These cables (сoaxial speaker cable) carry a digital signal from a source (such as the digital output of an HD player) to a digital input on an AV receiver or processor/preamplifier. The digital-to-analog conversion takes place inside the receiver. In this case, one digital cable can transmit both stereo and encoded multi-channel digital audio signal.
Digital audio cables designed for use in home audio systems come in two varieties. A coaxial digital audio cable has a circular cross section and is a metal conductor covered with a dielectric layer and a shielding braid (acting as a second, “common” conductor). A Coaxial speaker cable must meet one mandatory requirement - its high-frequency (or, as it is also called, “wave”) impedance must be 75 ohms. If this value deviates in any direction, the digital signal transmission will be distorted. Digital cable is equipped with RCA connectors, this is the most common type of connector in home audio.
Another popular digital audio cable is an optical cable (called Toslink after the company that developed this type of connector, Toshiba). It uses light pulses to transmit a digital signal, and the conductor is a light guide - glass or polymer. There is no electrical connection between the signal source and the receiver in this case.
The debate about which type of connector is preferable has been going on for decades, especially in audiophile circles. сoaxial speaker cable in most cases has a wider signal bandwidth than optical, so many manufacturers (and users) prefer this type of connector.
There is another opinion. It is based on the fact that a digital audio signal is just a sequence of bits, and the sound quality cannot be affected by how the digital signal was transmitted from the source to the receiver. In addition, when using an optical cable, the possibility of transmitting electrical noise and interference that may be present on the signal source body to the receiver is excluded.
However, other things being equal, we recommend using an electrical digital connector. As a last resort, if you have multiple digital sources in your AV system, use the сoaxial speaker cable to connect the one that potentially has the best sound quality.
Interconnect cables are designed to carry a low level analog signal. These cables are used when the components cannot be connected "digitally", or you want to connect the player to an amplifier or receiver in an analog way. To transmit a stereo signal, you will need two identical interconnect cables - one for each channel. Interconnect cables are also used to connect the preamplifier and final amplifier when they are assembled in separate housings.
The most popular type of interconnect cable is unipolar (unbalanced). Very often it has the same design as the electrical digital audio cable and is equipped with the same RCA connectors. Less common are the so-called balanced connectors, which use three conductors to carry the audio signal. One of the main advantages of balanced cables is their much lower sensitivity to external electromagnetic interference, so balanced cables are preferable to use where the signal must be transmitted over a long distance.
Speaker cables (designed to connect to the speaker amplifier) carry a high level audio signal. Typically, speaker cables consist of two conductors, each such "pair" is designed to connect one speaker. In addition, there are more "advanced" schemes for connecting speakers with an amplifier - two-cable, but we'll talk about them next time.
The most important characteristic of a speaker cable is its resistance. It depends on the thickness of the cable conductors and the material from which they are made, as well as the length of the cable. The lower the cable resistance, the better. Therefore (if you have not forgotten the school physics course) you should give preference to large-section speaker cables.
Cable cross-section is measured in gauge, and the smaller this value, the thicker the cable. In any case, we recommend avoiding cables "thinner" than 16 gauge, even if the distance from the speakers to the amplifier is not too great.
In any case, the shorter the speaker cables, the better for sound quality. With a cable length of 6-7 meters, its cross section should be at least 12 gauge. Of course, in surround sound systems, rear speakers can be connected with a thinner cable, for example, 16 gauge with a connection length of 8-10 meters. But there can be no concessions for front speaker cables, and if you need to use connectors of considerable length, their cross section should be at least 10 gauge.
We are sure that cables have their own "sound" (or at least can change the character of the audio system), but you can also find a lot of arguments for and against this point of view. In any case, our absolute recommendation is not to use cheap cables (like the ones you get "free" with your AV gear), and make sure to budget for the necessary cables when building your AV system.
In a 5.1 surround sound system, with a reasonable distance between components and speakers, it will be enough to lay down $50-$100 / meter for interconnects (or digital) cables, and about $500 for all speaker cables. Of course, you can save on cables as a last resort, especially when you use inexpensive AV components and acoustics. In any case, it must be taken into account that the difference in sound between two cables is much less noticeable than, for example, between two pairs of speakers from different brands.
In fact, you can change the cables in the system during its use, sometimes it is even preferable, since you will already know what exactly in the sound of your home theater does not suit you. But be aware that more expensive cables may sound different in tone than the cheaper ones used in your system, but this change in sound character is not always good for its quality. Many cables are designed to give a more pleasant sound, but not more accurate.
However, the task of "upgrading" the cables becomes much more complicated in cases where your audio system uses hidden wiring (for example, all connectors are bricked into the wall during the overhaul). In this case, when choosing cables, you must be very careful, since their subsequent replacement can cost significantly more than the cables themselves.
A relatively new type of AV connector, which, nevertheless, is gaining popularity literally "by leaps and bounds." The HDMI cable can transmit not only digital HD-Video signal, but also high-quality multi-channel audio. Within the framework of this publication, we will not consider the compatibility issues of two components equipped with HDMI connectors, and we will talk about HDMI cables as such.
When transmitting digital video, the HDMI cable is free from the disadvantage inherent in analog video connectors - the gradual deterioration of image quality as the length of the cable increases. Here we are dealing with slightly different technologies, and, accordingly, problems.
The first problem is the complete lack of image when using an HDMI cable. The second is that when transmitting video via HDMI, interference, the so-called "snow", may occur on the image. These problems may or may not occur depending on the length of the cable, its design, and the type (resolution) of the video signal being transmitted.
The digital video signal transmitted over an HDMI cable is distributed along its entire length. As a rule, there are no problems when using HDMI cables up to 5 meters long. If you need to transmit a signal over a longer distance, choose a cable with the largest possible cross-section of conductors.
There are special devices called repeaters. These are small active devices, using which several relatively short HDMI cables can be connected in a chain, and thereby transmit a signal over a long distance. In any case, if you need to make an HDMI connection over a distance of more than 10 meters, repeaters are indispensable.