Why 75 ohm coax cabling is the best cable for video signals.

I’m going to preface this by stating that I’m not a naturally competitive person and I’d rather our cable sell on its own merits and exist in a niche for people who know why it’s better. But without making some statements about exactly *why* our cable is better than what you can get elsewhere, the bulk of people are going to remain uninformed and also see our higher prices as an attempt to gouge more money.

They aren’t. We actually took a significant pay cut when we introduced higher grade coax. Our coax cabling is already “on sale” and in the current climate, it’s been permanently on sale.

Everybody else is playing this comparison game with photos and stating why their cable is better, so let’s go all out and show you the difference between our coax cable and the current competition for shielded RGB console cabling. Nobody right now can beat us on this *unless* they improve or change the sources of their cabling, and believe me when I say - I’d be perfectly ok with them doing so, ie selling high grade at similar price points to us instead of selling you a cheap lower grade alternative and telling you it’s high grade when it really isn’t.

 

Competitor 1’s full shielded cable:


Competitor 2’s semi shielded cable:


Our 6 core mini coax cable:


We are trying to sell something *different* and higher grade to other sellers as we don’t like going head to head, we don’t want a war because it’s stressful and we’re already frightened of the potential backlash to this very article. But we have to do it because it makes commercial sense to point out the differences when your product is a higher price. We’re the only seller offering console SCART cables made of real coax. We’re the only seller offering proper impedance matched cabling, with an impedance of 75 ohm - if you discount HD Retrovision that is, who don’t sell RGB cabling.

We need to express that our coax cables are not equivalent to those offered by other sellers, because we can’t simply reduce the price - coax cabling is not cheap and we’re trying to place ourselves in the high end of the market. This is not going to work if people don’t understand what true video coax cabling is doing. 

I don’t want people to just take my word for it, so please google around about impedance and why 75 ohm impedance is important in video signals. 

What is impedance?

In short, using cables with a characteristic impedance equal to that of your equipment (and for video signals, this is 75 ohm) prevents portions of your video signal reflecting back along the line.

Impedance is measured in ohms but when you’re talking about cable and connectors this number does not express a load on the signal itself. So you can’t take a 75 ohm cable and remove your 75 ohm resistors from the signal (a good few people have asked us this) - those resistors, that in many cases are missing in your console are needed in the cable to drive the signal and ideally, so is the 75 ohm cable. 75 ohm impedence rated cable means it is characteristically tailored to carry a 75 ohm signal. All non RF video signals (RGB, YPbPr, composite video, s-video) are 75 ohm signals. 

The characteristic impedance of a cable is achieved in the width of the internal conductors, the type of insulator used (chemical properties of the actual plastic), the width of said insulator from the outer shield, amount of shield used, to carry a 75 ohm impedance signal. (We’re at the thinnest mini coax width possible to achieve this - it is physically impossible to go thinner.)

 You can’t achieve this from simple individually shielded cable, and ideally every line should be insulated from adjacent lines, so that each line is individually impedance matched.

 In case anyone is wondering, yes it’s also fine to send analog (and digital) audio through 75 ohm coax and in the interests of keeping this article shorter - I’m talking about video here - please google this and find out why it’s not only fine, but the shielding used is more than adequate to isolate audio from video in a cable bundle.

 Coax cables should have *white* or pale internal insulators because the plastic in proper coax dielectrics is made of polyethylene, a plastic that can’t be dyed easily with vibrant shades (dye also affects the chemical properties and can compromise the characteristic impedence.) You might have seen polyethylene insulation in cheap vga cable where the red, green and blue lines are shielded with a single foil shield and the plastic insulators are dyed, yet muted in colour so much so that the red plastic looks pink. The external insulator (the outer sheath that you see in separated Bnc ends) can be pvc (and usually is) to denote the colour for the signal and also protect the cable from wear and tear, but if the central line is brightly colored, your centre dielectric is also pvc - it does not have the characteristics of true 75 ohm coax.

 What happens when impedance isn’t correctly matched? Well when you don’t match cabling to the source impedance of the electronics in your console, power is lost along the line. The longer your cable is, and the more connections you send it through, the more likely this is to happen. The part of the signal that’s lost has to go somewhere, and what happens is that portions of it reflect back in your circuit and combine with the signal traveling through the cables, which in its best case causes a slight loss of color fidelity and in the worst case can cause ghosting.

We do a lot in our business to cut down on returns and customers who have issues that we simply can’t pinpoint. Before we introduced the higher grade coax, we would have the odd customer reporting issues with ghosting in their setup and we simply couldn’t pinpoint the issue because we couldn’t exactly replicate the equipment. Since we introduced 75 ohm industry standard coax, these reports have entirely dried up.

People care a lot about the quality of connectors, capacitors used, distance of rgb signals from other lines (in mods), use of correct wire in mods and they talk about it a lot. Sometimes it’s frustrating to us to see this talked about at such length, because people are fine tuning their mods to such a high degree and then their customers send it through... a lower grade SCART cable that is marketed as, and accepted by the community as being a high grade cable. So if you wondered why you see people who mod suddenly recommending component cables over RGB, that’s probably got a lot to do with it. It’s not just about the voltages in SCART or the SCART connector being dodgy (RCA plugs are also a consumer compromise - they aren’t used for professional video connectors - 75 ohm BNC plugs are). It’s likely also because most SCART manufacturers are not using ideal cabling. The one seller of high grade component cable *is*.

Nobody talks about the quality and suitability of the cabling used between your console and the final device in the chain. A lot of talk is made about “individually shielded cable” and why it’s important to shield signals from each other to avoid coupling between one signal and another - especially in the case of composite video and audio lines. But this is just the first consideration. Cable that merely shields audio from video is still not really meant for video signals, and can’t hold up over longer distances. Most cabling you buy in this industry is not properly impedance matched. Decades of cheap imported scarts, s-video cabling and rca cabling have seen prices trend downwards in an attempt to attract customers with big bargains and the casualty of this is the loss of the use of proper coax in consumer equipment, plus a complete lack of understanding in the userbase about why the cabling is not ideal. We’ve been guilty of this in the past, using SCART grade coaxes and unshielded lines in our cheaper cable. What we’re offering now in our coax cabling is properly impedance matched cabling. It is not possible to bring the price of it down by very much at all and it’s not equivalent to cheaper “high end” cable.

 

Anyone selling a cable that’s significantly thinner than ours and significantly cheaper than ours is not selling a high end video cable. 

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