[QuadList] The Digitrak Tape area OT

[Roger Brett]

Hi Don,

In years past I spent a quick moment trying to play back a 1" tape from 
a VR-7500 series machine on a VPR-1.  Can't recall the issue since I've 
slept (numerous times!) since then ;-)  Since they were both type-A I 
thought it should have played, however there may have been a difference 
in modulator/demod frequencies between the two machines.  You spoke that 
your (gorgeous, well-preserved) VR-7900 had 3 modulator frequences. 
I've never really studied the differences that existed in the Type-A 
world and wondered if you knew why those two machines wouldn't play 
nicely.  Is it a low band/hi band issue or are you aware of additional 
incompatibilities, assuming they were both in alignment?

Thanks,

Roger Brett
Transfer Media, LLC

On 4/19/2013 9:21 AM, Don Norwood wrote:
>
>
>
> Hi Chris:
> On th 7800, the proc amp was on the right end of the main front card
> cage.  The two rear card areas accessible from the top of the machine
> were for heterodyne color and dropout comp.  The 7800 was before any TBC
> was available.
> The VPR-7900 was the first machine to have a companion TBC.  While the
> machine looks much like the earlier 7800, there are some major
> differences.  Probably most significant would be the addition of a 3rd
> carrier mode which is the same as Hi-Band quad and 1" Type-C, and the
> servo system which was the first 1" to have H-lock capability, allowing
> it to work with the small correction window that was then available with
> analog TBC's.  There are many other differences, but along with direct
> color recovery (no heterodyne), the VPR-7900/TBC-790 made 1" truly
> broadcast capable for the first time.
> The biggest problem with the 7900 (and all of its Type-A predecessors)
> was the movable guides.  That of course was fixed with the VPR-1.
> However, as visitors here can attest, the 7900 when properly set up
> looks just as good as Type-C.  To be fair, we use a TBC-7 instead of the
> original TBC-790, so correction range is much greater than the original,
> but the 7900 was the beginning of proving that 1" could be a viable
> alternative to quad.
> Don Norwood
> Digitrak Communications, Inc.
> www.digitrakcom.com <http://www.digitrakcom.com>
>
>     ----- Original Message -----
>     *From:* chill315 at aol.com <mailto:chill315 at aol.com>
>     *To:* Quad List <mailto:quadlist at quadvideotapegroup.com>
>     *Sent:* Friday, April 19, 2013 12:41 AM
>     *Subject:* Re: [QuadList] The Digitrak Tape area
>
>
>     ------------------------------------------------------------------------
>
>     I had a 7800 and it was not that great a machine.  The proc amp may
>     have been under the right rear cover.  Then the left rear may have
>     been for a simple TBC.  can anyone confirm that?
>
>     Chris Hill
>
>     On Apr 19, 2013, at 12:11 AM, "Don Norwood"
>     <dwnorwood at embarqmail.com <mailto:dwnorwood at embarqmail.com>> wrote:
>
>>
>>     I knew David would know!  Here's a pic of the other VPR-7900 we
>>     have before a capstan replacement.  There's even sort of a quad
>>     connection here. The original TBC-790 which was paired with the
>>     7900 is an analog design and Ampex used some of the same modules
>>     as in the AVR-1.  However, we now use TBC-7's which work much better!
>>     <vpr7900sml.jpg>
>>     Don Norwood
>>     Digitrak Communications, Inc.
>>     www.digitrakcom.com <http://www.digitrakcom.com>
>>     ----- Original Message -----
>>
>>         *From:* David Crosthwait <mailto:david at dcvideo.com>
>>
>>         **
>>         ------------------------------------------------------------------------
>>
>>         Yes Don it's your 7900.
>>
>>         Best Regards,
>>
>>         David Crosthwait
>>
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>     ------------------------------------------------------------------------
>
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