Underground Accelerator


The Underground Accelerator is the successor to both Particle Accelerator and London Underground.

Neither were perfect, but both had strengths that the other didn’t so, Underground Accelerator takes the best of both into one glorious preamp. It follows the same general structure of the London Underground, letting it get a little more grit than Particle Accelerator, but still keeping the deep low end that London Underground lacked.

It sounds great as a clean boost or mild overdrive on guitar, but bass is where it really sings, providing the rich bottom end missing in so many bass pedals.

*The newest version of the Underground Accelerator has an EQ bypass switch. Note that the main purpose of the EQ Bypass is to boost the gain of the pedal, and bypassing the EQ will produce approximately +30dB more gain. Passive EQs like the one used in Underground Accelerator are inherently lossy, so the bypass was added for those that want more gain and don’t need the use of the EQ. If you simply want a flat response without the gain boost, you can set Treble and Bass to minimum and Mids to maximum.

Available on backorder

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Additional information


Bass, Gain, Master, Mids, Treble, EQ (toggle)

Enclosure Size

4.7 in x 3.7 in x 1.34 in (119 mm x 94 mm x 34 mm)

Footswitch Behavior



1x 12AX7




Center-negative, like most guitar pedals

Milliamp Draw

500mA @ 9vdc Warmup, 250mA @ 9vdc After Warmup