Darkglass Electronics Micro tubes MTB7K-ULTRA Bass Distortion Effects Pedal Blend: Mixes the clean input signal with the overdriven signal. The clean signal remains at unity gain while the volume of the overdriven signal is set by the Level knob Attack Switch: Sets the amount of treble content to saturate Grunt Switch: Sets the amount of low frequency content to saturate by selecting between three different bass boost levels before the clipping stage. Direct Output: A balanced version of the  output, useful for running into PAs or studio mixing consoles. The "Boost" setting emphasizes the treble content extra clarity and presence. The "Flat" position leaves this register untouched while the "Cut" position will reduce the amount of high frequencies being saturated.