Boss GE-7B Bass Equalizer pedal schematic diagram

The Boss GE-7B pedal is a 7 band (62Hz - 4kHz) equalizer with a boost/cut of 15dB per band, designed specifically for bass guitars. The schematic is similar to the GE-7.

Fig. 2: GE-7B PCB - component side

Specifications:

• Residual Noise Level: less than -100dBm (IHF-A Weighted, Typ.)
• Equalizer Control: 7 bands, +/- 15dB
• 7 band EQ: 62Hz, 125Hz, 250Hz, 500Hz, 1kHz, 2kHz and 4kHz
• Level Control: +/- 15 dB
• Input Impedance: 470kΩ
• Output Load Impedance: more than 10kΩ
• Connectors: Input Jack, Output Jack, AC Adaptor Jack
• Power Supply: DC 9V dry battery, AC Adaptor
• Current Draw: 12mA (DC 9V)
• AC Adaptor: ACA-Series
• Width: 70 mm
• Depth: 125 mm
• Height: 55 mm
• Weight: 450g

ICs, transistors and diodes used in the Boss GE-7B Bass Equalizer:

• IC1-IC4: M5218P (dual operational amplifiers)
• IC5: HA1457W or HA12017 (low noise preamplifier)
• Q1: 2SC2240GR (NPN silicon transistor)
• Q2, Q3: 2SC945-P or 2SC1685 (NPN silicon transistors)
• Q4, Q5: 2SK30ATM-Y (N-channel JFET transistor)
• D1, D2, D3: 1S2473 (switching diodes)
• D4: RD5.6EB3 (500mW 5.6V Zener diode)
• D5: 1OE2 or S5500G (400V/1A diode)