The following is megabass circuit schematic (Mega Bass Circuit) . The megabass circuit using IC TL702 is a modified Baxandall tone control with no bass cut and no treble control. It boosts frequencies from about 30Hz to 160Hz can boost by 14dB.
Megabass Circuit Schematics
The input capacitor can be replaced with a .01uf cap if you wish.
The 10pf capacitor is optional and will start rolling off everything over 15kHz. 5pf will double this to 31kHz.The tone control requires a low impedence input. If you already have a low impedence input, the input buffer can be removed. However, the output is inverted.
The opamp is not critical. A 4558 would be just fine.
I do not show the parts for the +4.5 reference. Here is the +4.5 voltage divider I used.
IC A4558 Pinning
The A4558 is a monolithic Integrated Circuit designed for dual operational amplifier.
Absolute maximum ratings of A4558 Ap-amp
Supply voltage VCC 20 or ±10 V
Differential input voltage VIND 20 V
Input voltage VIN ±10 V
Power Dissipation PD 300 mW
Operating temperature Topr -45 ~ +85 °C
Storage temperature Tstg -55 ~ +150 °C