Let's touch on a topic like home recording studio wiring. In addition to all the musical equipment we looked at earlier, we also need a good cable patching system. That is, connecting all musical equipment with a cable. Most novice sound engineers do not attach much importance to this, since they consider it the last thing. But in fact, this is a gross mistake.

Believe it or not, I am completely convinced that the quality of sound in any class of studio depends on the quality of the connections. This has been tested many times in a variety of studios and equipment. Thus, a simple conclusion can be drawn. Good results cannot be achieved with an illiterate and poor-quality connection of musical equipment. It is for this reason that below I will talk about all the key points of switching in a home recording studio.

Cable types

All cables that are used in a recording studio are divided into two types:

• Balanced or balanced cables- contain two signal cables and one metal braid.
• Unbalanced or unbalanced- contain one signal cable and one metal braid.

I think it's worth using balanced cables in your studio. They are called so because they are soldered equally at both ends and their signal wires are not reversed. This wiring gives the advantage of less noise that arises from various pickups.

Connector types

Let's look at the types of connectors we need. However, first, you need to understand the constituent parts:

• Nest- this is where the cable is connected;
• Plug- this is what is connected.

There are 4 types of connectors used in a recording studio:

Jack (can be referred to as fat or big jack)- its size is 6.3 mm. It is also designated as 1.4 inches. The jack plug can be two-pin and three-pin. Two-pin (TS) derived from (Tip) (3), that is, the tip and (Sleeve) (1), that is, the sleeve itself. Divided it all by a plastic black ring (4) ... In fact, there are two contacts - type and sleeve. As for the three-pin jack (TRS), then there is Tip (3) , Sleeve (1) and additionally added Ring (ring in plug) (2), to which the pro-channel contact or inverted phase of the signal fits.

Three-pin jacks are used not only as stereo, but also as balanced mono cables with a certain pinout. That is, if a three-pin jack can be used in mono and stereo, then a two-pin jack can only be used as a mono jack. The jack is usually used when connecting guitars, keyboards (like synthesizer) as well as sound effect processors. Also, such a stereo jack connector can be used for balanced to a sound card and connecting a headphone amplifier to it. In fact, this is a pretty versatile connector.

- this connector, except as, is larger in size and does not differ. There are both two-pin and three-pin. In a professional environment, minijack is probably only used in. Therefore, we will not dwell on it in more detail.

Canon XLR (XLR 3)- this is a professional connector and, as a rule, is not used in household audio equipment. Is a metallic (sometimes plastic) three-pin connector. As with the jack, these pins correspond to three pins: sleeve, tip, and ring. A fairly large amount of studio equipment is connected using this xlr connector. For example, monitors, a preamplifier with a microphone, as well as a microphone with a mixing console, with an audio interface, and much more.

(tulip connector)- It is often found in consumer electronics, but can be found on some budget sound cards or monitors. Usually two connectors are used (left and right channels)... In professional recording studios, tulips are used mostly as digital S / PDIF connectors. Sometimes they are also found on as outputs for a recording device. But still, very often such a connector is found in household appliances and video equipment.

Cable wiring diagram

I will not consider the cable wiring diagram, as it is very long. But we simply cannot completely ignore such an important topic. Therefore, I am attaching graphic diagrams of wiring all the necessary connecting cables and connection diagrams for switching various equipment in a home recording studio. Click on the image to enlarge.

You ask: “Why solder at all? Why can't you buy ready-made connecting cables? " Yes, you can buy ready-made ones. But the problem is that not all cables are easy to find. And ready-made soldered ones will cost you more than buying a separate cable, plugs and further wiring. Another advantage is that you can buy exactly the required length of cable.

But there are also disadvantages here. The fact is that not everyone knows how to solder well. In this case, there remains one most optimal option - to buy the necessary cable and plugs separately. And then give it all to a professional who will weld everything together with high quality. It is beneficial in every way.

Now I want to give you some tips for connecting in your home recording studio. You must remember and follow them whenever possible. These are the guidelines:

• Use only quality cables and connectors... Don't skimp on this. Of course, buying a cable costing several tens of dollars per meter for less budget equipment will be pointless. But buying fake and low-quality products for a couple of rubles per meter from unknown manufacturers is also not an option. I trust manufacturers like Klotz and Proel.
• Use the same cables to connect the same components. For example, when connecting monitors to an audio interface, each of them must be connected to the interface with the same cable. Moreover, both in length and wiring, and in the manufacturer's company and even the model itself.
• Choose a balanced connection. This connection gives much less noise that occurs from various pickups and allows the use of longer cables.
• Prefer XLR connections whenever possible. They have better performance than others. But if you do not have such an opportunity, for example, when the outputs of the audio interface are used jack, and at the input jack and xlr, then use a jack-to-jack cable.
• If you decide to solder the cables yourself, be very careful not to mix up the signal wires. Otherwise, such a thing as antiphase may occur and when recording a stereo signal, in this case, the sound will not be heard at all. And during playback, the sound will be mutually suppressed, that is, one channel will eat the other. Therefore, if you decide to solder the cable yourself, then follow the diagrams that are attached in this article.

This concludes our discussion of the topic. Now you know what the switching should be like in a home recording studio. You already know which type of cable is better to use, what types of connectors and cable wiring diagrams are. Also at the end I gave you some helpful tips for cable patching in the studio. Make sure to follow them.

All connectors, which will be discussed, can be divided into two large groups: cable, that is, those that are designed to be installed on cables, and panel connectors, respectively, designed for installation on various panels, whether it be the rear or front panels of processing devices and sound recording, or a panel of switching devices. In this section, we will talk about cable connectors, due to the fact that in practice, users have to deal with their selection and installation more often. Panel connectors will mainly be discussed if they have any additional features.

In addition, the connectors are divided into sockets (in English they are also called "female", and in Russian - "mom") and plugs (in English they are also called "male", and in Russian - "dad"). While this division is obvious for jack connectors, in the case of XLR connectors, for example, the part of the connector with pins is a plug, and the mating part of the connector with holes is a jack.

Jack connectors
To begin with, the term "jack" is incorrect. From English (from which this word was borrowed) "jack" is translated as "jack". Initially, it meant "panel connector" (the cable connector was called "plug"), but now it is increasingly used in the same sense as the word "socket" in our country (mating part of the "female" type). That is, "jack" is a socket of any type of connectors, be it "XLR jack" or "RCA jack". But in the Russian language the word "jack" has already become established as the name of a certain type of connectors, and it makes no sense to change it.

At the moment, there are several types of jacks. According to the number of contacts, all types can be divided into two-pin and three-pin. The former (often called "mono" or "unbalanced" jacks) are designed for unbalanced signal transmission, while the latter (often called "stereo" or "balanced" jacks) can be used for both single-ended, balanced or two-channel signal transmission. The connector pins (both jacks and plugs), in turn, have specific names, and three-pin jacks are also called "TRS jacks" from the first letters of these names.

