Kurzweil K2500

Kurzweil K2500 is a first major upgrade of the famous K2000 synthesizer. It is a DSP based, 31 algorithm, synthesizer/sampler workstation. It doubles the K2000 24-voice polyphony to 48 voices and offers a number of new parameters and expansion board options.

	Kurzweil K2500X

Synthesis:

The synthesis, this instrument uses, is called V.A.S.T., which stands for Variable Architecture Synthesis Technology. It is a unique system of pre-defined algorithms with a number of variables, individually editable DSP functions and digital oscillators, combined with the internal or external PCM samples.

There are 8 MB of onboard Basic ROM + up to 3 sample ROM blocks (8 MB Orchestral board, 8 MB Contemporary board and 4 MB Stereo Grand Piano board) + max of 128 MB sample RAM. The ROM boards contain internal PCM samples and factory presets.

With an optional SMP-2K/R advanced sampling expansion board, which adds analog and digital sample inputs, K2500 works as a full sampler. Without the SMP-2K/R installed, it works as a fully functioning sample player.

The external RAM sample can be fully edited using the following functions: Sample Start, Attack, End, Cut/Copy/Paste; loop forward, backward, and bi-directional looping and loop bypass; truncate, fade in, fade out, reverse, cross-fade looping with selectable curves and many other functions. Some of the above mentioned functions can be used with the internal ROM samples as well.

Sample edit window		Sample edit window – Loop points locators

Sample edit window – Sample parameters		Sample edit window – Keymap

PCM samples or digital oscillators (digitally generated waveforms like sine, sine+ LF sine, saw, saw+, LF saw, square, square+, LF square) can work together within any one of the total of 31 DSP algorithms.

Algorithms overview		Variable DSP segment

Algorithm 10 – Digital oscillators example		Edit functions – Soft Keys

As mentioned above, algorithms have variable segments, or in other words, individual DSP units. The algorithms are not rigidly defined as is the case with the Roland JD/JV and XV series but the types of DSP units in an algorithm can be changed. Each DSP is fully editable. K2500 can thus emulate several types of synthesis. This feature makes it really unique among other sample-based instruments.

As could be expected, there are several limitations in DSP combinations. These, however, were resolved with later released and virtually limitless K2600 Triple Mode.

Internal or external samples can be filtered (HPF, LPF, 12db/oct, 24db/oct, BPF, notch, peak, all pass, steep resonance), equalized (several EQ types), mixed with digital oscillators (digitally generated waveforms like sine, sine+, LF sine, saw, saw+, LF saw, square, square+, LF square), distorted and cross modulated.

Other DSPs available are shaper, high freq. stimulator, digital wrap, noise generator, PWM, X-Fade, amplitude modulation, panner, etc.

All individual parameters are fully editable (Hz, cent, dB, sec, msec settings - nothing like usual 1-127).

Algorithm Nr. 1 - 4Pole LPF		Filter cut off frequency page

Filter resonance		Filter separation

There are 3 very fast envelope generators (AMPENV - amplitude envelope / ENV2, ENV3 user definable - 8 segments, looping), ENCTL (envelope control) for dynamic or continuous ADR parameters control, 2 LFOs (generators with many cyclic waveforms and adjustable phase angle between 0 – 270 degrees), 2 ASR envelopes for start and attack of user definable modulation functions, FUN (mathematical functions - formulas full of sin, cos, tg etc., for modulation of individual parameters of DSP algorithms e.g. pitch, filter, amplitude, pan, or direct control of LFO waveforms).

AMPENV – Amplitude envelope		ENV2

ENV3		ENVCTL – Envelope control

LFO		ASR

FUN – FUNctions:-)

The modulation matrix is very complex. "Everything can be modulated by everything" (you can use functions for modulation source control as mixers, negators, invertors, sample and hold, quantization, ramp, shape, etc.).

Each sound program can consists of up to 32 layers.

