With more zones than a one‑day Travelcard and an impressive array of physical real‑time control options, the keyboard version of Kurzweil's K2500 represents a new frontier in digital synthesis. Paul Ward heads for the border...
Kurzweil's new top‑of‑the range keyboard comes in two flavours; the standard K2500 (pictured here), with its semi‑weighted 76‑note keyboard, and the K2500X (not shown), which boasts 88 fully‑weighted keys. Other than this, the two machines are essentially identical (but see the 'Vive la Difference' box for some comment). The K2500 utilises the familiar VAST (Variable Architecture Synthesis Technology), offering 60 pick 'n' mix DSP functions arranged in a choice of 31 algorithms. VAST has a proven track record, offering an extremely wide range of powerful synth voices, from squeaky‑clean digital textures to alarmingly realistic analogue emulations — and every combination in between.
In terms of the basic building blocks, little has changed from the K2500R (which I reviewed back in SOS October '95) — or, indeed, from the K2000 (reviewed SOS March '92) or K2000R. Where the K2500R introduced extended polyphony and eight 'drum' channels, the K2500 not only adds a keyboard, but includes a host of physical control options, and heralds the arrival of a new operating system to take advantage of them. Furthermore, to coincide with the arrival of the K2500, Kurzweil have made a whole host of expansion options available (see pricing details at the end of this review) to add to the basic unit if you have the inclination — and the cash. Rather than repeat much of the K2500R review here, or the features mentioned in last month's preview, I'll concentrate on the aspects that make the K2500 differ from its rackmounting sibling.
Mission Control
Anyone familiar with the K2000/K2500R will probably have first‑hand experience of the bewildering array of control options within the VAST architecture. Just about anything is capable of being modulated by just about anything else (or multiple anything elses!). What the K2000 perhaps lacked was the provision of sufficient 'physical' controllers to take advantage of the extensive real‑time control possibilities. The K2500 is more than generous with its physical control options, making provision for the connection of up to four switching pedals, two continuous control pedals and a breath controller. These control sources are, of course, in addition to those available on board the instrument itself, in the form of eight programmable sliders, a pair of ribbon controllers, two programmable switches and the more traditional aftertouch, pitch and modulation wheels.
Between them, the two ribbon controllers actually provide a total of five control sources. The smaller of the two (located just in front of the pitch/mod wheels) is capable of generating separate MIDI control signals from position and pressure, while the larger ribbon, running just behind the keyboard, can be split into three control source sections.
The large ribbon, in particular, is a delightfully tactile experience, and I had great fun using it to sweep sync‑lead solo sounds and produce 'dive‑bomb' guitar effects. Many of the factory Setups make use of the small ribbon to generate pitch bend from left‑right movement, and modulation from pressure. I found this configuration to be somewhat problematic, since a degree of pressure is needed to let the ribbon know your finger is there. This makes it a near‑impossible task to create pitch bends in the absence of a simultaneous modulation effect. To a lesser extent the reverse is also true, with small movements of the finger producing pitch‑bend when only modulation was required. I was happier to restrict the small ribbon to producing only one control source, as it's easy to switch from one to another.
Each physical, continuous controller can be assigned its own independent MIDI control number, scaling, offset and response curve — the depth of customisation borders on overkill! Additionally, entry and exit values may be applied to controllers on entering a Setup. Used carefully, this should ensure that control data is not left 'hanging' between successive Setups. All of the parameters determining the behaviour of the physical controllers are stored along with a Setup. A new option has been added to the MIDI mode, where a 'Control Setup' is chosen to apply controller assignments in Program mode. All Programs will then respond to the controller assignments defined in Zone 1 of the Control Setup (Zones 2‑8 are not relevant in Program mode, since a Program can only occupy one MIDI channel). This is a reasonable way of working, but I feel it might have been better if Kurzweil had allowed us to save a set of controller assignments as a separate object, to avoid tying them to a Setup.
With the K2000 (and the first software release of the K2500R) three patches could be zoned or layered to produce a 'Setup'. With version 2 of the K2500/K2500R's operating system, this figure has increased to eight. If you thought the K2000 and K2500R were capable of some massive textures before, then be prepared to be gobsmacked now! Taken to its logical extreme, a K2500 Setup could now constitute eight patches, with up to 32 layers of up to four 'oscillators' per voice, using three software‑generated DSP oscillators (which, incidentally, don't use up any polyphony).
In the real world, with the exception of drum and percussion Programs, it's unlikely that most Programs are going to exceed three or four layers at most. The capacity for keyboard splits and Program stacking are enormous, and Kurzweil themselves take full advantage of the possibilities, with a new collection of ROM Setups. For anyone with any doubts as to how fat this machine can sound, turn to Setup 77, unlatch the arpeggiator by turning off control switch 1, and hit a few meaty chord patterns. The closest analogy I can think of is six polyphonic Minimoogs played in unison — believe me, if this machine could sound any fatter, it would need its jaws wiring shut!
