PRO series TB-600 combines 600 watts of power with total tonal finesse and versatility to produce thick, natural and balanced Fender bass tone that sits perfectly in the mix, be it recording studio, club gig or concert stage. Based on the acclaimed TBP-1 tube bass preamp, the key to its sound is the passive tone stack–the backbone of classic Fender guitar and bass amps–in which each control knob setting affects the sound of the other controls, producing big, warn notes that are the natural sound of a bass guitar. An overdrive section (Gain, Volume and Blend) sits on top of the clean channel, allowing you to dial in tones from a subtle grind to full on overdrive. Vari-Q™ is a smart semi-parametric EQ with a user selectable frequency and a cut/boost of 15 dB. When boosting frequencies, it automatically widens the focus of the Q for a broader, more musical boost. When cutting frequencies, it automatically narrows the focus of the Q for a well-defined cut (notch). This intelligent Q control keeps “on the fly” operation simple and effective. Room Balance is a global EQ shift for cabinets/stage response. Clockwise turn cuts lower end frequencies while simultaneously raising upper frequencies. Counter-clockwise brings up lower end frequencies while simultaneously lowering upper frequencies. This knob does not affect the XLR out, so you can “dial in the stage” while giving the soundman an unaltered signal. Free your mind and your bass will follow.