Entertaining reading on cables. Secrets of the cable If you are at our Forum for the first time

Typically, the connection between the DVD player and the receiver is made via digital channels, optical or coaxial cable. The signal goes to the 6-channel decoder of the receiver and ... I'll make a reservation right away: these types of cables are not considered in this article. If you are using an external decoder, the player's built-in decoder, or other sound sources (eg CD, MD) are present in your system, then you will definitely need low frequency jumper cables.

Opening the box.

Manufacturers often complete their products with such cables, such cables can be purchased inexpensively in commercial tents. It is a thin shielded wire with tulip connectors in a plastic case (often non-separable) at the ends.

Such a cable is very good to make sure that the device works, and nothing more. It kills the sound completely, although you can try to use them to connect the translation channel to a TV, boombox or music center. However, the best solution is to leave them in the box of the device and send them to the mezzanine, so that when this device is sold in the future, they can be passed on to the next happy owner. Manufacturers are not interested in overstating the cost of their equipment unnecessarily, because the kit always comes with the cheapest primitive cable. So, our path lies to the store ...

We buy a cable.

Let's take a look at a store that sells more serious cables. The first thing that will catch our attention is the relatively inexpensive cables from Vivanco and Hama. Externally similar cables in boxes with the inscriptions Video, Audio and even Audio gold look somewhat more impressive than thin cords in the packaging of devices. And here is a rack with "Monsters" and "Audiolinks", a thick cable, metal connectors, but prices, prices ... Not everyone has the courage to immediately buy a cable at a price of $ 50 - $ 100 per pair. But when you connect the decoder built into the player, you will need three pairs of cables at once. The look goes back to the counter with the Hama, they look less impressive, but the prices are much lower. Only plastic non-separable plug housings leave doubts.

_

This is where the memories come that sometimes you had to hold a soldering iron in your hands, and maybe something that is expensive to buy can be done by yourself. The audiophile store greets us with colorful boxes with connectors and cable reels. On closer inspection, it becomes obvious that a lot of money cannot be won. Of course, cable accessories are cheaper than ready-made ones, but the difference is not as great as we would like. We'll have to compromise.

Compromise.

Let's remember that not only audiophile companies produce cables with good parameters and gold-plated connectors. A sharp drop in price is inherent in mass production. Have you guessed? Our way lies to the computer store. accessories ... buy connectors. We go to the Brown Bear trading house. Product catalog, group: connectors, type: audio - here it is "RCA plug (tulip) for gold-plated teflon cable (RPC-3GT) (K29320T) Manufacturer: Taiwan. Code: 220034 Price: $ 1.44".

_

Teflon insulation, gold-plated contacts, low price ... The only "but" - it is intended for a coaxial cable. This means that we will make the first interconnect cable of a coaxial design.

Coaxial interconnect cable.

For a number of reasons, the cable "SAT 703b gas injected" 75 Ohm (made in Italy), used in satellite TV reception systems, was chosen for use. A thick central copper mono-core, a thick foamed dielectric, double shielding (braid and foil), low signal attenuation in the frequency band up to gigahertz - good qualities for an interconnect. The cable diameter is 6 mm, the cable is quite rigid and does not like sharp bends. The wiring is symmetrical at both ends of the cable, solder with a small silver content was used for soldering.

Cables were manufactured in lengths of 0.6, 1.0, 1.5 and 2 meters. The difference between them in electrical parameters and sounding by the available means was not found. At the same time, there was a plan to use these connectors for non-coaxial cable.

Interconnect cable - pigtail.

For manufacturing we will use a computer cable "twisted pair of category 5". It contains 8 insulated copper conductors twisted in pairs. We remove the outer insulation and separate the twisted pairs without untwisting them. In total, you need a piece of cable about 4 lengths of the desired interconnect (8 lengths per pair). We cut the removed pairs into 3 equal parts and collect them in bundles according to their colors (3 red-white pairs, 3 green-white pairs and 3 blue-white pairs). We intertwine these bundles with a pigtail and put on the ends pieces of cambric of a suitable diameter 3-5 cm long (for example, pieces of sheath from the SAT 703 cable), making sure that at the free end, pairs of the same color come out in the middle of the bundle, and pairs of two other colors are evenly distributed around.

For example, in the center - green, red and blue - along the edge. We solder the green wires to the center pin of the tulip, and the red and blue wires to the outer pin. At the opposite end of the cable, we solder only 2 harnesses (green and blue) to the connector, and simply cut the wires of the red harness a little shorter and leave them unconnected. The cable is directional, the end where the two harnesses are connected is connected to the source, and the one where the three is connected to the signal receiver.

The length of the interconnect cables in my case was 0.6 meters. So, we have material for comparison.

