Glockenspiel - Construction
The chromatically tuned bars lie in two rows, in the manner of piano keys, in a shallow wood box which is either mounted on an adjustable metal stand (the open glockenspiel) or simply placed on a table. All the bars are the same width and thickness; it is only the length that varies. The bars are held in place in one of two ways:
1. Each bar has a round hole in one end with a pin through it. The other end rests on a felt rail. This arrangement is found only on the table glockenspiel.
2. As on the xylophone, the steel bars have holes drilled in the sides at their nodal points, about 22% of the bar length from the end. A string passes through these holes on which the bars are suspended. Each bar is separated from its neighbor by pegs, which stabilize it and allow it to vibrate freely. This means of suspension is a result of acoustic considerations: because the points of contact between the bar and the rail (or the position of the holes) are located exactly at the nodal points the damping of harmonic partials is prevented, while the resonance of inharmonic partials is hindered. The harmonic partials lend the tone greater clarity. This arrangement is found only on glockenspiels with a damper pedal.
The glockenspiel has no additional resonators since the case acts as a soundbox.
A "piano-action" glockenspiel has a mechanism with small metal hammers beneath the bars which are operated by means of a keyboard. Damping occurs as on the piano, the dampers being raised by depressing a pedal. Although these instruments offer a greater variety of playing techniques than the mallet-played glockenspiel, the sound is inferior. It is for this reason that keyboard glockenspiels are only rarely used today.
The bars are not arranged horizontally but are held vertically in a frame which has the form of a lyre. This portable version of the glockenspiel was developed for marching bands and was already widespread in Germany in the 19th century. Today the instrument is used in many countries, especially the USA.