Date: February 11, 1997

My interest in scanning music rolls goes back to 1973, when I built a reader for transferring music rolls to tape. The resulting tapes were used with a device called the Model CC-3 Cassette Converter, which played Ampico instruments from cassettes. At that time, I did a number of experiments to determine the precision required to ensure that the performances would not suffer.

What I learned was entirely to be expected. The manufacturers of music rolls pushed the technology of the time to its limits in an attempt to create the best possible musical result. All three of the major reproducing systems (Ampico, Duo-Art, Welte) provide many examples of "close" coding, in which one or more notes are played with a given dynamic, and notes in the following row (punch advance) are played at a different, usually softer, level. Of course, the position of the expression coding with respect to these notes is critical. An error of even a small fraction of a row disturbs the effect, resulting in lower relief (that is, a smaller dynamic difference) between the accented and unaccented notes. (Listeners describe the subjective result as a "muddy" or "lacking in crispness".) Large errors, on the order of one row or more, can destroy the effect completely.

All of this is well known to workers in the field of reproducing pianos. It poses a problem directly when we want to replicate music rolls, because we need to have high-quality copies that perform like the original rolls of the 1920s. Very high quality copies can in fact be made; the approach is called "hole-for-hole" copying.

A very old style of perforator, probably used in the very earlier part of this century.

Making hole-for-hole copies involves two steps. First, an original roll (not a modern copy made using conventional techniques) must be scanned and the hole-for-hole punch pattern recovered from the scan. This is done by using phase-lock-loop techniques to find the centerline of each row; each hole in the roll is then assigned to its correct row. Second, a new roll is made, using this punch pattern, with a row advance equal to the advance of the original roll. This involves changing the gear ratio in the perforator to match the advance.

It may come as a surprise to learn how many different row advances were used during the period. Early Duo-Art rolls used a row advance of (nominally) 256 rows per foot; in the mid-1920s this was upgraded to 384. Early Ampico rolls advance at 240 rows per foot; around 1921 this changed to 360. Some very late Ampico rolls dating from after the merger with Aeolian were perforated on Duo-Art equipment, and therefore use one of the two Duo-Art advances; there are therefore four different advances for Ampico, not counting the Stoddard-Ampico rolls, which predated all of these. Early Welte-Mignon Licensee rolls were perforated at 360 rows per foot using the Republic perforators; in 1921 this too was changed, to 405. During the Depression some Licensee rolls were also perforated on the Duo-Art equipment, and therefore have Duo-Art advances.

Accomodating this large number of row advances is a nuisance. It calls for removing gears or sprockets and mounting different ones in their places. However, it is the only thing that needs to be changed to make hole-for-hole copies.

Properly made copies of music rolls of the 1920s perform identically to the original rolls made during the period. This is a fortunate circumstance, because many of the most important and valued rolls of the time were made in very small quantities. Today we can make copies of these rare rolls, making them widely available at reasonable cost.

Wayne Stahnke

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