Let's compare.

For comparison, "blind" tests were carried out on two sets of equipment. The source of the signal was the Pioneer PD-S605 and Micromega Minimum CD players, and the receiver was the Pioneer A-303R and Harman / Kardon 2.0 amplifiers. It should be noted that when using a relatively cheap set from Pioneer, the difference in the sound of the cables of both designs was practically not felt, and became clearly noticeable on a more expensive set of equipment. Here the "pigtail" clearly outplayed the coaxial, although it did not "hold out" to the expensive Kimber cable of a similar design, taken for comparison. On both sets of equipment, both homemade cables easily outplayed the inexpensive Hama products.

It should be noted that the parameters of the cables used for the manufacture of interconnects can vary greatly depending on the batch and manufacturer, especially for twisted pair, which does not guarantee repeatable results when using pieces of cable from different reels, purchased in different places and at different times. It is better to immediately prepare the required amount of cable for all interconnects, because to connect a DVD player with a decoder, you may need up to 8 such cables.

Cables were also manufactured using other coaxial cables (for a computer network of 50 and 98 ohms), and with different numbers of twisted pairs in the pigtail bundle. The designs described here (SAT 703 coaxial cable and pigtail with 3 twisted pairs per bundle - 6 signal conductors, 6 earth conductors and 6 shield conductors) showed the best results in their classes.

Deeper into the essence of the phenomenon, we discover new depths ...
This is, however, not about UFOs or transmigration of souls, but about a trivial cable.
However, this very cable, despite its external (and equally internal) simplicity, is fraught with a lot of surprises that do not have a clear scientific justification. The concept of voodoo science took root precisely among the manufacturers of high quality audio cables, then spreading to the field of accessories: all kinds of cones, stands, etc. No conclusions and precision measurements can reveal the reason for the sharp differences in the "sound" of cables. Those who have not encountered this in practice do not believe, especially the technique. How is this possible ?! In the range up to 20 kHz, but with a conductor resistance of tenths to hundredths of Ohm - what a difference there could be! Just take a nail instead of a cable, nothing will change! They turn it on - and it changes, it doesn't even reach the nail. For a certified engineer, this is a shock, and the more severe, the higher the marks in his diploma. The poor engineer begins to frantically remember the surface effect, dielectric absorption, group delay time (some do not even shy away from Ohm's law). The poor fellow trying to explain the clearly audible difference with a hastily cobbled together hypothesis is lucky if he did not think of making a bet!
Both in normal science and in its "voodoo" -surrogate, the same physical realities figure.
Exactly:
Surface effect... With an increase in the signal frequency, the current density increases closer to the surface of the conductor and decreases in the middle. This phenomenon becomes noticeable at sufficiently high frequencies, significantly exceeding the audio range. In theory. But seasoned "cablemen" argue that "the thick wire in the center of the cable provides good bass passage, while the thin ones on the periphery do not allow the high ones to weaken." In practice, these cables tend to really demonstrate deep bass and sonorous "top".
Group delay time... "Delamination" of the frequency spectrum, when its various components change the phase in different ways and, as a result, come "to the finish line" at slightly different time ratios than "at the start". This consequence of the distributed parameters of inductance and capacitance is aggravated by the surface effect (increasing the resistance of the conductor at a high frequency).

Electromagnetic interaction... Let us recall a simple school experience: a direct current is passed through two parallel wires, and if its direction is the same, the wires repel each other, arching, otherwise they attract. Such effects are fed by the energy of the current through the magnetic field induced around the conductor. This means that a part of the signal energy in the cable is wasted uselessly! Even in spite of the mass and inertia of the cable, the mutual influence of neighboring conductors with the same antiphase signals remains: where there is current, there is a magnetic field. In interconnect cables, the current is practically zero, but alternating voltage is transmitted there, which means that the interaction is also preserved - through the electric field. And the "voodooists" teach us that nothing can be neglected!
Conductor... As you know, cables are made mainly of copper. This is an excellent material: the resistivity of copper is low, and in this copper is inferior (and insignificantly) only to silver - by the way, confidently ahead of gold. But copper is different. It is believed that a good cable cannot be made of the same "dirty" copper as a regular electrical cable. Copper should be not just pure, but ultrapure (99.999 ...% Cu), it is customary to call it "oxygen-free". The purer the copper, the less it is susceptible to oxidation, while the impurities of various metals play the role of catalysts and accelerate oxidation upon contact with air. In essence, why is this bad? A film of oxides and nitrous oxide on the surface of a conductor can have semiconducting properties, while having a much higher resistance than the metal itself. But it is in the surface layer, as we know, that the current density at high frequencies is maximum.
Lurking behind the last "nine" ions of foreign metals, differing in size and valence, invariably violate the regularity of the crystal lattice. Maybe electrons are really uncomfortable jumping over obstacles, as we are driving a car on a rough road. But the special hatred of the champions of the purity of sound and copper is caused by the admixtures of metals of the iron group - cobalt, nickel, which, like iron itself, have magnetic properties. Even small losses of signal energy for reorientation of magnetic domains cause irritation, which may well arise in the presence of bunches of ions of these metals! Incredibly, there are cable models in which conductors are used not from metal, but ... from a carbon composite! There is certainly no magnetism here, although the resistance is much higher than that of copper. And such cables (Van Den Hull) are a clear example of excellent sound, albeit for fabulous money.

