The threshold control on the FILTRATION II G String should be adjusted by listening to the noise floor while no instrument signal is present. The threshold control should be turned clockwise until the noise floor becomes inaudible. It may be necessary to readjust the threshold with the guitar volume all the way on in order to accommodate the additional noise the guitar may induce. Adjusting the threshold too far clockwise may cause the downward expander to attenuate the output level too quickly and not allow the signal to decay naturally.