Keys
The total number of keys on the keyboard.
The more keys provided in the design, the wider the instrument's own range, the more notes it can play without resorting to octave shift or transposition. On the other hand, this characteristic directly affects the dimensions and cost, and an extensive range is not required so often. Therefore,
88 -key instruments corresponding to a full-size classical piano keyboard are quite rare. But compact models with only
25 keys(2 octaves), on the contrary, are popular: for the purposes for which MIDI keyboards are used, this is often quite enough. Other common options are the
49 -key (4 octave) and
61 -key (5 octave) models; somewhat less common are
32 and
37 keys.
Sustain
The presence in the keyboard of its own sustain control — the extension of the extracted note. With sustain on, the note continues to sound (slowly decaying) even after the key has been released—similar to depressing the right pedal on a piano. Note that many keyboards allow the connection of pedals, including to control this function (see "Connected Pedals"), however, here it means its own controller, which allows you to turn sustain on and off using the keyboard itself, without additional equipment.
Arpeggiator
The presence of an
arpeggiator in the keyboard.
The name of this function comes from "arpeggio" — a technique for playing chords, in which notes are not played all at once, but in turn. Accordingly, the arpeggiator is a function that allows you to play a taken chord in the arpeggio technique: the musician presses all the keys at once, and the keyboard plays them in turn. This effect can also be achieved manually, but in some cases the arpeggiator turns out to be more convenient: it plays notes at a clearly defined speed and interval, can accompany them with various effects, and provides other additional features. These features vary depending on the model, but some instruments allow you to create entire songs with the arpeggiator by simply pressing a sequence of chords.
Connectable pedals
The maximum number of pedals that can be connected to the keyboard at the same time.
Pedals are used as additional controls to change various keyboard settings. The “classic of the genre” in this sense is the sustain pedal (see “Sustain”) — if the device has
one connector for pedals, then this will almost certainly be the input for just such a pedal. Keyboards are produced, where there
are 2 or more such inputs — in addition to sustain, you can connect pedals to them for other adjustments and effects (in particular, changing the volume).
