Perforator Plans
By Spencer Chase
My interest in roll punch advance is mainly along the lines of practicality. I am interested in the historical aspect, to the extent that it provides useful information. I would like to scan rolls with a degree of precision that captures the information as accurately as it was punched. If it is possible to remove extraneous artifacts of the punching process and the effects of aging paper, and "recreate a master", that would also be a desired goal. I was thinking that knowing the original punch step would help in this process. Also it might help to determine a step size for the punching of recuts that would provide sufficient accuracy without slowing down the process.
I plan to step the roll .005" during the scanning process. Anything finer would be very slow and produce too much raw data for the simple methods I plan to use initially. Although I'm sure the data could be massaged later to synchronize the note onset and duration with the original step size (if that is ever determined) I would like to be convinced that I am choosing a reasonable resolution from the start. Does anyone have any ideas as to what timing accuracy is really necessary to not degrade the final recut? In complex music with subtle rhythmic interactions, I'm sure there is a greater chance of degradation, but what is a practical accuracy for which to aim? The original punching is a compromise from the master, but is it adequate?
About roll paper stability. From my experience with graphics and printing I recall that paper, like wood, expands and contracts along the grain much less (almost imperceptibly under normal variations of humidity) than across the grain. (The old offset presses which used conventional plates could only adjust the image stretch in one direction and this was adequate for accurate registration of maps as long as the paper grain direction was chosen correctly.) Of course seventy year old paper may have stretched as the fibers are broken down and the paper is pulled through the spoolbox many times, but there can be no assumed relationship between the change in the two dimensions.
Wayne Stahnke's idea about matching note spacing with musical intervals seems very reasonable as an explanation for choosing strange step sizes, but was this just a bias on the part of the original engineers or is there any validity in this choice. If a roll is hand played, to what extent does the recording match musical intervals anyway? Then when you consider that, at best, there are considerable differences in timing from one note to another in the player. What is really necessary to make the music sound good. To what extent does the human auditory apparatus correct for minor timing variations? Did you ever notice how much better a roll can sound after a glass or two of wine. Suddenly the music all falls into place and you can hear how well the editors captured (or didn't) the original performance. Is this better perception (less attention to distractions and more to the music) or better fitting of the perception to a musical model or ideal?
To sum up, I would like any input that would help me decide on a scan rate that would not degrade the source data. I would hate to dedicate a lot of time to building a scanner and scanning thousands of rolls, only to find later that the data captured was less than adequate. With respect to roll punching, I am less concerned. As long as the data is adequate, a method can eventually be developed to produce rolls of sufficient accuracy.
If anyone is interested in details of my proposed scanner design, I would be glad to provide such details. I would especially welcome advice as to whether I am proceeding along a reasonable path.
Spencer Chase
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(Message sent Wed 4 Dec 1996, 22:48:34 GMT, from time zone GMT-0800.) |
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