So, pin 1 (in the picture above) is called Sleeve or just S. Of all the meanings of the word "sleeve", in my opinion, "sleeve" is the most suitable for a connector. Pin 2 is called Tip (which means "tip") or T. Pin 3 is called Ring (in Russian - "ring") or R. There is no Ring pin in a 2-pin connector. When using a 2-pin connector, pin 1 (Sleeve) is connected to the common or ground conductor, such as a braided shield, and pin 2 (Tip) is connected to the signal conductor. The three-pin connector, when used for balanced switching, is soldered as follows: pin 1 (Sleeve) is connected to the common conductor. Pin 2 (Tip) is for in-phase signal transmission. In this case, it is called "hot", "plus", "phase", "phase plus" or "hot". Contact 3 is intended for signal transmission in antiphase. It is called "cold", "minus", "antiphase", "phase minus" or "cold".

In two-channel transmission, pin 1 (Sleeve) is used to connect to the common conductor, and pins 2 (Tip) and 3 (Ring) are used for the signal wires of the first and second channel, respectively. A special case of two-channel transmission is the transmission of a stereo signal. Headphones are a prime example of this. In stereo transmission, pin 1 (Sleeve) is common, pin 2 (Tip) carries the left channel signal, and pin 3 (Ring) carries the right channel. Another use of two-way jacks is for bi-directional audio signals. A prime example of this is the channel insert connector on a mixing console. As elsewhere, pin 1 is common, but there is no wiring standard for the second and third contacts. One of the two remaining contacts is the output and the other is the input.

Quarter-inch jack
As already mentioned, at the moment there are several types of jack connectors. One of these is most commonly referred to as "quarter-inch (1/4") jacks, but it can also be called "phone", "A-gauge" or "MI" (short for Musical Instrument). This is perhaps the most common type of connector. - it can be found on almost all types of audio devices. It transfers sound signals from recording and processing devices, musical instruments, timecode signals, various controllers, etc. Although the name of the type of this connector contains the number 1/4 " , which indicates the diameter of the plug, sometimes there are problems of incompatibility of mating parts: either the plug fits into the socket very tightly, or vice versa - the plug dangles in the socket. Problems are caused by a mismatch in the diameters of the plug and socket, but where these inaccuracies in diameters come from is difficult to understand. Probably one of the reasons is that manufacturers use different measurement systems (inch and metric).

Quarter-inch jacks are available in two-pin and three-pin versions. The pin names and wiring are fully consistent with the above rules. The contacts themselves are made by different companies from different materials. I've seen copper, brass, nickel, silver plated and gold plated contacts.

The TT jack is most commonly used in patch panels. Its name is an abbreviation of the words Telephone Type, and this connector is also called "Bantam" or "Tini". The history of this connector begins at telephone exchanges, where young ladies with pleasant voices sat in headphones in front of huge patch panels, and, having uttered the coveted word "connect", stuck jumper cables with TT plugs at the ends. At the moment, in most large studios, the switching of the mixing console and equipment is most often carried out through patch panels with TT jacks. This is due to the smaller connector diameter, which allows more jacks to be placed on the panel (96 TT jacks with label space on one rack unit versus 48 quarter-inch jacks). Besides patch panel applications, the TT jack is famous for its old-fashioned pin shapes and their generally non-standard 0.137 "or 4.4 mm diameters. There is also the creepy looking double TT connector that is used in patch panels for RS422 interface connections.

TT jacks are available with two or three pins. Its wiring and the name of the contacts correspond to the general practice for such connectors, that is, the contacts are called Tip, Ring and Sleeve, and they are designed to connect to the hot, cold and earth conductors, respectively. The contacts themselves are most often made of nickel alloys, copper, silver-plated or gold-plated. Some firms (Switchcraft, for example) make TT plugs with terminals for soldering conductors, but the so-called "crimp" plugs are more popular. The fact is that the connection of a conductor to a contact using a crimp is electrically more correct than soldering. The crimp method is not without its drawbacks, the main of which is the one-time attachment of the plug to the cable. You can also talk about the lower mechanical reliability of the crimp fastener, but if you do not actively pull on the cable, then everything will be fine with the contact. A special tool is required to crimp the connector pins.

This connector, like TT, is used in patch panels. TB jack is also called "B-Gauge". In addition, a slightly different MIL jack, also called "TM", "Long Frame" or "MS" (short for Military Style), is fully compatible with the TB connector. With all the variety of names, the diameter of all these connectors is 1/4 "or 6.35 mm. Connectors are two- and three-pin. The pin names and pinouts are fully consistent with the rules for jack connectors. TB jack differs from quarter-inch only in the shape of the contacts.

This 3.5mm jack is widely recognized in consumer electronics. In professional equipment, it is most often used to connect headphones, and even then - in small sound modules, portable equipment and other devices where the size of the jack is important. The minijack has become more widespread in multimedia equipment. Most often, three-pin mini-jacks are used, I saw two-pin only once - on the remote control unit from a CD player. The minijack connector is famous for its unreliability.

The pin names and pinouts follow the rules for jack connectors. Sometimes, when working with minijacks, one gets the impression that minijack contacts are made from what comes to hand of the manufacturer - some of them are all disposable. True, there are firms that produce good minijacks, for example, Canare. In the plugs of this company, you can safely insert a cable with an outer diameter of up to seven millimeters. Only one question: will the minijack jacks withstand the work with such a massive design (plug + cable)?

Features of jack sockets
Jacks of jacks, in addition to the main function of providing mechanical and electrical contact with the mating part, often have the functions of a switch, for which these jacks have additional contacts. For example, the United Switch quarter-inch jack and minijack jacks each have nine pins.

Here is their wiring diagram:

When the plug is plugged into this socket, in addition to connecting the plug contacts to the socket contacts 1, 2 and 3, two independent groups of contacts are also switched (terminals 4, 5, 6 and 7, 8, 9). And in the TB socket from Neutrik, for example, when the plug is turned on, contacts 4, 5 and 6 and the main contacts of the socket (1, 2 and 3) open.

Additional contacts in connector sockets are most often used where it is necessary to break or vice versa - to connect any internal or external elements and blocks of the audio circuit. The simplest example would be a channel insert jack on a mixing console.

When the insert cable is plugged in, the internal audio circuit is broken and the signal can only pass through the external device. In this case, contact T (Tip) is an output, that is, the signal from it must be fed to the input of an external device, and contact R (Ring) is an input, that is, a signal from an external device must be sent to it. In some models of sockets, the switching of contacts is made only when the plug is fully turned on, and when the contacts are not fully turned on, the switching of contacts does not occur. For example, Mackie uses this opportunity to "pick up" a signal to a multitrack tape recorder without breaking the signal circuit of the channel. There are several more options for using additional contacts for jacks, but this will be discussed in one of the next articles in the series.

About jacks from some manufacturers
Perhaps the most popular connector manufacturers are Neutrik and Switchcraft. There is often controversy about which connectors are better. To begin with, I will try to describe the designs of connectors from both companies - connectors that have become a kind of classic in connector construction.

