The Sushi Box FX Mayday is a compact, clean tube preamp with a flexible active EQ, built as a pedal and doubling as a DI box for recording or going direct to a front of house desk. Sushi Box FX positions it in its Pedals, DI and Preamp categories, and the maker's product page prices it at $300.00 through $313.00 USD as of the page dated 2026-10-251.
At its heart is a 12AU7 tube running at high plate voltage, which the maker says "brings unparalleled warmth and depth to your tone"1. The four-band active EQ is the other half of the design: Sushi Box FX describes it as helping you "dial in whatever sound you need for any style of music"1.
Outputs and the DI transformer
The Mayday gives you two ways out of the pedal: "a preamp-affected unbalanced 1/4″ output and a transformer-coupled balanced XLR D.I. output for flexibility"1. In practice that means your amp can take the 1/4-inch signal while the XLR feeds a mixing desk or audio interface with a balanced, preamp-shaped signal.
The DI side is built around an Unagi Magnetics E4305 transformer, custom-made to Sushi Box's specification. The maker says it "was designed specifically for use with tube preamps and was designed with bass in mind, giving a full-range flat response" down to 10Hz1. That low-frequency reach matters to bass players, since a DI that rolls off the bottom end defeats the purpose of a clean tube preamp in front of it.
The four-band active EQ
An active EQ lets you both cut and boost each band, and the Mayday's four bands are centered at frequencies chosen to cover the useful range of a guitar or bass signal1:
| Band | Center point |
|---|---|
| Bass | 60Hz |
| Lo Mids | 250Hz |
| Hi-Mids | 1kHz |
| Treble | 7kHz |
With centers spread from deep bass into the upper treble range, the EQ covers everything from tightening low end to adding presence, which is what makes the maker's claim of dialing in "any style of music" plausible on paper1.
Power requirements
The Mayday needs a supply that can deliver at least 500mA at 9-12VDC. Sushi Box FX warns that "using less than this can damage the power supply and/or the pedal," so it should not share a daisy-chain supply with low-draw pedals1.
The maker's recommendation is "a 9-12VDC power supply capable of delivering at least 500mA"1. That is well above what most small pedals draw, so a dedicated supply output rated for the current is the safe choice. When ordering, the product page offers an "Include Power Supply?" option with Yes and No variants, so you can buy one with the pedal or use your own1.
Size
The enclosure measures 4.8 in x 2.64 in x 1.58 in (122 mm x 67 mm x 39.6 mm), a standard compact pedal footprint that fits a crowded board despite the tube inside1.
Where it sits in the Sushi Box range
Sushi Box FX builds a family of tube preamp pedals, and the Mayday's clean preamp plus DI layout sits alongside other designs from the maker, such as the Sushi Box FX Finally v3, the Sushi Box FX Venus Z and the Sushi Box FX Dr. Wattson X. For a wider view of the category, see Preamp Pedals1.
Videos
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Questions
What tube does the Sushi Box FX Mayday use?
The Mayday uses a 12AU7 tube running at high plate voltage. Sushi Box FX says this brings warmth and depth to the tone, and running the tube at high plate voltage is what lets a pedal-sized circuit behave more like a conventional tube preamp stage.
Does the Mayday have an XLR DI output?
Yes. The Mayday has both a preamp-affected unbalanced 1/4-inch output and a transformer-coupled balanced XLR DI output. The DI uses an Unagi Magnetics E4305 transformer, custom-made to Sushi Box's specification, which the maker says gives a full-range flat response down to 10Hz.
How much current does the Mayday need?
Sushi Box FX recommends a 9-12VDC power supply capable of delivering at least 500mA. The maker warns that using less than this can damage the power supply and/or the pedal, so a standard low-current pedal supply is not suitable.
Can I run the Mayday on a weak power supply?
No. The maker recommends a supply delivering at least 500mA at 9-12VDC and states that using less can damage the power supply and/or the pedal. Check that your supply meets that current rating before plugging the Mayday in.
Does the Mayday come with a power supply?
The maker's product page offers the Mayday with or without a power supply, as a choice when ordering: an 'Include Power Supply?' option with Yes and No variants.
What frequencies does the Mayday EQ cover?
The four-band active EQ has center points at Bass: 60Hz, Lo Mids: 250Hz, Hi-Mids: 1kHz, and Treble: 7kHz, according to Sushi Box FX.
Sources (1)
- Mayday - Sushi Box FX, Sushi Box FX
