There are standards that devices are supposed to adhere to. These standards prescribe both the functional specifications of a device (the numbers of pins on a cable, the transfer rate of data, balanced of unbalances operation … etc.), and the quality of its performance. When talking about cables we could simplify this to mean the type and quality.


A quick search of online stores shows that there are many types of cables, with great variation in their prices. It is not unexpected for different types of cable to cost a different amount; but the same type of cable can often come in cheap or expensive versions, even if they are the same length. We ask ourselves if the quality varies between various cables of the same type.


Of course the quality does vary, but not in a way that directly relates to the price. Some cables are simply faulty; some cables will work up to a point, but aren’t capable of working at full speed or full power, at least not for long. Reasons for this vary, but often it’s just the wrong materials being used.


The physics of the situation is complex, but cables will have certain impedance.  This impedance, a combination of resistance, inductance and capacitance, is a property of both the conductive material and the way it is used in construction; two copper wires spaced 1cm apart will have a certain impedance; a copper wire with a shield around it will have a different impedance. If you even plug a 50ohm impedance cable into a TV designed for 75ohm cable you will get a TV picture with ghosting and slightly distorted colours. The cable works, but not very well. Running a longer length of cable will make the problems worse.


Computer cables tend to be more complex than old fashioned TV cables. If the wrong materials are used, or if the right materials are used in the wrong way, the cable will not work very well. It might be passable under low power conditions, but overheat when run near full power. Else, it might simply cause transmission errors when running at higher speeds, even if the transmission speed is within spec. Here we simply have a low quality product.


There can also be problems with cables just being faulty. And if multi-pinned cables cross the power with data lines they can cause serious damage to the equipment they connect. This is made all the worse when we realize there is probably no warranty to cover this. The damaged computer equipment is not responsible, and the cheap cable company probably doesn’t care.  The owner is stuck with an expensive problem.


Recently Amazon has announced that they will no longer allow the selling substandard USB-C cables. As Amazon will not be testing the cables themselves it will probably block sellers based on customer feedback. This is less than perfect as there is always the chance that the customer has made a mistake; and of course the cable has to fail (and possible cause serious damages) before the complaint is made. But Amazon’s decision is a positive one, and at least prevents further sales once a problem is discovered.