Reference

[19] J.S. Bach: Concerto in d, after Vivaldi, BWV 596, Allegro (AAD with preemphasis) 4:50
James Johnson (Flentrop organ)
Recording Venue: Busch-Reisinger Museum, Harvard University, Cambridge, MA
Recording Date: 1979
Recording Engineers: Peter W. Mitchell, Brad Meyer
Microphones: four Nakamichi CM-700s, two cardioid capsules in ORTF configuration, two widely spaced omnidirectional capsules
Microphone preamplifier: Mystic Valley Audio custom mixer
Recorder: ReVox A77 ¼" open-reel recorder at 15ips, with dbx noise reduction
Transfer to digital: Sony PCM-F1 (modified)
Digital Transfer: Northeastern Digital Recording
Original commercial release: 1988, James Johnson Plays Bach, Titanic TI-162 CD. (Titanic Records, P.O. Box 204, Somerville, MA 02144-0204. Titanic recordings are distributed in the US by Harmonia Mundi USA.) TI-162 was also available as an Ashmont LP.

Harvard's Busch-Reisinger Museum is a small chapel whose stone surfaces produce strong reverberation. The small organ, installed in 1958 by the Dutch company D.A. Flentrop, has a "positiv" rank of pipes mounted on the front rail of the Museum's balcony (often used for the melody), plus additional ranks of pipes 10' further back. To obtain an accurate recorded image of this spatial relationship, a semi-coincident pair of directional cardioid microphones was used in an ORTF array. Widely spaced omnidirectional mikes were mixed in at a lower level to enhance the sense of ambience and to reinforce the bass frequencies. (Unlike cardioid microphones, which tend to have a rolled-off bass except when very close to the sound source, omnidirectional microphones have a flat response to single-digit frequencies, in theory even to DC.)