Number of keys
The number of keys provided on the digital piano keyboard.
The immediate range of the instrument depends on the number of keys — that is, the set of notes that can be played on it without resorting to octave transfer or transposition (see below). Most digital pianos have
88 keys, the same number as a regular piano; thus, the ranges in electronic instruments most often match those of real pianos. However, smaller models are also produced — usually
61 or
73 keys (as in most synthesizers). This number of keys is found in two types of digital pianos — in inexpensive entry-level models and in some professional instruments designed mainly for "genre" music (rock, gospel, etc.), and not for classical piano parts.
Rigidity
Rigidity characterizes the force with which it is necessary to press the keys of a digital piano.
— Weighted. Weighted keyboards have high rigidity; if you are not used to them, they may not seem very comfortable. At the same time, such rigidity is an integral feature of the traditional piano keys. Therefore, all hammer action keyboards (see "Mechanics"), by definition, are made only weighted (and this is the type of mechanics that is typical for most digital pianos). Moreover, most models with simpler active mechanics have this rigidity — to ensure the greatest possible resemblance to traditional pianos.
— Semi-weighted. Keyboards of relatively low rigidity, which do not require such an effort when pressed, as weighted ones, however, are less reliable in response. They are found only in instruments with active mechanics, and even then rarely, mainly among low-cost-level models.
Technically, there is another type of keyboard — unweighted, in which each key, figuratively speaking, "falls through" under the finger, and the effort when pressed is almost imperceptible. However, such keyboards do not allow adequate pressure control, which is critical for more or less professional music performance. This is why digital pianos don't have unweighted keys.
Polyphony
The number of voices supported by the digital piano — more precisely, the maximum number of voices that the instrument can play at the same time.
This parameter should not be confused with the number of notes that can be played simultaneously on the keyboard. The fact is that in many timbres, several voices (tone generators) are used for each note at once — this is the only way to achieve a more or less reliable sound. Thus, the required number of voices can be many times higher than the number of notes — for example, the simplest chord of 3 notes may require 9 or even 12 voices. In addition, tone generators are used to play auto accompaniment parts and built-in songs (see below), and here the number of voices can already be measured in tens.
In light of all this, polyphony of less than 90 voices is typical mainly for relatively simple and inexpensive instruments that are not designed for complex tasks. The smallest number found in modern digital pianos is 32 voices. It is desirable for a more or less solid instrument to have at least 96 voices, and in top models this figure can reach 256.
Built-in timbres
The number of built-in sounds provided by the Digital Piano.
Despite the name, digital pianos are extremely rarely designed to imitate the sound of only a piano — the electronic hardware allows them to provide other timbres of sound. In addition, even the piano has its own varieties — for example, among the grand pianos there are 6 main classes, from large concert to miniature. So the built-in sounds can cover different kinds of pianos, as well as other instruments and sound effects.
The abundance and variety of timbres in digital pianos as a whole is not as great as in synthesizers, however, in this category there are very “charged” models, with a hundred timbres or more (in the most multifunctional, this number can exceed 900). However, it is worth specifically looking for a “multi-instrumental” model if you do not intend to be limited to the sound of the piano and would like to have more freedom of choice. It is worth remembering that a specific set of timbres can be different.
If the instrument is bought exclusively as a piano, then here, on the contrary, it is worth paying attention primarily to solutions with a small number of timbres. Such models are not only cheaper than "universals" — they can also sound better (due to the fact that there are few timbres and the manufacturer can carefully approach the sound quality of each built-in "instrument").
Tempo change
The range over which the tempo of the sound played by the instrument can change. It can be either a built-in melody or a part recorded on a sequencer, or an auto accompaniment, a tutorial or a metronome. For more information on all of these features, see the corresponding glossary entries. Here we note that a change in tempo is often required in fact — for example, to speed up an initially "sluggish" accompaniment or slow down a training programme that is difficult to master at the original tempo.
Tempo is traditionally indicated in beats per minute. The classical, "academic" range covers options from 40 bpm ("grave", "very slow") to 208 bpm ("prestissimo", "very fast"), however, in modern digital pianos, the working range of tempos is often significantly wider.
Sequencer (recording)
The presence of a sequencer in the design of a digital piano.
This function allows you not only to play music on the instrument, but also to record it with the possibility of later playback. However, this is at least; in addition to recording the parts of the instrument itself, the
sequencer can provide recording an audio or MIDI signal from the corresponding input, mixing several parts (including recording the music being played over the music being played “on the go”), working with the parameters of individual tracks (volume, tone, timbre), as well as specific functions such as quantization (smoothing uneven tempo). The specific functionality of the sequencer may be different, it's ok to check it before buying. However, anyway, this function can be a good help for the musician; it is especially useful for those who are not limited to the performance of ready-made music and want to compose their own compositions.
Octave shift
The presence of an octave shift function in the digital piano.
This function makes it possible to "shift" the sound by a certain number of octaves up or down — for example, in such a way that the bass register sounds on the keys of the first octave, or vice versa, the first octave "slid" lower, into the bass, and notes of the second sounded in its place or even the third octave.
This feature significantly expands the range of the instrument, allowing you to play notes that were not originally covered by the keyboard. This is especially important for instruments with 61 or 73 keys (see "Number of Keys"), but
octave shifting is not uncommon in full-sized 88-key models — it can be useful when splitting the keyboard (see above), when available for each hand the range is noticeably reduced, and the batch can be very low or very high. However, there are other options for using transfer — for example, so that when playing an updated version of the melody, you do not have to move from the usual octaves.
Chorus
The presence of the chorus effect in the digital piano.
Initially, this effect was developed as an attempt to simulate the choral sound of several instruments of the same type. Even a perfect choir never plays 100% in sync, which is what the creators of the chorus tried to reproduce. This effect works as follows: several copies are taken from the main signal, which are played along with it — but not strictly simultaneously, but with a small (up to 30 ms) delay, selected randomly for each individual signal. This really allows to imitate the effect of polyphony to a certain extent, however, such sound is still far from a full-fledged choir. However, the
chorus itself is quite interesting as an additional effect.
Transposition
The ability to transpose sound on a digital piano.
Transposition is a translation into another key, when each note rises or falls by a certain number of semitones. Support for this function allows you to at least "relearn" the keyboard, which is indispensable if you need to quickly change from key to key — for example, if the vocalist does not "stretch" his part and the melody needs to be lowered by at least 1 – 2 semitones. In such cases, it is enough to turn on transposition with the necessary settings — and you can play a familiar part on the same keys without learning it in a different layout. Transposition can also be applied to built-in songs (to adjust to the key of the main part), to tracks that the sequencer works with (to mix two parts in different keys), and so on.