The Mount Holyoke College organ case was designed by Charles Fisk and his son Josiah Fisk to reflect the Italian Renaissance and German Baroque origins of the instrument’s unique tonal specifications. The façade pipes, the largest of which is EE of the Great Prestant 16', are made of hammered lead with gilded mouths, and four are embossed after antique examples. The gilded pipe shades were hand carved by Morgan Faulds Pike. The organ’s placement is ideal – high up in a specially constructed timber gallery, above the main gallery at the rear of the Chapel.

Tonally, Opus 84 embodies two distinct schools of organbuilding. The sound and character of the 16' principal chorus of the Great is based on 16th-century Italian examples. The mixtures are divided by rank in the Italian manner, offering the organist complete flexibility in the composition of the upperwork. The flutes of the Great, as well as the entire 4' Positive division perched on the balcony rail, are distinctly 17th- and 18th-century German in origin. The instrument is voiced on 1¾" (45mm) of wind. This low wind pressure passing through pipes of high lead content was favored by the early Italian builders. In the fine acoustics of Abbey Chapel it results in a sonority that is at once gentle and strong, and with a remarkably wide range of expression. The temperament is fifth-comma meantone.

Margaret Irwin-Brandon, Organist to the College Chapel at the time of Opus 84’s construction, was, in her words “…involved in the very central issues of design and imagination for this organ. Its frustrations and finally its joys came as we pushed ideas to their extremes and discovered there both vastness and limitation. Perhaps the organ itself will provide this very experience to those who play and hear it. I am certain, however, that in the end, it is the organ which will inspire us, teach us how to play, and guide us as we find new ways of listening.”