Program Mode with 3 layers Brite Grand program

KB-3 Drawbar Mode

KB-3 Mode is part of the software upgrade since OS 2.5x downloadable from official www.kurzweilmusicsystems.com web site. It provides a powerful tone wheel organ synth model, fully polyphonic over the keyboard. Each single voice contains nine harmonics that may be blended in real time using the sliders. There are 4 organ maps available with rotary speaker emulation, vibrato/chorus, percussion attack, key click, parametric EQ, etc.

Drawbar page		Tone wheels parameters

Percussion attack		Key click

Parametric EQ

Sober multitimbral

K2500 is a 16 channel multi-timbral synthesizer with a sophisticated "invisible" multi mode. Each preset or user program in Program Mode can simultaneously work on a different MIDI channel (1-16). This means that no complicated Multi or Performance mode is used for multi-timbral operations. There are two dedicated buttons on the panel to browse between individual channels/programs.

MIDI Mode - Channel 1		MIDI Mode - Channel 1

However, for those who use the "Performances" and "Multis" the Setups are available as well.

Setups

There are several differences between programs and setups. Program can include several layers but plays only in one Zone on one MIDI channel. Setup enables user to utilize up to eight keyboard zones, each of which can have its own MIDI channel, program and control assignments. There can be up to 100 setups saved in each memory bank.

Setup main page		Setup channel page

Setup keyboard and velocity parameters

Sequencer

The K2500 internal sequencer is one of the best hardware sequencer ever made. It includes 32 fully editable tracks (16 song tracks + 16 arrangements tracks), linear and step recording – cut, copy, paste, quantization, event list editing, Advanced Auto Arranger (sequences can be triggered in real-time from the keyboard), and resolution of 768 ppqn.

The basic capacity of approx. 60 000 events is expandable up to approx. 300 000. A song is stored in program RAM, which means that it uses your limited internal program memory or expansive optional P-RAM capacity.

Main sequencer window		Sequencer arrange page

Sequencer track edit parameters		MIDI event editor

Effects

The basic built-in digital effect processor is based on simple Digitech chip and offers standard effect algorithms. It is an upgraded version of the original K2000 EFX unit with a few more editing parameters and better signal to noise ratio.

It provides fully programmable basic effect algorithms and their combinations (stereo chorus, stereo flange, stereo delay, 4-tap delay, ultimate reverb, room simulator, gated reverb, reverse reverb, parametric EQ, graphic EQ, parametric EQ + delay + mixer, parametric EQ + chorus + mixer, chorus + room + mixer, delay + room + mixer, chorus + hall + mixer, delay + hall + mixer, EQ + gated reverb + mixer, EQ + reverse reverb + mixer, parametric EQ + chorus + delay + mixer, parametric EQ + flange + delay + mixer, chorus + delay + room + mixer, flange + delay + room + mixer, chorus + delay + hall + mixer, flange + delay + hall + mixer, EQ + chorus + 4-tap delay + mixer, EQ + flange + 4-tap delay + mixer).

Since the K2500 is a really powerful synthesizer it is not necessary to add extra "charm" to its sound with reverb and chorus as with some cheap mass produced instruments. The dry sound is rich enough.

Effect main page – single effect example		Effect edit page – single effect example

Effect main page – multiple effect example		Effect edit page – multiple effect example

There are two effect buses available (dry and wet). Unfortunately, it is not possible to set the send level for individual channels in multi-timbral mode.

K2500 can be expanded with an optional KDFX board. KDFX is a very advanced and excellent sounding digital reverb and effect unit with digital I/O offering superb sonic possibilities. It is based on Kurzweil´s VLSI chip and it features 4 stereo buses, full bandwidth, 8 outputs and 2 inputs of Kurzweil Digital Stream (KDS) digital I/O (for connection with DMTi option) and flexible routing scheme.

Microtonal tuning

There are 17 pre-programmed intonation tables. All of them are freely user editable.

Microtonal table

Polyphony

The polyphony is 48 voices (together with a maximum of 192 oscilators - 48 sample playback and 144 synthesizer waveforms). Special voice allocation system, first patented for K250, is used. This system analyses the most frequently used sounds in multi-timbral mode so the "voice stealing" effect is nowhere near as obvious as with other synthesizers. Each program can consist of up to 32 layers.

