This stereo equalizer circuit is built with TL072 operational amplifier and performs an amplification or attenuation of each frequency range with around 13dB.
When all five potentiometers P1 + P5 positions are settled on the middle tier will get a virtual frequency response (0 dB). The entire controlled domain by this circuit is about 33 dB.
The signal / noise is 90 dB for an input signal with an amplitude of 1 V.
Resistance coils and resistors in series total in each feedback loop must be maintained to 680 ohms.