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").
User timbres
The number of user tones provided in the instrument's design.
A certain assortment of built-in sounds is a must for any digital piano; see above for more details. However, the specific list of these timbres may be different, and it does not always include the options required by the user. In this case, the possibility of creating user timbres is provided. The specific method of creation may be different: in some models, timbres are loaded from a computer or a USB flash drive, in others you can create modifications to the “instruments” available in memory (for example, by applying certain filters and effects), in others, you can set all sound parameters manually, achieving unique sound. However, the most popular is the first option.
Anyway, the presence of user timbres greatly expands the capabilities of the instrument. Choosing a model by their number is based on how many original timbres will need to be constantly kept in memory.
Accompaniment styles
The number of Auto Accompaniment Styles (see above) originally stored in Digital Piano memory.
Different auto accompaniment styles differ from each other in the same way that different melodies differ from each other — in tempo, time signature, rhythmic pattern, set of instruments used, etc. Accordingly, the more styles initially available in the instrument, the wider the choice of the musician and the higher the probability of finding the option that best suits a particular situation. However even numerous styles does not guarantee that among them there will be a suitable one; in addition, we note that with the same number of styles, their specific set in different instruments can also be different. However, custom styles can be provided for this case (see below).
Summarizing, we can say this: if you plan to work intensively with auto accompaniment, in addition to the number of styles, it will not hurt to clarify their specific range.
Custom styles
The number of User Auto Accompaniment Styles that can be stored in Digital Piano memory at one time.
See above for auto accompaniment and built-in styles. Here we note that these styles may not be enough — after all, the needs of the musician may not coincide with the decisions of the manufacturer. In this case, it is possible to write custom accompaniment styles to the instrument's memory, along with the standard ones. There are many ways to create and record these styles, but most often they need to be loaded from an external source — from a flash drive or computer. However, some models allow you to compose accompaniment manually.
It is worth paying attention to the number of user styles first of all if you plan to work intensively with auto accompaniment.
Learning mode
The presence of a training mode in the digital piano.
As the name suggests, this mode is designed to teach the game. At the same time, usually, it provides different levels of difficulty — from the most basic, for those who are just starting to master the "keys", to the advanced one, which allows you to train your technique and improve your existing performance skills. However, anyway, the principle of learning is the same: the tool independently tells the student which keys to press at one time or another. Such hints can be in the form of a backlight (see above) or as a graphic on the display. Such a method is doubtful from the point of view of classical academic learning, however, it is undoubtedly more convenient and faster than reading musical notation. Moreover, the instrument can also play the role of an examiner — launch prompts at the original tempo of the melody and check how accurately the student hits the notes.
Also note that
the learning mode requires the obligatory presence of a metronome (see below).
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.
Arpeggiator
The presence of an arpeggiator in the design of a digital piano.
The arpeggiator is able to decompose a chord taken on the keyboard into separate notes and play them sequentially, one after another (in the arpeggio technique — hence the name). Using an arpeggiator can be more convenient than playing notes by hand for a variety of reasons. Firstly, such a system works very clearly: notes are played strictly at a given tempo and sequence, with a given duration and interval. Secondly, only three notes are enough to recognize a chord, and the number of notes issued by the arpeggiator can be much larger. Thirdly, the executed notes can be supplemented with various effects or even a full-fledged accompaniment; many instruments allow you to create simple, but quite full-fledged melodies due to the arpeggiator alone. Although, of course, the specific features of this function may vary, it's ok to clarify them separately.
More features
Additional features and sound customization options provided by the instrument in addition to those listed above. In this paragraph, usually, various original proprietary technologies and solutions are indicated; the specific meaning of these functions is best specified in the documentation for the tool.
