A sweet spots is the SignVideo for YUV, and the Sima (forget model off-hand) for RGB. Powerful. But finding either unit is hard, and in good condition much harder. The SignVideo didn't handle studio abuse well, and the Sima was aimed at amateurs (that usually tossed gear, not resell it).Which is the long way of saying you'll likely have more success picking up a basic separate TBC and proc amp. For the latter, units from Sign Video seem to enjoy popular acclaim here and at DigitalFAQ
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First let’s define what a coax or “coaxial” cable is. The most basic definition of a coaxial cable is a straight conductor carrying a signal enclosed inside of a cylindrical conductor that carries the return for that signal. Because the two conductors share the same axis, the electromagnetic field carrying the signal exists only in the small space separating the conductors. Outside of the cable, electric fields from the two conductors perfectly cancel each other out. This special property means that signal propagating through coax neither causes nor is affected by electromagnetic interference. The wikipedia article on coaxial cable is a good place to start for more information: https://en.wikipedia.org/wiki/Coaxial_cable
Next, let’s look at how the TBC-1000 was originally wired. This is a photo of one of the original S-video wiring harnesses:
[Attachment 59552 - Click to enlarge]
At first glance it definitely just looks like 4 separate conductors. But after a little dissection, we see that this is actually two coaxial cables that have been pulled apart at the ends for termination purposes. Granted it doesn’t look like what most people think of when they think “coax”, it fits the definition: center conductor surrounded by an outer conductor and separated by an insulator.
[Attachment 59553 - Click to enlarge]
[Attachment 59554 - Click to enlarge]
So at least Datavideo and myself are using coax cable for video signals. But what about everybody else? You had mentioned that some of your S-video cables are amazing, and others are garbage. I’d venture to guess that the difference between them is coaxial versus non-coaxial wire. Just for fun, I cut open my cheapest s-video cable. No surprises here:
[Attachment 59555 - Click to enlarge]
I'd venture to guess that if we cut open a high-quality S-video cable, we would find a pair of coax cables inside. I couldn't bring myself to do it, but this is enough evidence for me: https://cablesondemand.com/shielded-s-video-s-vhs-cable-75-ohm-dual-coax-with-gold-s-v...svhsgdl4mm-001
Also just for fun, a cross-section of an okay-quality AV cable:
[Attachment 59556 - Click to enlarge]
[Attachment 59557 - Click to enlarge]
Coax. Even for the audio. Because for any single-ended signal, coax cable transmission is always better than non-coax cable.
Coax cable is theoretically perfect in its protection from external electromagnetic interference, but in practice this is difficult to achieve. In these original TBC-1000 wiring harnesses for example, the conductors are moved from a coaxial configuration to a parallel or twin-lead configuration. In this configuration, it is possible for the signal to be affected by external noise, so it’s best to keep them separated for as short a distance possible. Enter the BNC connector. BNC was designed for use with coax cable as it maintains the coaxial configuration of the signals as they pass through the connector and back into another coax cable. The RCA connector is really just a consumer-friendly version of BNC. For the most robust transmission of signal from device A to device B, the signal should be transmitted entirely through coaxially-configured conductors to avoid signal degradation.
Now consider the 4-pin mini DIN connector used for s-video in consumer electronics. The configuration of the 4 pins is definitely not coaxial, which means even if the cable leading to the connector is coaxial, it will have to be pulled apart to make connections with the mini-DIN. This will cause the signal to pick up some noise, and likely will cause some reflectance of the signal back to the source.
There really isn’t much to discuss here. Coax is the norm for transmission of analog video signals, full stop. Spreading disinformation in the form of disparaging comments is not helping to create a positive learning environment in this forum.
It's no surprise that BNC is still used even in the digital word, It carried all TV programs that we have enjoyed when we were kids and continue to do so today, Where was S-Video then and where is it today?
So it was extreme skepticism, not hostility. Read the post again, words like "potential" and "may" are used intentionally.
That insanely high initial asking price didn't help matters. It seemed like a typical excessive money grab, not much different from "parts or not working" TBC-1000s selling for $1k now.
