[QuadList] Blanking Issues

[Don Norwood]

Hi Park:

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.

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.

Don Norwood
www.digitrakcom.com  
  ----- Original Message ----- 
  From: C. Park Seward 



  Didn't some of the early Ampex 1" VTRs have the switch in visible picture but the 660 series had it lower???
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