The Mastro Valvola LEM Lysergic Emotions Module is a multi-head delay pedal with 8 effect modes, made by the Italian pedal builder Mastro Valvola. The maker describes it as designed to inspire dreamy and experimental ambiances, and Pedal of the Day's reviewer found it easy to run into unique, hypnotic or unexpected sound environments like shimmering repeats, reverse delays, multi-head modulations, pitch shifting, lo-fi sounds and more12. Alongside the delay modes it also works as an ambient reverb unit: Delicious Audio's Paolo De Gregorio called it "a tap-tempo and preset enabled ambiance machine" when the pedal was unveiled3.
What the LEM does
The LEM is built around eight ambiance types, and the modes cover a wide spread of delay territory. Pedal of the Day's reviewer, who demoed all 8 effect modes, described the pedal as packing "a boatload of delay options into an extremely pedalboard-friendly enclosure"1. The multi-head design takes its cue from tape delay behavior, where several playback heads produce repeating patterns rather than a single repeat, and the modes extend that idea into shimmering, reversed, pitch-shifted and lo-fi effects12.
Practical performance features sit on top of the modes:
- Tap Tempo for on-the-fly adjustment while playing13
- 4 on-board presets, plus a secondary control section12
- Separate Dry and Wet controls, so the clean signal and the effect level are set independently2
- A CTRL input that accepts an expression pedal, CV control or a remote switch2
The CTRL input is worth noting for players who automate their board: Pedal of the Day's reviewer pointed out that "External and CV control add more options into the mix"1, meaning a parameter can be swept in real time rather than only turned by hand.
Bypass and switching
Mastro Valvola specifies true bypass with a Timed Bypass System (TBS), which the maker says exists "to manage the trails and the bypass switching style"2. In practice that addresses a common question with ambient delays: whether the repeats cut off instantly when you switch off or fade naturally. The TBS gives the player control over how the trails and the switching behave.
Versions: black and limited
The LEM has been offered in more than one version. Mastro Valvola's product pages list a black version, described as "New and unique version in black anodized aluminum," and a limited version, listed as "LEM - lysergic emotion module - limited"256. Both the black and limited versions were listed at 295,00 € EUR on the maker's pages, the black version as of 2023-12-12 and the limited version as of 2023-06-16467.
Where it came from
Mastro Valvola lists the LEM, the Lysergic Emotions Module, at 295,00 € EUR, with black and limited versions offered at the same price8. The maker describes it as a multi-head delay pedal with 8 effect modes, designed to inspire dreamy and experimental ambiances21.
The LEM sits in Mastro Valvola's line alongside the TimeLab Multi Delay9. For a wider view of where the LEM fits among delay designs, see the site's Delay Pedals page.
What reviewers said
Pedal of the Day's review is the most detailed published account. The reviewer summed up the pedal's range this way:
"it's easy to run into unique, hypnotic or unexpected sound environments like shimmering repeats, [reverse delays], multi-head modulations, pitch shifting, lo-fi sounds and more"
The same review highlighted the pedalboard-friendly enclosure, the tap tempo, the four presets and the external and CV control as the features that make the modes usable in a live setting1.
Videos
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Questions
What does LEM stand for on the Mastro Valvola pedal?
LEM stands for Lysergic Emotions Module, sometimes written Lysergic Emotion Module on Mastro Valvola's product pages. It is the Italian maker's multi-head delay pedal, a name that points to the psychedelic, experimental sound environments the pedal is designed to produce.
Is the Mastro Valvola LEM true bypass?
Yes. Mastro Valvola specifies true bypass with a Timed Bypass System (TBS), which manages the trails and the bypass switching style. That means you can choose how the delay tail behaves when you switch the pedal off, rather than having the repeats cut off abruptly.
How many presets does the LEM store?
The LEM stores four on-board presets, according to both Mastro Valvola's product page and Pedal of the Day's review. The pedal also has a secondary control section alongside those preset slots.
Can I use an expression pedal with the Mastro Valvola LEM?
Yes. The LEM has a CTRL input that accepts an expression pedal, CV control or a remote switch. Pedal of the Day noted that external and CV control add more options to the pedal, so you can move a parameter in real time while playing.
Does the LEM have tap tempo?
Yes. Mastro Valvola describes the LEM as a tap-tempo and preset enabled ambiance machine, and Pedal of the Day's review notes that Tap Tempo lets you adjust what you are doing on the fly during a performance.
Can the LEM be used with synths and bass?
Yes. Mastro Valvola states the LEM's inputs are for guitar, bass, synth and any other stuff, so it is not limited to guitar. Players running keyboards or bass through pedalboards can use it as an ambient delay and reverb unit.
Sources (9)
- Mastro Valvola LEM Lysergic Emotions Module Delay, Pedal of the Day, 2025-04-01
- Mastro Valvola pedals, Mastro Valvola, 2023-01-25
- Mastro Valvola LEM Ambient Delay/Reverb, Delicious Audio, 2021-05-10
- Love Buzz, Mastro Valvola, 2023-12-12
- TimeLab - multidimensional delay - Mastro Valvola, Mastro Valvola, 2023-05-23
- OFF1 - Octave Fuzz Filter - Mastro Valvola, Mastro Valvola, 2023-06-16
- LEM - lysergic emotion module - black - Mastro Valvola, Mastro Valvola, 2022-03-04
- Mastro Valvola gets ethereal with its LEM delay pedal, guitar.com
- Mastro Valvola Launches TimeLab Delay Pedal, premierguitar.com, 2015-01-13
