[QuadList] The Digitrak Tape area OT

[Don Norwood]

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
>