2 + 1
This zither is a further exploration of ideas also touched upon in the instruments called Hans & Glenn and 2 + 2 + 1. Each of 2 + 1’s eight strings is divided into two segments by means of a center bridge. One segment is twice as long as the other, so that the longer segment produces a tone an octave below that of the shorter. The player plays only the segments on the longer side. By transmission across the bridge and sympathetic vibration, this indirectly excites the segment on the shorter side. Magnetic pickups are located under the shorter segment, so what you hear from the pickups is the shared resonances of the longer segment as manifest in and filtered through the shorter. It’s an odd and attractive sound, in which you hear primarily the unplucked shorter string resonating in sympathy at the octave, with the ghost of the lower string tone sounding an octave below. With eight strings tuned to a diatonic scale, you can play melodies by plucking whichever strings will give you the pitches you want — but there’s also this: a lever at the far end of each string allows you to vary the tension, thus providing a secondary pitch-control system. Special rocking bridges allow this tension variation to happen without throwing off the octave tuning of the two segments. The tension-control lever allows for all sorts of subtle and not-so-subtle pitch inflections. The pitch-bending also somehow affects the perceived tone quality of the instrument, imparting a peculiar liquid quality to the sound.
In the video linked below, 2+1 is the fourth of several instruments described.