So, the plug of a quarter-inch jack from Neutrik has the following design: a pin with two or three contacts is inserted into a metal sleeve in the shape of a truncated cone. Behind the contact pin, a plastic cable clamp is inserted into the sleeve, and then a plastic sleeve with a rubber conical tube is screwed onto it, sharply tapering at the end. Plastic sleeves can be of different colors, which is very convenient for identifying cables in a common pile. TB and MIL plugs from Neutrik have a cylindrical sleeve instead of a tapered sleeve, and do not have a plastic sleeve with a rubber tapered tube. Sleeve sleeves TB and MIL are available in different colors. Neutrik TT plugs are crimp.

The Switchcraft quarter-inch plug consists of a contact pin with a long Sleeve contact terminal, which is also a cable clamp. A cylindrical sleeve is screwed onto the contact pin, which is separated from the terminals for soldering the conductor by a polyethylene tube. Switchcraft TT, TB and MIL plugs have similar designs.

So, when using Switchcraft plugs, for some reason I constantly unscrewed the sleeve from the contact pin. Once I found that the sleeve of the plug, stuck into the guitar, completely unscrewed and slid down the cable two meters. Among other things, the cable dangled in the sleeve, like clothes on a string. Because of this, after some time, it broke at the soldering point. However, in the absence of variable mechanical influences on the Switchcraft plug, such problems did not arise.

There were no mechanical problems with Neutrik plugs.

So, I prefer Neutrik plugs. However, there are problems with them. One day I decided to try the Gina computer recording system, which has a junction box with ten jacks, five in two rows. In the process, I noticed that the three Neutrik plugs inserted into adjacent sockets, due to the close location of the sockets, stick out like a fan. The fourth plug, I was generally afraid to turn it on for fear of breaking the socket. But the Switchcraft plugs came in without distortions. True, I have not yet encountered the problem of simultaneously turning on several Neutrik plugs.

By the way, I constantly come across quarter-inch jacks of different diameters when connecting AKG K 240 M headphones to the mixer. the headphone plug and the mixer jack clearly do not like each other, which is reflected in the constant loss of sound in the left headphone channel. And with headphones equipped with a Neutrik plug (the console uses the jacks of this particular company), the disappearance stops, and the plug sits in the jack noticeably tighter. And someone else is talking about standards ...

XLR connectors
They are also called "Switchcraft", "Cannon" and "Canon". In the 1960s, ITT Cannon developed a series of connectors for use on Boeing aircraft. The letter "X" identifies the series (before that ITT Cannon released a series of connectors whose names began with the letter "U"), "L" stands for "Locking", "R" stands for Rubber. Since previous XLP connectors with plastic insulators had problems with oxidation of the silver-plated contacts, the XLR socket used a rubber insulator to connect the cleaning contacts. Switchcraft was one of the first to use XLRs for audio connections, adding a ground lug to connect to the sleeve and returning to a solid plastic insulator. In the 1980s, XLR connectors expanded on the less oxidizing gold-plated pins, and the value of the rubber insulator declined.

These connectors can have three, four, five or more pins. Three-prong XLR connectors are the most common in audio equipment. They are used for the balanced transmission of analogue mic / line level signals, digital signals, and sync signals. XLR connectors with more than three pins are used in tube and stereo microphones. For a 3-pin connector, the terminal numbering is shown in the figure.

Pin 1 is for connection to a common conductor, pin 2 is for positive, and pin 3 for negative. Pin 0 is the body of the connector, sometimes it is connected to pin 1. Such wiring is standard, but sometimes there are devices in which the signal in phase (plus) is transmitted through pin 3 (on such devices they usually write "pin 3 = hot").

The XLR connector is renowned for several features. Firstly, both mating parts of the connector, that is, sockets and plugs, can be both cable and panel ones (you must admit that you rarely find a panel jack-type plug). In this case, the mating part of the connector with pins (plug) is used to output the signal, and the mating part of the connector with holes (jack) is used for the input.

The second thing the XLR connector is known for is its reliability. It is provided with thick, durable contact pins and a locking tooth that snaps into place when both connector parts are connected. So the XLR cannot disconnect on its own. In addition, some companies, for example, Neutrik, produce rubberized waterproof cable connectors, connectors with switches and additional lock latches. These connectors withstand virtually all weather and mechanical disturbances.

The third is the electrically correct sequence of the connector pins. The fact is that you first need to connect the ground contacts, and then the signal contacts. Some models of XLR jacks have a slightly extended ground (1) pin, which makes it connect to the corresponding pin of the mating connector a little earlier than other pins.

There are two classic XLR connector designs. The Neutrik cable connector consists of a metal sleeve with an internal longitudinal guide slot, into which a plastic cylinder with tubular contacts and a longitudinal projection (in the case of a socket) or a plastic washer with pins and a longitudinal projection (in the case of a plug) is inserted. Then a plastic cable clamp is inserted and a plastic sleeve with a rubber corrugated conical tube is screwed on.

The Switchcraft cable connector consists of a conical metal sleeve with a longitudinal internal slot, a plastic cylinder with tubular contacts and a longitudinal projection (socket) or a plastic washer with pins and a longitudinal projection (plug). The plastic contact cylinder or washer is fixed in the sleeve by means of a screw. The construction is completed by a rubber conical tube, which is also a cable clamp.

Structurally, I like the Neutrik connectors better: the small locking screw of the Switchcraft connectors is sometimes lost. In addition, it is quite difficult to insert a large diameter cable into Switchcraft - the hole in the rubber tube is not large enough. There are no such problems with Neutrik connectors. And the material from which the contacts are made is better (mechanically more reliable and less oxidized).

This is a Neutrik panel combo jack for two types of jack and XLR plugs. It is used as an input connector and saves panel space. The jack is most often used to carry line level audio signals in both balanced and unbalanced ways, while XLR is used to carry mic and line level signals balanced.

BNC connectors
At the moment, there is no consensus about the origin of the name of this connector. However, the most authoritative sources adhere to the version that the name stands for Bayonet Neill-Concelman, where "bayonet" ("bayonet") means the type of connection (bayonets were attached to some rifles in a similar way), and "Neill" and "Concelman" are the names of the inventors of the connector ... Although the decoding is often found "British Naval Connector" ("British naval connector").

BNC connectors are most commonly used in digital equipment to carry synchronous clocks. In addition, BNC can be found as input and output connectors for digital audio interfaces (in particular, SPDIF). Connectors are available with a characteristic impedance of 75 ohms and 50 ohms (the latter are not used in audio equipment). The cable connectors are crimped and require a special tool to install them on the cable.

Structurally, the connector looks as follows: inside a metal sleeve with a snap-on locking sleeve (when it is turned, the detachable connection is securely fixed) there is a thin central signal contact. On the other side of the sleeve is the contact tube for the braided shield. The signal wire passes through this tube and is inserted into a pin that fits into the center contact. Another tube is put on the contact tube, which, in fact, is crimped with a special tool. The center contact is available in nickel, silver plated and gold plated. The sleeve itself is usually nickel-plated.

