The Complete Guide to Modulation Effects (Chorus, Phaser, Tremolo, Auto-Wah & Trance Gate)

Every effect in this guide is built on the same trick: an LFO — a low-frequency oscillator, a slow invisible wave — steadily moving one parameter of your sound up and down. Point that wave at pitch and delay and you get chorus. Point it at a chain of phase-cancelling filters and you get a phaser. Point it at volume and you get tremolo — or, if the wave is a hard on/off switch, a trance gate. Point it at a resonant filter and you get an auto-wah or a dubstep wobble. That's the whole modulation family: one moving wave, five very different personalities, from lush stereo shimmer to machine-gun stutter.

The good news is they all share the same vocabulary — Rate is how fast the wave moves, Depth (or Range, or Open) is how far it travels — so once you can dial in one, you can dial in all five. Each effect below is a free Quick Tool that runs entirely in your browser: no upload, no account, works on your phone. Here's every one of them, knob by knob.

#Chorus

A chorus takes a single performance and stacks shimmering, slightly-detuned copies of it across the stereo field — the sound of a lone vocal becoming a choir, or a flat synth blooming into something wide and dreamy. The Chorus tool gives you that ensemble shimmer with just three knobs.

#What a chorus effect is for

Chorus copies your signal, detunes the copies a hair, and slowly modulates them so they drift in and out of tune against the original. Your ear reads that motion as width and richness. Reach for it to:

• Fatten a thin lead vocal or backing vocals
• Widen a mono synth into a lush stereo pad
• Give clean guitars that classic '80s shimmer

#Dial in your chorus, step by step

1. Open the tool and load your audio.
2. Set Depth (0-100%, default 50%). This is the detune and modulation amount — how far the copies drift from the original. Higher Depth = thicker and more obvious; lower = subtle.
3. Set Rate (0.2-4Hz, default 1.2Hz). This is how fast the modulation swirls. Slow rates feel dreamy and gentle; faster rates get more shimmery and animated.
4. Set Mix (0-100%, default 60%). This blends the chorused signal against the dry original. Lower Mix keeps the original up front; higher Mix pushes the effect forward.
5. Preview, tweak, and export.

#Use the presets as starting points

• Lush — wide and shimmering, the big stereo treatment.
• Subtle — gentle thickening when you just want a touch more body.
• Dreamy — deep, slow swirl for pads and ambient textures.

Tap a preset, then nudge the three knobs to taste.

#Tips for a better chorus

• For width without wobble, keep Depth lower and let Rate stay slow.
• A faster Rate with high Depth pushes toward a vibrato-like warble — great for dreamy synths, too much for a vocal.
• Stack chorus before a reverb to make a part sound huge and far back.
• Backing vocals love high Mix; lead vocals want it dialed back.
• Depth vs Mix, in one line: Depth controls how much the copies detune and modulate; Mix controls how much of that effect you hear against the dry sound.

#Phaser

That swirling, underwater whoosh on funk guitars, electric pianos, and synth pads? That's a phaser. It sweeps a set of notches up and down through your sound, and the result is movement that feels funky one second and psychedelic the next. The Phaser tool gives you the whole sweep with three knobs.

#What a phaser does

A phaser runs your signal through a chain of all-pass filters that carve moving notches into the frequency spectrum. As those notches sweep, certain frequencies cancel and return in a continuous wave — the classic phaser swirl. It's perfect for:

• Funky rhythm guitar and clavinet
• Psychedelic synth pads and leads
• Adding slow, living motion to anything static

How is that different from a chorus? A phaser sweeps cancellation notches for a whoosh; a chorus detunes copies of your sound for width. Run the same loop through both and you'll never confuse them again.

#Build your phaser sweep

1. Open the tool and load your audio.
2. Set Rate (0.05-4Hz, default 0.5Hz). This is the sweep speed. Slow rates give a lazy, funky glide; faster rates get jet-like and whooshy.
3. Set Depth (20-100%, default 70%). This is the sweep range — how far the notches travel. More Depth means a wider, more dramatic sweep.
4. Set Mix (0-100%, default 60%). This blends the swept signal against the dry. Higher Mix makes the effect more pronounced.
5. Preview and export.

#Start from a preset

• Classic — a slow, funky sweep for guitars and keys.
• Jet Flange — fast and deep, a dramatic whooshing surge.
• Slow Drift — barely-there motion that just keeps a part alive.

#Tips for a great phaser

• For subtlety, pair a low Rate with moderate Depth and a Mix around 40-50%.
• Crank Depth to 100% with a faster Rate for that Jet Flange power-surge whoosh.
• Phasers shine on sustained sounds — pads, held chords, and ringing guitars — where there's room for the sweep to move.
• Automate nothing, just let the LFO breathe; a phaser is movement you don't have to draw in by hand.
• Can't hear it? Raise the Mix knob and make sure Depth isn't near its minimum — both control how obvious the sweep is.

#Tremolo

Tremolo is the oldest effect in the amp cabinet: an LFO that rhythmically turns your volume up and down. Slow it down and you get a gentle, breathing swell. Speed it up and it becomes a stuttering helicopter chop. The Tremolo tool gives you both ends of that range with just two knobs.

#What tremolo is for

Tremolo modulates amplitude — the loudness of your signal — on a repeating cycle. That single idea covers a lot of ground:

• Vintage surf-guitar and Rhodes shimmer
• Pulsing pads that feel alive
• Rhythmic, gated chops on synths and beats

(Note: tremolo moves volume. Vibrato moves pitch. They're often confused — this tool is volume, and pitch stays exactly where it was.)

