Lists of the collection of piano rolls and other Welte-Mignon materials,
donated by Richard C. Simonton to University of Southern California
(USC), can be viewed via the Internet at URL

  http://www.usc.edu/isd/locations/ssh/special/Spec_Archival_Guide.html

Near the bottom of this page is the description of collection no. 176:

  176. Welte Piano Rolls (Richard Simonton Coll.)
  176-1 through 176-40
  Player piano rolls recorded with the Edwin Welte system by prominent
  European and American musicians, 1905-1920; catalogs of the Welte
  Company in Freiburg, Germany.  The collection was brought to the
  United States in 1945 by Simonton, and some of the performances have
  since been released on modern recordings.

Active links are provided to two Adobe PDF documents:

  http://www.usc.edu/isd/locations/ssh/special/176WelteRolls.pdf
  http://www.usc.edu/isd/locations/ssh/special/weltecat.pdf

File 176WelteRolls.pdf contains 52 pages and lists more than 600 piano
rolls.  Many rolls are noted as duplicates; there is no indication that
any are master rolls.

The Simonton Collection is located at Doheny Memorial Library,
Department of Special Collections, University of Southern California,
Los Angeles, CA 90089-0182.  The collection may be viewed according to
the policies given at

  http://www.usc.edu/isd/locations/ssh/special/uscarchives/Policies.html

Thanks to MMDer Gerhard Dangel-Reese, Augustinermuseum, Freiburg, for
this information.

Robbie Rhodes