28 Nicolas Collinssecondary leads goes to the tip and which to the sleeve. If possible, slip the
plug’s barrel over the wires before you solder them up (as we did with the
contact mike;) there may not be sufficient wire length to allow this, in which case
you can wrap some electrical tape around the connections later (after you have
proven that the gizmo works, and being very careful not to squeeze the
connections together to make a short.
Solder one of the primary wires to the tip connection of a female jack that
mates with the plug you used on your contact mike (previous chapter.) Solder
the other primary wire to the sleeve connection of the jack. Once again, polarity
is irrelevant here – it does not matter which of the two primary leads goes to
which connection.
Plug the plug-end of the transformer assembly into the output jack of the
amplifier. Plug your contact mike (made in the previous chapter) into the jack-
end of the transformer assembly.
Plug a sound source into the amplifier input: a microphone, cassette recorder,
CD player, radio, etc. Slowly raise the amp gain. The disk should start to radiate
sound. If not, check your connections.
Use plastic spring clamps, clothespins or tape to clamp the disk to different
objects and resonate them with various sounds. Thin materials work better than
thick ones: pie tins, etching plates, paper cups, tin cans and balloons, rather than
bricks, anchors and baseball bats.
A quaint reverb unit can be made by sending signals into a spring or plate of
metal using a Piezo driver and picking them up with a Piezo contact mike (you’ll
have to solder up a few more Piezo disks.) This is similar to the technique used
in early plate reverb units common in recording studios before digital reverb,
and also the principle behind David Tudor’s famous “Rainforest” installation,
which used sculptural objects to transform sound material. You can patch the