Polyphony in a digital piano — 64, 128 or 256 voices?

What polyphony is, why 88 keys don't mean 88 voices and when you really start running out. An explanation without jargon, with practical examples.

Polyphony is one of those specifications that appears in every table and that hardly anyone can define exactly. Salespeople gladly stress the higher figure, buyers nod — and there the conversation ends.

It is worth understanding, because it is a specification that means nothing in some uses and decides in others whether notes start disappearing while you play.

What polyphony is

Polyphony is the maximum number of notes an instrument can produce simultaneously. It isn't about how many keys you can press, but about how many sounding samples the processor keeps going at the same moment.

And here the first misunderstanding appears: if I have ten fingers, why would I need 128 voices?

Why ten fingers use up far more than ten voices

Because a note doesn't end the moment you release the key. Voices are used up in several ways at once.

The sustain pedal

This is the main consumer of polyphony. While you hold the pedal, every note played goes on ringing — including those your fingers left long ago. In a run with the pedal down, several dozen notes can sound at once.

Stereo voices

Many piano voices are sampled in stereo. One pressed key then uses two voices, not one.

Layered voices

The Dual function, that is layering two tones on the same keyboard — piano with strings, for instance — doubles the consumption. Combined with stereo, one key can take four voices.

Accompaniment and metronome

An automatic accompaniment means further instruments playing in parallel. Each of them uses voices as well.

So how many are really needed

A simple calculation for a typical situation: you play a piece with the pedal, a stereo piano voice, in a denser texture. Ten fingers, a stereo voice, earlier notes still ringing — you comfortably pass 60 voices.

Hence the practical thresholds:

• 64 voices — enough for simple playing without the pedal and without layering tones. With heavy pedalling it may run short.
• 128 voices — a comfortable level for learning and playing at home, including with pedal and accompaniment.
• 192 or 256 voices — headroom for dense textures, layered voices and work with backing tracks.

How to tell that voices have run out

The symptom is characteristic and easy to recognise once you know what to listen for: the oldest notes fade prematurely. You play with the pedal, you build up the sound, and earlier notes vanish although they should still be ringing.

The instrument doesn't freeze or distort — it simply "cuts off" the oldest note to free a voice for the new one. That is normal behaviour, not a fault.

If you've never heard this in your own playing, the polyphony of your instrument is sufficient.

Is higher polyphony worth paying for

It depends on how you play.

It matters littleif you are learning from scratch, playing melodies and simple accompaniments, and using the pedal sparingly.

It mattersif you play Romantic repertoire with elaborate pedalling, like layering tones with the Dual function or work with accompaniments and backing tracks at the same time.

In fairness, though, it must be said that polyphony comes far behind the keyboard and the sound system in the order of things worth spending money on. An instrument with better action and more modest polyphony is a better buy than the other way round.

What to look at instead

When choosing a piano to learn on, far more important are:

• the key action — weighted hammer action as in the V9N and V10NB, or semi-weighted as in the V5N,
• the power and quality of the amplification — 2 × 12 W with a 16 × 24-bit DSP in the V9, V10 and V11 models against 2 × 10 W in the V5,
• a full pedal unit with sustain, soft and sostenuto,
• headphone outputs — two in the higher models.

Summary

Polyphony is a reserve of processing power, not a count of fingers. The pedal, stereo voices and layered tones use it up, which is why figures like 64 or 128 are not excessive. For a pupil and for playing at home, though, it is a secondary specification — the quality of an instrument is decided above all by how the keyboard works.

You'll find the specifications of all the models in the digital pianos.