How this piano makes sound from nothing
Most virtual pianos ship recordings — some patient soul sampled every key of a grand at several loudnesses, and the site plays the right file back. It sounds wonderful and weighs fifty-plus megabytes, which is why those sites load like glaciers and break offline. This piano carries no recordings at all. Every note you hear is computed the moment you press, from a recipe short enough to print.
The recipe
A struck piano string doesn't vibrate at one frequency — it rings at a fundamental plus a stack of overtones, each quieter than the last, each decaying at its own rate. The felt voice fakes this with five oscillators per note: the fundamental at full strength, the second partial at 45%, the third at 18%, then two whispering high partials deliberately detuned a hair sharp (4.01×, 5.02× — real strings are inharmonic, and perfectly tuned partials sound like an organ pretending). All five pour into one gain envelope: a four-millisecond attack — the hammer — then an exponential decay stretched longer for bass notes and clipped shorter for treble, exactly as real strings behave. Finally a lowpass filter whose cutoff tracks your velocity: strike soft and the note is felted and dark, strike hard and the brightness opens up. That filter is most of what "touch" means.
The failures worth keeping
Version one used perfectly harmonic partials and sounded like a doorbell in a cathedral. Version four fixed the tuning but decayed uniformly, so bass notes vanished absurdly fast — a piano where the left hand evaporates. The eleventh evening produced the pitch-dependent decay, and the fifth chord test (a big open C with sustain) finally rang instead of clanging. Synthesis is like this: the parameters are five numbers, and every one of them is a taste decision wearing a lab coat.
What five oscillators can't buy
Set against a sampled Steinway, this voice is simpler — you'd hear the difference in the third second of a held chord, where real strings shimmer and beat against each other in ways five oscillators don't. What you get in exchange: a piano that loads before your finger leaves the trackpad, works in airplane mode, and fits in a service worker's pocket. For learning, sketching tunes and sending riff links, that trade wins. For recording your album, rent the Steinway.