Dr. Steven Ball at the console of the historic 1924 IV/53 Kimball organ of the Saint Louis Scottish Rite Cathedral playing an Improvisation on the Christmas carol Deck the Halls.
This organ sits in a room enclosing well over a million cubic feet of space which is costly to keep warm in the winter and to keep cool in the summer. The instrument is spot-tuned twice a year in the Spring and Fall when the outside temperature moderates between warm and cold. This video was recorded in December 2020 when winter was approaching. Once the furnace was turned on and the auditorium warmed up to room temperature so the recording could be made an important principle was illustrated: As the room heated up the flue pipes went sharp as expected due to the warmer air creating greater air speed at their mouths. Under typical playing conditions the heat in the room has little if any tuning effect on the tongues or resonators of reed pipes, however -- not enough that is, for the human ear to notice it. The reeds therefore sound flat by comparison. These subtle tuning differences can be noticed in this recording and can leave a false impression that a warmer room flattens reed pipes by expanding the metal of which they're composed. We know this cannot be true when all-metal flue pipes tuned true in a cool room also are observed to go sharp (not flat) when the room is heated.
We offer our highest compliments and sincerest thanks to Mr. Brent Johnson of Organ Media Foundation and to Dr. Ball for making this video of this important instrument and posting it on YouTube for public viewing.