Tone Generator - Play Sine, Square & Sawtooth Tones

A tone generator produces a mathematically clean signal — the audio equivalent of a laboratory reference. This one synthesizes everything in your browser with the Web Audio API, so the pitch is accurate to a fraction of a cent and there is nothing to install. Beyond a steady tone from 1 Hz to 20,000 Hz in four classic waveforms, it adds the controls an audio engineer actually reaches for: an ADSR amplitude envelope, a linear or logarithmic frequency sweep, a detunable second oscillator, per-channel routing, and offline WAV or MP3 export. The ADSR envelope (attack, decay, sustain, release) shapes how the level evolves. A slow 200 ms attack removes the onset transient so you can judge steady-state driver behavior; a fast attack with a short one-shot duration approximates a tone burst, useful for spotting rattles that only excite on transients. Gate mode holds the sustain level until you stop — the classic signal-generator behavior — while One-shot fires a complete envelope of a set duration, repeatable click-free test shots every time. Sweep mode turns the generator into a chirp source. A logarithmic sweep from 20 Hz to 20,000 Hz spends equal time in every one of its ten octaves, which is why log chirps are the standard stimulus for speaker frequency-response checks and room-mode hunting: sweep the bass slowly and listen for spots where the level blooms (a room mode) or the cabinet buzzes (a mechanical fault). Linear sweeps concentrate time in the treble and are handy for finding narrow resonances up high. The readout shows the span in octaves so you can note exactly what a chirp covered. The dual oscillator earns its place at tuning time. Two oscillators at the same frequency detuned by a few cents produce audible beats at their difference frequency — detune 440 Hz by 4 cents and you hear roughly one beat per second. Musicians and piano technicians tune by eliminating exactly these beats, and the ±100 cent range covers a full semitone for interval training. The mix control sets the balance between the two. Channel routing sends the signal to the left speaker, the right, or both — the quickest way to verify wiring polarity mistakes, a dead channel on an amplifier, or a swapped pair behind an AV rack. Combine it with a low-frequency tone to confirm which subwoofer channel is actually driven. Finally, the export section renders the exact current configuration — tone or sweep, envelope, oscillator mix, routing — offline at 44.1 kHz stereo and downloads it as a 16-bit WAV or a 192 kbps MP3, from a tenth of a second up to a full minute. Load the file onto a phone or USB stick and you have a repeatable test signal for installs where a laptop and browser are impractical.