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Cables and their effects


Analogue Interconnects:

Much has been written about cables and the effect they have on sound.
Many believe that it is all "snake oil" and that substituting different cables is nonsense.
There are many ways to demonstrate that cables can make a difference.
Just steering away from audio for the moment - have you ever connected that high resolution monitor via an extension VGA cable, only to find that the picture has "ghosting" on it? Proof that cable can have an effect. I know at this point that it's going to be argued that the VGA signal is vastly different to an audio signal (although it's still analogue) - but that's not the point. The principles are the same. We have a cable, which exhibits a certain amount of capacitance, resistance and inductance. So how can a cable possibly not make a difference, even at audio frequencies? If it can cause such a picture disturbance on the VGA monitor, then why shouldn't audio be effected in the same way?
One typical argument, is that the frequency response of the cable has been measured, and cable 'A' measures the same as (or similar to) cable 'B' and so on. I too have performed some basic measurements on cables, and found their (measurable) characteristics to be similar - and yet they have yielded a very different sound, when connected in a Hi-Fi system, even when tested with a variety of different components.
It's easy to dismiss the arguments of different sounding cables when no measurable differences exist, but there's no escaping the fact that differing cables yield a different type of sound. (NOTE: I stated "different" type of sound - not necessarily better sound - just different sound). One must conclude that there is some interaction happening with the cable, causing a change to the sound. (By change, I mean the tonal balance of the sound, rather than actual perceived detail).
As most (all?) interconnects (both the cable and the input / output of the corresponding system) are not impedance matched, I'm certain this must play a large part in the audible differences between cables.
Take a radio transmitter for example - for optimum transfer, the antenna, cable and transmitter output must be finely tuned to match (particularly impedance) - or else reflections (standing waves) result - reducing both the efficiency, and in severe cases actually destroying the transmitter.
But with audio, we simply interconnect items and expect them to work at their optimum.
I note that there doesn't seem to be as many "audiophile" connectors on the market for balanced connectors - most aftermarket connectors seem to be single ended cables.
Does this suggest that balanced systems do offer better impedance matching - and that the "cable" effect is non existant - or minimised with this type of connection?

Digital:

Digital interconnects are another great area of debate. One would assume that a digital interconnect has a much simplified function, compared to an analogue interconnect. I don't believe this to be so.
The purpose of a coaxial digital cable, it to transfer a digital signal (usually some form of square wave) between two devices with the minimum of distortion. Any rounding of the edges, or similar distortion mechanisms must result in errors, however trivial. These errors in the digital signal have to be corrected by the receiving equipment. Depending upon the accuracy of this error correction (and the level of signal disruption), digital errors could occur, resulting in an inaccurate reconstruction of the analogue signal. There are also other issues to consider here, such as potential earth loops between the two devices, which could also result in corruption of the digital signal. Jitter is another consideration. My personal feeling is that optical transmission is superior to coaxial, however that is not the view of the vast majority. Does that make me wrong?

Speaker Cable:

Another contentious area. But there is no doubt in my mind, that certain speaker cable does sound better than others. In this case, I'm sure that it's not only the different sound delivered by different cable, as there does seem to be other factors coming into play here.
One possibility, is that of interaction with the feedback loop of the amplifier in use. Many transistor amplifiers have a choke coil in series with the speaker output - this is usually to limit stray RF signals picked up by the speaker cable / voice coils from entering the negative feedback loop of the amplifier, causing instability and subsequent additional distortion.
It is thought that this could be the reason why there can be such differences in sound with certain speaker cables. Any cables must interact with the feedback loop of the amplifier in use, resulting in changes (in some cases dramatic) to the sound. Quite why some cables have a more dramatic effect than others, is probably down to the properties of cables in use.

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