keyboard plays like a dream. The aftertouch is responsive and highly controllable. Unlike many keyboards, you can control the midrange instead of jumping from minimum to maximum at the slightest touch. Waldorf have taken this a step further with a fantastic feature that adds variable attack and release lag to the pressure response. You can, for example, trigger a slow rise in the filter cutoff when pushing into the key and have a snappy release on note‑off. The possibilities for both sound design and performance are huge. The Iridium takes the top spot as my favourite polyphonic aftertouch implementation.

Fans of microtonal music will be pleased to hear that Iridium supports Scala tuning files. A built‑in tuning editor also allows quick equal spacing tunings, such as 24‑edo or any mathematical division of an octave you can think of.

How Does It Sound?

It is always difficult to summarise a synth of this complexity. There is no clear character because it offers so many choices. It may seem obvious, but it should not be the first choice for traditional analogue sounds. I think that’s true of the Quantum too. If you want Minimoog basses, get a proper all‑analogue monosynth. Neither is it the right choice for realistic pianos, brass, orchestral sounds and the like. The Iridium and Quantum excel at complex digital sounds, whether sample‑based, granular, FM, physical modelling or wavetable.

The preset library is huge. There are 4000 preset slots, many of them filled by sound‑design giants like BT, Don Solaris, Howard Scarr and Richard Devine. It’s packed with cinematic textures, alien landscapes, ever‑evolving pads, percussive sequences, ’80s polysynth emulations, sci‑fi sound effects, DX7 pianos, Berlin sequences, and PPG tributes. And enough unclassifiable experiments to keep the most leftfield preset‑junkie happy. The real pleasure, of course, is making your own.

It is a fantastic synth — so deep that you could spend decades with it and still not hear all it has to offer.

Conclusion

My first question when approaching this review was, ‘How is Iridium different to Quantum?’ Well, Waldorf could have named the Iridium the Quantum Digital. Apart from the filters and extra voices, the synthesis engines are identical. There are hardware differences — shorter keyboard, tweaked front panel, polyphonic aftertouch instead of mono, and new Macro buttons — but they are essentially non‑identical twins.

The inclusion of analogue filters in the Quantum was problematic. For the premium price, eight voices seemed too few. Then there was the loss of stereo channels when using those filters. Many oscillator types produce wide stereo signals, so it was a shame to sacrifice that for the analogue filters.

The Iridium fixes that problem. It sticks to its digital roots and keeps the stereo signal path. With the digital filters, there are more choices too. It’s not that analogue filters aren’t great — everybody loves analogue. But the Quantum/Iridium synthesis is so complex that much of a sound’s character is already decided before it hits the filters. To me, the digital filters make perfect sense here.

Then there’s the doubled voice count. There is room to breathe with 16 voices, and bi‑timbral operation is more appealing (although the lack of a second stereo output is irksome). Some people argue that there should be even more voices because it’s fully digital. After all, digital workstations in the 1990s were boasting 64 or even 128 voices. But physical modelling and granular synthesis can be CPU hungry. Cutting‑edge sound‑design tools require more CPU cycles. In reality, I never felt like I was running into voice‑stealing problems. Sixteen is a good number.

One of the most important additions is polyphonic aftertouch. It makes perfect sense in this digital playground of physical modelling, FM, granular and so on, and the Iridium is a more expressive synthesizer for having it.

From his original review of the Quantum, Gordon Reid listed three cons:

• The lack of stereo analogue filters.
• The lack of USB host support for storage devices.
• The price (although he did concede that it wasn’t unreasonable, just high).

The digital filters fix the first item, as we already covered. The second was a feature added in a subsequent OS update. And thirdly, the price of the Iridium keyboard is £600$1000 less than the Quantum — a considerable saving. So, Waldorf have fixed every criticism from our Quantum review. Bravo!

If you’re in the market for a Waldorf flagship, there is the Iridium Desktop to consider. That decision is likely to boil down to space and cost. My choice would be keyboard, but if you already have a MIDI controller capable of polyphonic aftertouch, maybe the desktop version makes more sense.

In the end, it feels like Waldorf took all the feedback they got from the Quantum and rolled it into the Iridium. I think it’s a better synthesizer for it, but options are a wonderful thing. If the combination of digital and analogue appeals to you, the Quantum is still available, but the Iridium is not a downgrade at all. It is a fantastic synth — so deep that you could spend decades with it and still not hear all it has to offer.