Walrus Audio Monumental Harmonic Stereo Tremolo

The Walrus Audio Monumental Harmonic Stereo Tremolo is an analog, optical tremolo pedal with true stereo input and output, built as an evolution of the company's Monument line¹. It blends between standard tremolo, where all frequencies dip and rise together, and harmonic tremolo, where high and low frequencies are offset from each other, a voicing Walrus Audio describes as inspired by Fender Brownface amps¹².

Walrus Audio says the pedal produces "rich, luscious, warm pulsating modulation capable of peaks and valleys as smooth or as jagged as Monument Valley's"¹. It launched in April 2024 at $279³, and Walrus Audio's webstore lists it at $279.99⁴.

An analog optical harmonic tremolo in true stereo

The Monumental is the stereo successor to the Monument V2, which Walrus Audio has since discontinued⁵. Guitar Pedal X called it "at least a V3 edition of that circuit," noting that the Monument "evolves and becomes fully stereo with additional parameters and capabilities"⁶⁷.

In standard mode, all frequencies get affected at the same time. In harmonic mode, the high and low frequencies are offset from each other: a low-pass and high-pass version of the signal are modulated 180 degrees out of phase, which Walrus Audio describes as "a warm, almost 'chewy' tremolo"¹². Premier Guitar's reviewer noted that the pedal is "one of many that digitally approximates the elastic, phasey sound of brown-panel Fender harmonic tremolo"⁸.

The S-B-H knob blends between the two modes, and turning it counterclockwise gives more bite to the tremolo pulse and tames the out-of-phase harmonics¹⁹.

The controls

The Pan control is the stereo heart of the pedal. Counterclockwise, both channels share the same LFO for standard tremolo. Turned clockwise, it offsets the right channel's LFO phase; fully clockwise, the right LFO runs 180 degrees out of phase from the left, giving maximum panning¹².

The pedal also has two footswitches: a bypass switch and a tap tempo switch. The tap tempo footswitch sets the rate of the LFO, and tapping more times makes the rate more accurate; tap once to reset the rate³.

Power: 9V, 100mA

The Monumental runs on 9VDC to 12VDC, 100mA, center negative¹. There is no battery option; MusicRadar's review notes a 9V adapter is not supplied¹⁰. Running it at 12V is not about extra volume but headroom: at 9V the pedal has 1.7Vpp of headroom before the signal starts to distort, and a 12V supply raises that to 2.6Vpp¹⁴. Delicious Audio likewise notes it can be powered at either 9V or 12V for increased headroom¹¹.

Other specifications from Walrus Audio include an input impedance of about 1M, an output impedance of about 300 ohms, a frequency response of 40Hz to 20kHz, a noise level of -102.5dBu, and THD of 0.072% at -20dBu at 1kHz². The diecast enclosure measures 2.25" x 2.93" x 4.8" including jacks¹.

Presets, tap tempo and expression

The Monumental has three onboard presets plus an additional live mode, and each preset can save and recall every parameter¹. Press both footswitches simultaneously to cycle through the presets (Red, Green, Blue, with White being live), and hold both footswitches to save the preset¹. Live mode always returns to the current knob positions on the face of the pedal².

The Tap/Exp socket handles both tap tempo and expression, with internal dip switches configuring the jack⁶¹⁰. The pedal offers full expression control over every parameter⁹⁶. Tap divisions run from quarter notes through sixteenths⁷, and the pedal also has a Ramp function¹⁰, though MusicRadar flagged that the ramping speed is not adjustable¹⁰.

Mono and stereo use

The pedal can be used in mono; gearnews noted that "stereo is the way forward to get the full effect"¹². The jacks are labeled Mono Left In, Stereo Right In, Mono Left Out and Stereo Right Out⁶. Premier Guitar's reviewer put it more strongly:

MusicRadar's Trevor Curwen found the stereo behavior the pedal's high point, writing that "The pedal's crowning glory, however, is that it sounds stunning when used in a stereo role," with a huge stereo spread and a great sense of depth and movement¹⁰.

Versions and editions

The Monumental has been offered in orange/copper or black finishes¹³, with artwork by David Hüttner⁴². Walrus Audio also released a limited Black Friday 2024 Floral Series edition, offered as a blemished unit with cosmetic damage only, such as scratches or dents in the finish; it is now sold out¹⁹. Blemished units of the standard pedal have also been sold, again with cosmetic-only flaws².

What reviewers said

Reviews were largely positive. MusicRadar's Trevor Curwen concluded that "From the subtle to the extreme, Walrus Audio Monumental Stereo Harmonic Tremolo could satisfy all your tremolo needs," calling its comprehensive feature set "an extremely practical compact choice for onstage needs"¹⁰. His one listed reason to avoid was the non-adjustable ramping speed¹⁰.

Guitar World's review, also by Trevor Curwen, summed up:

Guitar Pedal X awarded it Gold in a 2024 round-up of new modulation pedals, calling it "One of the very best Harmonic Tremolos out there now," while noting it is "not quite as full flavour as the JAM Pedals Harmonious Monk"⁷. Premier Guitar noted the price step over its predecessor: "You'll pay 60 extra bucks for these extended capabilities"⁸.

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