Kurzweil SP7 Grand

Kurzweil’s new stage piano makes the case for simplicity as a virtue.

There was a time when almost all electronic stage pianos were horrid affairs capable of generating a small range of sounds that sounded nothing like their namesakes. Then Kurzweil changed the landscape forever with the sample‑based piano in their K250. Soon after, the market was awash with digital pianos from the likes of Roland, Kawai, Korg and Yamaha. A decade or so later, workstations got in on the act and, while early attempts lacked the quality of dedicated instruments, this changed in the 21st Century, and the choice of keyboards offering high‑quality acoustic and electro‑acoustic piano emulations is now extensive.

Throughout all of this, Kurzweil held their heads high. Following on the heels of the K250 plus its K1x00 spin‑offs, VAST synthesis appeared in 1991 and, for more than 30 years, almost all of Kurzweil’s synths and pianos were based upon this. Indeed, recent Kurzweil pianos such as the Artis (SOS May 2014) and Forte (SOS November 2015) offered access to the full VAST synthesis engine including its KB3 organ extension. But last year, the company announced a pair of 88‑key stage pianos — the SP7 and SP7 Grand — based upon a hugely simplified sound generator that they call ATST (Authentic Timbre Synthesis Technology).

You probably want to know what the differences between the two models are and, to my surprise, there are not many; the Grand sitting beside me has a metal case that makes it feel more robust than the plastic SP7, it uses a Fatar rather than a Medeli keybed, it boasts a 7‑inch touch‑sensitive screen rather that the cheaper model’s 4.3‑inch screen, and it’s black not white. In the other direction, the SP7 has four cursor buttons and an Enter key deemed superfluous on the Grand. Then there’s the... umm, well... no, there’s not. As far as I can see, those are the only differences between the two models, so the rest of this review is applicable to both.

Introducing ATST

ATST itself draws upon Kurzweil’s huge sample library but, instead of allowing you to edit and control everything you can think of (and some things that you probably haven’t) it offers a selection of preset sounds that you can tweak to taste. It has also dispensed with the common Patch/Multi architecture and replaced it with a single programming environment called Sound Mode, which is, in essence, a 16‑part multi‑timbral... umm, Multi. A number of manufacturers have dabbled with this approach in recent years and I wish that they would stop — it doesn’t make it easier to understand or program an instrument, and I would venture that it makes it less so.

You can place up to 16 presets in a given Sound. Each occupies a Zone with its own key and velocity ranges so that you can create complex multi‑timbral setups as well as lush layers. The presets are drawn from 14 categories: pianos, e‑pianos, organs, brass and so on, plus a User category into which you can save your own tweaks. Unfortunately, there’s no way to create categories into which you can, for example, save Sounds for specific projects.

Much of the Zone editing is aimed at performance; for example, you can select the destination and value range of each physical controller for each of the Zones. The choice of destinations looks impressive but, as I later discovered, it’s far less flexible than I had assumed and it lacks many capabilities that I had expected. You can also modify the presets themselves, although the range of parameters is tiny: velocity response, a simple ADR contour generator, a filter with controls for cutoff frequency and a mild resonance, vibrato, portamento, fine‑tuning and pitch‑bend. You mix the Zones using the Channel Mixer, and this provides access to the pan and volume for each preset as well as its sends for the four insert effect busses and the main chorus/delay and reverb effects. Unfortunately, the manual offers neither a full description nor a block diagram of the effects architecture, so I fear that (like me) you’ll have to experiment to find out what’s happening.

Each insert effect bus offers four pre‑defined slots — dynamics, EQ, modulation/wah, and delay/tremolo — that can host your choice from 21 editable effects algorithms. You can only pass the sound from a given Zone down one bus at a time so you can’t use the modulations slots in two busses to apply (say) phasing and flanging to the same sound. But, despite the limitations, you can obtain some pleasing results. There’s also a four‑slot auxiliary effects section that, in my view, should be named the Master Effects section. You can determine whether or not each Zone and the output from each effect bus is passed through this, at what level, and how the delay, chorus, reverb and EQ within it interact.

To spice things up a bit, there are eight latchable arpeggiators that can act in the traditional fashion or as simple step sequencers. If the former, three modes, three tempo ratios, four swing settings, four gate times and two velocity modes are provided, and you can also determine the range of notes within which the arpeggio will be played. Alternatively, you can use the step‑sequencer grid to program patterns of up to 32 steps. In addition to the type of event occurring on each step, you can choose which note in a held chord is affected, and define its pitch and velocity. Although it’s quite a simple system, some impressive results — including rhythms and accompaniments — can be obtained.

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