The Sushi Box FX London Underground X is a tube preamp pedal based on the preamp of the Orange AD200B, the bass amplifier head the maker calls legendary. It carries a single 12AX7 tube and a five-knob control set of Bass, Gain, Master, Mids and Treble, with a single footswitch for bypass1. It sits in the preamp pedal category on the maker's site1.
Power and what it means on a board
The pedal runs on 9 to 12V DC with center-negative polarity, the same standard as most guitar pedals1. The current draw is the figure to plan around: Sushi Box FX lists 500mA at 9V DC during warmup, falling to 250mA at 9V DC after warmup1. That is well beyond what most daisy-chain outputs supply, so the pedal needs its own dedicated power output rated for the draw.
With a real 12AX7 tube on board and a warmup draw of 500mA at 9V DC, this pedal needs a dedicated high-current supply output rather than a shared daisy chain1.
Voicing and the Particle Accelerator option
Sushi Box FX describes the London Underground as having some similarities to the Underground Accelerator family's Particle Accelerator, but says that aside from a different voicing, the London Underground also gets more drive when the gain is turned up1.
"It has some similarities to Particle Accelerator, but aside from a different voicing London Underground also gets more drive when the gain is turned up."
A popular request, according to the maker, was a London Underground with a Particle Accelerator tone stack, which gives the bite of the London Underground with that voicing. Sushi Box FX offered this option at no additional cost, requested by noting "PA tone stack" in the notes section when ordering1.
Availability
The London Underground X is listed as archived on the maker's site, with a list price of $180.00 USD shown alongside that status2. In other words, it is no longer part of Sushi Box FX's current lineup, though the maker's product page still documents its specifications.
Questions
Is the Sushi Box FX London Underground X still available?
The London Underground X is listed as archived on Sushi Box FX's own product pages, so it is no longer part of the maker's current lineup. The maker's page still documents its specifications, including the 12AX7 tube, the Bass, Gain, Master, Mids and Treble controls, and its 9 to 12V DC power requirements, which is where the details on this page come from.
What tube does the London Underground X use?
It uses a single 12AX7 tube, according to Sushi Box FX's product page. That is the same dual-triode tube found in countless guitar and bass amp preamps, which is consistent with the pedal being based on the preamp of the Orange AD200B. Because it contains a real tube, the pedal draws considerably more current than a typical digital or solid-state pedal, especially while the tube warms up.
How does the London Underground X differ from the Particle Accelerator?
Sushi Box FX says the London Underground has some similarities to the Particle Accelerator, but beyond a different voicing, the London Underground also gets more drive when the gain is turned up. Players who wanted a blend of the two could order the London Underground with an optional Particle Accelerator tone stack at no additional cost, requested by noting PA tone stack in the notes section when ordering.
Is the London Underground X center-negative?
Yes. Sushi Box FX specifies center-negative polarity, like most guitar pedals, so it uses the same standard barrel-style DC supply polarity as the majority of effects pedals. The important thing to watch is the current draw: at 500mA while warming up, it needs a supply rated well above what many daisy-chain outputs provide.
How much current does the London Underground X draw?
Sushi Box FX lists the draw as 500mA at 9V DC during warmup, dropping to 250mA at 9V DC after warmup. That is far more than a typical pedal, so it needs its own dedicated supply output with enough headroom rather than a shared daisy-chain connection.
Is the London Underground X meant for bass?
Sushi Box FX describes it as based on the preamp of the Orange AD200B, which is a bass amplifier head, and the pedal carries a full Bass, Mids and Treble EQ plus Gain and Master controls. The maker does not limit it to one instrument, but its origin in a bass amp preamp makes it a natural fit for bass players looking for that voicing.
Sources (2)
- London Underground X, Sushi Box FX
- Underground Accelerator, Sushi Box FX