RCA connectors
They are also called "phono". The Radio Corporation of America (RCA) developed these connectors in the 1930s for interconnecting radio and television sets. These connectors were widely used in turntables to connect a phono cartridge to a preamplifier, since the connectors were inexpensive, matched well with the thin shielded cables used for the phono cartridges, and because the turntables were monaural and a single-core shielded cable was sufficient.

RCA connectors are used for unbalanced transmission of analog line level signals, mainly from various recording devices. In addition, this connector finds application in the digital interface of the SPDIF format. RCA is initially the wrong connector because the signal pin of the plug is connected to the signal pin of the jack before the ground is connected. Some firms, one of which is still the same Neutrik, produce RCA plugs with an extended spring-loaded ground contact that connects to the ground contact of the socket before the signal contact.

All RCA connectors can be divided into two groups. Some are designed to transmit an analog signal, and the other to transmit a digital SPDIF signal, as a result of which they have a characteristic impedance of 75 ohms.

The connectors of the first group have terminals for soldering conductors, and the connectors of the second group are crimped. In any case, whatever the connector, its wiring (or crimping) is completely unambiguous: the central contact is signal, and the cylinder around the central contact is common.

EDAC connectors
The name comes from the company EDAC, which produces these connectors, and they are also called ELCO after another company that also produces connectors of this type. These are multi-pin connectors. They are used to transmit analog signals at line and microphone levels. Patch panels aside, perhaps the cheapest device with an EDAC connector is the ADAT tape recorder, where this connector is used to simultaneously connect eight inputs and eight outputs. Many cable manufacturers make special sixteen-channel cables for connecting ADAT recorders to a mixing console. These cables have an EDAC connector on one end, while the other can have sixteen jack or XLR connectors. However, EDAC is most widely used on large mixing consoles, where all inputs and outputs are made on this type of connectors.

In terms of design, the EDAC connector is a rectangular connector block with two guide pins, enclosed in a metal casing. One corner of the shroud has a hole with a cable clamp. An interesting feature is that this angle can be rotated. As a result, the cable can exit the connector both straight and sideways. A fixing screw passes through the casing and the terminal block, which must be tightened when connecting the two parts of the connector. Terminal blocks are available with 12, 20, 38, 56, 90 and 120 contacts. At the same time, the number of contacts in the connector can be any, but, of course, not more than that for which the block is designed. The contacts themselves are gold-plated and are flat plugs. Very reliable multi-pin connector.

D-Sub connectors
The full name of this multi-pin connector is "D-Subminiature". Most often it can be seen on computers. In audio equipment, it is used to transmit analog signals at microphone and line levels, as well as for some audio digital interfaces, such as TDIF. In addition, the D-Subminiature connector is used in various RS interfaces.

To transmit analog signals in audio equipment, connectors with twenty-five and thirty-seven contacts are most often used. At the same time, the former are used mainly for eight-channel balanced transmission of line-level audio signals. An example is Tascam's eight-channel DA series digital recorders, which have two connectors, one for eight inputs and one for eight outputs.

The D-Sub connector consists of a pin strip with two rows of pins (in other areas, three-row D-Sub connectors are also used), with the number of pins in the first row being one more than in the second. The contacts are protected by a metal casing bent in the shape of the letter D. The terminal block itself is covered by a plastic or metal casing. The connector is famous for the following: firstly, compared to many other multi-pin connectors used in audio equipment, it is small. The dimensions allow it to be installed in places where space is limited, such as on computer sound cards. Secondly, the D-Subminiature connector is notorious for being unreliable. Even with tightly tightened fixing screws, the contact can be lost or the casing can fall apart (especially if it is plastic). Thirdly, a normal eight-pair multicore can be pushed into the hole in the casing of this connector with great difficulty. The connector pins are usually gold-plated.

This Neutrik invention is used to connect speaker systems. There are three types of connectors: two-pin, four-pin, and eight-pin. The most commonly used four-pin connectors. With the help of them it is possible to connect broadband and two-way speaker systems. The eight-pin connector is most commonly used for three- and four-way speaker systems.

The connector is designed as follows: a plastic cylindrical contact block with two, four or eight contacts is inserted into a plastic sleeve with a lock. The wire is attached to the pins with a clamping screw, which requires an Allen key. Behind the terminal block, a plastic cable clamp is inserted into the sleeve, after which a plastic union nut is screwed onto it.

Type of.
Contact.

Type of. The type of connector is indicated: (k) - cable, (p) - panel.
Contact. The number of contacts of one connector and the material of the contacts are indicated: (N) - an alloy of nickel and silver, (Z) - gold-plated, (C) - silver-plated.

Switchcraft A&T Trade Canare, Neutrik ISPA

Switching, part 4 (practice)

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Open systems, private terms

Systems will not become open as long as private terms are used in their creation and operation. The vagueness of terms affects the quality of services in the Russian cable systems market, which includes thousands of companies, tens of thousands of specialists and many times more users.

Transmission medium

Structured cabling systems (SCS) of office buildings are now becoming the same natural engineering subsystems as power wiring. More and more people are using network technologies, including professionally.

Open systems standards appeared in 1991, and a few months later SCS began to be installed in our country. During this time, the frequency range of conductive systems has expanded from 1 to 100 MHz. Standards for new categories with the 200 and 600 MHz bands are being developed. The data transfer rate has increased to 1000 Mbps. Category standards appear every four years. Symmetrical conductive cables have properties that no one could even dream of ten years ago. Products and technologies are rapidly updated.

Standards allow you to move from private to open systems that have unified parameters and support the operation of equipment from any manufacturer. The difference between SCS and equipment is that they are created by thousands and tens of thousands of independent organizations, always in a single copy and always at their own discretion. Cell manufacturers who provide multi-year warranties for these systems control a very small percentage of installations.

The quality and consistency of systems cannot be achieved without knowledge of the basics of their construction and a unified understanding of the categories. The importance of accurate terminology is evidenced by the fact that all SCS standards begin with a dictionary of definitions and a list of abbreviations. Cabling documentation has been in use for ten years or more. Therefore, the terminology of cabling systems must be cleaned up first. The state here is more than deplorable: mass myths and illusions prevail. Obvious concepts are mixed, there is a lot of confusion, and there are almost as many options for dividing the SCS into subsystems and functional elements as there are projects.

Cable jargon

The terminology for structured cabling systems (SCS) is primarily American. International standards not only appear later, but have not yet been adopted in areas such as cabling, administration, grounding, metering, centralized architecture, open offices, etc.

A feature of a number of American terms is that they reflect the visual and sometimes secondary properties of objects. For an elementary understanding of what is at stake, pictures are required. The existence of such terms is impossible without illustrations and visual demonstrations.

