Comparison Roland RP-102 vs Casio Privia PX-870

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.

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").

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).

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.

The ability to add a reverb effect to the sound of the instrument.

Reverb is the repeated reflection and decay of sound. Most of all, this effect is noticeable in vast spaces with a pronounced echo — for example, large caves; however, in any environment, the coloring of the sound characteristic of such an environment is mainly due to reverberation. Thus, this function allows you to simulate music that sounds in different rooms — for example, to give the impression that the instrument is in the hall of a Gothic cathedral, or, conversely, in a small room with soft walls. However, it is also possible to use reverberation as a classic sound effect, which is not aimed at simulating the situation and only gives the sound a specific colour.

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.

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.

The power of the native acoustics installed in the Digital Piano.

This indicator directly affects the maximum volume that the instrument is able to produce "on its own", without connecting external speakers. At the same time, it is worth noting that many manufacturers go to the trick and indicate in the characteristics not the rated power (rms power when operating at full volume), but the peak power, which is the highest power that the acoustics can deliver at short “ups” of volume. Peak power values can be quite impressive — in the tens and hundreds of watts — but these figures have a very indirect relation to the actual capabilities of the speakers. Therefore, before choosing, it is worth clarifying what kind of power is mentioned in the characteristics. To do this, it is not necessary to look for detailed data on the instrument, it is enough to compare the power of the speakers with the power consumption (see below): if the claimed power of the acoustics is greater than the power consumption of the entire instrument, then the manufacturer indicated exactly the peak value.

The number of bands provided in the Digital Piano's native acoustics.

In single-way acoustics, the speakers are responsible for reproducing the entire frequency range. Such systems are simple and inexpensive, but their amplitude-frequency response is far from perfect — most often they reproduce the mids well, but the bass turns out to be weak and unsaturated, the high frequencies are fuzzy and blurry. This is due to the fact that for each frequency there are separate requirements for the design of the speaker, and it is impossible to combine them in one speaker.

Thus, loudspeakers, including the built-in speakers of digital pianos, can be split into bands when the design provides for specialized speakers for a certain group of frequencies. The most advanced variant found in digital pianos is three-way, with separate sets of drivers for bass, mids, and treble. This allows you to achieve high-quality and reliable sound throughout the entire range, but complicates and increases the cost of the design. Therefore, three-way acoustics are rare, mainly in top-class instruments. But in mid-range instruments, two-way speakers are more often used (high frequencies on one set of speakers, medium plus low frequencies on the other).