Sushi Box FX Underground Accelerator

I’ve owned both the regular and the handwired version of this pedal.
What is the Sushi Box FX Underground Accelerator? It is a tube driven pedal that uses the Fender tone stack EQ. Bass and Treble are boost only, while Mids are cut only. The flattest setting is somewhere in the region of 1-10-1. The newer versions of this pedal have a switch that disables the EQ section.
The Underground Accelerator has two parents, the Sushi Box FX Particle Accelerator, which was the Sushi Box take on the Alembic F-2B preamp and the Sushi Box FX London Underground, which was an amp-in-a-box version of the Orange AD200 amp. Those two got mashed together, keeping the EQ section of the Particle Accelerator, but using the gain stage from the London Underground. I’m recalling all this from the top of my head, feel free to fact check me on this and report back if I’m wrong.

However, use this pedal with a good power source. It takes 9-12V, and at 9V it wants to see around 400mA, settling for less when it’s warmed up. Running higher volatages does nothing, the incoming power gets transformed up to voltages that can actually hurt people and it does not matter if it starts at 9 or 12 volts.

Finally, let’s talk about how it sounds. It sounds great. You will not be able to push your mids and will end up with some kind of scoop unless you’re running bass and treble at zero. And you won’t be keeping those knobs at zero. They simply sound too good to be kept all the way down. Both bass and treble are shelving, and while the bass knob brings the thunder, the treble knob brings the sparkle.
We got a tube here, running at a respectable plate voltage, so it’s none of these pedals that sport a tube for the looks and the mojo. This one is really running and doing tube things. Tube things, you ask?
Yes. That organic drive that happens when the harmonics are conjured up in the sizzling vacuum above the heater plate. It’s hard to define a sweet spot, because there is a large area that’s really so many sweet spots in a row you’d not be wrong to call it a sweet line. The gain knob really has some travel to it. I don’t really care for the first and last quarter of the total distance, but everywhere else, it’s really good.

Ride the bass and treble knobs really high and have the gain in the early breakup stages and you get a bedroom tone to die for.
I used to feed it into a pedal downstream that would boost a little bit in the area around 600Hz and that brought the bass signal up front instead of hiding it in a mix.
Also, running a Wampler Belle or Nobels ODR-1 into the Underground Accelerator yielded great results – it felt like pushing a tube amp over the edge.
I did describe the dirt as organic, and I use that word sparingly. The reason for that is this very pedal. Once you heard the kind of dirt you get from a tube driven circuit with a Fender tonestack, you’ll have to raise the bar for using that description in the future.

To add a grain of salt to an otherwise super positive review, I need to talk about noise issues. I owned very early versions of both the Underground Accelerator as well as the Handwired Underground Accelerator and I know there have been changes that addresses possible noise issues.
I want to add that I ran my Sushi Box pedals off a single outlet of Cioks power supplies – so I used a quality power supply and even though I often run a lot of pedals, I never used a noise gate, because I never had reason to. However, my Handwired UA would occasionally emit something – it was not audible, but made the compressor clamp down with full force, so while my ears were not getting it, the compressors trigger did. The normal UA did have a bit of a whine, but that was around 13kHz, and I used a LPF to get rid of it. Nonetheless, those were issues I had, and things I needed to watch out for, so I feel they should be mentioned.
I wanna say I spent a lot of time getting this stuff under control – the pedals worked better after the comp, with a stronger input setting, had some issues with other pedals that I kicked off the board with no mercy.
Usually I’d identify the pedal that has issues and wave it good bye, but those Sushi Boxes sounded so darn good, I was willing to bend as far as I could to make them work, and that is a weird form of the highest praise.