A reed stop of the Regal class, so named because of the shapes of its resonators (knopf = “knob”), each of which consisted of a short cylindrical tube surmounted by a hollow globular or pear-shaped head in which a slot is cut, thus resembling a sleigh bell or, as Wedgwood describes it, a Gothic bishop's mitre. Irwin says that the resonators are seldom longer than 6", and describes the tone as “thin, brilliantly reedy, somewhat acid”, and less muffled than some other Regals. Adlung lists it as a synonym for Apfelregal. The illustration is Audsley's.
Knopfregal 8', Rückpositiv; Marienkirche, Stralsund, Germany; Stellwagen 1653-59. This is the only known example.