Polyphony monitor

"Gameboy" inside :-)

A tired programmer can play the computer game called "Pong" on the K2500 display.

Pong Game

To play Pong press the "Master" button, then select Utility and press the second function button under the display from the right hand side (or fifth from left hand side) – it is the blank position on the display, then press the setup button and here we go! (Max Score of 168 pongs was achieved by a "tired" Art of Sound programmer.)

Memory and expansion boards

Kurzweil K2500/K2500R – RMB-P2

Basic sample ROM: The basic 8 MB of ROM is expandable to 28 MB with Contemporary (rock, pop, ethnic), Orchestral and Stereo Grand piano ROM boards. (The Orchestral ROM board contains a unique collection of orchestral sounds. If you are in film scoring it provides the ultimate solution.) An optional daughterboard is required for the installation of these ROM boards. Both the Orchestral and Contemporary ROM boards are the same as for K2000 (and K2600) the daughterboard, which carries the ROM boards, is new to carry accommodate the Stereo Grand Piano ROM.

Program ROM: There are 200 presets/100 setups in the basic ROM, the optional: Contemporary ROM board includes 100 presets/50 setups, the Orchestral board inculdes 100 presets/50 setups and the Stereo Grand Piano board includes 30 presets. The ROM presets can be overwritten with new user programs at any time.

Program RAM: K2500 comes with 240 KB of internal program RAM, which is expandable to 1.25 MB using a battery-backed P-RAM memory expansion module, allowing up to 1000 user programs or approx. 300,000 sequencer events to be stored in memory. The program memory is addressed untraditionally for a synthesizer. The addressing is done much like in a sampler. The sounds consist of objects (edited ROM samples, keymaps, sound programs - (the sound patches) and user DSP settings). Each object has certain size in bytes. Generally the more complicated the sound is the more memory it occupies.

Sample RAM: 0 - 128 MB (30-pin SIMM, 72-pin for later motherboard revision), Max. 12 min of 44.1 kHz stereo recording.

The optional SMP-2K/R interface can be installed to add 18-bit DAC (analog IN, AES/EBU a SPDIF digital IN/OUT) 29.4/32/44.1/48 kHz analog sampling rates, sample-while-play capability. The Live Mode can be used for processing any incoming signal via the optical, analog or digital inputs with VAST, built-in effects or KDFX.

Kurzweil K2500R – SMP 2R (Sample option) – AES/EBU and S/PDIF outputs

The DMTi Digital Multi Track interface allows direct digital interfacing between K2500, ADAT and DA-88 formats (with optional interface card), and AES/EBU, providing four stereo pairs of AES out and two stereo pairs of AES in.

KDFX: The KDFX is an advanced, excellent sounding though a little bit over-sophisticated digital reverb and effect unit with digital I/O offering superb sonic possibilities. It is based on Kurzweil´s VLSI chip. The module offers 4 stereo buses, auxiliary EFX, full bandwidth, 8 outputs and 2 inputs of Kurzweil Digital Stream (KDS) digital I/O (for connection with DMTi option) and flexible routing scheme.

Physical appearance

Keyboard: Velocity and touch sensitive 76-note semi-weighted or 88-note weighted action keyboards. Pitch-bend, modulation wheel, eight sliders, two ribbon controllers (a small one under the modulation wheels and a large one above the keyboard), footswitches, pedals and breath controllers – all assignable.

Display: 64x240 fluorescent, blue backlit LCD - easily readable

Analog I/O: 8 Audio Outs (double as inserts) + 1 Master mix stereo pair, 600 Ohm stereo headphone out. With SMP-2K/R sampling options: Stereo ¼ in. unbalanced analog hi-Z input (tip/ring/sleeve); two balanced lo-Z (XLR inputs).

Digital I/O: With SMP-2K/R: AES/EBU (XLR), S/PDIF (optical) inputs and outputs. With DMTi & KDFX: AES/EBU (XLR), S/PDIF (optical), ADAT or DA88 inputs and outputs (with optional interface cards).

