Maestro Bass Brassmaster BB-1

A 1971 bass distortion/fuzz unit. Besides the main foot switch, framed in a large orange triangle, it has 3 knobs with a 2-position switch between each, which are, from top to bottom, Brass Volume, Brass 1/2, Sensitivity, Harmonic 1/2, and Bass Volume.
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Mentioned by @Billy in a "gear update" tweet on 2011/06/18, during the recording for Oceania.