What Does a Tremolo Pedal Do? How Does it Work?

Tremolo is the grandfather of all effects, as it was one of the very first to appear in music tech. Before the rack units and effects pedals came around, the oldest tremolos were found in guitar amps.

Because guitarists didn't have very many options when it came to getting cool and crazy effects, tremolos became the "far out," propelling it to popularity very quickly.

Many of you might use tremolo pedals or at least know the sound of the effect when you hear it, though many don’t know what it actually is.

In this article, we’re going to be exploring everything there is to know about the wonderful world of tremolo. This will allow you to utilize it to the best of your ability, giving you the understanding to help enhance your music. To start, let’s get down to the science of what’s going on behind the scenes.

What Is Tremolo?

Tremolo is, at its foundation, a modulation effect that manipulates your signal's volume.

Modern-day tremolo effects, however, vary quite a bit, meaning there are many different ways that they work to change your signal. With that said, there are a few characteristics that remain constant. For starters, all tremolos use LFOs, which create waveforms to adjust the signal volume.

The way that we make it a “musical” effect is by controlling how those waveforms adjust the signal volume. This is why if you look at the face of a tremolo pedal, you will typically see at least two controls: Rate and Depth.

​​Rate is the control that allows us to change the actual tempo of the oscillating waveform so that we can better match it to the tempo of the piece of music.

Depth controls the amount of volume loss with each change. Essentially, the higher the depth control, the more obvious your effect will be. Depending on the type of tremolo pedal that you get (which we will get into later), you can get some pretty drastic effect changes.

Check out the video below for some examples of these effects:

How Does Tremolo Work?

So now that you have a basic understanding of what tremolo is, it’s time to get into the actual circuitry.

The main thing that you should keep in mind is that the fundamental effect of tremolo is volume change. The loudest part of the signal that comes through (unless boosted with the tremolo pedal) is going to be however loud your dry signal is. The lowest point is going to depend on your depth setting.

As for the actual circuits, there are many different types used in tremolo pedals today. Typically, you’ll find that they make use of . The reason most tremolo pedals use VCA is that it's incredibly reliable and always provides the same sound. Others use LFO-based circuits as we talked about earlier, typically paired with high and low-pass filters. Lastly, there are companies that use. The signal is routed through a small bulb that flickers on and off, effectively turning the volume up and down.

As for the actual circuits, there are many different types used in tremolo pedals today. Typically, you’ll find that they make use of VCA (Voltage Controlled Amplifier). The reason most tremolo pedals use VCA is that it's incredibly reliable and always provides the same sound.

Others use LFO-based circuits as we talked about earlier, typically paired with high and low-pass filters.

Lastly, some companies use photocell components. The signal is routed through a small bulb that flickers on and off, effectively turning the volume up and down.

History Of Tremolo

Many people agree that a man named Harry DeArmond produced the very first electronic tremolo effects. In 1948, he created the 800 Trem Trol, a foot-operated unit that was comprised of a small motor that shook a sealed bottle filled with electrical contacts and conductive fluid.

Listen to the music of Bo Diddley, and you'll hear this tremolo in action, as he was one of the more popular artists to use it.

​It wasn’t until the early 1950s that companies started putting their tremolo effects into guitar amplifiers. One of the more popular iterations of the tremolo could be seen on the early Fender Tremolux.

These tremolo circuits used very few components and a part of the preamp circuit tube. They worked thanks to bias wiggle - The bias of a tube was turned on and off using a pure sine wave. This created the choppy volume effect that we know and loved from Fender.

Types Of Tremolo

Tube Bias Tremolo

The tube bias tremolo is the original type of tremolo effect that comes from the bias of tubes in tube amps. It works by pushing a sine wave through power tubes to vary the bias. This helps to modulate the volume of those tubes, effectively creating a tremolo effect.

While many old Fender amps labeled this as "vibrato," those two effects are actually quite different.

One of the most popular songs of the late 50s that used tremolo in full force was "Rumble," by Native American Guitarist, Link Wray. You can hear the effect throughout the whole song, and you can also hear the depth being turned up near the end:

Optical Tremolo

Besides the tube bias tremolo, you could actually find quite a few different photocell tremolo components within classic Fender amps, especially the Blackface amps of the 1960s.

Guitarists love the optical tremolo because of the unmatched smooth sound that it creates.

With that said, optical tremolos can sound a bit messy and are difficult to sync. It creates somewhat of a pulsing effect that is perfect for creating a more “organic” sound.

One of our favorite optical tremolos out there is the Dazatronyx Optical Tremolo. It’s a true hybrid of vintage and modern components that create a wildly responsive and natural-sound tremolo effect.

Stompbox

Stompbox tremolo effects are pieces of modern technology that have been able to capture the sounds of tremolo in the form of a foot pedal. With stompbox tremolos, you can have anything from a simple footswitch with rate and depth knobs, to a wildly versatile interface with the ability to adjust different waveform shapes, tempo, tone, etc.

Stompbox modules are far more flexible than amplifier modules, though many of them still work to recreate classic sounds while adding a bit of a twist.

Some popular modern songs that make use of tremolo include “Boulevard of Broken Dreams” by Green Day, “Planet Telex” by Radiohead, and “Ultimate Painting” by Bills.

​​Continue reading more about tremolo types here: An In-depth Look into the Different Types of Tremolo

​Tremolo Wave Patterns

Triangle Wave Tremolo

The triangle wave tremolo is easily one of the most widely used tremolos, as it is the one that comes built into larger Fender amps. If you've ever played through a Fender Twin, you’ve most likely had your chance with a triangle tremolo.

The reason many people love triangle wave tremolos so much is that they have an even rise and slope, giving you an effect with clarity and linearity.

Check out the below video of the Fulltone Supa-Trem for a great example of smooth, triangle wave tremolo:

Sine Wave Tremolo

Sine wave tremolos can be found in many different amps as well, as they work by modulating power tubes. While it isn’t as popular or “accurate” as triangle tremolo, it does provide a much simpler, smoother, and drippier sound.

Sine waves change volume less linearly, meaning you will likely get a tremolo that is bit lopsided. This can be an incredibly cool effect if you don’t want that perfect, polished sound.

​Tremolo Vs. Vibrato

Thanks to the old labels on Fender amps, many guitarists confuse tremolo and vibrato. This is because Leo Fender began referring to the whammy bar on his guitar as a “tremolo arm” when in reality, it’s providing vibrato.

This is because there is no change in volume or dynamics when you play with the tremolo arm, but instead, a change in pitch. When you press down on the arm the pitch falls, and when you let it go, the pitch goes back to its original state.

Vibrato, even in its most subtle form, is a change in pitch, not a change in volume.

​At Any Rate…

Even though tremolo effects are simple at their core, they should never be underestimated. They can create some pretty impressive effects to help enhance your music in a way that is still organic.

Hopefully, by now, you have a good understanding of the circuitry of these pedals and how they function.