The Microtubes B7K takes the powerful dynamic saturation circuit of the B3K and adds a four-band equalizer and a balanced line driver for even greater versatility. Designed for both studio and live use, it will take your direct sound to a whole new level. Controls Level: Sets the volume of the overdriven signal. Drive: Sets the amount of saturation in the overdriven signal. 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, allowing for fine control of the blend ratio. Grunt Switch: Sets the amount of low frequency content to saturate by selecting between three different bass boost levels before the clipping stage. Attack Switch: Sets the amount of treble content to saturate: 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.