We've seen botched TBC mod home/hobby projects put on eBay before -- including at least one VP-299 bypass in past years, and it was a botched mod. And the seller wasn't the one who did it, supposedly, and it came from an estate sale (something not known until AFTER problems arose, not in the auction description). So much eBay video stuff comes from estate sales these days, it's insane. You'd think it was a format that ended 50 years ago, used only by retirees now. Clearly not the case, so WTF?
Any initial skepticism on my part is gone now. If anything, I'm interested in giving you ideas to make it a better 2.0 mod version. I will be getting back to you. (BTW, I wasn't alone in that skepticism. The entire reason I came to this thread was due to PMs elsewhere alerting me too it, asking my input on the topic.)
So WTF, or huh, is all there was.
However, now it's far more clear. And great post, very detailed info.
I do have concerns about how well that coax solder work will hold up in shipping, and in various hot/cold climates. That's a weak link in this early attempt, something you may want to look into.
So for the purpose of clarification...
- Composite (RCA yellow) is an inferior signal carrier, compared against s-video (separated video, better known as Y/C).
- Composite composites (smashes together) the luma and chroma signals, and you get crosstalk.
- Y/C maintains separation, so no crosstalk (crawl) occurs, unless the wire is made badly.
- Due note, however, that composite is not a horrible soft and noisy signal. Quality composite exists, minimal softness, minimal noise. The problem is generally that other devices suck, both internally, and at the connectors. Plus cheap cabling. The only composite cables I use are the ones originally supplied by DataVideo.
In a pro setting, BNC Y/C is two complete separate wires, going to two separate Y and C BNC on the unit. That all works great. But when you adapter BNC down into an s-video cable, bad stuff can happen. Crosstalk, noise. And sadly, that's often the case, even with "name brand" cables (Extron, Aja etc) as its just Chinese-made crap wires. So while BNC>svideo is perfectly fine in theory, in practice it's a nightmare. Even cheaply made s-video cables generally perform better, though do break down in time after use, and are more susceptible to outside noise. (Plug/unplug seems to exacerbate the cheap s-video cable failing.)
In a 2.0 version of your TBC-1000 mod, it'd make far more sense to split an output to both s-video in/out, as well as BNC. You have the rear port room for it. While splitting can induce noise leakage (into the signal), it can be avoided or mitigated. And that split will be far better than any external adapter in practice.
As of now, my advice to others, on this exact unit, is to get it for BNC usage. Not to adapt to non-BNC needs.
The VP-301x cards were variable in quality (not exactly the same as TBC-100 cards), but a good card makes a nice clean TBC.
It's mainly the coaxial structure, The locking mechanism is a distant second, Every cable design has good and bad qualities, choose wisely. S-Video is better than composite in terms of the signal that carries not the design and immunity to interference, Why do you think component signal is carried in RCA cables and sockets?
I don't really have a dog in this fight but have used S-video cables quite extensively and BNC cables in building security systems and personally I've had more trouble with BNC than S-video, contrary to what one might think looking at both where BNC seems to be the more professionally built and has the nice locking mechanism. The issue I've had with BNC is poor connections, resulting in having to wiggle the cable to get a good signal, that or in the case of a camera multiplexer, push the whole multiplexer in or out to get one of the many channels from acting up. When it comes to S-video I've had only a couple of cables give me trouble, either a poor signal or B&W video, other than that I've had good luck. And for the S-video cables, I like the cheaper the better, by cheap I mean thin, I once bought 6 S-video cables from Monoprice with thick cable and large ferrite things near each end, those cables I didn't like. They were so stiff and heavy they tended to pull out, I still have them but should probably just toss them or give them to someone, I really don't like using them.
To me the first thing I like to do with devices that have BNC is to purchase and install BNC to RCA converters, which of course doubles the potential failure points but does get me away from BNC as fast as I can.
That's completely a different use of BNC cables where price per foot matters because 100's of feet are used, The connectors often snap off from the cable due to either cheap connectors or badly made on the job site, I can start telling you the horror stories about RG-6 cables and connectors but that's not the cable to blame. Do start using S-Video cables for your camera system and let me know how it goes. Never the less I never said S-Video is bad, it is not durable, not reliable for situations where plugging unplugging is required, It is the best way of capturing analog video where BNC is not available.
