The present document relates to audio coding systems which make use of a harmonic transposition method for high frequency reconstruction, and to digital effect processors, e. The user interface varies properties of displayed background particles to provide the user with an indication of the contents of a selected folder without requiring the user to open the selected folder. The frequency of a PWM input clock signal is increased to N times of the original frequency of the PWM input clock signal by the frequency multiplier, so that the counting cycle of the PWM counter is shortened to 1N of the original counting cycle of the PWM counter. The threads extend radially outward from the inner surface into the connector opening and include a first thread portion and a cutback that extends through a portion of the threadform.