How to Build MIDI Trigger Pads

Manufacturers like Roland and Yamaha lead the way in commercial electronic drums.

Electronic drum kits use a sound module triggered by sticks hitting a velocity-sensitive pad. While the pads have an aura of mystery to them, the signal is created using the piezoelectric effect, the properties of which are used for microphones and instrument pickups. Piezos are inexpensive, commonly available and, with careful construction, reliable as drum triggers. Using a piezo element as a drum trigger requires expanding the contact surface and protecting it from direct impact, while allowing it to sense variations in stick impact.

Things You'll Need

• Tunable drum practice pad
• Piezoelectric element
• Soldering tools
• RCA chassis-mount female plug
• Wire (optional)
• Disk of tin or other thin metal, sized to fit inside practice pad with 1/2-inch clearance
• Two disks polyurethane foam same diameter and density as foam inside practice pad
• Epoxy
• Utility knife
• Electrical tape or shrink tubing
• Drill with 1/4-inch bit

Instructions

1. Disassemble the practice pad. Discard the foam and plastic disk inside the pad. Drill a hole in the base of the pad to receive the RCA jack. Remove the plastic casing from the piezo element, taking care not to bend or damage the element itself.

2. Solder the black wire from the piezo element to the ground ring on the RCA connector. Solder the red wire to the center terminal of the jack. Use additional wire to extend the leads between the piezo element and the plug hole, if necessary.

3. Score the metal disk in the center with the utility knife to give a gripping surface for the epoxy. Spread a circle of epoxy in the center of the disk and press the side of the piezo element without wires onto the glue, pressing gently to ensure even contact. Set aside to let the epoxy cure.

4. Cut a small opening in one of the foam disks to pass through the RCA jack. Feed the jack through the hole in the bottom shell and secure it with the supplied hardware. Set the cut foam disk inside the shell with the metal disk on top of it, with the piezo element against the foam. Add the uncut foam to the top of the metal plate. Reattach the drumhead and tune it to your preferred tension.

Tips & Warnings

• Hot glue may be used to glue together the foam around the metal disk, but drumhead tension is enough to keep things in place. Use an RCA-to-1/4-inch phone plug to connect your drum trigger to a sound module.

References

• ElectronicDrums.com: Do-It-Yourself Drum Trigger Pads
• Sound on Sound: DIY Drum Pads And Pedal Triggers