Low-pass filter

A passive low-pass filter

An active low-pass filter

Signal being filtered with 1 rad/s cutoff frequency low-pass filter

A low-pass filter is an electronic filter that passes the frequency component of a signal below a certain value (called the cutoff frequency). The frequency component above that certain value will be suppressed to almost zero. In other words, a low-pass filter takes away all frequencies above the cutoff point, letting the ones below it stay.

In music, a low-pass filter will remove or decrease the volume of high pitches in a timbre, allowing lower pitches, called bass, to seem louder. An envelope can be used to change the cutoff frequency in real time, so an electronic instrument can sound like it has been plucked.

Related pages

• High-pass filter
• Band-pass filter
• Band-stop filter