The Boss HM-2 Heavy Metal pedal generates a unique distortion effect specially designed for Heavy Metal music. It has an interesting design with both asymmetric soft-clipping diodes, hard clipping diodes and a Ge diode pair in series with the signal for crossover distortion and simple noise gate.
A wide variety of tone color creation is made possible with the 2 color mix controls.
Fig. 1: Boss HM-2 Heavy Metal guitar pedal schematic diagram
Fig. 2: Boss HM-2 PCB - component side
4 Control Knobs: Level, Color mix (Low, High) and Dist.
Connectors: Input, Output, AC Adaptor
Input Impedance: 1MΩ (FET input)
Recommended Load Impedance: more than 10 kOhm
Recommended AC Adaptor: ACA Series
Current Draw: 10mA (DC 9V)
Dimensions(mm): 70(W) x 55(H) x 125(D)
Dimensions(inches): 2-3/4(W) x 2-3/16(H) x 4-15/16(D)
ICs, transistors and diodes used in the HM-2:
IC1-IC3: M5218L or NJM4558S (dual operational amplifiers)