Innsbruck-Wilten, Stiftskirche

The basic idea of transmission (octave coupling) intends a reduction of pipes by a specific construction of the wind chest. Every key can open not one but three pallets and thus pipes in the distance of one and two octaves. For example with the Principal rank it means that with octave couplers active the key for c¹ sounds the c¹ as well as c² and c³ of the same rank. Thus every rank gives three stops. At a price with pipes for two additional octaves above the manual compass three ranks seem to give nine stops with remarkably reduced space and material. This so seemingly fascinating technical construction comes with a severe musical disadvantage though. If eg (8’+4’ pulled) a chord of  c¹-e¹-g¹-c² is to be played, the highest note is not sounding properly since its pipe serves already as the upper octave of the lowest note. The results are audible sound gaps which, depending on the structure of a composition, can severely diminish its impression. Therefore during the 16th to 18th century octave couplers were considered an emergency measure for example for single pedal stops or within limited space. As a basic principle of a complete organ the octave couplers of Wilten organ are unique in this era.

In the late 19th and early 20th century octave couplers became very popular to impress customers with ever growing numbers of organ stops.