Removed since unrelated to discussion at hand
Last edited by ccbradley; 25th Jun 2021 at 21:28.
And for the S-video cables, I like the cheaper the better, by cheap I mean thin, I once bought 6 S-video cables from Monoprice with thick cable and large ferrite things near each end, those cables I didn't like. They were so stiff and heavy they tended to pull out,
This turned out to be an embarrassingly-long post, and maybe this deserves to be its own thread, but at the level at which we are discussing things, terminology is becoming extremely important. In most cases I don't think we actually disagree with each other, but the terminology we are using is not making that very clear. I know most of this seems obvious, but my goal is to highlight some of the subtle ambiguity we’ve been glossing over:
== Signaling Standards ==
Signaling standards specify what we are transmitting. Examples include:
- Composite video: full video signal transmitted over a single pair of conductors
- Component video: video signal transmitted over three pairs of conductors (Y/Pb/Pr)
- S-video: video signal transmitted over two pairs of conductors (Y/C)
- SDI: digital video signal transmitted over a single pair of conductors
Now, a signaling standard may specify things like cable types and/or connectors, but they are more focused on the signal itself (frequencies, timing, the meaning of the signals, etc)
== Cable Types ==
- 75Ω Coaxial - used almost exclusively for video-related applications
- 50Ω Coaxial - used for everything else (mostly radio)
- Cat6e - used for computer networking (usually ethernet)
- Simple 4-conductor 22AWG Shielded Speaker Wire (used by anybody for anything that needs some wire)
Some cable types are extremely versatile and are used for many purposes. Some are designed specifically to support a specific signaling standard. They all have their strengths and weaknesses. And there usually is a right and wrong type of cable to use for a given signaling standard.
== Connector Types ==
Here when I use the term coaxial I mean a straight center conductor surrounded by a cylindrical conductor along the same center axis:
- F Connectors: What most of us think of when we think “coax cable”. This is a coaxial connector used for connecting antenna to television, or for connecting cable to cable modem.
- BNC: A coaxial connector similar to the F connector but with a quick-release mechanism
- RCA: A coaxial connector designed to accidentally fall out of your equipment. Comes with fun, color-coded dielectric material.
- 4-Pin mini DIN: The infamous “S-Video” connector. Mostly used these days in fog machines to connect the remote control to the main unit.
- RJ-45: Networking connector designed specifically for ethernet. The only type of connector that Cat6e cable is designed to be used with.
== The Problem ==
We’ve been making a lot of comparisons of various things to “s-video”. BNC versus s-video. Coaxial versus s-video. Composite versus s-video. There really is no formal standard for what “s-video” actually is, so it’s come to mean many things based on context. To most of us, it means the signaling standard by which the video is split into Y/C signals.. but it also is the name we give to the 4-pin mini DIN connector that’s most commonly used in consumer electronics… it’s also the name of the entire cable itself. When making comparisons we should be specific: we aren’t comparing BNC to s-video, we are comparing BNC to mini DIN.
I’m going to go out on a limb here and make a few sweeping claims and see if anybody disagrees. Keep in mind that any cable, connector, jack or piece of equipment can be made cheaply. The fact that sometimes we encounter cheap versions of any of these things isn’t really material to the discussion. For the remainder of this post, let’s assume everything I mention is of the highest quality available.
- Claim: Analog video signaling standards ordered from lowest to highest quality: composite, s-video, component
- Claim: Cable types for any of these three signaling standards ordered from lowest to highest quality: random straight wires, twisted pairs of wire, 75Ω coaxial cable
- Claim: Connector types for any of these three signaling standards ordered from lowest to highest quality: stripped wires shoved into jack, mini-DIN, RCA, BNC or F connector
- We have experienced such huge variation in “s-video cable” quality because we don’t really know what’s inside of them. The best way to carry an s-video signal is through a pair of 75Ω coaxial cables, regardless of anything else. If you have an s-video cable that you feel is very high quality, it’s probably dual coax. This cable is dual coax but looks the same as any other “s-video cable”. https://cablesondemand.com/shielded-s-video-s-vhs-cable-75-ohm-dual-coax-with-gold-s-v...svhsgdl4mm-001
- If you don’t know what type of cable you are using, it’s probably the wrong type. It’s not enough that the connector fits.