The difficulty of translating incomprehensible words leads to the emergence of jargon. The problem is that in the original American language, a number of terms are surprisingly unfortunate. The meaning of some terms is far from their real content and actual meaning. Examples of the most common jargon are shown in Table 1.

Table 1. Terms, their meaning and actual meaning

Professional term	The meaning of the word	Actual value
patch cord	stitch rope	patch cable
balun	balrazbal ( ball ans- broke ans)	wave adapter
shotgun	shotgun	twin cable
harmonic	harmonic	comb (connector)
termination	termination	equipped with connectors
octopus	octopus	splitter
backbone	ridge	highway
campus	campus	building complex)

Western terms that capture secondary signs are not so bad. Very often understandable and easily translatable words are used in foreign transcription or transliteration. Among them: demorak (demonstration stand), plenum (duct), conduit (pipeline), rodents (rodents), adhesive (glue)... They penetrate the spoken language from articles, brochures, price tags and even textbooks on SCS, published in the form of books.

Moreover, the authors of textbooks and articles record the surrender of their own possibilities of using the Russian language, switching to the interspersing of terms and abbreviations in English. For example, cables UTP, STP, powersum, hybrid, plenum, riser, zip-cord, highway HC-IC, contact IDC, Light-emitting diode LED, technology fiber to the desk, system air-blown fiber and so on and so on. Such specialists want to convey their ideas to colleagues, but do not care about making them easier to understand. Perhaps they think that readers know a foreign language better and will figure it out themselves. It is also natural that such authors spread their own delusions.

Connector - Connector - Socket

Examples of how a word is ambiguous connector led to a confusion of different concepts in professional terminology, found in almost every article where this term is mentioned, and in most projects. To outline the framework, we turn to the dictionary entry.

Connector - The end of a cable for a dial-up electrical or optical connection. A connector is an element of a cable connector that provides electrical connection of conductors. In other words, to connect cables to each other, you need two types of electrical contacts: one-piece - for conductors, and separable - to connect two cables. The most common way to permanently connect symmetrical conductors in SCS is a cut-in contact through the insulation, a detachable one is spring-loaded contacts.

In cable systems with modular connectors, shown schematically in Figure 1, Photos 1 and 2, the differences between connector and connector are obvious.

The confusion of concepts is not limited to this. The term telecommuпication outlet - "telecommunication connector" is widely translated into Russian incorrectly. Both professionals and customers believe that it means "telecommunication socket". This is all the more surprising since American standards emphasize the meaning of "connector" - "telecommuication outlet / connector".

In fact, the connector and the socket are the same as the connector and the connector. A socket is a connector fixing element that does not participate in the transmission of electromagnetic energy, does not belong to the transmission medium and to the functional elements of the SCS. The sockets are installed on walls and other surfaces. Depending on the design, the socket can have from one - two to twelve connectors.

Telecommunication connector (TP) is a functional element and interface of the SCS. It is recommended to install two TRs at each workplace. If we assume that the telecommuication outlet is a socket, this recommendation is perplexing. Surprise and bewilderment are the companions of illusions. Most experts reading this article will be surprised to learn that in modern standards there is not even a mention of an outlet. The term corresponding to the concept of "telecommunication socket" will appear only in the second edition of the international standard ISO / IEC 11801 and the European equivalent EC 50173, which will be published at the end of 2001. Exact translation - single-user and multi-user build of TR. In the first case, we mean a socket with two, in the second - a socket with four or more telecommunication connectors.

The confusion of these concepts can be explained by the fact that the design of traditional sockets is modular: the connector, socket and socket constitute one non-separable element.

Cable connections can be balanced or unbalanced. Unbalanced cable connectors are classified as female or male. Balanced connectors are connected using connectors. Rough use of the terms has led to the fact that connectors and fiber couplers are also called connectors.

Rice. 2. Balanced connector

Traditional fiber optic connectors are balanced. The connector serves for mechanical alignment of fiber axes and fixing of connectors. A connector is a type of adapter. If the connectors are of different types, such as SC and ST, an adapter is required to connect them.

In unbalanced fiber-optic connectors, there is no connector, the alignment of the fiber axes is ensured by the shape of the connectors, which have the features of a plug and a socket. This is a new generation of connectors for centralized systems.

Constructive elements - functional elements - subsystems

There is another literally borrowed term Components... Outside of the cable theme, rarely does anyone confuse the word "components", which refers to uncountable nouns, with "elements." We say "components of a chemical reaction", but "structural elements", "elements of engineering subsystems". It is impossible to say, "Through the glass wall we see the components of the building structure." But as soon as it comes to cables or connectors, not in the everyday sense, but in relation to SCS, the term appears Components, for example, socket components. In this case, there is an uncritical borrowing of foreign terms.

Cables and connectors are the transmission medium. Sockets and panels are used to fix the connectors. To organize channels, boxes, trays, stairs are used. All these are constructive elements. Lines, highways, points of connection and commutation refer to the functional elements of the SCS. The division into functional elements allows you to highlight the areas of the transmission medium that perform different functions.

There is no uniform interpretation of functional elements even at the level of standards. International and European standards subdivide SCS into eight functional elements. All of them - from the telecommunications connector to the distribution point of the building complex - constitute the transmission medium, that is, the structured cabling system itself. This allows you to isolate subsystems and draw precise boundaries between them.

In the American standard ANSI / TIA / EIA-568-A, functional elements include two types of cables, three types of rooms, a building structural element, and telecommunications infrastructure documentation. The most important components of the SCS, such as, for example, the backbone of the complex and all points of connection and switching, for some unknown reason, are not included in this category. In addition, different terminology is used. The differences are shown in Table 2.

Table 2. Functional elements of SCS

Functional elements of SCS
ISO / IEC 11801 and EN 50173	ANSI / TIA / EIA-568-A
	Refers to functional elements	Does not apply to functional elements
Distribution point of the complex (buildings) (RP of the complex)		Main switching point *
Complex highway (MK)		Highway between buildings *
Building distribution point (building RP)		Intermediate switching point *
Building Highway (MH)	Vertical cables
Floor distribution point (floor RP)		Horizontal switching point *
Horizontal cables (GK)	Horizontal cables
Transition point (TP)		Transition point
Telecommunication connector (TP)		Telecommunication connector
Are not a transmission medium
	Workspace
	Telecommunication premises
	Hardware
	Building entry
	Administration

* differing terms

In American standards, there is no division of SCS into subsystems. However, subsystems and functional elements are often confused. There are five, eight, and even nine subsystems in the brochures of a number of companies. Proponents of the American model always single out the administration subsystem and try to outline its boundaries on functional diagrams. It is not an easy task to portray labeling and documentation as a transmission medium.

The administration system is defined by a separate standard. It includes the notation system, the reference system, the documentation for the cable system, which takes into account all telecommunication premises. The entry point, which is an element of the building, telecommunications rooms and control rooms also do not agree well with the definition of SCS as a medium for transmitting low-current signals. In the international standard that came out later, this logical flaw in the American one was eliminated.

