Polyphony
The polyphony supported by a synthesizer, in other words, is the number of “voices” (tone generators) that can simultaneously sound on it.
This parameter is often described as the number of notes that can be played simultaneously on the keyboard. However, this is not entirely true due to the fact that in many timbres one note can activate several tone generators. As a result, for example, to play a chord of 3 notes in a timbre with 4 tone generators per note, polyphony of at least 3 * 4=12 voices is required. In addition, Auto Accompaniment and Preset Songs (see related sections) also use tone generators, requiring even more voices to work effectively with these features.
The minimum value for a more or less functional modern synthesizer is polyphony for 32 voices — and even then such an instrument can be used mainly for initial training and simple melodies. For a more solid application, it is desirable to have at least 50 – 60 voices, and in professional models (in particular, workstations where you have to deal with several audio tracks at once), there are models with polyphony for 150 tone generators or more.
In general, a more advanced synthesizer is likely to have more extensive polyphony, however, it is only possible to evaluate the class of an instrument by this parameter very approximately — instruments with the same number of voices can differ greatly in level. The only exception to this rule are children's synthesizers (see "T...ype"), which support up to 20 voices.
Built-in timbres
The number of built-in sounds provided in the synthesizer.
The number of timbres is often described as the number of instruments that a given model can imitate. However, this is not entirely true — rather, this parameter can be called "the number of instruments and sound effects." For example, the same instrument — an electric guitar — with different "gadgets" (distortion, overdrive) will sound differently, and in the synthesizer each such gadget will be considered a separate timbre. The “drums” timbre usually combines different types of drums and other percussion instruments — in other words, it allows you to portray both the “bass drum” and the cymbals without switching settings, just by pressing the desired keys. And some timbres may not have analogues among real instruments at all.
The more built-in timbres, the more extensive the possibilities of the synthesizer, the more diverse the sounds that can be extracted from it. At the same time, in high-end models like workstations (see "Type"), this number can reach 1000 or even more.
User timbres
The number of memory slots for user tones provided in the synthesizer.
For Voices in general, see “Preset Voices” above. User timbres are sound settings that were not originally provided in the synthesizer's memory and are created by the user according to their preferences. This feature is indispensable in cases where the built-in set of timbres does not contain the necessary options. However, the capabilities of the User Voices may vary from model to model. So, one instrument only allows you to edit and supplement existing timbres (for example, add a “wah-wah” effect to a bass guitar and save such a bunch as a user setting), another makes it possible to set the sound parameters almost manually, and the third even allows you to load timbres through USB (see below).
The more user timbres in the synthesizer, the more personal “instruments” you can register in its memory.
Auto accompaniment
The presence of the auto accompaniment function in the synthesizer.
This function allows the instrument to automatically play an accompaniment melody that you can play along with the main part on the keyboard. At the same time, the left hand of the musician can control the accompaniment: it is enough to take a chord on the left half of the keyboard, and the auto accompaniment will automatically “decompose” it into instrument parts that sound in accompaniment. Thus, the musician turns into a "man-orchestra": one synthesizer can replace the whole ensemble, or at least a solid part of the ensemble. Of course, the sound quality in such models can be different, and not every synthesizer with accompaniment is suitable for an event more serious than a children's party, although there are quite advanced models.
In addition, playing to accompaniment can also be useful for educational purposes: it contributes to the development of general technique, a sense of rhythm, and additional accompaniment is very convenient during improvisation exercises.
It should be taken into account that not only the sound quality, but also the number of accompaniment styles (melodies) can be different; and some models allow you to record your own melodies. See below for more details on these features.
Accompaniment styles
The number of auto accompaniment styles (see above) originally provided in the synthesizer, in other words, the number of accompaniment options available to the user.
The more extensive this set, the higher the probability of finding among these melodies suitable options for a particular case. At the same time, the abundance of styles in itself is not yet a 100% guarantee that among them there will be a suitable one, especially since different synthesizer models can differ markedly in a specific set of melodies. So the list does not hurt to clarify before buying. Also note that the situation can be corrected by user styles (see below) — many synthesizers with auto accompaniment support them.
Tempo change
The range in which you can change the tempo of the programme played by the synthesizer — auto accompaniment, lesson tune (see above), metronome (see below), recorded sample, etc.
Pace is measured in beats per minute. Changing it allows you to adjust the speed of the synthesizer to the specifics of the situation — for example, slightly slow down the tutorial if it is too hard to master at the initial pace. The wider the range of tempo adjustment, the more options the musician has to choose from, especially in the area of very slow and very fast tempos.
Note that the traditional range of musical tempos covers values from 40 beats / min (“grave”, “very slowly”) to 208 beats / min (“prestissimo”, “very fast”), however, in synthesizers it can be more extensive — for example, 30 – 255 bpm.
Metronome
The presence of a built-in metronome in the design of the synthesizer.
A metronome is a device that produces sharp sound signals (beats) at certain short intervals specified by the user. In music, such a device is used primarily to maintain a given tempo. A metronome can be useful both for a beginner musician, for developing a sense of rhythm, and for a professional, for example, when learning a new melody, especially if it is to be played without accompaniment and you will need to maintain the rhythm yourself. In addition, the sound of the metronome can also be used as an effect in musical compositions.
Built-in compositions
The presence of built-in compositions in the design of the synthesizer.
This function is similar to the auto accompaniment described above — in the sense that it involves playing songs on the synthesizer itself. However, unlike Auto Accompaniment, Preset Songs play strictly by note and cannot be controlled using chords on the left half of the keyboard. In other words, with auto accompaniment, the musician has a lot of freedom, and you have to play along with melodies in strict accordance with it.
Built-in compositions can be used for a variety of purposes. One of the options is training: the musician listens to a reference recording and then tries to reproduce it, either plays along with the melodies according to the given notes, or improvises to it. In addition, in some cases (for example, at mass events), the ability to turn on the synthesizer as a player can be very useful. Also, built-in songs are used to test and demonstrate the general capabilities of the instrument: it is assumed that the recorded song can be repeated using the synthesizer itself.
Octave shift
Synthesizer support for
octave shift function.
This function allows you to shift the sound of the instrument one or more octaves up or down — for example, so that the keys of the first octave sound the notes of the second, or vice versa. This function can be used for both simple convenience and more practical purposes — it allows you to play very low and very high notes that are not initially covered by the keyboard range. This is especially useful for shortened 49- or 61-key synths that do not initially fit the full range of the piano.