What makes a piano VST feel realistic?

A realistic piano VST requires much more than high-quality recordings of an acoustic grand piano. For a pianist, realism is determined by the complete interaction between the keyboard, samples and software: how naturally the instrument responds to touch, how quickly the sound reacts, how dynamics and articulation change while playing, and how closely the pedals behave like those of an acoustic grand piano.

This is particularly important when a virtual piano is used for serious practice or live performance. A convincing sound may be sufficient when a piano VST is used as part of a music production. When the virtual instrument itself is being played, however, its response becomes just as important as its sound.

The following sections explain some of the most important factors that determine how realistic a piano VST feels to the pianist.

WHY REALISTIC PIANO RESPONSE MATTERS

A realistic piano is not just about sound. An acoustic piano is an interactive instrument. The pianist continuously adjusts touch, dynamics, articulation and pedaling according to the response of the instrument.

This becomes particularly important when practicing for a performance on an acoustic grand piano. If the instrument used for practice responds very differently from the concert grand, an interpretation developed at home may require considerable adjustment when transferred to the acoustic instrument.

A virtual piano designed for practice should therefore reproduce not only the general sound of a grand piano but also its dynamic and expressive behavior as closely as possible.

For students, this has another advantage. If the instrument responds predictably, it becomes easier to distinguish between limitations in playing technique and limitations caused by the instrument itself.

WHY COMPUTER-BASED PIANOS CAN BE DIFFICULT TO PLAY

Computer-based virtual instruments have access to processing power and storage capacities that allow highly detailed piano simulations. At the same time, using a computer introduces challenges that do not exist to the same extent in a dedicated digital piano.

One of the most important is latency.

After a pianist presses a key, the MIDI signal must be processed by the computer, the appropriate samples must be triggered and the resulting audio must pass through the audio system. Even relatively small delays can influence the connection between finger movement and perceived sound.

For live playing, the complete system therefore has to be optimized for both low latency and reliable operation.

But latency alone does not determine whether a virtual piano feels natural. Even a system that responds almost immediately can feel wrong if the relationship between the keyboard and the piano samples has not been calibrated correctly.

MATCHING THE PIANO VST TO THE MIDI KEYBOARD

Different MIDI keyboards and digital pianos produce different velocity values for the same physical playing intensity.

The piano VST, on the other hand, interprets those MIDI velocity values according to its own dynamic mapping.

Simply connecting a keyboard to a piano VST therefore does not guarantee that the two will behave like a coherent instrument.

Velocity response

MIDI velocity represents the speed of a keystroke and is normally transmitted using values from 1 to 127. In a sampled piano, these values influence which dynamic samples are played and how their level is reproduced.

If the velocity response of the keyboard does not match the response expected by the virtual piano, several problems can occur.

Soft playing may become unnecessarily difficult, fortissimo may be reached too early, or parts of the available dynamic range may hardly be accessible at all. Transitions between different sample layers can also become more noticeable.

For a pianist, this affects much more than volume. Acoustic piano tone changes significantly with playing intensity, so an incorrect velocity mapping can also change the perceived timbre and articulation of the instrument.

Dynamic range

A concert grand has a wide dynamic range extending from very quiet pianissimo to powerful fortissimo.

A virtual piano intended for serious playing should make this range accessible in a controlled and predictable way. It should be possible to reach both extremes without compressing most normal playing into a small part of the keyboard's velocity range.

For our own piano instruments, we therefore analyze the relationship between MIDI velocity, sample layers and resulting sound level rather than relying solely on a generic velocity curve.

Attack and tonal response

The attack of a piano note is especially important because it strongly influences the perceived articulation.

If the attack is too pronounced, quiet passages can become harsh and fast passages difficult to control. If it is too weak, the instrument may lose clarity and definition.

Differences between recorded samples can also produce unwanted changes in brightness, warmth and presence across dynamic layers.

Creating a convincing virtual piano therefore requires the samples to behave as a continuous instrument rather than as a collection of individual recordings.

THE ROLE OF SAMPLE PROCESSING

Recording a high-quality concert grand is only the beginning of building a virtual piano.

A large sampled piano can contain thousands or even tens of thousands of individual recordings. Differences between these recordings can influence tonal balance, dynamics and the consistency of the final instrument.

Sound from the pianist's perspective

The position from which a piano is recorded has a major influence on its sound.

A microphone setup designed for a finished music production does not necessarily reproduce what the pianist hears while sitting at the instrument. For a virtual piano intended primarily for playing, we consider the pianist's perspective particularly important.

The goal is not simply to make the instrument bright or detailed. Individual notes should remain distinguishable in complex chords while the instrument should still retain the tonal size and character of the original grand piano.

This becomes particularly noticeable in music containing dense polyphonic structures or subtle differences in articulation and dynamics.

AI-assisted sample processing

Modern processing methods can help analyze and modify very large numbers of individual piano samples.

This is one area in which we use AI-assisted processing. Instead of treating a piano library merely as a finished stereo recording, individual samples can be analyzed and processed consistently across the instrument.

The objective is not to replace the character of the recorded piano but to preserve it while correcting inconsistencies and optimizing the sound for the pianist's perspective.

This can include work on tonal balance, unwanted resonances, clarity and the consistency of the instrument across different registers and dynamic levels.

Preserving the size of the instrument

A concert grand should also sound like a large instrument when reproduced through a suitable speaker system.

This quality is sometimes described as projection: the impression that the sound has sufficient scale and presence to carry into the room.