However, let's leave the purity of the signal, here it is unlikely that any of the certified engineers would argue with the "voodooists". The latter often also refer to the molecular structure of copper, emphasizing that it influences sound very strongly. Any metal has a polycrystalline structure. But ordinary rolled copper consists of fibers, as if sintered with each other, and the length of these fibers is on the order of a millimeter. Special technologies make it possible to increase it almost indefinitely - so that within one cable the fibers turn out to be continuous. This improves cable performance by reducing internal unevenness.
But what are we all about copper. There is also silver! Audiophiles are divided into two camps, copper and silver. Both metals have fairly distinct sonic properties. For example, copper sounds more physical, velvety, while silver - light, airy and unusually transparent. What to prefer is a matter of taste. The combination of silver and copper in one cable did not reconcile "copper" and "silver". Although there are very good cables among similar models. Finally, silver-plated copper wires are used very often, especially in video and digital quality: there the surface effect is really noticeable, and the silver coating smoothes it somewhat. Solid silver, and even with a large cross-section of the cable, is not cheap. Silver speaker cables often cost over $ 1,000. per running meter.
Insulation... You are wrong if you think that the quality of the metal in the cable is everything. Insulation! It has only two useful functions: proper insulating and mechanical. The rest of the properties are harmful. And above all - dielectric absorption.
The fact is that part of the signal energy is spent on the orientation of the dipole molecules in the polymer structure of the dielectric. That is, the heat generated by "internal friction". Some of the energy comes back, and this is worse than its loss: the "ricochet" smears out small details, since it lags slightly behind in time. This process also has a frequency dependence, which makes the picture even more sad.
In addition, static charges can build up in the insulation layers, affecting the signal. Therefore, you will never find a good cable with PVC conductor insulation (the outer layer is most often made of it, also of nylon, silicone, etc.). Polypropylene, polystyrene, polycarbonate are considered good dielectrics (they are also used in high-quality capacitors). Much worse - polyethylene, lavsan. The king of all dielectrics is Teflon. Of course, it is expensive, not too technologically advanced (in particular, Teflon has a rather high melting point), but it is used quite often. However, foamed polymers of "lower" origin make it possible to noticeably approach the "royal person". Air is very close to vacuum - an ideal dielectric. Of course, foamed Teflon is in the lead here too.
To ensure the drain of static charges, the insulator is sometimes impregnated with graphite powder (while the electrical conductivity remains negligible, since the carbon particles do not come into contact with each other). The same purpose in some cables serves the so-called. drain wire: a special conductor that is grounded at one end of the cable. But why can't the same charges flow down the signal conductors? If the drain wire (or the whole screen) is located on the surface of the cable, or even shallow, then it really equalizes the electrical potentials of the inner and outer surfaces of the insulation.
Geometry... There is no particular variety in the design of cables. Standard options are straight or twisted pair, open or shielded, and coaxial design. The latter is used at high frequencies: in video and digital cables, where it is necessary to adhere to the standard wave (characteristic) impedance (usually 75 ohms, in some cases 50 or 110 ohms). This is achieved simply by choosing the desired ratio of the diameters of the center conductor and the hollow shield. Above, there may be one or more screens insulated with a dielectric layer - to protect against airborne interference, the level of which is becoming more and more noticeable in large cities. In particular, from the "digital air background", which is constantly growing due to the abundance of digital technology and impulse devices, especially dimmers, which sharply cut off part of the period of the mains voltage sinusoid and pollute both the network (sharp voltage peaks can reach several kilovolts) and the air ... And, finally, trivial pickups from the 50 Hz mains (and the second harmonic of 100 Hz) very often appear in the form of an unpleasant hum. Therefore, not only high-frequency coaxial cables are shielded, but also interconnect "pairs" (acoustic cables do without a shield).
An unshielded cable often sounds unlikely better than a shielded cable, apparently because the signal energy is not spent on inducing currents in the screen. If the "electromagnetic microclimate" makes it possible to do without a screen (that is, its absence does not lead to an increase in noise and low-frequency hum), an experienced audiophile will prefer a "bare" cable.
Let us recall once again the example with parallel wires, which are attracted to each other or repelled depending on the mutual direction of the direct current. If the wires are run at a certain angle, the mutual influence will weaken and completely disappear when this angle becomes right. That is why twisted pair is more popular than ordinary one: the wires in it are at a certain angle to each other. In addition, they wriggle in a spiral, they better "average" pickups. Interference induced on both wires turns out to be in-phase, their effect is less than that of antiphase, especially in balanced circuits and cables (having two "hot" conductors along which similar, but antiphase signals go, and a common "ground"). Balanced cables allow, without much interference (in the literal sense), to transmit weak signals over considerable distances, hence the prevalence of balanced configuration.

