[QuadList] Contact tape duplication (was Little more fun)

Tue Mar 9 19:43:19 CST 2010

Pat Shevlin can tell us a thing or five about contact duping. He had  
quite a few (understatement) running VHS and other formats.

In a Feb. 17 2009 post re: 	

[QuadList] Responding to: Excellent Exchange - Non-Contact Extraction  
of the Program from Quad Tape - Ampex non-moving head

Allen McConnell described using the Ampex High Speed duplicator at  
Byron's Motion Pictures in Washington DC.

Archives have the post here:
http://mail.quadvideotapegroup.com/pipermail/quadlist_quadvideotapegroup.com/2009-February/thread.html

For folks new to the list, you might enjoy reading through the archives:
http://mail.quadvideotapegroup.com/pipermail/quadlist_quadvideotapegroup.com/

At some point we'll try to make them searchable. I may ask for some  
help from Rob Linglebach of the TIG.

Enjoy!

Ted (now in Atlanta, GA and heading for "Bill's Place" in Nashville,  
Thursday afternoon.)

On Mar 9, 2010, at 7:21 PM, georgenann at aol.com wrote:

> Bill,
>
> Tnx fer info, very interesting.  I guess the tape onto which the  
> mirror image was recorded was not a standard tape? Was it made just  
> for this purpose??
>
> GK
>
>
>
> -----Original Message-----
> From: Bill Carpenter <wcarpen107 at yahoo.com>
> To: Quad List <quadlist at quadvideotapegroup.com>
> Sent: Tue, Mar 9, 2010 6:51 pm
> Subject: Re: [QuadList] Little more fun
>
>  Hi Folks,
>
> The Ampex contact duplicator operated on some very basic magnetic  
> principals, by using a high coercivity mirror image tape held in  
> direct contact with a blank standard tape, a copy was created when  
> the two were placed in a magnetic field, almost like contact printing.
>
> The keys were making a exact mirror image master, hence the AVR-1  
> mirror kit with the special MK 20 head assy and other stuff.
> Also the duplicators clamped the two tapes together in a vacuum  
> while the tapes were ridding over a large rubber faced drum, maybe  
> it was over two inches high by about 10" in diameter and had a  
> vacuum "shoe" that was controlling or clamping the contact area  
> which was probably over 90 degrees of the rotation of the drum and  
> the field was applied here also.
>
> The tapes needed very good hi speed tension control, so we used  
> AVR-1 reel motor assemblies. The clamping/drum  assy which was  
> removable like a quad head was the only part the needed rebuilding.
>
> All I remember is that there was one great engineer in our Sunnyvale/ 
> Cupertino plant that could get it done and test it and he never  
> smiled at me when I had another assy. to rebuild.
>
> We had seven systems installed, and another in storage somewhere,  
> with the AVR-1, with the kit installed, ready for one of the eastern  
> oil rich countries, if we would ever get the shipping clearance?
>
> The master tape did not get erased by the transfer field since the  
> coercivity was up at about 1500-2000 oersteds as I remember.
>
> This was called hysteric duplication and you could also do thermal  
> duplication, same principle, but replace the magnetic field with  
> something that would bring the tapes up to the "currie point" and  
> then cool them quickly with out melting the backing, which was very  
> difficult.
>
> CVS, the folks that made the first DTBC in 1973, tried to do this  
> and then had to time base correct to make a good helical master.  
> Once they built the DTBC they forgot about duplication very quickly.
>
> Bill Carpenter
>
> --- On Tue, 3/9/10, georgenann at aol.com <georgenann at aol.com> wrote:
>
> From: georgenann at aol.com <georgenann at aol.com>
> Subject: Re: [QuadList] Little more fun
> To: quadlist at quadvideotapegroup.com
> Date: Tuesday, March 9, 2010, 2:35 PM
>
> Tnx fer info steve.  I wish I was in on that system, sounds  
> interesting.
>
> 73,
>
> George
>
>
>
> -----Original Message-----
> From: Walton, Steve <SWalton at tribune.com>
> To: Quad List <quadlist at quadvideotapegroup.com>
> Sent: Tue, Mar 9, 2010 5:28 pm
> Subject: Re: [QuadList] Little more fun
>
> Hi,
>
> By placing the two tapes together in a magnetic field, some of the  
> magnetic image from the master would be transfered to the blank tape  
> (similar to a print-through).  It left just enough of a magnetic  
> signal on the blank tape to be recoverable by some machines.
>
> Obviously there was a limit to how many copies could be made this  
> way, but I do not know what that limit was.  One would think that  
> every time this process was repeated, the image on the master would  
> diminish slightly.
>
> Steve Walton
>
> From: quadlist-bounces at quadvideotapegroup.com [mailto:quadlist-bounces at quadvideotapegroup.com 
> ] On Behalf Of georgenann at aol.com
> Sent: Tuesday, March 09, 2010 5:19 PM
> To: quadlist at quadvideotapegroup.com
> Subject: Re: [QuadList] Little more fun
>
> Hi Steve,
>
