I.DEN time base correctors

[johnkins]

Anybody know anything about this company? Absolutely no information online about them. Particularly trying to find operating manuals for the time base correctors they made: IVT-9SPM, IVT-7P


[Attachment 59860 - Click to enlarge]

[lordsmurf]

These are problematic.
- Never calibrated, very fiddly to do. Always abused knobs and buttons, does not cooperate easily, or at all.
- Noisy fan must be bypassed.

I have the manual for the IVT-7, somewhere, always forget to scan it.

The IVT-7 is probably the only rackmount unit that was designed with consumer analog sources as an "also" feature. So it can work, if in good shape. But essentially all of these units have problems, good shape ended years ago. I don't want to get anywhere near them.

[johnkins]

Thanks for the reply,
I've currently got one of each of the models I mentioned in first post. They're actually in surprisingly good condition and are producing solid picture correction through composite. You're spot on about the fan...

What interests me most about them is the 7-pin dub i/o that they both have (see image). The IVT-9 seems to have a single 7-pin input for component, yc443 and u-dub (which I assume is umatic dub?) and then separate 7-pin outs for each of these. Not entirely sure how these all function as I don't have the 7-pin cables to test with currently, but hoping it could function as a way of capturing using dub signal from u-matic.

I'd greatly appreciate if you could find the IVT-7 manual. Would be very helpful to at least know more about these models.


[Attachment 59871 - Click to enlarge]

[nogginvid]

UMatic dub is a bit like Y/C - but instead of carrying the 4.43MHz or 3.58MHz PAL or NTSC chroma subcarrier on a separate pin, it carried the off-tape 'colour under' heterodyned chroma (which is usually around 600-700kHz instead of 4.43 or 3.58MHz). This was designed to improve the quality of 'dubs' (i.e. copies) made - as it avoided a double conversion to and from baseband composite (the concept pre-dated S-video).

It may be that the IDEN delivered improved decoding quality if you fed it Y/C or Dub and took a Component output from it.

[johnkins]

Hi nogginvid,

Yes, aware of the differences between dub and Y/C, but was thinking that this IDEN potentially can convert dub to Y/C443 similarly to how certain DPS transcoders can. But I'm probably just being overly hopeful. Currently working through some U-matic tapes but am keen to avoid using the composite signal if I can. No way to tell until I actually track down some 7-pin cables or just make some myself...

[energizerfellow]

I'm in agreement about avoiding these I.DEN units or really any of the in-period hardware. All these Dub-native TBCs and Dub transcoders all appear to be from the late 80s or so and concerns about the age of the electronics in them are real. Also, that I.DEN IVT-7 unit should have remote with it for the proc amp, as seen here:




For something in current production, as discussed in the other U-matic thread, there's the Keystrobe Dub-optimiser. This will let you use a much more modern TBC with S-video inputs like the BrightEye 75 or AJA FS1 (and get modern features like 10-bit color with the TBC enabled, SDI outputs, etc).

[dellsam34]

Keep in mind that the Keystrobe device is not a true Y/C device, It gets the luma Y from the DUB connector and chroma C from the composite output with some filtration, So it's kind of a comb filter. I asked him in that DIY forum if it is possible to tap into the machine's guts and look for the Y and C signals here is what he has to say:

As designer of the product you mention, it's entirely feasible to DIY a solution, indeed the product developed from such a situation.
The concept is to extract Y and C before they have been remixed into a composite signal. The reason for this is that they have been processed separately in the machine and are no longer coherent. When added together there is a loss of resolution since the C includes an amount of unfiltered Y. An added gain is that it's possible to extract the Y component before the rather primitive noise coring in those machines.

So what do you need:

The Y signal can be taken from the Dub connector where it can directly drive a 75 ohm line. You could use that directly as Y but it would be better to filter some of the out of band components if you intend to digitise to a lossy format. If any of the playback is of Hi-band tapes (in suitable machines) you will need some gain as the DUB Y signal drops from 1V P-P to 0.5V P-P with these tapes.

The C signal is bit more problematic. You will probably have to dive into the machine and pick up the 4.43 or 3.58MHz subcarrier just before it is added to the Y. You will doubtless need to build a 75 ohm cable driver. The amplitude of this signal is not so critical as the burst is used as a level reference.

Once you have the Y and C signals, make sure they stay apart. The worst thing you could do is send them down a cheap S-Video cable where often the signal cables share a common shield.

The above is how we started out. Unfortunately there are so many different U-Matic models, each with its own locations for chroma takeoff, and you have to go inside.
To make a "plug-n-play" product we extract C from the composite output and pass it though an active filter. It took a lot of effort to get the results as good as the direct C takeoff, so I don't recommend this for DIY.