There are also extreme cable designs, the angle between the conductors in which is really equal to 90 °.
Further. There are solid and stranded wires and, accordingly, cables. Single-core are much less common. Sometimes conductors of different cross-sections are combined in one cable, referring to a certain optimal "recipe" found experimentally. This is possible: in any case, in cable business the empirical method undoubtedly prevails over the analytical one. It is impossible to "calculate" a cable with a given character of sound, but with given physical parameters it is a common practice.
It is easy to make a multi-core cable of any desired cross-section while maintaining acceptable mechanical properties (this is especially true in acoustic cables). But the larger the cross section, the greater the consequences of the surface effect: although the surface increases with an increase in the cross section, the unevenness of the resistance also increases for different frequencies. In this sense, a stranded wire is no better than a single-stranded wire with the same cross-section; moreover, individual veins either come out to the surface or "dive" into the depth, introducing additional uncertainty. It is quite another matter in the case of using litz wires: multicore cables with individual insulation of each core, which behaves like a separate cable, and their conductivities are summed up without increasing the surface effect. Another solution was proposed by an American firm Kogan-Hall: hollow thin-walled copper tubes. However, this is impractical due to their stiffness and fragility. The most interesting direction in terms of geometry is cables with flat conductors. A conductor of a sufficiently large cross-section rolled into a thin strip of foil has a significantly larger surface compared to a cylindrical one, and at the same time is practically deprived of depth. Moreover, such a speaker cable costs nothing to "hide".
The geometry of the insulator does not always fully correspond to the geometry of the conductor. Often, conductors are not just insulated from each other with a layer of dielectric, but are separated by some distance. In this case, the lumen of the insulator can exceed the diameter of the conductor, which in this case is surrounded by air on almost all sides.
Then: the outer insulation acts as a mechanical damping function for the cable: acoustic vibrations (such as music) cause vibrations, and the signal can be modulated by these vibrations. For example, in a multicore cable - due to changing contact between the veins, in a cable of any type - due to the instability of the distance between the conductors. Voodooists take cable “mic effect” seriously. And despite the seeming absurdity, their observations in this case were useful, which has been proven by practice.
Now a little about the companies that have made a significant contribution to the arsenal of cable art masterpieces.
AudioQuest(USA). A wide range of cables for any purpose, excellent reputation and guaranteed maximum return on investment. A lot of patented advanced technologies. HyperLitz- improved litz wire: insulated single-core conductors form a hollow cylinder, which, among other advantages, excludes irregular electromagnetic interactions in the cable. SST (Spread Spectrum Technology, spread spectrum technology) uses different cross-sections of conductors in the litz wire. This makes available, according to the authors, fine "tuning" of the cable for uniform transmission of a wide range of frequencies. Company AudioQuest first began to use long-fiber copper and silver, as well as "air cushion" - the conductor is in contact with the insulating tube only along one line, being in a "dielectrically ideal" air environment. In many models, the soldered joints (in terminals) are replaced by welded or combined - crimping and soldering, the latter more "preserves" the contact, protecting the metal from oxidation, and provides greater strength. In general, any solder, even silver-containing, is inferior in many characteristics to copper and silver.
Monster cable(USA). Huge assortment, rather complicated design, high-quality handpieces. A lot of advantages, thanks to which the company manages to maintain its leadership in the market, despite the significant increase in competition over the past 10-15 years.
Kimber kable(USA). The signature handwriting is a "braid" of several stranded copper or silver wires in the form of a "pigtail", veins of various sections. Most models are not shielded. Insulation is mostly Teflon, with the exception of the most inexpensive models. Characteristic soft, noble sound. World bestsellers - speaker cables 4TC and 8TS as well as interblock PBJ is one of the most popular budget cables. About ten years ago, a record was set: the company released an arm-thick Black Python speaker cable, the outer sheath was filled with vibration-damping gel. The cable cost $ 15,000!
XLO Electric(USA). "Hollow litz wires" in the form of several wound on a tubular base in two spirals (strictly at 90 °), individually insulated copper conductors (interconnect and digital (!) Cables), ordinary litz wires of a large total cross-section as acoustic cables. In expensive models, Teflon insulation. Pronounced sonic signature, resulting in exceptional transparency and good detail.
Ultralink(Canada). A young company making progress both in the local and global markets. The products do not have exorbitant prices, but at the same time they are very, very high quality. Oxygen-free copper "six nines" of special rolling technology is used, Teflon and polyethylene foamed with nitrogen are used as dielectric. Also interesting are the original spring-loaded RCA-tips, which guarantee high-quality contact for a long time. Recently the firm Ultralink acquired the famous American XLO Electric with the right to use the brand name of the latter.
Chord(United Kingdom). The company, which produces many wonderful cables, is looking not only for the best materials and design solutions, but their optimal combinations. For example, successful combinations of "silver plus teflon" and "copper plus foamed polyethylene" have been experimentally established. Interconnect cables series Signature use a coaxial design, the outer shield is grounded on one side or has a separate terminal with a "crocodile". Low-frequency hum is reduced due to closed “ground” contours. Much attention is paid to the purity of the metal.
MIT, Transparent Cable(USA). These two remarkable companies have in common the fact that they supply their cables with passive correctors of reactive parameters (capacitance and inductance), placed in boxes hanging on the cable. Extensive research and instrumental measurements lead to conscious cable optimization, without reducing the linear inductance and capacitance at any cost, as is the case. According to MIT, for better power transmission, an acoustic cable should have well-defined and mutually correlated values ​​of reactive parameters. Transparent Cable also actively combats cable noise (like an antenna) with its corrector filters. The products of both companies are truly admirable.