#Dial in your tremolo

1. Open the tool and load your audio.
2. Set Rate (0.5-16Hz, default 5Hz). This is the pulse speed. Low rates give a slow swell; high rates turn into a fast chop or flutter.
3. Set Depth (0-100%, default 70%). This is how deep the volume dips on each cycle. Low Depth is a subtle shimmer; high Depth fully ducks the sound toward silence.
4. Preview and export.

Two knobs, endless feel — it's all in how you balance speed against depth.

#Start from a preset

• Amp Tremolo — that vintage, shimmering amp pulse.
• Helicopter — fast, hard chop that nearly gates the sound.
• Slow Swell — a gentle, breathing rise and fall.

#Tips for better tremolo

• High Depth + high Rate is the helicopter/gate sound — great for a quick rhythmic effect on a held synth note.
• Keep Depth modest on full mixes so the track pulses without ducking out entirely.
• A slow Rate with moderate Depth is perfect for adding life to a static pad.
• Want hard on/off chopping rather than a smooth wave? Reach for the Trance Gate tool instead — more on that below.

#Auto-Wah / Wobble

One effect, two famous sounds. Slow a resonant filter sweep down and you get the funky quack of an auto-wah. Speed it up and crank the resonance and you get a dubstep wobble bass. The Auto-Wah / Wobble tool is that LFO-swept filter, and three knobs take you from one to the other.

#What it does

The tool sweeps a resonant filter up and down with an LFO. As the filter moves, it emphasizes different frequencies, creating that vocal "wah" or growling "wob." Use it for:

• Funky guitar, clavinet, and synth (auto-wah)
• Aggressive dubstep and bass-music wobbles
• Subtle movement on pads and leads

#Dial it in

1. Open the tool and load your audio.
2. Set Rate (0.1-10Hz, default 2Hz). This is the sweep speed. Slow rates give a relaxed, funky wah; fast rates give the rhythmic dubstep wobble.
3. Set Range (20-100%, default 70%). This is the filter sweep range — how far the filter travels. More Range means a more dramatic, full sweep.
4. Set Bite (0-100%, default 60%). This is the resonance — the "vocal" emphasis at the filter peak. More Bite means a sharper, more aggressive quack or growl.
5. Preview and export.

#Start from a preset

• Auto-Wah — slow, funky sweep for guitars and keys.
• Wobble — fast and dubstep-y, with that growling bass movement.
• Gentle Sweep — subtle movement to keep a part breathing.

#Tips for a better sweep

• For a clean auto-wah, keep Rate low and Bite moderate — too much resonance gets shrill.
• For dubstep wobbles, start with the Wobble preset, then push Rate higher so the wob lines up with the beat and Bite up for more growl.
• Big Range + high Bite is the most dramatic, in-your-face setting; pull both down for the Gentle Sweep vibe.
• Bass and mid-range synths take the sweep best, since there's plenty of harmonic content for the filter to chew on.

#Trance Gate

You know the sound: a sustained synth chord chopped into crisp rhythmic chunks, pulsing in perfect time. That's a trance gate, and it's the same trick behind the Stranger Things synth stutter. The Trance Gate tool turns any held sound into that pulse with two knobs.

#What a trance gate does

A trance gate slams the volume hard on and off in a steady rhythm. Unlike a smooth tremolo wave, a gate is more like a switch — sound, silence, sound, silence — which is what gives it that tight, stuttering edge. It's made for:

• Sustained synth pads and chords
• Big, droning bass or vocal textures
• Any held sound that needs rhythmic energy

#Build your trance gate

1. Open the tool and load your audio (a long, sustained sound works best).
2. Set Rate (1-16Hz, default 8Hz). This is the pulse speed — how many chops per second. The default 8Hz lands right around that classic eighth-note feel.
3. Set Open (10-90%, default 50%). This is how much of each beat stays open (audible) before the gate slams shut. Low Open means short, tight clicks; high Open means longer chunks with brief gaps.
4. Preview and export.

#Start from a preset

• Trance Gate — the classic eighth-note pulse.
• Stutter — fast and tight, short stabs of sound.
• Slow Pump — a slower, breathing on/off pulse.

#Tips for a tighter gate

• Lower Open for the sharpest, most percussive stutter; raise it for a smoother, more connected pulse.
• A higher Rate with low Open gives that frantic, machine-gun Stutter feel.
• Drop Rate down and open it up for the Slow Pump breathing effect under a drop.
• Sounds muddy? You probably fed it an already-rhythmic part — gates work best on sustained, held sounds.
• Want a smooth volume wave instead of hard chopping? That's Tremolo.

#Which one do you reach for?

Effect	The LFO moves…	Sounds like	Best on	Tool
Chorus	Detuned copies of the signal	Width, shimmer, ensemble richness	Vocals, synths, clean guitars	Chorus
Phaser	Notches sweeping the spectrum	Swirling, psychedelic whoosh	Pads, held chords, funk guitar	Phaser
Tremolo	Volume, in a smooth wave	Vintage pulse to helicopter chop	Guitars, Rhodes, static pads	Tremolo
Auto-Wah / Wobble	A resonant filter	Funky quack or dubstep growl	Bass and mid-range synths, clav	Auto-Wah / Wobble
Trance Gate	Volume, as a hard switch	Rhythmic on/off stutter	Sustained pads, drones, held notes	Trance Gate

Same wave, five flavors — pick the parameter you want to move, load a preset, and let the LFO do the work.