> Thanks for the reply about the HS Dubber.  The part I don't quite  
> understand is the RF field, what kind of field was it?  How did it  
> pass the mag info to the blank tape?  Also did it damage the  
> original mirrored master?  I ran into a fellow who worked on one and  
> he told me he had lots of trouble with it, it was a "Bear".
>
> 73,
>
> George Keller
>
>
>
> -----Original Message-----
> From: Walton, Steve <SWalton at tribune.com>
> To: Quad List <quadlist at quadvideotapegroup.com>
> Sent: Tue, Mar 9, 2010 5:11 pm
> Subject: Re: [QuadList] Little more fun
>
> Hi,
>
> It was my understanding at the time (70's) that the "high speed  
> dubs" were first recorded on a special "master" machine (AVR-1?)  
> that was specially manufactured to record a mirror image onto the  
> master tape.  This special machine was identical in all respects to  
> a standard machine, except that it was a mechanical mirror (head  
> rotated backwards, tape ran backwards, I am not sure).  But the net  
> result was that it recorded a tape that was a mirror image of a  
> normal recording.
>
> This mirrored master tape was then copied as stated below by  
> bringing the master and a blank tape into contact and passing them  
> through a magnetic field.
>
> These high speed dubs were easy to spot because they had a very low  
> RF level.  Some machines (VR-2000's) would not play them, but an  
> AVR-1 would usually get them to play without problem.
>
> Steve Walton
>
> From: quadlist-bounces at quadvideotapegroup.com [mailto:quadlist-bounces at quadvideotapegroup.com 
> ] On Behalf Of georgenann at aol.com
> Sent: Tuesday, March 09, 2010 4:45 PM
> To: garyada at ix.netcom.com; quadlist at quadvideotapegroup.com
> Subject: Re: [QuadList] Little more fun
>
> Hi Gary,
>
> Actualy, I think if you had the oxide side of the tape on the heads,  
> the heads would be completely slanted in the opposite angle from the  
> recorded tracks.  With the back of the tape on the heads, we didn't  
> get enough signal to make any video at all.
>
> You just rang another bell.  Has anyone run into the Ampex High  
> Speed Dubber?? I only saw one once at EUE in New York, briefly.  I  
> understand an AVR-1 was needed to make a mirror image tape first,  
> then the dubs were made by putting the new mirror tape against the  
> blank and some kind of field was shot thru them and the video was  
> recorded on it.
>
> George Keller
>
>
>
> -----Original Message-----
> From: Gary Adams <adam7889 at bellsouth.net>
> To: 'Quad List' <quadlist at quadvideotapegroup.com>
> Sent: Tue, Mar 9, 2010 4:32 pm
> Subject: Re: [QuadList] Little more fun
>
> Because the quad tracks were mostly (not completely) perpendicular  
> to the tape, backwards got some picture upside down and backwards.   
> You were still reading the oxide side.  This put the control track  
> where the audio heads expected audio so you hear control track.   
> Capstan would free run without control track.  Some clever people  
> put 240hz tone on the audio track allowing the capstan to be a bit  
> more stable as a joke.  I think newer machines did not like this too  
> much but I’ll bet the AVR1 could play it and probably turn the  
> picture back up  J  (just kidding).   I think on a 1” the tracks  
> would never line up since they were so slanted to the tape.  So the  
> heads would read across the track rather than with the track.
>
> Gary
>
> From: quadlist-bounces at quadvideotapegroup.com [mailto:quadlist-bounces at quadvideotapegroup.com 
> ] On Behalf Of georgenann at aol.com
> Sent: Tuesday, March 09, 2010 4:04 PM
> To: quadlist at quadvideotapegroup.com
> Subject: Re: [QuadList] Little more fun
>
> Hi Joe,
>
> This was after FF to the TU reel then puting it on the supply side  
> so it is looking at the back of the tape, we were getting a "Nil  
> heard signal" from the tape.
>
> Now that you mention it I do remember at some time having a tape  
> upside down on a machine, it did come out upsidedown, but bad  
> picture and lock up with a funny tone from the CTL coming out of the  
> audio. BUt this was with the oxide side facing the tape.
>
> Mny Tnx,
>
> George
>
> -----Original Message-----
> From: Joe Owens <jpo at prestodigital.ca>
> To: Quad List <quadlist at quadvideotapegroup.com>
> Sent: Mon, Mar 8, 2010 5:18 pm
> Subject: Re: [QuadList] Little more fun
> [Flipping the tape over takeup/supply] On some machines, the video  
> would play upside down and in reverse, but no audio, obviously.
> On 6-Mar-10, at 11:49 AM, georgenann at aol.com wrote:
>
>
> I think this would work on the 1" machines also, but I never tried it.
>
> Joe Owens
> Presto!Digital Colourgrade
> 302-9664 106 Avenue
> Edmonton, Alberta T5H0N4
> +1 780 421-9980
> jpo at prestodigital.ca
>
>
>
> =
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Ted Langdell
Secretary

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