[QuadList] Quad Carts--Links to RCA and Ampex photo examples

[Norman Hurst]

Ampex was caught off-guard when RCA introduced the TCR-100, and responded at the next NAB with the ACR-25, and one-upped them with twice the play time (6 min vs. 3).  But more than that, the ACR could cycle a cartridge in half the time, which meant that the ACR could play 10 second spots back to back but the TCR needed 20 seconds to rewind a tape and cue the next one.  Either machine could play a short spot as the last in a break.  


(I think the 10-second spec was sometimes met by "deferring" rewind, especially for longer tapes.)

The ACR-25 had such a fast cycle time due to it's amazing tape handling.  It threaded the tape by sucking it out of the cartridge with vacuum and bringing the capstan and vacuum guide 
up from under the deck after the tape was in the path.  The mechanical 
repeatability of that moving vacuum guide (also used in the AVR-1) was a brilliant piece of engineering by Dale Dolby, the lesser-known mechanical-engineer brother of Ray Dolby.  Another reason for the fast cycle time was that the cartridge belt was circular, not oval, which allowed a larger minimum radius, which allowed it to spin faster.  The downside was that it was dangerous and had to be kept hidden inside the machine, so operators did not have random access to all the carts.


Another bit of trivia: The TCR-100 used DTL logic chips.  The ACR-25 used the brand-new TTL chip technology, which was much more sensitive to static discharge than DTL.  At NAB, RCA engineers would shuffle across Ampex's carpet and touch the ACR-25 to see what crazy thing it would do.



________________________________
 From: Steve Greene <Steve.Greene at nara.gov>
To: 'Quad List' <quadlist at quadvideotapegroup.com>; garyada at ix.netcom.com 
Sent: Thursday, August 16, 2012 2:51 PM
Subject: Re: [QuadList] Quad Carts--Links to RCA and Ampex photo examples
 



  
Thanks everyone for the information!  The three I've found (so far) are Ampex. 
 
I'll try to take some pictures of my own.  I always like to put a pencil or my keys in the foreground for scale when I shoot something like that.
 
Steve

>>> "Gary Adams" <garyada at ix.netcom.com> 8/16/2012 2:20 PM >>>

Just to provide the other view.  The doors covered the tape fairly well.  These were the 3 minute versions, but the one minute carts were more commonly used.  It was interesting that Scotch 400 tape was used and recommended.  When 420 came out, it clearly had a better picture with less noise or “chroma spread” but the tape had serious issues with “stiction” in the machine.  The smooth surface against the posts and audio head assembly caused the tape to stall after it was cued and ready to go.  I spent quite a bit of time at customer sites sorting this out after they rebuilt carts using 420 tape.  It was easy to demonstrate.  Too bad since the picture was noticeably better.  
 
While both RCA and Ampex carts produced proper quad recordings, I’m fairly certain the procedure of removing the tape and playing it on a quad was seldom used.  Even at our low end station, we always had the original quads on the shelf.  It would have been a lot of trouble to actually perform the complete task.  And they wouldn’t have easily been interchangeable between machines since both used a different method of cueing (timecode vs. tones) and the end of tape sensing would have been different.  Not efficient in any case.  We were luck to have either of these machines in the day as it really freed up the manual task of loading 2-4 quad machines for a break.
 
Gary
 
 
-----Original Message-----
From: quadlist-bounces at quadvideotapegroup.com [mailto:quadlist-bounces at quadvideotapegroup.com] On Behalf Of Dennis Degan
Sent: Thursday, August 16, 2012 9:37 AM
To: Quad List
Subject: Re: [QuadList] Quad Carts--Links to RCA and Ampex photo examples
 
 
______________________________________________
Please trim posts to relevant info when replying.

Change subject to reflect thread direction. Thanks.
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