AB
1"
½"
¾"
CD
1½"
Fig. A: Nested vinyl and polyethylene tubing make fret-like spacers between drum pads. Fig. B: The cable end
of the pipe, with a keyhole slot for the string barrel.
toward each other, onto the string. Pass the wire
through the slotted hole in the pipe, and anchor it
by sliding the brass ring under the slot. Feed the
other end of the string down through the hole at
the opposite end and thread it onto the tuning peg
inside. Slide 1 stopper to each end, and tighten the
string so that it doesn’t touch the foil.
2. Connect the pads.
2a. Feed a wire through each of the 1" foil pad
holes and out the left end of the pipe. Strip 3" of
insulation off the pad-side wires, lay the bare copper along the edge of its foil pad, and tape it down
with a ¼"-wide strip of foil tape (Figure D).
NOTE: The adhesive on the bottom of the foil is nonconductive, so the copper wire must touch the top
surface of the pad foil.
2b. Cut a serial cable in half. Take the female half
and tie a knot 6" from the cut end. Use solder and
heat-shrink tubing to connect the pad wires to the
wires for serial pins 1, 2, 3, and 4, as specified in the
schematic diagram, available at makezine.com/15/
90 Make: Volume 15
Fig. C: The right end of the pipe, with the tuning peg for
tightening the string. Fig. D: Taping stripped wire to the
foil drum pad.
electronicdrum. Pads are numbered from left to
right. Use a multimeter to associate the wires in the
cable with the corresponding pins on the connector.
3. Connect the piezo elements.
The Zoom MRT-3B drum machine has 2 pressure-sensitive piezoelectric elements that detect the
force of pushes on its drum pad buttons. We’ll
remove them and put 1 underneath each pipe, so
they’ll perform the same function there.
3a. Pry the volume knob off the drum machine and
unscrew and remove the back of the case. Remove
the 4 screws inside that hold the battery case and
the 2 screws on the MIDI connector. Write down
where they go, and save them in a cup.
Photography by Tom Zimmerman
3b. The piezo elements are the disks behind the
circuit board from the drum pad buttons (Figure E,
bottom). Unsolder both and gently remove them.
Solder and heat-shrink two 36" wires to each, and
thread the wires through the side pad hole near the
middle of each pipe. Slip the piezo element between