In accordance with international standards, SCS includes three subsystems: the backbone of the complex, the backbone of the building and the horizontal subsystem. As can be seen in Figure 3, the subsystems are strictly delimited, the structure of the SCS includes all eight functional elements, and the transmission medium is formed by fixed and commutation cables and their detachable connections. At the same time, subscriber and network cables are outside the SCS.

Rice. 3. SCS subsystems

Different interpretations of standards, their flaws and a "damaged telephone" gave rise to many private interpretations. In brochures, training courses, reference materials and articles, structural elements and their details, subsystems and functional elements are mixed, confused, defined and delineated in different ways. In principle, this is logical - a bunch of uncountable concepts can only consist of components.

Private UTP term

Without a good translation, even professionals understand foreign terms differently. Take for example the most obvious one - UTP... This abbreviation of the term unshielded twisted pair means unprotected twisted pair(WZVP), that is, a cable whose twisted pairs are not individually shielded. In cables shielded twisted pair (STP) each pair has a screen. In this case, the cable can have a common shield for all pairs.

Photo 3. Cable "protected twisted pair"

Rice. 7. Channel with switching

AK - subscriber cable, KK - commutation cable, SK - network cable, TP - telecommunication connector, RP - distribution panel, PP - intermediate panel

The three types of connecting cables, also called flexible cables, are distinguished according to the place of connection. Work area cables are used in the work area, equipment cables are used to connect equipment in distribution points. Subscriber and network cables provide the creation of the channel, but are not part of the SCS. Patch cables (patch-cords) serve for connections between panels, are part of the SCS and are simply absent in the most common channel model with two connectors (Figure 6). But this is exactly how - patch by cords- erroneously named all flexible cables, including subscriber and network.

This illustration explains a few more terms and provides a clear distinction between them. The structure of the SCS includes the elements highlighted in yellow in Figures 6 and 7 and constituting a horizontal subsystem. No more than four detachable connections are allowed in the channel. In this case, one connector - the transition point - is considered additional and is not included in the line budget. In other words, the jump point can be set if there is a reserve of channel parameters. Active equipment connectors are not counted. Thus, the channel in Figure 6 has two connectors, in Figure 7 - three connectors.

Cables, cords or cords?

Let's analyze the meaning of the term patch cord... Connecting cables have two important features - stranded conductors and plug connectors at the ends. In accordance with the requirement of the standards, the copper conductors of each pair are not solid wires, as in line cables, but have seven strands twisted in the form of a cable. This feature is recorded in the English term. cord... The closest translation of it is cable... A cord, in its meaning, can be called a rope made of intertwined threads. Hence another private term - connecting cord... As for the adjective connective, this is the definition for all types of flexible cables. It would be more accurate to say commutation... And here is the word cord like cable, reflects the secondary characteristic of the connecting cable - its flexibility. Moreover, the term cord even more unfortunate than cable, which at least reflects the sign of electrical conductivity. The exact term is patch cable.

In order to convey the image of an object without distortion, it is necessary to fix the main, and not secondary signs. For a person who does not know English and cable jargon, the phrase patch cord doesn't mean anything. If you say patch cable, then the understanding of this phrase will be facilitated by common sense and elementary everyday experience.

With rare exceptions, patch and subscriber cables are similar. The network cables may differ from these. Specifically, a network cable with 25- or 50-pin Telco-style connectors at both ends connects the multi-line port of a network device to the connector on the back of the backplane.

In a properly planned and installed system, users only deal with interconnect cables. Horizontal and trunk cables are hidden from view, rigidly fixed and, if the installation was of good quality, do not require maintenance for many years.

Trunk (backbone cables), horizontal (horizontal cables) and connecting (cords, telecommunications) cables make up the physical channels of the transmission medium (cabling)... Another approach is also possible. The cables that form the fixed lines can be called linear... In this case, the channel consists of line and connection cables. Although this approach is private, it does not contradict the definitions of the standards.

I think everyone will agree that a good term helps to better understand what is at stake. So why not talk patch cable instead of patch cord and not lumping all types of jumper cables together? So we put everything in its place. Think about how your understanding of the terms patch room, patch panel, and patch cable has changed?

Hooks or crosstalk?

I gave examples of relatively simple and intuitive concepts. When it comes to more complex parameters, inaccuracies grow into myths.

Consider the terms aiming and crosstalk... Hooks are unwanted signals in one pair when there is a signal in the other. Crosstalk is an unfortunate term used for crosstalk. . This is why it is unsuccessful: under transient processes in electrical engineering they mean a delay in the growth of an impulse, a voltage surge and other oscillatory phenomena. Attenuation is the attenuation of a signal by the transmission medium. It's hard to even imagine what it might mean crosstalk attenuation. In fact, this is a fixation of an imprecise speculative idea of ​​the pickups of one of the pioneers of radio engineering, which appeared more than fifty years ago.

Have English terms NEXT and FEXT, denoting tips, their disadvantages. Literally, NEXT is translated as crosstalk at the near end, and FEXT at the far end of the cable. Most experts understand their meaning in this way. But they are just disoriented. Actually, NEXT is bi-directional pick-up, and FEXT is unidirectional pick-up.

Before the advent of gigabit protocols, the concept of unidirectional pickup had no practical meaning. Bidirectional crosstalk was called crosstalk. This is also true, since in traditional circuits, one pair is transmitting and the other is receiving. Signals travel in opposite directions, each pair interfering with receivers at both ends of the cable.

Taking into account the new parameters when using all four pairs for the simultaneous transmission of signals in both directions required to take into account the interference of both types. When measuring the parameters of lines and channels of four-pair cables, a field tester records six values ​​of bidirectional and twelve values ​​of unidirectional interference at each end of the line / channel.

The inaccuracy of these terms has made some of the messages on the cable testers' display look funny. For example, "measured NEXT (near-end crosstalk) at the far-end." The precise terminology makes it possible to convey what is meant: "Far-end bi-directional crosstalk is being measured."

Software developers get it right, but they are forced to use unfortunate terms. However, if you do not translate these messages and do not try to comprehend them, the subject of discussion does not arise.

Attenuation to pickup ratio

The parameters of the ratio of attenuation to pickups provide a clear example of how imprecise terms not only distort, but make the meaning of concepts inaccessible. The quality of signal transmission is characterized by two important parameters: ACR and ELFEXT. ACR means the excess of the signal above the noise floor of bidirectional signal transmission, ELFEXT - unidirectional.

The first term is perfectly accurate: "attenuation to crosstalk ratio" literally translates as "attenuation to crosstalk ratio". The second is surprisingly distorted: "equal level far end crosstalk" - literally means "equal level crosstalk at the far end". In one of the solid textbooks on SCS, it is translated as "equivalent level of crosstalk at the far end" and is supplemented by a comment that it is not possible to explain this. Judging by the published articles, few experts understand the meaning of the term. One of the best interpretations I've ever come across explains ELFEXT as analogous to ACR, but for unidirectional transmission. The following phrase is also quite typical: "this remark makes sense for those who understand what ACR is."

