Boss SD1 Super OverdriveThe Boss SUPER OverDrive SD 1 gives you the warm, smooth distortion of an overdriven tube amp without blurring the nuances of your picking technique. The unique symmetric drive circuit delivers a more rich, authentic sounding overdrive effect. Here's an overdrive pedal that has Level, Drive, and Tone controls that make it easy to go from mild to hard, or even use the SD 1 as a signal booster.