Marshall-SHALL SPEAKER SIMULATION CLASSIC M-Sa based on Tech21 SansAmp Character British,GUIDE TO CONTROLS LEVEL: Adjusts the output level of the unit.This control has an exceptionally wide range for maximum compatibility with a variety of equipment. LOW, HIGH, MID: On-board post-EQ section gives you full control, like having a studio mixing board at your fingertips. Unlike passive tone controls that only cut, these active controls cut and boost ±12dB. Low is tuned to 125 Hz; High frequency is 3.2 kHz. Mid is custom tuned for each model. DRIVE: Adjusts the overall amount of gain and overdrive, similar to when the output section of a tube amp is being pushed.The first half of the rotation will increase the volume as well as the overdrive. VOICE*: Voiced differently for each pedal in the series. It sweeps through various tonal possibilities associated with each style of amplifier. In addition to modifying the frequency response, Voice also influences the attack and drive characteristic of each particular amplifier style.Therefore, you may need to adjust your gain and tone settings after tweaking the Voice control.