Each plate has two holes in its upper edge. Through these holes wires are passed from which the plate is suspended. The holes are drilled at the plate’s nodal points, i.e. in places where it does not vibrate. In this way any impairment of the sound is avoided (if holes were drilled in places that vibrate the sound quality would be poorer).
The dimensions of the rectangular plates are approximately as follows: the smallest is about 30 cm long x 25 cm wide, the largest 100 cm x 75 cm. An aluminum plate of this size (pitch: C2) weighs about 6 kg, a plate with the pitch C5 (approx. 30 x 25 cm) weighs about 1 kg. If the largest plates are made of bronze they weigh about 30 kg, the pitch is C2. The volume such plates can produce is considerable, as one may imagine.
The individual rectangular plates of aluminum alloy, bronze or steel are suspended on a frame. It has become common practice to hang only those plates on the frame that are necessary for the piece to be performed.
However, a set of chromatically tuned plates can be arranged to correspond to a keyboard; 13 plates make an octave and can be hung on a semicircular frame in the same order as the keys of a piano (the lower row represents the white keys, the upper row the black ones). In other words the musician has what amounts to a gigantic mallet instrument. To save having to reach over great distances, the player may decide not to arrange the plates chromatically but in the order most convenient for the piece to be performed.
The possibilities range from a single plate held in the percussionist’s hand to sets of bell plates with a compass of between 1½ and 3 octaves.
The plates are both vibration generator and resonator.
To amplify the lowest partials of particular plates, which can produce only a limited volume, box-shaped resonant chambers can be placed behind the plate. In the past this was common practice, but nowadays electronic amplification with microphones and loudspeakers is most common. This has the advantage not only of amplifying the lowest partials but also of making even the most delicate tone settings and the most subtle playing techniques audible.