Data terminals: MIDI IN, OUT, THRU/OUT, 2 x 25 pin external SCSI (+ internal SCSI connector for HDD, Hard-drive installation kit HDC-25K/R required)

Compatibility: MS-DOS (floppy disks 3,5" FDD is built in, hard drives, ZIP, CD-ROM) Akai S-700, S-900, S-950, S-1000, S-1100, S-3000, Ensoniq EPS a ASR, Roland S-7xx series, PC Wav, Mac AIFF, reads and writes SMF 0, writes SMF 1

SCSI devices: External HDD, ZIP, CD-ROM, JAZ, internal HDD

Dimensions: K2500 keyboard – 121,5/45/13 cm, 25 kg, K2500X keyboard – 138/45/13 cm, 33 kg, rack - 13/43/35.4 cm, 11,2 kg

Kurzweil K2500R (an Art of Sound machine, which has been put through more than 10,000 hours of programming without a single problem or defect:-)

Kurzweil K2500R – rear panel

Audio Outputs detail

Price: K-2500/K2500X keyboards sell for approx. $ 4,500/$ 5,400, K2500R rack version for approx. $ 3,700 (sample board $ 800, P-RAM $ 400, sample ROM $ 350).

The second hand market prices are typically a lot lower (for current second hand prices visit http://www.prepal.com)

Sounds never before imaginable

The instruments has a unique "fat" sound and is excellent in multitimbral settings. It is not necessary to "sweeten" the sound up with reverbs. The rich editing functions offer immense sound possibilities for analog emulations. The instrument offers superb acoustic sounds, excellent pads, as well as aggressive non-harmonic digital colors. K2500 is suitable for all music styles and is excellent for electronic and techno music. This instrument can easily outperform VA synthesizers which were produced a whole decade later. To evaluate the instrument's capability, please listen to our K:Works Modern Synth demo here, and K:Works Gold demo here.

Models available

Kurzweil K2500XS Audio Elite System

Plus

• Excellent sound
• Programmability (beginner could be afraid of the parameters quantity, but the OS is well arranged and logically structured
• Multi-timbral - easy and quick operation - no complicated performance or multi sounds settings
• KB3 Drawbar Mode
• Arpeggiator
• Quick Acces Mode
• File Managements – AFMS provides user friendly cataloguing and retrieval of individual objects
• Program list (besides the active sound program there are other 5 neighbouring sounds displayed for better orientation, which is an excellent idea
• OS stored in Flash ROM for updates via floppy disc or SCSI
• MS-DOS compatibility
• CD-ROM compatibility (Akai, Ensoniq, Roland, MS Windows Wav, Mac AIFF)
• Upward compatibility with the K-2600 model. Most of the sounds can be used downward as well.
• Control sliders and ribbons
• Expandability (RAM, ROM, HDD)
• KDFX digital effect option
• Analog outputs – 1 Master mix stereo pair + 8 audio outputs (double as inserts)
• Large graphical 64x240 fluorescent, blue backlit LCD (for easy sample and program editing or pong game playing:-), etc.), better than that on K2000
• Design – one of the top synth designs ever made

Minus

• Expansion module prices
• Instalation of ROM board upgrades is complicated. First version of the motherboard use 30-pin SIMM modules for sample RAM - not all brands are compatible (Same problems as with the E-mu ESI32, e64 and other older samplers)
• SCSI drives incompatibility - some HDD and CD-ROM (all NEC, some Sony drives, etc. Toshiba CD-ROMs are recommended. A complete list of compatible devices can be found here: http://www.k2users.org/k2/k_main.htm)
• Still the same algorithm “limitations” as with K2000 model - resolved in the later and virtually limitless K2600 Triple Mode
• Aliasing on some internal ROM samples and digital oscillators
• No 61-key synthesizer keyboard version available

Web resources

http://www.kurzweilmusicsystems.com/ - Kurzweil company web page
http://www.k2users.org/k2/k_main.htm - essential web page for all K2xxx users

Original Kurzweil product brochures

K2500 product brochure in English.

K2500 product brochure in German.

K2500R product brochure in English.

K2500XS Audio Elite System product brochure in English.

All presented brochures are copyright of Young Chang Akki Europe GmbH. or Young Chang Co., Ltd.