Audio Note(Japan, UK). The iconic character of both divisions' products Audio Note fully applies to cables. The latter are distinguished by a relatively simple design; silver is often used in them. They are distinguished by the fact that polyurethane is used as a dielectric. In the most expensive Japanese models Audio Note The purest silver is coated with layers of polyurethane right at the last stage of rolling, practically eliminating contact with air (although silver is not as susceptible to oxidation as copper). Some models are made in the form of litz wire.
Nordost(United Kingdom). Emphasized interest is aroused by the line of flat interconnect and speaker cables made of oxygen-free copper and silver. Dielectric - stamped Teflon. Conductors of rectangular cross-section (several pieces for the forward and reverse directions) run strictly parallel and in the same plane. This minimizes reactive components. It is noteworthy that the linear capacitance and inductance are given by the company for each cable model. Naturally, the capacity in this configuration is minimal.
Goertz(USA). Silver flat copper cables with polypropylene dielectric. In contrast to models Nordost, forward and backward conductors are superimposed on each other like a "sandwich", generating (with a fairly wide foil) God knows what capacity! However, the company has its own opinion on this matter: a large linear capacitance reduces the characteristic impedance, thus bringing it closer to the standard 8 Ohms (input impedance of speakers). The theory is very controversial: the output impedance of the amplifiers is very far from this value, and the speaker impedance is highly dependent on frequency. But practice in this case beats theory: with a good docking with the amplifier and speakers, cables Goertz able to pleasantly surprise even a seasoned audiophile.
Cardas(USA). One of the most aristocratic cable companies, successfully applying the principle of the golden ratio in their designs. Litz wire consists of copper conductors of various diameters, gradually decreasing towards the center in the ratio of the golden ratio. Foamed Teflon insulation. This eliminates electromechanical resonances and, according to the manufacturer, improves the remaining characteristics of the cable, in particular, allows a stable electrical Q-factor to be achieved. Traditionally cables Cardas get the highest marks from experts.
Stereovox(USA). This is the pinnacle of cable art. Chris Sommovigo, developer and head of the firm, rose to prominence in the early 90s for his revolutionary digital cable Black orchid... Today's products are packed with innovations. For example, silver conductors of elliptical cross-section in multilayer insulation made of foamed Teflon are surrounded by a screen of parallel conductors (interconnects). The speaker wires use silver plated copper wire. The tips of the original design are soldered with silver-containing solder, the composition of which is strictly standardized. By resolution and transparency cables Stereovox surpass the best models of other companies.
In conclusion, we add that a cable, even a network cable, is undoubtedly a full-fledged component of an audio system. Of course, he must be given time for "running-in" and connected in the exact direction (usually it is indicated by arrows or determined experimentally). To underestimate the role of the cable is to deprive your system of fine tuning. Cables should be selected individually, as a tie is selected for a dress suit.
However, serious defects, for example, obvious flaws in tonal balance, cannot be corrected by the cable: this is still not an equalizer. The cables have too many sores of their own to be able to successfully heal strangers!

