[QuadList] RCA Models

Fri Feb 25 20:30:32 CST 2011

Hi Bill:

If the octaplex recorder turned on every other head, it would be a standard 
quad recording, but with a 5-mil track, so I'm pretty sure that's not what 
was going on.  I think I get the "picture" that you are describing, and I 
assume that maybe if you were able to center the head between the two 
tracks, then perhaps the demod output would alternate between the stronger 
fields as they passed by.  I can't imagine that the results would be very 
good, but more to the point, I still can't imagine why the octaplex would 
have been used in the first place.  The only purpose is 2-channel recording, 
and I assume from what you have said that what you ended up with was one 
continuous picture, not 8 lines of one image alternated with 8 lines of a 
different image.

You are correct about not having any problem of this sort with recordings 
from a VR-3000.  Even though the Mark Eleven head in the 3000 is ball 
bearing, the time base error is well within the range of a standard quad.

Don Norwood
Digitrak Communications, Inc.
www.digitrakcom.com

----- Original Message ----- 
From: <bill.spencer at northstarstudios.tv>
To: <dwnorwood at embarqmail.com>; <quadlist at quadvideotapegroup.com>
Sent: Friday, February 25, 2011 6:42 PM
Subject: RE: [QuadList] RCA Models

I wish I had a screen shot of the demod output as it would 'splain it
better than I can.  If you can imagine the usual 16 line head pass split
with 8 lines displaced slightly to the other 8 lines in that 16 line
pass.  I believe the octuplex head was turning on record to every other
head so that instead of a smooth pass there was a switch from one to the
other hence the jump in time from one to the other.  Playing with head
penetration and height you can get sort of a sawtooth pattern and it is
within the TBC's ability to give a clean ouput.  I have only seen this
on field remote stuff done with the machine they had out at TNN and have
always thought it to be a TPR-10 as I don't remember seeing that kind of
display on the VP-3000 stuff we did at PBS in the 70s.

Bill Spencer
NorthStar Studios, Inc.
3201 Dickerson Pike
Nashville, TN 37207
(615) 650-6610
CP (615) 445-5616

-----Original Message-----
From: quadlist-bounces at quadvideotapegroup.com
[mailto:quadlist-bounces at quadvideotapegroup.com] On Behalf Of Don
Norwood
Sent: Friday, February 25, 2011 5:20 PM
To: quadlist at quadvideotapegroup.com
Subject: Re: [QuadList] RCA Models

I must be missing something.  The purpose of the octaplex system was to
record two different video signals simultaneously.  The tracks are 5-mil

with a 45 degree displacment on the drum between channels.  So a 10 mil
head
would certainly cross-track them, but in addition to the tracking
errors,
you would have 2 different signals "on top" of each other.  I'm still
not
understanding how you recovered that, or what the purpose was if the
octaplex was recording the same thing on both tracks.

Don Norwood
Digitrak Communications, Inc.
www.digitrakcom.com

----- Original Message ----- 
From: <bill.spencer at northstarstudios.tv>
To: <dwnorwood at embarqmail.com>; <quadlist at quadvideotapegroup.com>
Sent: Friday, February 25, 2011 4:43 PM
Subject: RE: [QuadList] RCA Models

No, every other head pass was displaced by a few microseconds and there
were twice as many, but within the 10 mil head it picked up all and the
TBC lined them all up.  The machine was one owned by the production
people at National Life/Opryland/Gaylord/TNN/CBS Cable/MTV Networks, but
I don't know what the disposition of it was during all the acquisitions.
There are some old-timers still in town that might know what happened to
it.

I remember that Sony tried something similar in early Betacam where the
camcorder had a drum half the size and recorded a track in two
revolutions, actually I think all the camcorders worked that way after
the BVV-5.

Bill Spencer
NorthStar Studios, Inc.
3201 Dickerson Pike
Nashville, TN 37207
(615) 650-6610
CP (615) 445-5616

-----Original Message-----
From: quadlist-bounces at quadvideotapegroup.com
[mailto:quadlist-bounces at quadvideotapegroup.com] On Behalf Of Don
Norwood
Sent: Friday, February 25, 2011 3:06 PM
To: Quad List
Subject: Re: [QuadList] RCA Models

Hi Bill......

So are you saying that you used a 5-mil head and recovered two different

programs from the tape?

Don

----- Original Message ----- 
From: <bill.spencer at northstarstudios.tv>
To: <quadlist at quadvideotapegroup.com>
Sent: Friday, February 25, 2011 11:37 AM
Subject: Re: [QuadList] RCA Models

I have dubbed some tapes from a 10 and the head was definitely an
octoplex
as there was differential timing from one set of heads to the other.
The
good news is that the digital TBC in the AVR-2 was able to correct it
and a
previously thought 'lost' piece of material is now safe on a new digital

format.

Bill Spencer
RF Engineering Supervisor
(615) 650-6610
(615) 445-5616 CP

________________________________

From: quadlist-bounces at quadvideotapegroup.com on behalf of
Chill315 at aol.com
Sent: Fri 2/25/2011 9:19 AM
To: quadlist at quadvideotapegroup.com
Subject: Re: [QuadList] RCA Models

David

I have seen the portable one displayed.  It was a military unit that was

sold to the public.  I was told somewhere that the original military one
was
a Octo-plex unit.  I have vague memories of someone previous mentioning
the
model and working with it.  So we have to assume that it was sold.

Any way this has been an interesting discussion.

Chris Hill

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