[QuadList] High Speed dubbing

[rabruner at aol.com]

>>Also, I didn't realize that the VHS tapes were made in this fashion, I just figured someone had 100 vhs machines which were started with a remote control device.  I am not a movie type so I wouldn't notice if there is much quality difference in the tapes, if any. Besides, the only tapes I ever bought were at great "Discounts" which I bought on 44th ST. in New York after midnight. (HI).>>






>>Also, I didn't realize that the VHS tapes were made in this fashion, I just figured someone had 100 vhs machines which were started with a remote control device.  I am not a movie type so I wouldn't notice if there is much quality difference in the tapes, if any. Besides, the only tapes I ever bought were at great "Discounts" which I bought on 44th ST. in New York after midnight. (HI).>>




The Otari VHS contact printers -- pictures posted by someone on here -- used industrial lasers to heat the tape up to the Curie point while the master and the copy were held together in a vacuum shoe similar in some ways to the guide on a two inch machine. The mass of the guide cooled the tape quickly.  The copies were very high quality, but there were problems with the process. It depended on using CrO2 tape for both the master and the copy, which was very expensive, more than three times the cost of ferrichrome VHS tape.  Since most of the cost of a dub is in the tape, it made the process expensive.  There were also technical problems with the master which was a loop stored in a bin.  When the loop went zipping through the machine at high speed, the straightening of the folds in the loop bins caused a temporary magnetic anomaly which lasted long enough to be transferred to the dub.  These looked like tape creases moving through the image and were called "CLDs" or crease-like-distortions.  They were mostly a problem with longer masters, such as for feature length films.  These had more tape and hence tighter folds in the loop bin.  Shorter tapes, in the range of a half hour to 45 minutes, didn't usually experience this problem.  So you are not likely to have seen many contact print VHS movies. The cost was too high, and the difficulty of getting clean transfers mitigated against it.  Bell and Howell-Columbia-Paramont -- later Rank Video Duplicators -- the largest duplicator in the US at one time, doing around 80 percent of the titles sold domestically, used all methods of duplication, but the majority of their product was generated either on banks of 7000 in-cassette duplicators or 6000 open reel 2x speed duplicators.  The Otari machines were used for industrial productions of shorter form for premium clinents who would pay more.  '100 machines' wouldn't even make a test run for national level movie distribution in those days . . . 

Bob Bruner
W9TAJ







 


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