Ultimate Guide To
Guitar Tremolo & Vibrato

Differences between Tremolo, Vibrato and Rotary Simulator Pedals

Let’s start by debunking myths. Tremolo, Vibrato and Rotary Sim are not the same thing! Contrary to popular belief these effects are actually very easy to tell apart, and this can only be done once you understand the terminology.

Tremolo is a steady increase and decrease in volume.

Vibrato is a steady increase and decrease in pitch.

Rotary Sim is a steady increase and decrease in both pitch and volume due to the Doppler effect.

Vibrato and Tremolo modulation both affect your signal in a similar sort of rhythm, and due to that in-and-out of phase sound, you can understand why they could be easily confused.

If you’re after a warbly, underwater type sound with an undulating and motion then go for a Vibrato pedal. If you’re after a more stuttery, staccato pulse then you should consider a Tremolo pedal.

It’s also worth noting that the famous tremolo arm on the Fender Stratocaster was incorrectly named. This name stuck and now, unfortunately, most of the guitar community don’t know the difference between the two.

A Strats trem arm actually produces a vibrato effect because it alters the pitch and not the volume! Mind blown?

The Tremolo effect sounds absolutely gorgeous on a mildly driven or clean amp. When used subtly it can give your tone depth and space that really allows your chords to breathe.

Tremolo Effect in Tube Amps

It would be impossible to speak about guitar Tremolo without speaking about its place in guitar tube amps. Fortunately, these days you can find very convincing tremolo sounds in a guitar pedal which means you don’t need to cart around a massive amp in order to achieve that sound.

As most guitarists often say, nothing really beats a good tube amp. This may be true for Tremolo to, but thanks to pedal designers like Wampler and Keeley, we can now achieve tones that are as good in a simple stompbox format.

Notably, the Fender Tremolux and Vibrolux were some of the first amps with trem on-board. The effect was achieved by simple ‘bias wiggle’ where the bias of the amp was modulated (turned off and on) in a pure sine wave form. This means it had a steady, even rhythm that produced a lush, warm, pulsating sound.

Optical Tremolo

Later, Fender Blackface and Fender Silverface amps actually used an optical tremolo which produces the effect with a light dependent resistor called an ‘optocoupler’ or more commonly, the photocell.

An LFO is used to turn the bulb on and off which in turn will turn the signal up and down creating a very smooth, pulsating tremolo sound. This type of tremolo is much easier to use in the context of a normal song because you aren’t creating choppy, staccato effects.

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Which Tremolo?

Whilst the options are vast, you’ll need to decide if you want a lush, slow-moving trem or a harsh staccato sound for EDM type guitar sounds.

Note: You might want a Tremolo with a Tap Tempo if you’re pedantic about making sure your modulation is in time with the song you’re playing. Just like delay, this can make or break a song – you don’t want to sound out of time.

Vibrato pedals tend to be more aggressive sounding than tremolo. Though it works in a very similar way you’ll notice that you can get quite different sounds out of a vibrato pedal. Imagine Vibrato as a chorus pedal with slightly more attack and pitch variation.

Modern Vibrato pedals are available in two formats:

• Standard Stompbox-Style
• Expression pedal – This allows you to control the intensity of the effect with your foot as you would a wah pedal which means you can as creative as you want to be.

Rotary Sim pedals are based on the mighty Leslie Speaker which was invented in 1941. The effect gained popularity throughout the 60s and 70s with artists like Jimi Hendrix and The Beatles using it to full effect for otherworldly, psychedelic sounds.

History of the Leslie Cabinet

The Leslie Cabinet was initially intended for use with an organ, but electric guitarists decided to experiment and the rest is, well, history.

It works using the doppler effect. When the speaker rotates it gives the impression the volume and pitch altering due to the soundwave being closer and then further away.

Ultimately, you could describe the Rotary Sim effect as a combination of Tremolo and Vibrato because it captures both effects in one unit. In this regard, you can easily achieve fairly ‘out there’ sounds. And it tends to marry up with a steady spring reverb beautifully.

Rotary Sim in Stereo

The Rotary Sim definitely sounds best when used in stereo because then you get a truer sense of the cabinet rotating in between the 2 speakers. When using Rotary Sim in mono you do get a similar effect but with a little bit less width. This same effect can be achieved by using a Vibrato and Tremolo pedal together.

It’s worth remembering that the original Leslie Cabinet had a built-in preamp which drove the sound of the organ. This preamp can add a touch of gain to your guitar signal giving you a harmonic, driven response that you wouldn’t really get from another pedal.

Where should I put Tremolo, Vibrato or Rotary Sim in the signal chain?

The Tremolo, Vibrato or Rotary Sim pedals can slot into different places on your board but should probably be kept towards the end of your signal chain due to the pedal varying the volume of the entire signal.

Important Notes:

• The Tremolo effect can be completely destroyed by running it before a compressor because it tries to diminish the changes in volume.
• When running a tremolo with high-depth settings (ie. The volume goes all the way down) you can affect the delay repeats – this is because the signal simply isn’t going into the delay pedal.
• You can use amp tremolo and pedal tremolo at the same time with different settings for interesting, creative results.