Switching the audio part of the complex

We continue the conversation. This article will focus on switching audio signals between the components of a home theater complex. In addition to advice on the actual switching, this article pays attention to cables, as well as the problem of saving money by making homemade cables. Is it worth the candle?

Cables

Varieties of interconnect cables

Interconnect cables are more complex than speaker cables. There is a different design of the cable itself, where a much larger number of innovations are applied both in terms of the used conductor material and in the field of dielectrics, as opposed to columnar ones. Secondly, the presence of connectors at both ends of the cable is mandatory. And, of course, today it is difficult to imagine a modern interconnect cable without presentable and stylish appearance of not only connectors, but also the cable itself.

And on the market now you can find "interconnects" for every taste, color and wallet. A ready-made cable in a package can now be bought for both $ 10 and $ 500. Much depends not only on the quality of the cable, but also on the “brand” of the manufacturer (its reputation and fame). However, today we will talk mainly about quite affordable interconnect cables, and not about super-elite wires in gold-plated boxes with velvet gut.

All interconnects can be divided into two main categories: cables that carry analog signals (called "interconnects" or "analog" cables) and cables that carry digital data, referred to as "digital" cables for simplicity.

"Analog" interconnect cables

This type of interconnect is designed to transmit low-current signals from a source to processing devices, a switch, an amplifier, and so on. For this type of connection, a shielded audio cable is usually used, built according to a coaxial conductor arrangement, where the center conductor is protected from interference by a screen, usually made of many thin metal conductors. This design avoids interference from nearby electrical devices, and allows a low-current signal from one component to another with minimal losses. To connect such cables to devices, convenient RCA connectors (popularly called "tulips" or "bells") are used, which are the most common connectors in household audio equipment. Usually, the definition of "interconnect cable" is the following: a connector consisting of two cables and 4 RCA connectors (that is, more simply, a cable "2 tulips to 2 tulips"), capable of transferring a signal of two channels from one component of the system to another.

"Digital" cables

In turn, this type of cable is divided into two types: cables designed to transmit a digital signal in the form of an electric current ("digital coaxial" in the common people) and to transmit a digital signal in the form of light (fiber optic or, more simply, "optical" cables) ... Let's start with the first ones.

Outwardly, this cable practically does not differ from an ordinary "analog" interconnect. Outwardly, the only difference is the absence of a second connector. That is, “digital coaxial” is just one cable with connectors at the ends (usually RCA connectors). Or, to put it simply, the cable will be called "1 tulip - 1 tulip". The "digital coaxial" is manufactured only according to the coaxial scheme (hence the corresponding name), and, in contrast to the "analog interconnect", the "digital coaxial" must have a characteristic impedance of 75 ohms.

It is also highly desirable that the connectors also have a wave impedance of 75 Ohm, however, this [desirable, but not mandatory] condition is fulfilled only when making rather expensive "household" and almost all professional cables.

And finally, fiber optic cables. Everything is simple here: a digital signal is transmitted in the form of light through flexible optical fiber, which can be made of a special polymer (in relatively inexpensive cables and mid-price cables), or of special flexible glass (these cables are already more expensive).

Optical cables have several advantages over electrical "coaxials": firstly, potentially "optics" are capable of transmitting a larger amount of digital information. Secondly, optical fiber allows you to make ground isolation between two components (this is especially important when connecting the computer's system unit to the receiver). But a high-quality optical cable is very expensive, and its inexpensive implementation (usually up to $ 40-50) and data transmission schemes in budget equipment do not allow enjoying all the advantages of "optics". Therefore, if you do not want to pay more than $ 30-40 for a “digital” cable (usually these are the “digital” cables that are bought most often for a DVD-player and an entry-level and mid-level receiver), then it is better to pay attention to the coaxial “digital” »Cable.

Frequently asked questions on this topic:

But still - which is better in sound: "optics" or "coaxial"?

Even if we talk about the components of the middle class ($ 400-800 for each), then there will be no fundamental difference in sound. Moreover, the probability that you will not hear a difference at all between “optics” and “coaxial” is 99%. So, connect as you like, but remember that all other things being equal, "coaxial" is almost always cheaper than "optics" of the same class.

What is the maximum length of a digital cable?

For optical cable - 7 meters. There are no such clear restrictions for "electric coaxial", since everything depends on the quality of the cable itself. When using a good quality coaxial cable, digital data can be transmitted over 10-15 meters or more without any problems.

Most satellite receivers only have an optical digital output - is it worth buying an expensive cable?

No, not worth it. The fact is that the sound quality in satellite TV is not the highest (relatively low bitrate of the digital audio data stream) in relation to a music DVD or, say, a CD, so even a very simple optical cable for $ 10-15 will be more than enough.

