High Pass Filter (HPF)

In Short

A filter that attenuates frequencies below its setting.

In more Detail

A particular audio signal will carry frequencies within its range. Sometimes certain types of frequencies can affect the sound and are unwanted in the signal, Sometimes a particular audio device is not designed to handle certain frequencies. These are 2 examples of where a HPF can be used.

In the 1st case we see frequencies affecting the sound we are dealing with. This could be a vocal microphone on a stage for a loud band. Stage noise and popping sounds from the vocalist can be picked up by the microphone. A HPF is a way of minimizing this. On many mixing consoles a switch is pressed to activate a HPF at a set frequency. On larger mixing consoles the frequency may be variable. Usually vocals will need this activated. this will provide a cleaner sound. Many instruments will benefit from this, although instruments that produce low frequency (some drums and bass guitars and keyboards) do NOT require this.

In the 2nd case a particular speaker system may not be capable of handling low frequencies. A HPF is used here to eliminate frequencies below a set level from the mix. This is usually done with a Crossover and the frequency point and Slope are usually variable.

See also

• Low Pass Filter (LPF)
• Band Pass Filter
• Crossover