CTK-691
 
61 keys with touch response
ZPI sound source (stereo sampling)
32-note polyphony (max.)
790 tones: 566 presets (300 advanced, 128 GM, 72 various, 16 drum sets, 50 drawbar organs), 224 user-programmable tones (100 user, 20 user + wave, 4 drum sets + wave, 100 user drawbar organs)
piano-setting button (allows direct switchover to piano mode with stereo piano sound and activates pianostyle)
drawbar function
synthesizer
key transpose and tuning control
split- and layer function
232 digital effects: 100 DSP + 16 reverbs + 16 chorusses + 100 user
equalizer: 10 levels, 4 bands, 16 user
140 rhythms (including 20 piano patterns) + 16 user
16 drum sets and 4 user sets
one-touch presets
registration memory 4 x 8 Banks
flash ROM 2 MB (wave, SMF, tones, accompaniment patterns, DSP, songs, OTP, registration)
SMF direct play (flash rom)
song sequencer: 5 songs, 6 tracks, real time rec., step rec. (10,000 notes)
mixer
General MIDI
LC-Display (backlit)
terminals: headphone / audio out, pedal in (assignable), MIDI in/out
loudspeaker: 2 x 12 cm (bass reflex),
2 x 2.5 W
power supply: AD-5 G (9.0 V) or 6 batteries, size D (both optional)
size (w x d x h): 96o x 375 x 146 mm
weight: 5.6 kg approx.
 
New ZPI Sound Source (Zygotech Polynomial Interpolation)
Optimized data compression and a polynomial interpolation based waveform playback process combine to produce amazingly clear and realistic sounds. Piano tones are produced using digital samples of two concert grands. Other sounds include saxophone tones that incorporate realistic breath techniques, rich strings, and guitar sounds so realistic you can hear the strings being strummed.

INTERNET DATA EXPANSION SYSTEM
The latest wavedata sounds, rhythms, DSP settings, registration storage data and melodies can be downloaded from the website CASIO Music Site. Then the data is transferred to the keyboard via MIDI.

DRAWBAR ORGAN FUNCTION
Provides 50 drawbar sounds. These give you direct access to optimize the individual foot positions in live performance. 100 user channels are available for your own combinations.
ADVANCED TONE
A total of 300 Advanced Tones are programmed with DSP tones to make them richer and more powerful. Advanced tones like Stereo Piano and Tremolo Electric Piano enhance the Piano and Electric Piano tones to create a totally new sound.

FILTER SYSTEM
A progressive filter system modifies sustained sounds in such a way that they come even closer to their analogue originals. Not only the relative volume is influenced by the touch; greater pressure also produces harder sounds, whereas a gentler touch creates softer tones.
 
 
 
 
DIGITAL EQUALIZER
Free selection from plenty of pre-programmed equaliser settings that support a whole range of sounds and styles. In addition, the basses, lower middle notes, higher middle notes and high notes are adjustable. (10 preset equaliser accompaniment patterns: standard, volume, rock, dance, jazz, classic)

MUSICAL INFORMATION SYSTEM (BACKLIT LCD)
Displays timbre, rhythm, metronome, tempo, beat, keyboard tone, tone of the score, the make-up and designation of the chord, the 16-channel mix and lots more besides.
Specs are subject to change w/o notice.