Schematic for 4-band stereo equalizer?
A graphic EQ doesn't usually have LP &amp; HP sections (otherwise it wouldn't be graphic). The schematic in your link is a 7 section EQ with sections from about 60Hz to 15kHz. To maintain these extremes with a four-section EQ, you would need two intermediate sections with frequencies of about 400Hz and 2.4kHz to maintain equal logarithmic spacing. These would need these capacitors :-

400Hz  -> C1=15nF, C2=150nF
2400Hz -> C1=2n7,  C2=27nF

(These are the nearest E24 preferred values and are approximate).