Virtual Theremin Online

Play the theremin directly in your browser. Drag your mouse or slide your finger inside the coordinate pad to play. Move Left ↔ Right to change the pitch (frequency), and move Down ↔ Up to change the volume. Turn on Scale Lock to easily stay in key, customize your sound using vibrato, echo, and reverb effects, and record your performance!

Click & Drag inside this area

Left/Right = Pitch  ·  Up/Down = Volume

🎼 Pitch

—

80 Hz – 1200 Hz

🎵 Active Note

—

Scale Reference

🔊 Volume

—

Vertical Position

Pitch
D6
Volume
100%
Master Out:
🔊
Scale Lock Snapping (Stay in key!)

Active Note Grid Scale

🎛️ Synthesizer Effects Cabinet

LFO Vibrato
Speed (Rate)Hz
Wobble (Depth)
Space Echo Delay
Time
Feedback
Echo Mix
Ether Reverb

Convolution space simulation engine.

Reverb Mix

Oscilloscope Waveform

Screen Recording

Record your wailing space performance as a WebM video clip.

Recording system ready.

How to Play the Virtual Theremin

  1. Click Enable Sound first — standard browsers block web audio contexts until a manual screen interaction occurs. You'll hear a brief test note chime.
  2. Drag your cursor (or finger) across the dark 2D grid pad above.
    • ↔ Moving left-to-right increases the pitch (frequency).
    • ↕ Moving bottom-to-top increases the volume (loudness). Releasing triggers a smooth decay to absolute silence.
  3. Activate Scale Lock to snap your cursor directly to the closest harmonious scale notes. This allows you to play clean, beautiful melodies even with no previous music experience!
  4. Modulate sound with FX Dials:
    • Turn on **LFO Vibrato** and slide Rate / Wobble to create the classic haunting, tremulous wailing sound.
    • Turn up **Space Echo Delay** and **Ether Reverb** to envelope the theremin in ethereal, spacious retro echo layers!

How a Physical Theremin Works

The physical theremin — invented by Soviet physicist **Leon Theremin (Lev Sergeyevich Termen)** in 1920 — is famously the only musical instrument played **without any physical contact**. It consists of a wooden cabinet housing vacuum tube circuitry, featuring two metal antennas: a vertical rod on the right side controlling pitch, and a horizontal loop on the left side controlling volume.

The instrument utilizes **high-frequency radio waves** generated by two internal radio-frequency oscillators: one fixed-frequency oscillator, and one variable-frequency oscillator. The player's body acts as a grounded capacitor. Moving the hand closer to the vertical antenna alters the electrical capacitance of the antenna circuit, shifting the variable oscillator's frequency. Because these radio frequencies are far beyond human hearing, the theremin utilizes **heterodyning** (combining these two high-frequency currents to produce a beat frequency equal to their difference), which falls squarely within the human audible spectrum. The left hand controls volume in a similar way by bringing the hand close to the loop antenna, which acts to ground out and damp the audio signal.

Understanding Synthesizer Waveforms

Changing the active waveform modifies the instrument's **timbre** (tone color):

  • Sine Wave: The purest shape with no high-frequency harmonics. This generates the standard, classic theremin sound — very smooth, flute-like, and clean.
  • Triangle Wave: Adds very minor odd harmonics, creating a warmer, slightly hollow flute tone that blends perfectly with reverb.
  • Sawtooth Wave: Has rich, bright even and odd harmonics. Generates an edgy, string-like or brassy sci-fi sound that cuts through mixes easily.
  • Square Wave: Comprises strong odd harmonics. Delivers a buzzy, hollow, hollow clarinet-like tone with a nostalgic, vintage video game flavor.

Frequently Asked Questions

What is the difference between this and the Air Theremin?

The **Air Theremin** uses your device's webcam and real-time hand-tracking computer vision algorithms to capture hand distance. The **Virtual Theremin** uses mouse drags or touch events on a premium 2D pad. The Virtual version is highly optimized, runs smoothly on low-powered devices, requires no camera permissions, and integrates professional synthesizer controls like LFO vibrato wobblying, echo feedback delays, and scale-lock pitch snapping.

How does Scale Lock Snapping work?

When you move your pointer horizontally, the coordinate maps to a decimal frequency. By default (Continuous Chromatic), the sound glides seamlessly. Enabling **Scale Lock Snapping** mathematical snaps that decimal frequency to the closest frequency of the selected scale (e.g. C major pentatonic, Pygmy, Celtic). This lets you easily slide your finger without hitting off-key notes.

Why does a theremin naturally sound spooky?

The physical theremin's continuous, sliding portamento glide mimics a human voice crying or wailing. The natural instability of hand control adds a trembling wail. When combined with odd harmonic waveforms, feedback echo delays, and deep reverberation, it generates the eerie, floating, outer-space atmospheric sounds famous in old-school sci-fi films and suspense soundtracks.

Can I record and download my theremin track?

Yes! Using the built-in **Screen Recorder** module at the bottom of the card, click "Start Recording" to capture both the visual grid animations and the generated audio track. When done, click "Stop Recording" and hit "Download" to export a clean WebM video clip to show off your melodic skills.

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