Customers pay a lot of money for testing SCS and receive a complete list of parameters. It seems that in most cases only one of them is used - the result expressed as PASS - FAIL. It means that the line / channel corresponds to a certain category / class. Few people know that the parameters of category 5e / class D 2000 are worse than the requirements of modern protocols of class D. To evaluate the SCS at a higher level, it is necessary to use a field tester with the data of network protocols and understand the measurement results.

If customers and specialists do not understand or misrepresent the values ​​of the tested parameters or harbor illusions about complete harmony of standards, then the certification process is more like a ceremony than a real business. The guarantees of compliance with SCS standards are useless for users, since it is not clear how the protocols will actually work. This can be learned from the results obtained, but no one knows how to do it. And the results themselves are interpreted differently or simply do not understand.

Here are some practical examples. A certain percentage of SCS baselines have a length exceeding 90 meters. This is permissible. The lines have been tested and correspond to category 5. The contractor notes in the documentation that he does not give guarantees for these lines. The customer has the measurement results, but considers them substandard. In fact, the lines have an excellent reserve and exceed the requirements of not only SCS, but also protocols. It also happens the other way around: network problems are created by channels with all guarantees, customers change network equipment and cannot find the cause. The main reason is the lack of professional knowledge.

In the domestic literature on SCS, there are up to a dozen terms for the abbreviation ELFEXT, and none of them gives a literal translation and all are inaccurate. But here, too, everything is very simple: ELFEXT is the ratio of attenuation to unidirectional interference, ACR is the ratio of attenuation to bidirectional (cross) interference. Indeed, these are similar parameters, as can be seen from good terms.

Why not speak Russian?

By precisely defining terms and categories, manufacturers, distributors, system integrators and users will be able to facilitate, above all, their professional activities. The same concept or term takes on the same meaning for everyone. In this case, both professionals and even non-specialists begin to understand each other better. Less confusion arises with orders, design and installation, preparation of documentation and operation of the system for many years. This requires professional training. However, the overwhelming majority of RAS training centers, manuals and popular articles replicate jargon, misconceptions and confusion of concepts.

It is encouraging that professionals seeking to improve their skills may be able to siphon off information. Logical classifications and understandable terms are more convenient and therefore easier to remember. A designer who understands the difference between flex cables will not document them as patch cords. Anyone who has been told the design of a connector will not confuse it with a connector. Having paid attention to the terms "male connector" and "female connector", even an untrained manager will not designate them in the price list as "male connector" and "female connector".

When the textbook author understands the terms, he will not propagate distorted representations such as NEXT is "near-end crosstalk", ACR is "security", and ELFEXT is "far-end equivalent attenuation". Customers who know what ACR and ELFEXT are will choose the best systems for reliable numerical parameters of the signal excess over the noise floor. There would be a desire to sort it out and put things in order - it is already easier to sort everything out on the shelves.

What is so special about this dictionary?

The SCS glossary of terms is the fifth edition of the systematization of terms for three years.

The original definitions included terminology and categories of international (ISO / IEC 11801), European (EN 50173) and American (TIA / EIA 568-A) standards. On the territory of the Russian Federation, the ISO / IEC 11801 standard "Information technology. Structured cabling systems of the customer's premises" is in force, it is used by all European companies, therefore, the definitions of the international standard are at the heart.

The new edition of the dictionary also includes terms from the standards for installation, administration, grounding, centralized systems and open offices:

• EIA / TIA-569 Standards for the Laying of Telecommunication Channels for Commercial Buildings;
• TIA / EIA-606 Standard for Administration of Telecommunications Infrastructure in Commercial Buildings;
• TIA / EIA-607 Requirements for Grounding and Electrical Connections for Telecommunications Systems in Commercial Buildings;
• TIA / EIA TSB 72 Guidelines for Centralized Fiber Optic Cabling Systems;
• TIA / EIA TSB 75 Additional Requirements for Building Horizontal Cabling for Open Offices.

In addition, the dictionary reflects the most common concepts of the theory of signal transmission and future standards. It contains a list of abbreviations from the standards listed above with explanations.

When compiling the dictionary, the author's three-year experience of work at the ITT NS&S Training Center in Moscow was used. Accurate terminology makes it possible to easily and easily convey the provisions of standards and data transmission technologies.

From the Editor: You can discuss the issues raised in this article in ours.

08.05.2011

Audio cables- seemingly quite a simple topic, but once you are faced with a choice, you will quickly find that they vary greatly in purpose, price and quality. This guide will help you understand the different types of cables and connectors.

With all the variety of cable types, they all have similar designs. If we consider the cross-section of the cable, then in its center there are one or more wires covered with a layer of insulation. These wires, together with a natural textile gasket, which serves to strengthen the structure and reduce the microphone effect, are placed in a shielding braid. All of this is covered with one or more layers of insulation.

Quality characteristics of various audio cables

Cheap cable wires are most often made of ordinary copper. The wires of more expensive cables are made from oxygen-Free Copper (OFC), obtained by melting at a very reduced pressure. Cables are even more expensive, the wires of which are made of silver and gold. Such cables are used where it is necessary to transmit the signal as accurately as possible. In addition, no less expensive carbon wires made from polymer carbon fiber are used to transmit audio signals. Most cables are usually insulated with polyvinyl chloride (polyvinyl chloride), plastisol and polyurethane.

In addition to electrical characteristics, the main of which are resistance, inductance and capacitance, a wire also has important physical characteristics - diameter, cross-sectional area, or gauge. Wire diameter is measured in millimeters, cross-sectional area is in square millimeters, and the American AWG system ( American wire gauge). To compare AWG gauge, diameter and cross-sectional area of ​​round wire, there is table .

The main purpose of a cable is to move an electrical signal from one component to another without significantly degrading the signal or introducing noise. There are expensive, excellent quality cables for the true audiophile, and they are designed and manufactured to keep the signal intact and operate without interference. Most musicians do not need this quality when performing, however, this is not an indicator, and high-fidelity cables will not interfere with you. Quality cables will carry the best sound, and as you know, if you have better sound, you will sound better.

Other signs of "quality" such as gold-plated connectors and oxygen-free ( Oxygen-free) copper wires are not that super important. Gold plating can reduce resistance, but is more susceptible to wear and tear than nickel plating, so it may not be suitable for plugs that are plugged in and unplugged frequently. Oxygen-free copper wires may offer less resistance, but the width of the wire helps a lot.

Mostly you need a cable that is flexible, durable, of good quality material with well-soldered connections. Other characteristics are connectors with a choice of epoxy pots or hot glue (filled with one substance or the other to prevent the ends of the wires from moving and firmly fix them) and reduce heat at the ends of the cable braids (plastic sheath around the wires and terminals, which, when heated provides a snug fit of the wires and their fixation). Instrument cables must be especially robust. They move constantly during a performance, are often accidentally pulled out or stepped on, and are often plugged in and out of the network. There are no perpetual instrument cables, but there are ones that last longer. Another criterion is that it is advisable to buy cables that are sufficient in length, but not too long (since the longer the cable, the greater the likelihood of noise).

