The Markbass Compressore Compressor packs real tube-drive compression into a convenient package designed for bass but applicable to any instrument. Powered by an ECC 81 vacuum tube, the Compressore expands on the standard effect by including controls typically found on outboard units like Ratio, Attack, and Release. Intended for the bass, this nuanced pedal will also find easy footing on any guitarist or keyboard player's rig.