Easy Sliders
The eight slider controls can be used in three basic ways. Their default usage is as MIDI controllers, much the same as the ribbon controllers, with the same parameters to determine their MIDI channel, controller number and response characteristics, including entry and exit values. By selecting the 'Mixdown' button, the sliders will take on the role of MIDI volume faders, applying standard MIDI volume messages to both internal and external sound sources. While still in Mixdown mode, a click of a softkey will allow the faders to generate MIDI pan data. A further softkey toggles the bank of faders between MIDI channels 1‑8 and 9‑16.
The current 'virtual' position of the faders (as opposed to their current physical position, which may differ) is shown by some neat on‑screen graphic representations of the slider controls. The third usage of the sliders is selected by the 'MIDI Faders' button, and presents a similar set of on‑screen representations, with the ability to define a MIDI controller number and a MIDI channel. This use of the sliders for MIDI control data is separate to their assignment within a Setup. Four banks of MIDI control definitions are selected by softkeys.
If this all seems a little mind‑boggling, rest assured that the system is far easier to use than it is to explain. The illuminated buttons and function‑specific screen displays let you know exactly where you are, and in no time at all you'll be finding all kinds of uses for the K2500's sliders, to control both internal and external sound sources. Eight buttons, positioned just above each slider, allow Zones to be muted or solo‑ed, with a tri‑colour LED on each button to indicate the current status of each Zone.
When I reviewed the K2500R, I was sufficiently happy with the new features and extra polyphony to give it a hearty thumbs‑up, but wondered whether this was sufficient incentive to capture new business, or encourage existing K2000 owners to upgrade. Certainly, as far as K2000 keyboard owners are concerned, there is now a very strong case for doing so, in the light of the extra control features and the 8‑zone Setups. And if you are one of the many who bought a K2500R, the story certainly has a happy ending, since a software upgrade will give you the new 8‑zone Setups and the arpeggiator features in your existing machine. I'd still like to see a higher polyphony count though: 48 voices seem a healthy amount, until you have three or four stacked Programs in action, whereupon things could get a little tight.
Summary
With a machine as deeply programmable as the K2500, a review such as this can only take the reader on a whistle‑stop tour of the highlights. The K2500 is a powerful and eminently configurable machine — but power comes at a price. This could by no means be thought of as a 'budget' purchase, yet when you stop to consider the price of the equivalent separate elements, such as a hardware sequencer, a MIDI fader control station, a synth with the capabilities of the VAST synthesis engine, and a weighted master keyboard, the asking price doesn't seem unreasonable. As for myself, I'd love to end on the cliché that I bought the review model, but I'll have to do a little more saving yet!
Many thanks to The M Corporation (01425 470007) for the loan of the K2500X used in this review.
Vive LA Difference: The K2500 & K2500X
During the review period, I was able to experience both models of the K2500, thanks to Kurzweil dealers The M Corporation (01425 470007), who were able to supply the K2500X, in short supply in the UK at the time of writing.
As explained in the main text, the only difference between the different models is the number of keys and the keyboard weighting. The fully‑weighted action of the K2500X may be a little too 'springy' for players brought up on a piano keyboard, and although I'm not generally taken with weighted actions, I did find the 76‑note, semi‑weighted K2500 particularly smooth and responsive.
Life As A Latch‑Key Kid: The Arpeggiator
Kurzweil have seen fit to endow the K2500 with an arpeggiator — and that gets them a gold star in my book. Though arguably not quite as sophisticated as those seen in other recently released devices, particularly from the likes of Quasimidi, there are enough control options to keep you busy for a while — and a few that I had not seen before, such as note‑shifting. To go into detail about all of the options would take up too much space here, but it's sufficient to accept that all of the usual arpeggiator controls are here — and then some.
There did appear to me to be one fundamental flaw in the implementation, however. Although the arpeggiator allows you to 'latch' an arpeggio, any notes pressed after latching are always added to the arpeggiated pattern. This is a bit of a pain, since you can't hit a chord pattern, leave it arpeggiating, then hit a new chord pattern and have it replace the one currently playing. Having grown up with Roland's early arpeggiators, such as those on their Junos and Jupiters (and I have a feeling I'm not alone!), I'd call this a fairly typical usage. I spoke to Kurzweil about this, and they assured me that they had implemented similar arpeggiators in earlier equipment, and no‑one had ever requested this feature. I suddenly felt very lonely...
Arpeggios may be latched by use of MIDI controller 119, to which any of the onboard or external control sources may be assigned. A key range is declared, in which the arpeggiator will look for its note patterns, and individual Zones within a Setup may specify whether they are willing to make use of the arpeggiator or not.
Pros
- High‑quality master keyboard/ production station, with control facilities to match.
- Powerful VAST synthesis architecture.
- Expandability.
- Flash ROM software upgrades.
- Still has the operating system by which all others should be judged.
Cons
- Standard onboard effects processor is still pretty limited by today's standards.
- 48‑note polyphony might be seen as restrictive, given the capabilities for layering within the instrument.
Summary
Kurzweil uphold their reputation for quality with a workstation that meets the demands of musicians at all levels. The plethora of control sources and wide range of expansion options will also make the K2500 a favourite of project studios and MIDI programming suites. Start saving now!