The Sushi Box FX Ambassador is a high-voltage tube overdrive pedal based on a classic Matchless circuit, built to put that amp's Vox-derived voice on a pedalboard. Instead of op-amps or transistors, it carries two 12AX7 tubes running at full voltage, and the maker describes it as "a great way to get that classic Vox chime out of any amplifier in a convenient pedalboard-friendly package."1 It sits among overdrive pedals rather than distortion pedals: the aim is touch-sensitive breakup and chime, not heavy clipping.
Controls and power
The Ambassador keeps its faceplate simple, with four knobs covering gain, volume and EQ1:
| Control | What it does |
|---|---|
| Gain | Sets how hard the tubes are driven |
| Master | Sets the pedal's output level |
| Bass | Cuts or boosts low end |
| Treble | Cuts or boosts high end |
A single footswitch handles bypass.1
Power is where the Ambassador differs from nearly everything else on a board. It runs on 9 to 12 V DC with center-negative polarity, "like most guitar pedals," but the tubes make it hungry: Sushi Box FX specifies 900mA at 9V DC during warmup, settling to 480mA at 9V DC once warmed up.1
A standard daisy-chain output or a low-current digital-pedal outlet will not run this pedal. Your supply needs a dedicated high-current output that covers the 900mA warmup figure at 9V DC.1
Status and what it sounds like
The Ambassador is listed as Archived on the Sushi Box FX product page as of October 2026, so it is no longer part of the active lineup.1
As for tone, the maker's own description is the reference point: the Matchless-based circuit and 12AX7 tubes are there to deliver "that classic Vox chime out of any amplifier in a convenient pedalboard-friendly package."1 Matchless amps built their reputation on a Vox-style circuit voice, and the Ambassador translates that into a pedal format rather than asking you to carry the amp.
Questions
Is the Sushi Box FX Ambassador discontinued?
The Ambassador is listed as Archived on the Sushi Box FX product page as of October 2026, which means it is no longer an active product in the lineup. If you are looking at one secondhand, note that it is a high-voltage tube pedal with unusual power demands, so a standard daisy-chain supply will not run it.
What tubes does the Ambassador use?
The Ambassador uses two 12AX7 tubes. Because it is a high-voltage tube design rather than a starved-plate circuit, the tubes run at full voltage, which is why the pedal draws considerably more current than a typical solid-state overdrive.
Why does the Ambassador draw more current while warming up?
Tube heaters pull extra current as they come up to temperature. Sushi Box FX specifies 900mA at 9V DC during warmup, dropping to 480mA at 9V DC once the pedal has warmed up. Your power supply needs to cover the higher warmup figure.
Is the Ambassador center-negative?
Yes. Sushi Box FX states the Ambassador is center-negative, like most guitar pedals, so it uses the same barrel-plug convention as a typical pedalboard supply, just with far more current on tap.
Does the Ambassador sound like a Vox amp?
Sushi Box FX describes the Ambassador as a great way to get that classic Vox chime out of any amplifier in a convenient pedalboard-friendly package. The circuit is based on a classic Matchless design, and Matchless amps are themselves known for that Vox-derived voice.
Sources (1)
- Ambassador, Sushi Box FX