Outsmarting Sony (or, Stupid U-Matic Tricks!)

[captain18]

So, part of the reconfiguration of my edit suite/man cave has been to recable everything to use S-Video instead of composite video for the highest quality video I can get from my collection of professional and prosumer gear. This was pretty easy on the S-VHS front since that's where S-Video was developed to begin with, and my Betacam deck does S-

Comments

a clue... now perhaps an interpretation???

[turnkit]

As I read your response I was thinking... perhaps Chroma could come from the composite signal -? But I don't understand the electronics well enough to know if that would make sense.

Then I am glad you reminded me to look through my email requests which I made to Harris and to Panasonic... just as you had done. Perhaps it was the way in which I begged that got me the user manual .pdf for the DPS-295. (Send me your email address to turnkit@gmail.com and I'll forward it to you if you get no response from Harris.)

So a little of RTFM-time:

INPUTS:
...
DUB Input (7-pin) .... 1V p-p Luminance, 75 Ohms
Chrome derived from NTSC In #2
...
NTSC-2/DUB-C Input:
Composite NTSC-2 input and DUB chroma input. This input may either be used as a second NTSC input, or as the chroma source when using the DUB input mode. When used as a second NTSC source, see NTSC-1 input for details on selecting the correct input mode.
When used as a DUB chroma input, this signal should be connected to the the (sic) NTSC output of the playback VTR in addition to the connection made via the 7-pin DUB-Y input. If the subvarrier feedback is NOT being used, the input mode should be set to HET. If the subcarrier feedback is to be used, then the input mode MUST BE set to DIRECT.

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So I've got to get back to the edit bay and try to hook it up. But I am confused about subcarrier. If I hope to get the absolute best signal how should I use the subcarrier signal? How do I loop it? I am only interested in playback from the deck, not record. I always assumed subcarrier was used for record. Am I wrong there.

Anyway... I just bought a $40- DPS-210 off eBay. Argh. More money thrown on this thing... but am super-glad there is (colorful) light at the end of the tunnel.

Re: a clue... now perhaps an interpretation???

[captain18]

Actually, taking the chroma off of composite would be an elegant solution, if you think about it. Any TBC by design is going to split the chroma and luma from the composite signal to begin working with it. Since the luma is already S-Video compliant, DPS saved themselves some circuitry by pulling the chroma from composite rather than adding the extra bits to transform the 688 kHz color to 3.58 mHz.

This leaves a question though about just how good the quality of that color signal is. In theory it should be lower from being mixed with the luma but I don't know by how much. In practice it may not be noticeable.

Having the chance to compare the DPS-295 and DPS-210 outputs will be valuable though, to see whether there's a difference in taking the chroma off composite as opposed to decoding it off dub.

For the subcarrier mode, all you need to do is add a cable from the Subcar Output on the DPS-295 to the SC Input on the BVU-950. My best understanding is this forces the VTR to lock the video signal to the TBC's subcarrier. Since the SC acts as color reference, the TBC can slightly alter it to impact the color reproduction.