A truly extraordinary effect by MXR. Basically, the "Blue Box" is a kind of octaver, but there is already the MXR Bass Octave. The Blue Box is more for people who prefer something special or anything else: the guitar signal is first distorted and then lowered by 2 octaves. The balance between the dry and the effect signal can now be adjusted. With a discreetly used effect more typical octaver sounds are possible, especially if one plays rather high notes on the guitar; The higher the effect percentage increases, the more natural it sounds. Try it out!