- 75Ω cable and connectors cannot be mixed with 50Ω cable and connectors. You can plug a 50Ω BNC into a 75Ω BNC jack.. it will fit (kind of).. but it will be an RF disaster. Impedance mismatching is the cause of bad signal here, not the BNC connector style itself.
- Most people don’t understand the concept of cable impedance. There isn’t really anything useful to gain from learning about it. All you have to remember is never use anything that is 50Ω. And if it’s not specified, it’s probably 50Ω. And the people selling it never know what they’re talking about. Case in point: https://www.amazon.com/ANVISION-4-Pack-Jumper-Connector-System/dp/B07MMH23RP/ref=sr_1_...4667775&sr=8-9 This is marketed as something you can use to connect video equipment. It doesn’t explicitly say it’s 75 ohm, but it’s for video so it must be 75…. I’ve bought this item in the past and guess what… it’s 50 ohm cable.
- My most controversial opinion of the day: being that the 4-pin mini-DIN connector is the most inferior connector, it should be avoided as much as practically-possible. That means that if you need to run s-video signal between point A and B, and you have the option of (A) using mini-DIN on both sides, or (B) mini-DIN on only one side and BNC on the other, (B) will give the better result, because passing the signal through mini-DIN only once is 100% better than passing it through two mini-DIN connectors. And remember that we are only talking about the highest quality materials here. I know that it may be difficult to find a high-quality mini-DIN to BNC cable, but they exist or can be made. I've never made one myself but that may change later tonight because I had never considered it until just now...
the only comment i'll make is it's probably not the "connector" that makes or breaks a cable. as a mil-spec certified assembler, i'd blame the soldier job. before you soldier anything you have to have good crimped metal to metal connection. a wire in the center of a puddle of soldier in the middle of a connector is crap, soldier itself is a terrible conductor.--
"a lot of people are better dead" - prisoner KSC2-303
The cable type and connector type are the two factors we are considering. We are assuming they are not poor quality.
Claim: Analog video signaling standards ordered from lowest to highest quality: composite, s-video, component
from lowest to highest quality: mini-DIN, RCA, BNC or F connector
from lowest to highest quality: stripped wires shoved into jack, mini-DIN, RCA, BNC or F connector
I was under the impression that feeding from s-vid out of a VCR will give you better results. Or... can you separate chroma and luma down the line for the same results and it doesn't matter which comes first?
The differences we're talking about is this. Outputting s-vid from VCR directly to TBC, and outputting s-vid out of TBC to capture device. The second option taking BNC composite out of VCR into TBC, and outputting s-vid from the TBC. Is there any advantage doing the first way?
No one said to use composite. we were not talking about the types of signal nor comparing them, we were discussing the design of the cable, read ccbradley posts they are very informative and they have the answer you are looking for.
^ Anyhow that's my question. I would love this statement to be clarified. (Is it because em interference?)
Not knocking BNC of course. It's an industry standard for a reason. I'm a fan.
Last edited by BenKlesc; 26th Jun 2021 at 15:41.
You have the right to disagree but it was explained why coaxial connectors are better than non coaxial connectors, The losses are very small and the average user should not care about them. If your equipment is all S-Video continue to use S-Video DIN connectors.
1. Input selector
2. Composite input
3. S-Video Y input
4. S-Video C input
5. Composite output OUTPUT
6. S-Video Y output
7. S-Video C output
8. Power ON/OFF switch
9. DC 12V 1.2A center-positive input jack
Okay this clears up my confusion. It has s-vid input not just output. So this mod can work with s-vid output from a VCR.
If this had only composite my opinion about that statement may have changed. In a professional environment if I had the choice to use only S-Video DIN or Composite BNC coax I would use DIN every time. I understand what you are getting at though. We're talking strictly cable.
Last edited by BenKlesc; 26th Jun 2021 at 16:52.
