This series consists of photographic negatives.

This series contains French language reports prepared by the Ministère des Affaires culturelles du Québec, Direction régionale de Montréal, Direction du Patrimoine, by various authors. Each report is typescript and contains black and white photographs.

This series includes large-scale drawings, preliminary sketches, and general plans of various parts of the organ, such as the buffet, console, keyboards, and windchest. This series is divided into three subseries: organs with opus number; organs without opus number, which includes Wolff’s plans for proposed but ultimately not-constructed organs; and finally plans by other organ builders or Wolff’s drawings based on historical treatises and documents.

The Pamphlets series includes programs, program notes, and general publicity for several of the organs in Wolff’s opus. These are stored in folders and divided into three subseries: documents associated with Wolff organs, publicity for Wolff & Associés, and pamphlets for non-Wolff instruments.

This series contains the print copies of journals and conference proceedings in Hellmuth Wolff’s library. There are some annotations on several of the issues. The works are listed in two separate bibliographies in Appendix 1: Periodicals/Journals Bibliography and Appendix 2: Conference Publications Bibliography.

The Photographs series contains photographs of church organs, professional photos of Donald Mackey alone and with others. Also includes correspondence from Helen Mackey to Cynthia Leive.

This series consists of photographs taken of Bernard Gagnon.

The photographs in this series cover the several stages of the organ-building process. This series includes both colour and black-and-white images of the construction of a given organ at Wolff’s atelier, the installation of the organ, as well as concerts, dedications, and social events at or around the time of the organ’s installation.

This series consists of photographs with Sonde event number indicated if known.

This series consists of photographs with a de Mestral event number indicated if known.