If a nine-foot concert grand has been sampled, excessive processing should not reduce the perceived instrument to the dimensions of a much smaller piano. Tonal optimization therefore has to preserve not only clarity but also the apparent size and character of the original instrument.

WHY ARTICULATION MATTERS

Piano notes do not differ only in pitch and volume. Their character also depends on how they are played and released.

This presents a particular challenge for sample-based virtual pianos.

Staccato and note duration

On an acoustic grand piano, a note played very briefly can sound distinctly different from the same note held for a longer period.

A conventional sample player may reproduce the same basic attack regardless of how quickly the pianist releases the key. This can make staccato passages less convincing.

Where suitable recordings are available, a virtual piano can instead use dedicated samples and playback logic that respond to note duration.

Adaptive release behavior

For this reason, our software can change the release behavior according to how quickly a key is released.

Rather than treating every note release identically, the engine can select appropriate release characteristics based on the pianist's articulation. If dedicated staccato recordings are available in the underlying sample library, these can also be integrated into the behavior of the instrument.

The result is a closer relationship between the physical gesture of the pianist and the resulting articulation.

REPRODUCING THE PEDALS OF A GRAND PIANO

Pedaling is an essential part of piano technique and cannot be reduced to a simple sustain switch.

A realistic virtual piano therefore has to consider what happens while the pedal is moving, not merely whether it is on or off.

Half pedaling

On an acoustic grand piano, the dampers can gradually approach the strings as the sustain pedal is released. This allows the pianist to control how quickly the strings are damped.

With a suitable continuous pedal and keyboard, a virtual piano can receive intermediate pedal positions rather than only two states.

The software must then translate these positions into corresponding damping behavior. This makes techniques such as half pedaling possible and gives the pianist more precise control over resonance and note decay.

Repedaling

Repedaling occurs when the sustain pedal is released and pressed again while notes are still sounding.

On an acoustic piano, the dampers may begin to stop the strings but can be lifted again before the sound has disappeared completely. This allows the pianist to retain part of the resonance while changing harmony without allowing the sound to become excessively blurred.

A realistic virtual piano has to model this transition dynamically rather than treating each pedal movement as an isolated on/off event.

Una corda

The left pedal of a grand piano — the una corda or soft pedal — does more than simply reduce volume.

On a grand piano, pressing the pedal shifts the action so that the hammers strike the strings differently. This changes both the level and the tonal character of the instrument.

Some piano sample libraries include dedicated una corda recordings. When these are available, they can be integrated directly into the virtual instrument.

Where dedicated samples are not available, processing can be used to approximate the softer tonal character, although this is inherently different from reproducing separately recorded una corda samples.

ADDITIONAL DETAILS THAT CONTRIBUTE TO REALISM

Several additional effects contribute to the behavior of an acoustic grand piano. They may be less immediately noticeable than velocity response, latency or pedal behavior, but together they can increase the realism of the instrument.

Sympathetic resonance

When a piano string vibrates, other undamped strings can begin to resonate at related frequencies.

This sympathetic resonance contributes to the complex sound of an acoustic piano, particularly when the sustain pedal is used.

Sample-based sympathetic resonance can reproduce this effect using recordings of the resonating strings. The level of the effect is important: excessive resonance can make a virtual piano sound impressive in isolation while behaving less naturally during actual playing.

Pedal catch samples

Additional recordings can be used to reproduce transitions that occur when the sustain pedal catches strings that are already vibrating.

If these recordings exist in the original sample library, they can be incorporated into the virtual instrument to make pedal transitions more detailed.

Repetition strikes

Repeated notes present another challenge.

The mechanics of an acoustic grand piano allow a note to be restruck without the key returning completely to its resting position. Depending on the source recordings available, dedicated repetition samples can be used to reproduce aspects of this behavior.

FROM PIANO SAMPLES TO A PLAYABLE INSTRUMENT

The realism of a piano VST cannot be reduced to a single specification.

A large number of velocity layers does not automatically create a realistic instrument. Neither does a large sample library, an expensive microphone setup or sophisticated processing on its own.

What ultimately matters is how all of these elements interact while the instrument is being played.

The keyboard has to be matched to the dynamic response of the sampled piano. Latency must be low enough that the pianist maintains a direct connection with the instrument. Samples must transition naturally across registers and dynamics. Articulation has to respond to the way keys are pressed and released, and pedal behavior has to follow the continuous gestures used in real piano playing.

This is the approach behind the development of Live Grand: treating the virtual piano as an instrument for the pianist rather than simply as a collection of recorded piano sounds.

CONCLUSION

A realistic piano VST is the result of an entire system working together.

The quality of the original recordings remains fundamental, but realism also depends on keyboard calibration, dynamic mapping, latency, sample consistency, articulation, pedal modeling, resonance and the way the sound is presented to the player.

For music production, some of these differences may be relatively subtle. For a pianist practicing or performing with the instrument, they can fundamentally change the playing experience.

The closer the relationship between physical touch and resulting sound becomes, the less the pianist has to compensate for the technology — and the more the virtual instrument can behave like a piano.

Authors

Dominik Schulte is a pianist, piano teacher, software developer and co-founder of Live Grand. Combining his practical experience as a pianist with his background in computer science and AI, he developed the technical concepts behind Live Grand, including precise keyboard calibration, low-latency performance, advanced piano modeling and AI-assisted sample processing.

Paul Bittmann is a freelance composer for film and games with a background in computer science, audio systems, music implementation and sound design. He studied composition at Berklee College of Music and works with Dominik on the development of Live Grand.

What Makes a Piano VST Feel Realistic?