A sheet feeder (200) feeds sheets separated from a stack (202) toward take away nip rolls (212). The sheets are separated from the stack by fluffers (206,207) and acquired by an acquisition surface of a feed head (209) which is in communication with a vacuum pressure. An air knife (251) is used, in conjunction with a corrugation surface, to separate any secondarily acquired sheets from the acquisition surface. The time for acquiring the sheet is determined from the opening of a vacuum valve (224) in communication with the feed head (209) to the acquiring of the sheet by the acquisition surface. The time for acquiring the sheets is dependant on the sheet characteristics. A controller (300) adjusts the pressure to the fluffers (206,207), air knife (251) and the vacuum pressure to control the sheet acquisition time based on the sheet acquisition times of a predetermined number of previously successfully fed sheets and a standard deviation as compared to a table of predetermined sheet acquisition times and standard deviations for the particular sheet characteristics. IMAGE
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