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MMD > Archives > December 1996 > 1996.12.06 > 11Prev  Next

Re: Roll Reader Plans
By Rob DeLand

Spencer, I have a few inputs regarding your roll reading. First, keep in mind that perforated rolls were in production before hand-played rolls were introduced (by Welte in 1905; by QRS in 1912; by others later), so the steps-per-musical event would have been debated and resolved long before the hand-played rolls came along. By that time, I doubt that there would have been any interest in re-hashing the "step" issue, both because arranged rolls would presumably still need to be perforated on the same machinery, and because the step accuracy was (hopefully) adequate that a re-design shouldn't be necessary.

I won't go into tedious detail on the step issue here because it's been done already, and it can get quite involved. Remember, 12 steps per beat is divisible into quarter-note (12 steps), eighth-note (6 steps), sixteenth-note (3 steps) notes, eighth- & sixteenth-note triplets (4 & 2 steps), and so on. However, there are some really interesting aspects of it you should know. For instance, Dave Junchen wrote a series of interesting articles about the steps used by Clark and Capitol A roll arrangers; these appeared in the April & May 1983 AMICA bulletins. (I can fax or snail-mail them to you if you wish. Give me a fax number or address; I have them handy!) He includes illustrations and explains the audible effects of Clark's choice of 10 steps per beat, and the fact that triplets were perforated 4+3+3 steps to get them to fit in a single beat. You can read the article to learn the results so I won't go into it here.

It seems to me that I was told that at some point the Welte rolls were perforated at 22.5 steps per inch of paper travel, and that would lead to a min. sampling rate of 45 steps per inch, or .02222 inches per step. If you're talking about .005, you'd be 4x over that min. rate. Perhaps your answer lies somewhere between these extremes; perhaps not!

I am very interested in accurately reading hundreds of my rolls into my computer, in addition to the rolls I recut via the Tonnesen's from time to time. It is not practical in time or cost to have them all read & recut, so I would love to develop my own ability to read. At the same time I really don't want to design a reader, so I guess I'd better keep up with what you're doing -- please send me details! Did you already discuss whether you plan to read optically or pneumatically? My preference still leans toward the latter because I want to be able to trouble-shoot it if there are problems, and I don't want to have to dig into code or microprocessor application notes!

Rob DeLand

(Message sent Fri 6 Dec 1996, 16:30:35 GMT, from time zone GMT-0800.)

Key Words in Subject:  Plans, Reader, Roll

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