what group of frequencies are controlled by low,band, and high pass filters in an equalizer? I am thinking to make a audio equalizer. I need range of frequencies for low pass, high pass and band pass.

 

Hello,

On this page from ESP you will find a lot of information to make an equalizer:
http://sound.westhost.com/articles/active-filters.htm

Bertus

 

Typical "Tone Controls" call "Bass" anything under 250Hz, and "Treble" anything over 2kHz. "Midrange" is 250Hz-2kHz. This is very roughly speaking.

EQ bands are normally octaves, each frequency roughly doubling, such as 30Hz, 60Hz, 120Hz, 240Hz, 500Hz, 1kHz, 2kHz, 4kHz, 8kHz, 16kHz.

The bands can be expanded by covering half octaves, or reduced by having each band cover 2 or more octaves.

 

there is still one problem; how to control low,mid and high frequency sound output ? Can i connect those three filter in parallel and variable resistance to control gain from each filer?

 

Does phase shift affect sound quality? In my filter design; i use -40 dB/dec attenuation.
what is the phase shift in Butterworth filter?

 

First hit using Google & "equalizer circuit" - http://freecircuitdiagram.com/2008/11/25/3-band-graphic-equalizer-circuit/