The majority of the noise caused by DIN connectors will be from signal reflectance. As I mentioned before, coaxial cable and connectors come in two variety: 50 ohm and 75 ohm. In order for signal to be transmitted cleanly, all part of the transmission line must have the same impedance: the source equipment, the connector on the source equipment, the connector on the cable, the cable itself, the connector on the other end of the cable, the connector on the receiving device, and the receiving device itself. In the video world, everything we use must be 75 ohm.
So what happens if we use a 50 ohm cable? Or we retrofit a device with brand new 50 ohm connectors instead of the correct ones? This is called an impedance mismatch, and the result is signal reflectance. Exactly as the term implies, when the signal crosses the boundary from one impedance to another, some of the signal will continue to move forward, and the remainder will be reflected backwards. When that reflected signal comes back to the source, it will bounce forward again. This cycle repeats and you can imagine the damage that can be done. And this happens at every impedance mismatch boundary (i.e. both ends of the connector).
There is a somewhat weird video on youtube that might help explain this if you’re more of a visual learner like myself. Signal reflectance at impedance mismatch boundary is shown at 2:40 in the video: https://youtu.be/ozeYaikI11g
Now, coaxial cable manufacturers are very good at creating cable that has the special characteristic impedance of 75 or 50 ohms. It’s one of the most important characteristics of this type of cable, so they pay a lot of attention to it. Same goes for the manufacture of BNC connectors. But what about the impedance of 4 pin mini-DIN connectors? Is the impedance 75 ohms? These connectors existed before JVC started using them for video, and they weren’t really being used for anything where impedance matters, so my guess would be that they’re not 75 ohms. Maybe by some chance of luck they are 75 ohms.. but nobody who manufactures them is calibrating them or guaranteeing their impedance.
So that’s the main reason that two DIN connectors will be twice as bad as one: You will have 4 cases of signal reflectance rather than 2. Hope this makes sense… thanks for asking!
I found a great write up by Blue Jeans referencing exactly what you are saying.
Is there Really a True 75 Ohm RCA Plug?
"The solution, it would seem, is to use only true 75 ohm connectors all throughout your system; but this is not as easy as it might appear. BNC connectors made for video use (but not those made for other uses!) are designed for 75 ohm characteristic impedance, as are F-connectors, so it's easy enough to keep a consistent impedance in your lines when using these connector types. But as we all know, most consumer video equipment doesn't use these connector types for baseband video signals. Composite and component video generally run through RCA connections, while s-video is run through four-pin mini-DIN plugs, and many projectors and HDTV receivers these days use 15-pin VGA-type plugs. Maintaining 75 ohm impedance on mini-DIN and HD-15 plugs is a lost cause."
That’s a really well-written article. Nice find!
@BenKlesc, @ccbradley, to add to the above past few posts...
Another consideration is the internal wiring of the gear in use.
This thread features the TBC-1000 mods by ccbradley, to attempt to correct poor internal design by DataVideo (though I disagree with BNC in/out if being re-adapted s-video, and it should only used in a BNC-only workflow). Those bad DataVideo designs may have been for cost-cutting, or simply poor engineering, or both. Perhaps even availability. And yet, it's still far better designed than most video gear (VCRs, converters), as it was (at the time) a premium video device. And it still is, for SD capturing needs.
Most other items have pitiful internals. Combo decks especially have the s-video input crushed into bad composite internally, so what's the point of the DIN connector? Same for component, which can be butchered internally both with processing and internal wiring/connections. And it was entirely done for cost cutting, to save a few pennies. Profit is better than quality, right?
So discussing external wiring is nice an all, but if it's not matching quality wiring from end to end, a high-end cable on a crappy device still results in a crappy signal. And the external wiring tends to have far less effects on quality than the internal wirings.
Just adding some perspective for future readers.
So you're the one that snagged that lot of several for repair on ebay last year :P
Very nice. I'll probably contact you at some point about doing some mods on mine.
Where did you find those, in a gold mine? If you price them right they will sell fast, You should start consediring moding VCR's with BNC connectors, people who seek quality capture they will be looking for them.
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