Since Pro Audio Review is an audio journal – not a synth magazine – this review treats the new Kurzweil K2600XS as a multichannel digital audio workstation, rather than as a music keyboard, per se.
Product PointsApplications: Sound design, music synthesis and sample playback
Key Features: Extensive access to real-time control; backward compatibility with K2500 and K2000 soundware; fully integrated KDFX processor
Contact: Kurzweil/Young Chang America, Inc. at 253-589-3200 Web Site
+ Eight balanced audio outputs (plus stereo mix)
+ AES/EBU and S/PDIF stereo I/O
+ 8-channel digital I/O ready; user-installable options
+ Support for ISO9660 PC CD-ROM format
– 16-bit digital input digital audio resolution
– No direct-to-hard disk recording
The Score: A keyboard that excels as a musician’s digital workstation.
I owned the previous rackmount model, the K2500RS, for four years and bought the K2600XS 88-note keyboard in May 2000. I have used the 72-pound Kurzweil onstage, in clubs as well as in my studio, and enjoy every minute I spend with it.
The K2600 series, comprising a three-rack-space unit, 76-key, semiweighted action and 88-note fully weighted action keyboards, offers about 450 built-in programs, state-of-the art interactive sounds, effects and VAST flexible architecture. The keyboard models feature eight sliders, 600mm and 20mm ribbon controllers, wheels, switches, pedals, mono-pressure, breath controller inputs and more – providing incredible performance control; 12 MB of uncompressed high-quality sounds are standard (expandable to 44 MB via four plug-in sound ROM option boards). Available so far are the K2500’s Orchestral and Contemporary ROM boards, and a brand-new triple-strike Piano ROM, adding 8 MB of medium and soft strikes to the standard 4 MB Stereo Piano module.
All K2600 models include KB3 tone wheel organ programs, a new 24-band vocoder and a built-in 32-track sequencer. The current OS is 2.0 and includes support for multiple 2 MB partitions on large SCSI hard disks and the first batch of a new series of “triple modular processing” algorithms. These extend the K2600’s VAST programming possibilities threefold, enabling users to create superlayers (called triples), which combine the sound-generation and DSP capabilities of three layers into one – each single layer having its own set of more than two dozen algorithms, even before adding time-based DSP effect processing!
The K2600 comes with 64 MB of sample RAM (via standard 72-pin SIMMs) and can be expanded to 128 MB. Completely redesigned circuit boards now include 4 MB of Flash ROM, necessary for its evolutionarily advanced software features.
The sampling option provides 16-bit stereo input, true 20-bit digital output and sample-while-play capabilities. It allows external analog or digital stereo signals to be processed via “Live Mode” through the entire architecture in real time. Pertinent DSP functions available include time compression/expansion, pitch-shifting, re-sampling, pasting samples on a beats-per-minute timeline, volume ramps, sample mixing and many others – 31 VAST algorithms and 21 sample DSP processes in all, not including the literally thousands of new ones in Triple Mode.
Battery-backed Program RAM holding programs, setups and other “objects” can now be extended to 1.5 MB. Intelligent use of P-RAM, along with the Kurzweil operating system’s macro feature, enables users with internal hard disks to boot up their instruments at will with different collections of installed samples, programs and setups. For anyone who relies solely on the ROM samples, saved programs and setups return instantly upon startup.
The eight-channel DIO-26 option allows the K2600 to process eight incoming digital signals via a DMTi unit (PAR, 6/97, p. 59) from ADAT, TDIF (four in/eight out with AES/EBU or S/PDIF signals) sources and send processed signals out separately, or digitally mix them to stereo (analog, AES/EBU or S/PDIF) outputs, adding effects, VAST processing and real-time control. It is these two features – Live Mode and multichannel I/O processing – that help set the Kurzweil apart from its competitors.
Eight balanced analog outputs (and a L/R stereo mix pair) are standard, along with dual 25-pin SCSI connectors for external storage. As true balanced outputs, the analog outputs cannot be used as inserts (as in the K2500 series), but a superior method for providing multichannel input will be detailed later.
Hard disk formatting is DOS-like; one can use DOS-formatted floppies, removable or fixed hard drive media interchangeably on the K2600’s SCSI bus. Most CD readers or CD-R drives are supported. I have used a portable Panasonic 4X drive, as well as my trusty Yamaha 4216 CD-R burner with no problems.
For studio use, the K2600 can read most popular sample formats except Em-u’s. One can access Akai S900, S950, S1000, S3000, Ensoniq EPS, EPS16 and ASR files directly, as well as samples from the Roland S700 series. K2600-series instruments can also read all previous Kurzweil K2000 and K2500 formats, including sequences, programs, samples, etc.
