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

[John M]

I always remember the card backplane on the ACR - wire wrap! - I think it was available as a spare part in case of fire etc ;). Our 2 machines had the optional IDA facility that was feed to our on air suites for the benefit of our preso guys and gals...

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From: quadlist-bounces at quadvideotapegroup.com [mailto:quadlist-bounces at quadvideotapegroup.com] On Behalf Of Glenn Gundlach
Sent: Friday, 17 August 2012 18:22
To: Norman Hurst; Quad List
Subject: Re: [QuadList] Quad Carts--Links to RCA and Ampex photo examples


The ACR-25 could play the sequence 90-10-20 and while that was near the edge it never failed. The logic bay had RTL and DTL in it along with TTL. It's been a long time since I had a look though. 

The ACR had essentially instant lock requiring no preroll so unless you really blew it, it never needed a 're-cue' and being a quad with a vacuum guide, it could sit in 'ready' as long as power was available with no transport, tape or head wear. No, those weren't 'good old days' but they were fun.

G�

--- On Thu, 8/16/12, Norman Hurst <gnormhurst at yahoo.com> wrote:




From: Norman Hurst <gnormhurst at yahoo.com>
Subject: Re: [QuadList] Quad Carts--Links to RCA and Ampex photo examples
To: "Quad List" <quadlist at quadvideotapegroup.com>
Date: Thursday, August 16, 2012, 7:22 PM



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.



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