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<div dir="ltr"><font face="Tahoma" color="#000000" size="2">It was in the SMPTE standard. Ampex made it an option and Sony made it standard. The concern was that something in the future might need the V.I. However in type C only lines 4 to 14 were missing so
VITC and VITS were still there. I think there was also an issue where Sony did not want tp pay re a patent Ampex had on control track update (or something like that)and needed the V.I. to do it their way. Can anyone shed more light on that?</font></div>
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<font face="Tahoma" size="2"><b>From:</b> quadlist-bounces@quadvideotapegroup.com [quadlist-bounces@quadvideotapegroup.com] On Behalf Of Scott Thomas [scottgfx@mac.com]<br>
<b>Sent:</b> Saturday, February 06, 2010 11:59 PM<br>
<b>To:</b> Quad List<br>
<b>Subject:</b> [QuadList] Blanking Issues<br>
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<div>Talking about Type-C for a moment; I can't remember if it was Sony or Ampex (or both?), but they had a separate "sync" head on the scanner. I'm assuming that was to have a clean sync pulse on the head switch? A problem obviated by a TBC?</div>
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<div>Scott Thomas</div>
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<div>On Feb 6, 2010, at 5:20 PM, Don Norwood wrote:</div>
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<div>Hi Park:</div>
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<div>All of the Type-A 1" machines up thru the VR-7800 had the switch above the vertical interval. The VPR-7900 was the first to place it in the vertical. Remember also that the Type-A machines are single head, so there is more than a "switch", there is a
dropout for several lines. The VR-660 is a 2-head design so there is a switch and no dropout.</div>
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<div>When Sony made their first 1/2" machines, there was apparently some "reverse engineering" done on their Ampex predecessors. Although the Sony machines were 2-head, they had a "blanking" circuit that covered up the switching point and produced a totally
blank area in the same location as the Ampex Type-A. There was no logical reason for that other than replicating the output signal of the Ampex. The practice was discontinued in subsequent models.</div>
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<div>Don Norwood<br>
<a href="http://www.digitrakcom.com" target="_blank">www.digitrakcom.com</a> </div>
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