The positive organ Organo di Legno, or “Wooden Organ” in translation, which our workshop is building, is truly unique. Its sound is produced by wooden principal pipes, which were widely used during the Renaissance and early Baroque periods, most often to accompany singing. Compared to tin principal pipes, the sound of wooden pipes is much softer, yet still reveals a rich spectrum of harmonic overtones.
A harmonic overtone is a tone that sounds together with the fundamental tone. Organ pipes do not produce only the fundamental tones (tones at the base frequency), but also integer multiples of these base frequencies. These multiples are called overtones. The first overtone is at roughly twice the frequency of the fundamental, the second at three times, and so on. The intensity of each overtone shapes the unique sound characteristics of a particular instrument. In the case of the Organo di Legno positive organ, overtones give its sound a special softness, smoothness, and fullness. During the Renaissance and early Baroque periods, wooden organ pipes were most often made of cypress wood, which we replaced by maple due to its similar density and comparable acoustic properties.
Just like the pipes, maple wood is also used for the organ case, which is finished with a brown shellac polish. The front, below the pipes, is decorated with three carved heads with lower parts that can be opened. The overall decoration is inspired by motifs from Italian Renaissance and early Baroque furniture, making its use on the organ case quite original. Small bone carvings also adorn the façade pipes, which are covered with bovine bone to imitate ivory, creating a striking contrast with the dark case. The pipe edges are finished with fine ebony strips for additional detail. The instrument’s overall dimensions are minimalist, allowing for easy transport (height 150 cm, depth 40–55 cm, width 93 cm). For transport, the entire façade can be closed with doors hanging on brass hinges coated with silver leaf, which are sturdy yet appear light and elegant.
The natural keys are covered with boxwood, while the sharps have ebony overlays—an authentic combination popular in Renaissance and Baroque Italy. The key fronts are decorated with small tin castings shaped like leaves, which also appear on the keyboard frame and prospect columns. The great octave is covered for space reasons, just as in unique late Renaissance Italian organs with mostly wooden pipes from around 1580, such as those in the Silver Chapel in Innsbruck, Austria.
Inside the case is a pumping bellows operated directly by the organist using a pedal. However, due to the instrument’s design, a calcant (human assistant) can also help with pumping. The reservoir bellows, with a lead weight bearing our workshop’s logo on top, maintains constant air pressure and sits atop the instrument. When filled, it forms an impressive and elegant fan shape.
The great octave is short, in accordance with historical practice, and includes the notes CDEFGABH, with the instrument’s range from C/E to c3. At the request of the future owner, the positive is tuned to a1 = 411 Hz, with no possibility of transposition. The sound of this positive organ comes from the 8’ wooden principal. From the front, a 16’ (or 8’) regal is projected into the area behind the carved heads, for which the mentioned openings in the lower parts of the heads function as a mute (sordina) for the regal stop. When the organist pulls the prepared lever, the chin and claws of each head retract into the instrument, creating openings. When fully opened, that is, when the chin and claws are fully retracted, the regal’s sound is full and strong and is more directed toward the listeners. When the openings are closed, the sound is more intimate (sonorous) and significantly muted. The stop slider is operated by a dedicated handle (manubria), which is hidden on the right side next to the keyboard. In terms of design, these are iron rods ending in a trefoil shape.
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