The following is megabass circuit schematic (Mega Bass Circuit) . The megabass circuit 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 Schematics Note: 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 O...