What is a virtual instrument?

Every instrument does two jobs: it takes what you play, and it turns that into sound. A virtual instrument keeps the first job and hands the second to software. The keys or pads are the way in; the sound is calculated and sent to your speakers or headphones.

They come in two families, and the difference explains most of what you will hear.

1. Sampled. Someone recorded a real instrument note by note, sometimes at several strengths. Playing a key plays the recording. A sampled grand piano sounds like a grand piano because it is one.
2. Synthesized. Nothing was recorded. The sound is built from a recipe: waveforms, filters and envelopes. Synths, electronic drum machines like the 808, and most keyboard "pads" work this way.

A plugin is a virtual instrument packaged to run inside music software: a DAW like Logic, Ableton or FL Studio. The formats you will see are VST, AU and AAX. The instrument is the same idea; the plugin is the box it ships in.

The other box is a web page. Online instruments run in the browser and need no DAW, no install and no account. They cannot be used inside your DAW either, so the two do different jobs: the plugin is for producing, the online instrument is for playing right now.

Synthesizers and drum machines have always made their sound from circuits rather than strings or skins, so moving them into software changed less than it did for a piano. The same recipe of oscillators, filters and envelopes that lived in a 1980s box now lives in code, and a virtual 808 is built the way the real one was.

That is why the electronic side of virtual instruments feels so complete: a synth pad, a bass, a drum machine in the browser are not imitations of an acoustic thing. They are the thing, running somewhere new.

Less than you would think.

• A computer, phone or tablet with a browser. The instrument runs on your device; nothing is uploaded.
• Something to play it with. A computer keyboard works: the letter keys become two octaves of piano. A MIDI keyboard is better, because it sends how hard you hit each key.
• Headphones or speakers. The built-in speaker on a laptop or phone works, but a real piano note has a lot of bass in it.

No DAW, no plugin, no sign-up. If you have a MIDI keyboard, plug it in with a USB cable and allow it once when the browser asks.

Sampled ones, yes, within limits. A well-recorded piano with several strengths per key sounds like the piano it came from. What it cannot do is respond to every subtlety a real instrument would: the sympathetic ring of other strings, the way a note changes when you press harder mid-note.

Synthesized ones sound like themselves, and that is the point. Nobody wants an 808 to sound like a real drum. It has been the sound of hip-hop for forty years because it sounds like an 808.

Latency is the other honest caveat. The gap between pressing a key and hearing it is a few milliseconds in a browser on a good day, and it grows with a slow computer or Bluetooth headphones. Wired headphones keep it tight.

HitJam is a set of free online instruments that run in this browser. Each one is its own page:

• Grand Piano: a real concert grand, recorded note by note across all 88 keys.
• Wurlitzer: a real Wurlitzer electric piano, recorded note by note, the reedy bark of classic soul.
• Church Organ: a real church pipe organ, recorded pipe by pipe; hold a chord and it rings for as long as you like.
• Hammond Organ and Combo Organ: the drawbar organ of rock and gospel, and the buzzy 60s garage organ, both synthesized.
• Electric Piano, Slow Pad, Gameboy, Bali Cave, Prayers: synthesized sounds built from recipes.
• Growler, Tech My Bass, Bass Punch: synthesized basses.
• Standard Drum Kit: a real rock kit, recorded piece by piece, drawn as a drum set you can hit.
• Drum Machine: sixteen real TR-808 recordings on an MPC-style pad bank.
• Congas & Bongos: real hand drums with open tones and slaps, plus shaker, guiro, claves and agogo.
• Trumpet: a real trumpet with vibrato, every note tuned, and a brassier take for hard hits.
• Trombone and Tuba: a real tenor trombone and a real tuba, the low end of the brass section.
• Full Strings, Pizzicato Strings, Spiccato Strings: a real orchestra string section, held, plucked and bounced.
• Flute, Clarinet, Oboe and Bassoon: the orchestra's woodwinds, real recordings with every note tuned.
• Saxophone: a real alto sax, played loud with vibrato, for jazz lines and solos.
• Upright Bass: a real double bass, plucked, for jazz walking lines.

All of them take a MIDI keyboard or pad controller, and all of them work with the letter keys.

Plenty of virtual instruments are free to download as plugins, and the good ones are very good. The catch is the setup: a DAW to host them, an install, sometimes an account, and a computer that can run it all.

Browser instruments trade a little sound-shaping depth for zero setup. HitJam is free with no time limit and no premium tier. The recordings it uses are open-licensed, and every one is credited on the licenses page.