[QuadList] What Would a Newly Designed Quad VTR Do and Have? Reply by 6/1...

[Chill315 at aol.com]

Interesting dreams.
 
So let us start with what has to be given.
 
The SMPTE standard for quad tape sets the shape and distances between the  
erase stack and the audio heads.  This is a shape and distances that can  
not be changed.  Anything outside this can be changed.  We have seen  it with 
different designs of the reel placement.  The tapes that we are  trying to 
recover have been recorded on a deck that we know of today.  
 
The history of quad technology has created some really big issues that had  
to be designed into the servo systems.  Everything has had to have been  
backward compatible.  Even the RF systems have issues.  Example are  the early 
pre-emphasis that was used by RCA.  
 
So the servo will have to take care of all the issues that we will never  
see.  As an example, when was the last time you changed the track selector  
on the VR series control panel?  Bad physical edits that require  relock?  
The 50 hertz and 60 hertz machines are not that big an  issue.
 
The head design is locked in place.  we will still be stuck with the  same 
basic design.  Air bearings will be required.  The harmonics of  the 
vibrations and jitter from the ball bearings precludes using  them.  Vacuum is 
required to meet SMPTE standards.
 
Once off tape, it will still require the use of head  switching and a 
demod.  We can improve the design and filtering  to get cleaner signals.  Still 
it will be are limited to the 6  standards and the early ones that are legacy.
 
Now after it is off the tape then it becomes a dream.  The design  could 
use a very wide window TBC but it should not be a frame.  The  conversion from 
video to all other standards is easy.  Just tack on the  technology from a 
number of manufactures.  Audio could be AES or even re  clocked to 44.1.  
The tools to clean up the audio and video should not be a  part of the machine.
 
Those are the limitation.  Now what can you do with the rest of  it?  
Transport designs will be interesting.  Yes the reel motors have  to be 
substantial.  Placement of the reels and what you want to do between  the reel and 
the start of the canoe and after the audio stack is anything  goes.  I am 
going to assume that we use a capstan that pulls tape and not  push it.  I would 
use a capstan without a pull in puck.  They cause  skewing and damage.  So 
a vacuum capstan is the answer.  I would use a  vacuum chamber like the 
AVR-1 to buffer the tape.  Would I use a  cleaner?  Maybe.  But the design may 
cause problems.  
 
So we are stuck with the basic transport other than the placement of the  
reels.  Everything else is up in the air.  If you think about it, the  
machine would be about the size of a TR-5 and weigh a lot less.  The  control 
would be a micro processor.  The electronics could fit on one or  two cards.  
the biggest thing is the Motor Drivers to the capstan and head  wheel.  The 
human interface will probably take more space than the control  system.
 
Chris Hill
WA8IGN
 
 
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