Each bell is individually constructed for its intended purpose. When adding a bell to other existing bells, the most important partial tones (partials) of the existing bells will be analyzed in advance. Depending on the musical requirements or cultural tradition, the new bell is defined in terms of its future sound harmony which is the basis for the calculation of its rib (as the bell shape is called). The specification of a bell is based on the most perceptible main tone, the so-called striking tone (nominal tone).
A medium-weight octave bell with the striking pitch a/1 weighed approx. 450 kg in the German-speaking world in past centuries. In southern Europe, bells with a striking tone of a/1 weigh generally less (approx. 370 kg). If more bronze is used for the same striking tone, the sound spectrum of these bells is perceived as emotionally fuller and more beautiful. For this reason, nowadays more and more bells are cast with a heavier rib and there are GRASSMAYR bells with a striking tone of a/1 with a weight of 800 kg.
Since the international conference in London in 1939, a/1 = 440 Hertz has been the standard concert pitch in many countries; the unit Hertz (Hz) indicates the number of vibrations per second. Most bells are tuned to a/1 = 440 Hertz. Bells with a different number of hertz were cast and tuned by the Grassmayr bell foundry for famous orchestras, such as an a/1 bell with 444 hertz for the Berlin Symphony Orchestra.
The larger a bell is, the deeper its partials sound. A bell with a heavy rib and a striking tone (nominal) of a/3 requires only 10 kg of bronze, whereas the deeper-sounding a/0 bell weighs ca. 4.400 kg.