Number of keys
The greater the number of keys — the wider the range of the instrument, the lower and higher notes you can take on it right during the game, without resorting to tricks like octave shift (see below). By comparison, a full size piano keyboard has 88 keys. However, in synthesizers, such an amount is rare, because. the instrument would have turned out to be too bulky and expensive, and not every musician, even a professional one, needs such an extensive range. Thus, 88-key keyboards are used primarily in high-end workstations (see "Type"). For ordinary synthesizers, the standard is
49, 61 or 76 keys ( there are also options for
73 keys) — this is usually quite enough (while the "golden mean" option is considered to be
61 keys). And small children's models can have 32 keys.
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.
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.
Sampling
Synthesizer support for sampling.
Samples are short sound fragments used in the creation of musical compositions. Such a fragment can contain almost any sound — from a note on a musical instrument or a fragment of a drum part to a siren signal, a bird's chirp, the sound of a mechanism, etc. Specifically,
the sampling function implies the ability to use the synthesizer to record samples for further use. Recording can be done either through the built-in microphone or through the audio input (from an external microphone or other audio device). At the same time, many synthesizers with this function are able not only to keep the sound not only "as is", but also to pass the incoming signal through the processing circuits, adding various effects to it — echo, "wah-wah", metallic sound coloring, etc. And ready-made samples can usually be "bound" to individual synthesizer keys and played back in real time. Other functions are possible, depending on the level of the instrument.
Mixer
The presence of a mixer in the design of the synthesizer.
A mixer in this case is a device designed to control individual audio channels that make up the sound of a synthesizer as a whole. The list of these channels includes, in particular, the main voice, the layered voice (see “Dubbing voices”), several auto accompaniment channels (main, bass, drums, etc.). With a mixer, the musician can manually control these channels — turn some of them on and off, switch the timbre, tempo, key, etc. This greatly expands the possibilities for using the synthesizer.
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.