Miago Trod is a set of 22 threaded rods up to 42” long, mounted in a frame, tuned chromatically and played by percussion. The main mounting piece is a heavy steel bar — actually, there are two of these mounting bars — and each rod passes through its mounting bar with a shorter playable segment above and a longer playable segment below. The special character of the instrument is to be found in the relative tuning of the upper and lower segments. The segments are long enough that the fundamentals are subsonic, and the tone that you hear is that of various overtones. The range of rod lengths is chosen so that in the upper, shorter segments, one overtone is strong enough to stand out as the defining pitch, while other overtones contribute to a reasonably coherent blend. This blend is mostly a matter of fortuitous pitch relationships within the rod in this length range, but it’s also enhanced by the addition of a well placed weight partway along the rod to slightly modify the overtone relationships. Meanwhile, the longer lower segment has a length such that a similar fortuitous set of overtone relationships arise, with a predominant pitch an octave below that of the upper segment. When either the upper or lower segment is struck, the two parts interact to further enrich the tone.
In the audio clip, Miago Trod is joined by scattered percussion sounds.