Additive Synth Playground

Additive Synth Playground · harmonic laboratory

Stack sine waves into a new timbre.

Raise eight harmonic drawbars. Their exact integer frequencies assemble the waveform and sound you see.

Sculpt the spectrum: each vertical drawbar sets one sine partial at 1× through 8× the fundamental. Tap a ratio badge—or press number keys 1–8 while the lab itself is focused—to audition that partial alone. Arrow keys adjust drawbars and move among pitch/recipe buttons; the Fundamental tray transposes the whole bank and Spectral recipes load editable level sets. The spectrum loom remembers two complete eight-partial states: imprint A or B, then drag between them to hear every amplitude interpolate rather than jumping presets. Sound: “Hold the assembled timbre” sustains the mix, “Climb the harmonic ladder” schedules active partials low to high, “Lower every drawbar” demonstrates the zero-component case, and Chamber level trims the output. With the lab itself focused, M moves the loom through A, midpoint, and B. How to play folds this guide and Fullscreen expands the lab. Tip: imprint Hollow reed into A and Bright brass into B, then listen for the spectral center climbing.

Sum waveform

C3 · 8 partials

y(t) = Σ aₙ sin(2πnf₀t)center 406 Hz

Harmonic drawbar bank

integer multiples of f₀

8C3
131 Hz

6C4
262 Hz

5G4 +2¢
392 Hz

4C5
523 Hz

3E5 −14¢
654 Hz

2G5 +2¢
785 Hz

1B♭5 −31¢
916 Hz

1C6
1.05 kHz

Fundamental tray

concert A = 440 Hz

Spectral recipes

editable starting points

Spectrum loom A 100% · B 0%

Drawbar organ: a balanced integer spectrum with a firm fundamental.

Audition chamber

gate closed

Chamber level38%

Use this interactive widget to create sounds through stacking of sine waves. Drawbar-style vertical sliders controls the tone. You can use a keyboard or a mouse to control it. Press the keys to use the controls and hear the sound. Click on them to adjust the sound in real time.

In the middle is the harmonic drawbar bank. Each vertical slider represent a different harmonic partial. The bottom slider control the fundamental frequency. Above are integer multiples of the fundamental. As you drag a slider up, it raise the volume of that sine wave. Dragging it down will remove it from the mix.

How to Use the Sound Widget

To the left is the scope display which give you a combined waveform to see how your adjustments change the sound texture. Auditioning each partial separately allow you to hear how it contributes to the overall blend. To do this, click on the little number badge over any of the sliders to audition that single frequency. Or, better yet, press the keyboard numbers from one to eight. A quick burst of that harmonic is triggered. It’s training your ears to hear what’s lacking or overly present.

The arrow keys allows you to jump around among the pitch buttons as well as all recipe options. Change the base note. You also have the option to change the base note of the instrument with the Fundamental tray. Here you can click on one of six button to set the pitch to C3, D3, E3, F3, G3 or A3. The other harmonic sliders then moves to match this new root frequency. So you can listen to the same harmonic balance at varying pitches in musical scale. You can choose these by using the arrow keys too if you prefer not to use your mouse.

For sound design there are spectral recipes as well that give you a jumping off point. They’re buttons that will load up a set of settings on the sliders for a particular type of sound. For example: there’s a bright brass texture, an organ that’s balanced, a hollow reed, and just a pure sine wave. Clicking one of them loads all the sliders and sets them to those kinds of setting. Then from there you adjust the sliders individually to sort of dial in the preset. That’s pretty nice if you need to move quick around different tonal family sounds.

Finally we have some way of combining sounds that is more sophisticated than sliders. Clicking one of the Imprint buttons saves the state of the sliders in either slot A or slot B. After you fill both slots, you can use the slider below to morph from one to the other. The loom will then smoothly blend the level of each partial giving a smooth transition between different timbres. To step through the morph positions press the M key.

Click on the big button marked Hold the assembled timbre and it will hold the currently selected mix, keeping the sound playing even after you release the button. Pressing the Climb the harmonic ladder button will starts a series of ascending active partials. To reset everything back to zero and start again press the Lower every drawbar button. The Chamber level slider allow you to control total output level.

How do you put it to good use? Some practical advice follows: For a thin tone, try using just a few harmonics above the fundamental. To get a warm sound, cut out the higher partials and emphasize the ones below. Put contrasting recipes into slots A and B on the Spectrum Loom to produce evolving textures. Move the sliders around and watch the waveform scope transform simple sine waves into complex shapes. The sound’s harmonic content is completely under your control.

Where you place the sliders isn’t right or wrong. Try setting one slider high to isolate the seventh partial for a dissonant effect, or balance all eight for a rich chord. Small adjustments to levels can radically change the character of the sound. Enjoy the responsive user interface that gives instant feedback via audio. Begin with your favourite basic pitch. Load up one of the recipes as a starting point and start adjusting the drawbars from there. Really listen out for the part each harmonic plays in the overall texture. Engage the ladder function to trigger a sequence of active partials. It’s an instrument designed to be played with audibly and is a tool for discovery. Play around with the sliders and buttons. What will you produce?