Duo-Art Punch Advance
By Wayne Stahnke
|As before, this note is intended primarily for Spencer Chase, but it is provided through the Digest for the benefit of other subscribers with an interest in the subject.|
Spencer, the editor of the Digest pointed out that I had not in fact answered the question you posed. This note is an attempt to make amends, and give you what you asked for in a direct manner.
(1) The punch advance of "coarse" Duo-Art rolls corresponds to 253 punch steps per foot. This number is a surprise, since 256 punch steps per foot corresponds to 3/64 inch punch advance. (A fractional-inch advance would have been a natural choice for machinery designed and built in the United States in the early part of this century.)
(2) The number given above was determined by counting punch steps in the master roll for the 1921 Electric Duo-Art Tester, the standard test roll used throughout the early and mid 1920s. (This roll was replaced in 1927 by the New Duo-Art Test Roll No. 3.) There are 11 foot markers in all, with displacements of 0,1,2,3,4,5,6,7,8,9,10 feet from the start of the Tempo Test, as identified by the printed annotations on the roll. These markers are perforated into the roll as two adjacent speaking notes, and occur in rows 0, 253, 506,759,1012,1265,1518,1771,2024,2277,2530.
(3) The punch advance was changed sometime in the mid 1920s. The new "fine" punch advance is very nearly 2/3 times the old one. Its exact value is not known.
(4) You can determine the ratio of "coarse" to "fine" advances by examining the Duo-Art perforators, which still exist. The change was effected on the factory floor by moving a pawl so that it engaged one or the other of two rachets, one for "fine" and one for "coarse." The ratio can be found by simply counting the number of teeth on the ratchets. The perforators can be located through Robin Pratt, the publisher of the Amica Bulletin, who knows of their whereabouts. Robin is a subscriber to this Digest.
(5) I sincerely hope you will go to the trouble of locating and examining the Duo-Art perforators and solving this riddle for all of us once and for all. I (for one) can make use of the information to improve my roll translations. There are others who would also be grateful for your contribution.
(6) Starting in the early 1930s, Ampico popular rolls were perforated on the Duo-Art perforators and therefore use either "coarse" or "fine" Duo-Art punch advance. Thus, a complete understanding of the Duo-Art machinery also solves the question of the punch advance used for Ampico popular music of the '30s.
I hope this note is more to the point than my earlier one. With best regards, I remain
(Message sent Wed 4 Dec 1996, 16:38:56 GMT, from time zone GMT-0500.)