The Pedal Projects Undertow Tremolo is an all-analog optical tremolo pedal, described by Pedal of the Day as "an all-analog optical machine that features both simple controls and complex sounds"1. Optical tremolo works by varying the guitar signal's level with an internal light, producing the pulsing volume swell that defines the tremolo effect. The Undertow is a compact stompbox format pedal2.
Controls and wave shapes
The Undertow keeps its control layout simple. Speed and Depth knobs set the rate and intensity of the pulsing, the two controls Pedal of the Day called "pretty essential to make any tremolo pedal work at all"1. A Volume knob rounds out the front panel, and a toggle switch selects between two wave shapes1.
| Control | What it does |
|---|---|
| Speed | Sets the rate of the tremolo pulse1 |
| Depth | Sets the intensity of the effect1 |
| Volume | Sets output level; can act as a boost1 |
| Toggle switch | Selects Sine wave or Square wave mode1 |
The two wave settings behave differently. Pedal of the Day's reviewer, Mike B, described the difference: "Sine tends to be smoother, a bit more mellow and lying underneath your guitar's tone, while the Square wave gets incredibly intense, and will produce thick, choppy sounds if given the opportunity"1.
One extra option sits inside the pedal rather than on top of it: the brightness of the LED can be set internally, which the reviewer counted as "one more option to this gorgeous analog stompbox"1.
Volume as a boost
The Volume knob is always present in the circuit, and that makes the Undertow usable beyond straight tremolo. Mike B found it "can really give a much-needed boost to your rig," whether used to bring the tremolo to the forefront of the amp or as an effect booster in its own right1. Players comparing it with a dedicated clean boost should note the Undertow's boost function is tied to the same knob that sets the effect's output level.
What reviewers said
Pedal of the Day's 2015 review came away favorably, describing the Undertow as producing "wonderfully rich, warm and intense throbbing vibe sounds, with a big range in the middle for a multitude of options"1.
"Dynamic, expressive, bold and aesthetically pleasing as well, the Undertow would a perfect fit on many pedalboards."
Videos
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Pedal of the Day
Questions
Is the Pedal Projects Undertow analog or digital?
The Undertow is an all-analog optical tremolo. Pedal of the Day's review described it as an all-analog optical machine with simple controls and complex sounds. Optical tremolos use an internal light and sensor to vary the signal level, which is how the Undertow shapes its pulsing volume effect without digital processing.
Can you adjust the LED brightness on the Undertow Tremolo?
Yes. The LED brightness can be set internally, inside the pedal rather than from an external control. Pedal of the Day noted this as one more option on the Undertow, useful for players who want the indicator light to match the rest of a pedalboard's look or visibility on a dark stage.
Can the Undertow Tremolo be used as a volume boost?
Yes. The Volume knob is always present in the circuit, and Pedal of the Day's reviewer found it can give a much-needed boost to a rig, whether used to bring the tremolo effect to the forefront of the amp or simply as an effect booster on its own.
What is the difference between sine and square wave tremolo?
On the Undertow, a toggle switch selects between Sine and Square wave settings. Sine tends to be smoother, a bit more mellow, and lies underneath the guitar's tone. Square wave gets incredibly intense and produces thick, choppy sounds when pushed, giving the two modes distinctly different characters.
Sources (2)
- Pedal Projects Undertow Tremolo, Pedal of the Day, 2015-05-23
- Pedal Projects Undertow Tremolo, Pedal of the Day, 2015-05-13