Synth Pad

Listen & Download

What Is This Sound?

This is a synthesized ambient pad sound created entirely using web audio synthesis — no samples, presets, or recordings involved. The warm, evolving texture you hear is generated in real-time by your browser, producing a lush, slowly moving soundscape built from detuned sawtooth oscillators and a modulated lowpass filter.

Synth pads are the foundation of ambient music, film scores, and atmospheric game audio. They fill sonic space with rich harmonic content while remaining unobtrusive — a sustained bed of sound that supports melodies, dialogue, and other foreground elements without competing for attention.

How Is the Synth Pad Created with Code?

The pad sound uses detuned unison oscillators processed through a modulated lowpass filter with a slow attack. Here is the Tone.js implementation:

Step 1: Create Two Detuned Sawtooth Oscillators

The richness of a pad comes from running two sawtooth oscillators at the same fundamental frequency but slightly detuned from each other. This creates a natural chorus effect through acoustic beating:

const osc1 = new Tone.Oscillator({
  type: "sawtooth",
  frequency: 261.6,
  detune: 7, // +7 cents sharp
});

const osc2 = new Tone.Oscillator({
  type: "sawtooth",
  frequency: 261.6,
  detune: -7, // -7 cents flat
});

Step 2: Apply a Modulated Lowpass Filter

Raw sawtooth waves are harsh and buzzy. A lowpass filter tames the high harmonics, and a slow LFO sweeping the filter cutoff between 400 Hz and 1200 Hz adds gentle movement and warmth:

const filter = new Tone.Filter({
  type: "lowpass",
  frequency: 800,
  Q: 1,
});

const lfo = new Tone.LFO({
  frequency: 0.2,
  min: 400,
  max: 1200,
});
lfo.connect(filter.frequency);
lfo.start();

Step 3: Add a Slow Attack Fade-In

Pads are defined by their gradual onset. A 1.5-second fade-in gives the sound its characteristic slow bloom:

const gain = new Tone.Gain(0);
gain.gain.rampTo(0.5, 1.5);

osc1.connect(filter);
osc2.connect(filter);
filter.connect(gain);
gain.toDestination();

osc1.start();
osc2.start();

Step 4: Signal Chain

2× Sawtooth Oscillators (±7 cents detune) → Lowpass Filter (LFO 0.2Hz, 400–1200Hz) → Slow Gain Fade-In → Speakers

The Science Behind the Synth Pad

Detuned Unison and the Beating Effect

When two oscillators play the same note with a slight frequency difference, they create acoustic beating — a slow amplitude fluctuation at the difference frequency. With ±7 cents of detuning at 261.6 Hz (middle C), the two oscillators differ by approximately 2.1 Hz, producing a gentle pulsing chorus effect. This is the same principle behind the rich sound of a 12-string guitar or a string ensemble where no two instruments are perfectly in tune.

The sawtooth waveform is ideal for pads because it contains all harmonics (both odd and even) at decreasing amplitudes. This provides maximum harmonic raw material for the filter to sculpt, resulting in a rich, full-bodied sound.

Filter Modulation and Perceived Warmth

The lowpass filter removes high-frequency harmonics, softening the harsh sawtooth into something warm and inviting. The LFO-driven cutoff sweep at 0.2 Hz (one cycle every 5 seconds) creates a slowly evolving timbral shift that the brain perceives as organic movement. Without this modulation, the pad would sound static and lifeless. The 400–1200 Hz sweep range was chosen to stay within the frequency band where timbral changes are most perceptible to human hearing.

Why Slow Attack Defines a Pad

The 1.5-second attack time is what makes this sound a “pad” rather than a “lead” or “brass” sound. Sounds with slow onsets are processed differently by the auditory cortex — they are perceived as non-threatening, ambient, and environmental rather than event-like.

Frequency Spectrum

Common Uses

• Ambient Music Production — The foundational texture for ambient, new age, and drone music genres
• Film & TV Scoring — Atmospheric beds underneath dialogue, establishing mood in dramatic scenes
• Game Audio — Background ambiance for menus, cutscenes, exploration areas, and emotional moments
• Meditation & Wellness Apps — Soothing, continuous background audio for guided meditation and relaxation
• Podcast & Video Intros — Subtle atmospheric element for setting tone in content introductions
• Live Performance — Sustained harmonic bed for live electronic or experimental performances

Technical Details

Frequently Asked Questions

Can I use this pad sound in my music?

Yes. The sound is generated by code in your browser. The downloaded WAV file is yours to use freely in any personal or commercial project, including released music, film scores, and game soundtracks.

How do I change the key?

Change the frequency value of both oscillators. For example, use 329.63 Hz for E4, 392.00 Hz for G4, or 440.00 Hz for A4. The detune, filter, and LFO settings can remain the same regardless of the fundamental pitch.

Can I make it sound darker or brighter?

To make it darker, lower the LFO max value from 1200 Hz to 600 Hz. To brighten the pad, raise both LFO min and max values (try 800–2400 Hz) and increase the filter Q slightly for a subtle resonant peak. You can also switch to triangle wave oscillators for a softer, darker character.

How do I loop this seamlessly?

The 3-second output can be looped directly. For the smoothest results, ensure the LFO completes a full cycle at the loop boundary, or apply a short crossfade at the splice point in your DAW. Since the LFO runs at 0.2 Hz, a 5-second duration would create a perfect single-cycle loop.