If you plan to connect a VCR, game console, karaoke, tuner or similar devices, then regardless of the price category of these devices, you can limit yourself to very inexpensive "interconnects" for $ 10-20, or make them yourself (more on that below). It makes sense to buy a high-quality interconnect cable only to connect a good stationary CD-player or DVD-A / SACD player with an amplifier or a sufficiently high-quality receiver. For example, for a mid-range CD player ($ 300-500) it makes sense to buy an interconnect cable for $ 40-70. Further in ascending order - depending on the class of components. If you do not believe in the ability of cables to influence sound, then you can buy an inexpensive "interconnect" for a good CD-player (or a high-quality DVD-A / SACD player) or make the cable yourself.

Can you save money by making an interconnect cable yourself?

If you know how to solder, then you can save a lot on the purchase of interconnect cables. As already mentioned, most of the components of the system (karaoke, VCR, separate tuner) do not need particularly high-quality cables, so you can and should use homemade cables to connect these components. Is it profitable? Undoubtedly. Moreover, not only from a financial point of view, but even from a quality point of view (!) The fact is that good (but very inexpensive) professional microphone or instrument cables (Proel, Canare, Tasker, etc.) are used to make homemade interconnect cables. There are many manufacturers of professional cables), which are sold in any professional audio equipment store. And the quality of these cables is usually a cut higher than that of very inexpensive "branded" interconnects. A meter of such a professional cable costs about $ 1. High-quality RCA connectors will cost $ 1-2 apiece (remember, you need 4 of them). So it turns out that a good homemade cable with connectors will cost $ 5-10. This is despite the fact that the quality of such an "interconnect" will be at the level of about $ 30 purchased interconnect cable, or even higher. Do not forget, because in the case of a ready-made cable, you pay for the box, advertising, the work of a shareholder and a sales assistant.

Can you make a good interconnect cable for a CD player?

Many people do this, but they already buy better quality microphone or instrument cables for $ 1.5-2 per meter and good connectors for $ 2-3 apiece. If you use high-quality solder and do everything correctly, then such a "self-made" interconnect cable can easily compete in sound with a Hi-Fi interconnect cable for $ 50-70 or more.

Anyone who does not believe in the ability of cables to "sound" - unambiguously solders a similar interconnect cable himself. Well, if you doubt whether a purchased cable will be able to "replay" a homemade one, then do this: solder (or ask a skilled person to do it) one "interconnect" from a good microphone cable and RCA connectors. then go to any large salon or store selling Hi-Fi and take on bail several ready-made "interconnects" from well-known manufacturers that are suitable for the price. At home, compare the sound, connecting in turn to the CD-player, either ready-made cables, or home-made ones. Although, it is better if someone else connects - it will be honest "blind" listening. There, decide for yourself two questions at once: is there any difference in the sound of the cables, and you will also understand how much worse / better a homemade cable, given that it is several times cheaper than a purchased one. If the purchased cables "win", then at least the already made cable you can use to connect the same VCR. And if the home-made "wins" - rejoice. Thus, you can save hundreds of dollars on cables, if by the sound you are satisfied with homemade cables.

I believe that the cable changes the sound of the system, but I don't know which one to choose.

It couldn't be easier. Go to any major hi-fi showroom or store, take a few affordable interconnects on bail and compare their sound on your system. It is on your system and in your room. This will give you a better idea of ​​how each cable "sounds".

Can you make a digital cable yourself?

Yes, only if we are talking about a "digital" coaxial cable, since making an optical cable at home will take too much effort, or even money - it's easier to buy a ready-made one. But "digital coaxial" can be done by yourself quite, especially if your system consists of entry-level or mid-level components. It is also worth making a "digital" cable, if you are not eager to give a lot of money for the purchased one, knowing that in practice there will be no gain from the purchased one in your case. So what are the requirements for “digital coax”? Firstly, the coaxial design, and secondly, the characteristic impedance of 75 ohms. These requirements are met ... by an antenna cable. Yes, it is a high-quality antenna cable ($ 0.8-1.5 per meter). If possible, you can buy a high-quality antenna or video cable (for example, the same Canare) at a price of $ 0.8-3 per meter in a professional equipment store, since such a cable is guaranteed to be better in quality than the antenna sold on the radio market, albeit very good, according to the seller.

It is important to remember: if you do not have very expensive components, if you plan to make a cable of short length (1-2 meters), then you may not even remember about the influence of a digital cable on the sound of the system, since even a homemade "digital coaxial" (pictured below) assembled from a piece of good antenna or video cable with two good RCA connectors (such a cable together with connectors will cost $ 4-6) will be no worse than any purchased digital coaxial cable for tens of dollars. Unless you have a beautiful box and fashionable nameplates on the connectors and cable. However, homemade can also look good.

