[QuadList] The Digitrak Tape area OT

[Roger Brett]

Don, thanks for the detailed explanation.  When these machines were 
popular, I was standing behind IVC 800 & 900 series machines.  The Ampex 
VRs were an enigma to me then and have continued to be into the present. 
  However my friend,  you have shed a tremendous amount of light on some 
of the perhaps lesser-known (at least by me!) attributes of the Type-A 
format.  Thanks again.

Roger.

On 4/19/2013 3:38 PM, Don Norwood wrote:
>
> Hi Roger:
>
> The VPR-1 is equipped only for what was called "Very High Carrier" in
> the Type-A format.  This is the same as Hi-Band Quad and Type-C.  The
> VR-7500 that you referred to did not record in that mode, but instead
> offered what was called Low-Band (the original Ampex 1" B&W frequencies)
> or Hi-Band (the carriers used for Ampex 1" color).  These were roughly
> equivalent to LBM and LBC used for quad recordings.  So any recording
> made on a VR-7500 would not be compatible with a VPR-1.   Ampex did
> design a board to allow playback of the older standard on the VPR-1 and
> in fact we have schematics, but other list members & I have looked into
> this and as far as we have been able to determine, the product was not
> actually produced.
>
> The VPR-7900 family (7900/7950/7900A/7950A) is the only Type-A machine
> that includes all three modulation standards, so it is backward
> compatible with the earlier machines.  All earlier machines were wide
> band recording with a pilot signal added in the color mode, so the 7900
> can directly reproduce the older color recordings and simply eliminates
> any need for the pilot if it is present.  As a result, even color
> material recorded in the oldest B&W carrier mode can be recovered in
> color by the 7900.
>
> Don Norwood
> Digitrak Communications, Inc.
> www.digitrakcom.com
>
> ----- Original Message ----- From: "Roger Brett" <rcbindy at comcast.net>
>>
>> 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
>>
>
>
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