The primary purpose of a good compressor is to smooth and balance the dynamic range of an instrument. The VELVET COMP is a compression pedal designed to make your bass sound silky smooth. Gain, ratio, and threshold are all adjusted in sync with the COMPACT knob, and the attack and decay are preset to optimize the signal passing through. To get the most out of this unit, you should set it so that the volume change caused by turning the pedal on and off is as small as possible. This can be achieved by adjusting the INPUT and OUTPUT level controls. The INPUT rotary control features a three-band (white, blue, red) LED meter to help you set the appropriate input level before applying the compressor. The appropriate level is when the blue meter remains lit. If the red meter is constantly lit, the input is too high, so lower the INPUT level until it is appropriate. Once the input signal is appropriate, use the OUTPUT control to set the output to the amplifier. After setting the appropriate level, use the COMPACT knob to control the compression while maintaining dynamics and keeping the sound consistent. Some simple bass compressors don't offer good control over the compression of either the high or low strings, but the VELVET COMP accurately expresses this across the entire frequency range.