These three effects all wobble your sound, but they wobble different things. Tremolo moves your volume. Vibrato moves your pitch. A rotary speaker does a bit of both, plus some movement in space.
Tremolo
Tremolo turns your volume up and down in a steady pulse. It's one of the oldest guitar effects: many amps from the 1950s and 60s had it built in, often labeled "vibrato" by mistake.
The wave shape decides the feel:
- Sine (or triangle): smooth, gentle swells. Great for surf, country and moody ballads.
- Square: hard on/off chops, almost like a rapid stutter. Good for choppy rhythm parts and more aggressive sounds.
Rate sets the speed, Depth sets how far the volume drops. Try Depth around 2 o'clock and set Rate so the pulses line up with the song's beat or its eighth notes. Some tremolos have tap tempo, which makes this easy.
Vibrato
Vibrato bends your pitch slightly sharp and flat, over and over, like a singer's wavering note or a whammy bar wobbling. A little sounds lush and dreamy. A lot sounds wild and seasick. Keep Depth low (about 9 or 10 o'clock) to start, since even small amounts are very noticeable.
A word on the Uni-Vibe. Despite its name, it's built more like a phaser: it sweeps a set of filters to create a throbbing, watery swirl. Most Uni-Vibe-style pedals have a switch between "chorus" and "vibrato" modes; only the vibrato mode is pitch wobble. It's widely associated with Jimi Hendrix's late-60s sound.
Rotary
A rotary speaker (often called a Leslie, after the famous cabinet) physically spins a horn and a drum. That spin creates volume changes, pitch shifts from the Doppler effect, and a sense of sound moving around the room. Rotary pedals simulate this, usually with a slow and a fast speed and a switch to ramp between them. That ramp, speeding up or slowing down, is the signature sound.
When to use them
| Effect | Reach for it when |
|---|---|
| Tremolo | You want rhythmic pulse on chords |
| Vibrato | You want a dreamy, warped lead or chord |
| Rotary | You want organ-like swirl and motion |