Mad Professor Royal Blue Overdrive Effects Pedal - The Mad Professor Royal Blue overdrive offers a wide range of tones from light into distortion and at lowest Distortion knob setting works as an EQ. It can also be used to create tube amp-like crunchy‘strike hard for distortion’ effect. There is not much filtering on the overdrive, provide transparent tone that you tailor with both Treble bass-guitars controls.Like best boutique amps, OD lets determine amount breakup by how strike strings your pick, and/or adjusting volume guitar. add this level expressiveness any clean or slightly overdriven amplifier. amps, Effects, Effects Pedals, Distortion & Overdrive Effects Pedals