This is the first organ since the 18th century to be built using Johann Sebastian Bach's tuning. Bach specified this method on the title page of his _Well-Tempered Clavier_, 1722, submitted as part of his audition materials for a professional position in Leipzig. Bach's organ music and vocal music from Leipzig confirm that this was his all-purpose tuning solution for church use, in addition to deployment on harpsichords and clavichords. It offers complete flexibility to use all scales and all chords, as smoothly as equal temperament does; but unlike equal temperament it has a built-in range of subtle expressive nuances. Every key signature has a distinct "personality" from every other: music with sharps sounds bright, while music in flats is more mellow and plaintive.

GC alumnus Bradley Lehman (1986) discovered this lost temperament in 2004. After his B.A. in both music and mathematics at Goshen, Lehman earned two master's degrees and the Doctoral of Musical Arts (harpsichord performance) from the University of Michigan. His research article about Bach's tuning has been published in 2005 by Oxford University Press.

Admission charge: $5 adults, $3 seniors/students. GC students admitted free with ID.