At the time the contract was signed for Opus 51 at Zion Mennonite Church, the church building was still in the design stage. For the first time in his career Charles Fisk was able to work in collaboration with the architect, Edward A. Sövik, as the design unfolded.. The spare but graceful design of the case and the favorable acoustical climate of the building were thus achieved by organ builder and architect in an atmosphere of mutual respect.
In a letter dated March 1965, Charles Fisk wrote to Mr. Sövik:
Height in a building permits multiple sound reflections amongst hard surfaces before absorption in the audience can take place. Because you have a large area of floor, which is not to be covered by seating, it appears that adequate reverberation can be achieved without great height, but reverberation is by no means the whole story in room acoustics. The reverberant field needs adequate excitation from the musical sources to have its proper effect on the music.
In executing the visual design of the organ great care was taken to ensure that the instrument complemented its surroundings. As the cross is placed on the centerline of the church, it became apparent that the organ should be positioned to face the cross, thereby directing visual attention back to the center of the room and maintaining the sense of serenity that characterizes this church.