The CTK-691 has a blue back-lit LCD screen

CTK-691 is a 61-key portable Casio keyboard which has a ZPI sound source, DSP effects and a drawbar organ function. A backlight is the form of illumination used in a Liquid crystal display (LCD ( is a Japanese electronic devices manufacturing company founded in 1946 with its Headquarters in Tokyo. Its Internet Data Expansion System allows users to download resources from the internet, such as waveform data. The model has 566 preset tones (300 Advanced tones, 50 drawbar organ tones, 128 GM tones, 72 various tones, 16 drum sets), 156 rhythms, 232 digital effects (16 reverbs, 16 choruses, 100 Preset DSP, 100 User DSP), 32-note polyphony, a layer/split function, 3 levels of touch-sensitivity (can be switched off), a 16 channel mixer function and a digital equalizer. The organ (from Greek όργανον – organon "organ instrument tool" is a Keyboard instrument of one or more divisions each In Music, polyphony is a texture consisting of two or more independent Melodic voices, as opposed to music with just one voice ( Monophony Equalization (or equalisation, EQ) is the process of changing the frequency envelope of a sound in Audio processing.

The Casio CTK-691 has a synthesizer that can edit and create new tones. Using the synthesizer while the drawbar organ function is on lets you control the drawbars manually. Because this model is compatible with General MIDI, it includes an SMF player which lets you store MIDI files that have been uploaded from a PC. A song memory function with a maximum of 6 tracks lets you record pieces using either real-time recording or step recording. A Piano Setting button is also included. When pressed, the tone automatically sets to 000 St. GrPno and the rhythm automatically sets to 120 PnoBld 1.

The keyboard itself weighs 5. 9kg and is 960 x 375 x 146mm. The sockets on the rear of the keyboard consist of a DC 9V adapter socket, a phones/output jack, sustain/assignable jack, and MIDI IN/OUT terminals. MIDI ( Musical Instrument Digital Interface, ˈmɪdi is an industry-standard protocol that enables Electronic musical instruments Computers 6 D-size batteries can also be used to power the keyboard.