The external option most interesting to pro audio users would be the addition of one or two DMTi units. In a nutshell, Kurzweil’s Digital Multitrack Interface can transfer digital audio, bidirectionally between Kurzweil K2500 or K2600 instruments, AES/EBU, S/PDIF, ADAT or TDIF sources. It is also a versatile digital audio sample rate and format converter that can synchronize the sample rate clocks of up to four independent stereo signals.
Kurzweil instruments utilize a proprietary KDS digital I/O format. Although my old K2500RS had a single KDS out connector and could connect only to one DMTi unit – allowing only multitrack digital audio input – the new K2600XS features both KDS in and KDS out ports, thus permitting the possibility of connecting two DMTi units, for true bidirectional multitrack transfers and the effecting of external sources.
The Kurzweil 2600’s KDFX circuitry is a full 20 kHz bandwidth, four-bus (plus master stereo bus) processor with literally dozens of effects. I reviewed it (PAR 10/98, p. 48) and subjectively evaluated its available effects. Since KDFX consists of custom VLSI DSP chips, it can easily be upgraded with new firmware.
Let’s look at the stereo sampling possibilities first. The ADCs in the Kurzweil sound pretty nice, especially considering the fact that they’re only 16 bits. So what can you input via analog? I plugged in two microphones during a live gig – one for me and one for my vocalist – and put a different reverb program on each. Who needs an external mixer for a small club gig when you have a K2600XS? Two beyer M500 microphones, an M Audio DMP2 stereo mic preamp and a pair of Dynaudio BM6As was all I needed!
Adding two Kurzweil DMTi units to the K2600 turns it into a powerful hardware digital audio/MIDI production environment. It provides eight channels of digital mixing, four effects busses, a stereo master effects bus – all on top of the keyboard’s sounds, sample playback/manipulation capabilities and 32-track sequencer. The only thing missing is true recording to its internal hard disk. I have placed that feature at the top of my wish list.
Sure, one can record “RAM tracks,” which are much more convenient than other samplers’ protocols for recording (and then assigning and triggering) long samples, but they aren’t quite the same as the real thing. I have high hopes that a future OS upgrade will offer users the ability to record those RAM Tracks, thus freeing up the RAM for sample playback purposes. But for the present, I have used RAM Tracks frequently as an integral part of the couple of elaborate sequences I play along with on certain gigs – as in, “Hey, where is his sax player hiding?”
Before sending multitrack digital audio data through a DMTi to a K2600XS, one must first consider its bit depth and sample rate. The DMTi has 16-bit digital input, so one must properly dither and/or noise-shape the data being input before it is truncated from 24- or 20-bit depth. Furthermore, since the native output sample rate of the K2600 (and its KDS format data) is 48 kHz, one must use the DMTi’s built-in SRC circuit to resample any other input’s sample rate. The K2600XS can set its analog inputs to sample at 29.4, 32, 44.1 or 48 kHz, but KDS requires use of the DMTi’s SRC stage to accept digital data at rates other than 48 kHz.
The difference between Live Mode (stereo) I/O and KDS (multichannel) I/O is that the former goes through the sampling board and its RAM, while the latter goes directly to the synth engine on its way to the KDFX circuitry, which ultimately feeds the various outputs. Skipping the sampling board eliminates its latency; the only downside is that you can’t pitch-shift or reverse the audio in KDS mode since, by bypassing the sampling engine, these digital streams bypass the Pitch block in the VAST algorithms.
Setting up my K2600XS to receive multichannel digital data from DMTi#1 was simple. On the Sample Page, I set the sample mode from stereo (or mono) to Live In. I then edited the default settings for program #199 by changing the playback mode on the Keymap page from Normal to KDS1 or KDS2, or 3 or 4.
I routed the multichannel output to DMTi#2 by editing the Output page of the program that contained the KDFX “studio” I was using. Once I confirmed which effects busses were routed to the individual outputs A,B, C and D (corresponding to the respective KDS output pairs), I was able to pass signal through to the DMTi.
Space limitations preclude me from detailing the various mixing and effecting tasks I was able to do using my K2600XS’ multichannel digital I/O, but I will state that they were comparable in complexity to the usual current standalone digital mixer suspects, while far surpassing them in algorithmic sophistication and “mangling” possibilities. Certainly, a considerable learning curve was involved, and the lack of a physical mixer’s control surface was daunting – until I got used to it. For me, however, the ability to do everything involving my music on one piece of equipment far outweighed the (eventually surmountable) obstacles.
New Kurzweil 2600 owners are urged to spend time with the Synth-Tek instructional interactive CD-ROMs and subscribe to the Kurzweil Internet mailing list (KurzList@yahoogroups.com). Learning a complex instrument like this definitely takes all the help one can get – and these are the two best ways I know to climb up the learning curve.
The Kurzweil K2600XS/dual DMTi setup is truly a musician’s DAW. And, as is the case with any true musical instrument, the more time one spends with it, the more proficient one becomes.