Commutation

There are no video signal inputs / outputs on the schematic images of the devices, so that they do not distract, because today we are talking only about the switching of audio signals.

Connecting DVD Player to AV Receiver

It's pretty simple. The entire audio stream in digital form is transmitted through a single "digital" cable: optical or coaxial electrical (only the method of signal delivery changes, but the essence remains the same: deliver the digital stream from the source to the decoder). Therefore, the digital output of the DVD player must be connected to the corresponding digital input of the receiver with a single "digital" cable. How exactly, I have already described above. In this case, the DVD-player will give a "raw" digital stream, and the "brains" of the receiver will convert this stream into multichannel sound, or into stereo sound (depending on the format of the original digital stream and receiver settings). If your DVD player is equipped with a built-in multichannel audio decoder, but is a device of the same class (aka prices) with an AV receiver, then there is no point in using the decoder built into the DVD player, since the decoder and DACs (digital-to-analog converters) of the receiver will not worse, however, they will provide more opportunities for adjusting the sound for a specific listening room.

What does the CD player also do in the diagram? It is one of the possible options for expanding the complex in order to improve the reproduction of music. It's no secret that even mid-range DVD players (not to mention budget models) do not have the most outstanding abilities in terms of music reproduction, often inferior in this even to relatively inexpensive stationary CD players. Likewise, many mid-range AV receivers ($ 500-600) cannot boast of good DACs. Therefore, many people find a way out: having bought a pretty decent AV receiver with a multichannel analog input, they buy a very inexpensive DVD player only for movies (in all honesty, we can say that a DVD player for $ 150-200 is not that much worse than the device for $ 400-600, especially if you watch the picture on the TV 21 "-29"), since the receiver will still be engaged in decoding the multichannel sound, it means that the DVD-player requires only digital audio output and more or less decent image quality. And the money saved is spent on buying a high-quality (at least $ 400-450) CD-player. In this case, the owner of the system receives both high-quality sound when playing music, and a very good cinema.

So, the purchased CD-player is connected not to the “CD” input on the receiver, as one might think, but to the multichannel analog input. Why? Let me take a look at the diagram:

If you look at the diagram, you can see two possible analog signal paths inside the receiver (from the analog inputs to the amplifier). The top half of the graph shows the signal path from any analog input like TAPE, AUX, CD, etc. In this case, the analog signal is digitized (ADC - analog-to-digital conversion), then a DSP processor works with the already digitized signal, which "at the request of the client" can decompose the original stereo signal into a multichannel signal (say, using the Dolby Pro Logic II algorithm), filter out low frequencies to send them to the subwoofer, process the sound with an equalizer or one of the presets of spatial modes. After all these manipulations, the signal is again converted to analog (DAC - digital-to-analog conversion) and only then goes to the amplifier. But the problem is that the "weak link" in this circuit is not so much the DAC as the ADC, which, of course, determines the "ceiling" of the sound quality. And the ADC in receivers is usually quite mediocre, although it is quite enough for digitizing the audio signal from a VCR, tuner or karaoke. But if you plug in a good CD player, you will immediately hear that the sound of your good CD player has become "cheaper" and "poorer". To exploit the potential of your CD player, it must be connected to the front channels of the multichannel input. After all, only the signal from the multichannel input is not subjected to the ADC> DSP> DAC (lower half of the circuit) procedure, which is destructive for a high-quality signal. That is, the signal from the multichannel analog input goes straight to the pre-amplifier, and then to the power amplifier. And the vast majority of modern AV-receivers work according to this principle. It is very simple to check the “honesty” of the receiver's multichannel input: no sound adjustments should be available for the signal arriving at the multichannel input (equalizer, tone block *, spatial sound modes) - only the volume control should work. In this case, everything is in order.

* unless, of course, the receiver has a non-analog tone block, made in the form of mechanical handles on the front panel

Class above

If you have a fairly serious receiver and a high-quality DVD player with the ability to play DVD-Audio and / or SACD discs, then you probably won't need a separate CD player. We will then connect the components as follows: for cinema, the digital connection remains ("coaxial" or "optics" is not so important), and for DVD-A / SACD discs, you need to use analog, connecting the 6-channel output of the DVD-player decoder with a multichannel input receiver with 3 pairs of decent interconnect cables, since in this case the player's DACs will certainly be of better quality than those installed in the receiver, and besides, the receiver will probably simply "not understand" the digital stream of DVD-A (this can only be the newest and expensive models), let alone SACD (Super Audio CD). So we can safely use two types of connection.

The rest of the components (karaoke, VCR, cassette deck, and so on) are connected to the free analog inputs of the receiver. The sound quality of these devices from the internal processes taking place in the receiver will practically not be affected by hearing.