Cable types BY FUNCTION

Musicians who deal with cables generally divide them into four main categories: instrument cables ( Instrument cables) , connecting cables ( Patch cables) , speaker cables ( Speaker cables) , and microphone cables ( Microphone cables) ... Rule number one: when making a purchase, choose a cable designed for the specific purpose you need. The instrument cable should not be used to connect speakers. It will work, but not as expected and, under certain circumstances, can cause problems. And you never want to use a speaker cable as an instrument cable or jumper cable because it is an unshielded option and is extremely susceptible to noise sources.

Instrument cable: As the name implies, it connects guitar, bass, keyboards, or other electronic devices to an amplifier. It has a positive lead and shielding that serves as a ground. It is designed to transmit low voltage audio signals from the instrument and most often has a 1/4 "(6.35 mm) TRS jack, or so-called" jack "(eng. jack).

Connection cable: short cable, used to link various components for a recording circuit or amp setup, or to connect effects pedals to each other and automatically connect the instrument to an amp. Most often, connecting cables are similar to instrument cables, but they can also be balanced (see below), and can have different types of connectors (XLR, 1/4 "phone, TRS, RCA).

shielded and balanced XLR male cable ( male) at one end and XLR female ( female) with another. Some microphone cables have a TRS mini-jack or USB connector at the end for connecting directly to your computer's sound card or digital recorder. A microphone cable is often used as a long, balanced cable connecting a connected microphone to a mixing console. In addition, a microphone cable is often used for DI communication (DI box) between an amplifier and a mixing console. Microphone cables are also sometimes used for AES / EBU digital output.

Speaker cable ( Speaker cable ): An unshielded two-wire cable is much thicker than jumper, instrument or microphone cables. They have more wires because they carry a much higher voltage. Even a ZIP cord (or tube cord) can be used as speaker cables. They can have 1/4 "phone jacks, banana clip(also called MDP connectors), binding post(typically found on stereo amplifiers), or Speakon connectors.

Multichannel cables ( Snakes, or "multicore", "multicore cables"): consist of several single cables, enclosed in one powerful common insulating sheath. They are used for multichannel transmission of analog and digital signals, most often over long distances. In addition to single cables, this sheath can contain a plastic or textile cord, which gives the multicore mechanical strength. It is also convenient to use this cord to tie the end of the multicore to the patch panel frame, for example. Single cables in multicore can be of all three types. Stage "snakes" can contain microphone, connecting and speaker cables and are used for two-way communication between the stage and the remote mixing console of the sound engineer. They can have a whole fan of different connectors at one end, and a box at the “stage” end, which is a connector panel with “jacks”. There is also a type of studio multicore where separation of different cables is required to connect studio equipment. The shielding and insulation of single cables can be either individual, which is good, or common, which is bad due to the impossibility of separating common wires for individual transmission channels. This should be taken into account when buying multichannel cables, in addition to the basic parameters: length and type of connections.

Balanced and unbalanced cables (Balanced and unbalanced)

Line level interconnect cables are of two types: balanced and unbalanced. Balanced cables are quieter and are often referred to as “professional”, while unbalanced cables are called “household”. Balanced ones are often used to connect equipment for which noise is unacceptable. An unbalanced cable usually ends with an RCA plug. Balanced cables are easily recognizable by the 3-pin XLR connector (or TRS connector). This is due to the fact that there are three conductors inside a balanced cable: two of them carry a signal (positive - positive and negative - negative), and the third is connected to ground. Signals are conducted simultaneously in both conductors, and reversed polarity cancels out any interference *.

* When two signals of exactly the same but opposite polarity, transmitted on a balanced line, enter the component receiving the signal, the input of the differential amplifier, the noise induced on the cable is eliminated. This is because the differential stage only amplifies the difference between the two signals. Noise penetrating into the line is the same in both conductors, therefore, the differential amplifier will be able to suppress them. This method of eliminating interference that is identical in both conductors of a balanced line is called common-mode rejection. Differential inputs are characterized by their ability to suppress the signal common to both conductors. This parameter is called the Common-Mode Rejection Ratio (CMRR). Remember that a balanced line will not make a noisy signal clear. It only prevents additional interference from occurring in the interconnect cable transmission. A differential amplifier will only eliminate interference if it is identical in both conductors.

Because balanced cables eliminate any interference and noise, they can be longer than unbalanced cables. Unbalanced cables over 10 inches in length are susceptible to noise and require ground reinforcement.

When purchasing, it is important not to confuse single stereo cables with balanced mono cables. Although they have the same TRS connectors, their purpose and connection are completely different.

Shielding

All cables used in audio equipment, with the exception of speaker cables and optical cables, are shielded to protect the signal from interference that generates noise. This means that there must be a conductive surface (shield) around the signal wires of the cable to protect the cable wires from electromagnetic radiation. The shield is most often used as a common wire. The goal is to protect the signal from noise sources such as radio signals, power cords, fluorescent lamps, dimmer rheostats, and some appliances. When you hear radio through your amplifier, it usually means that the shielding, shielding around the components of your amplifier is inadequate, but you should also bear in mind that poor shielding of the cable to your instrument may be the cause. A good shield can also serve as a ground connection.

In audio cables, the screen is three types: foil, wire mesh or wire spiral... In the manufacture of the shield, cable manufacturers try to ensure that it completely covers the signal wires of the cable. The easiest way to achieve this is by making the screen from metal (usually aluminum or copper) foil. This foil is wrapped around the signal wires of the cable and a bare wire is laid under it to contact it. This shield provides 100% coverage of the signal wires. However, the foil shield has disadvantages, the main of which is mechanical unreliability, therefore it is used in cables intended for stationary use.

Braided screen is the most mechanically reliable and flexible form of screen. This is the most common type of screen. On stage, mic and instrument cables are constantly bent, pulled, stepped on, and braided is the best you can think of for these conditions. But at the same time, it is difficult to manufacture, and it is difficult to achieve 100% coverage of signal wires with it. Typically, the braided shield covers 60 to 85% of the signal wire area. Some firms make very dense mesh braids, covering up to 96% of the cable area in the cable.

Spiral wire braid shielding has one big advantage - it provides the cable with flexibility that cannot be achieved with a foil shield or mesh braid (cable flexibility is of great importance in concert environments). True, this is where all her advantages end. The spiral wire braid covers no more than 80% of the area of ​​the signal wires and, when exposed to physical influences, quickly deteriorates (although not as quickly as a foil shield). At the same time, the area covered by it sharply decreases. It is also less immune to radio frequency (RF) interference because it is actually a coil that has inductance.

Some companies manufacture cables with double shielding. Most often this is a combination of foil with a thin mesh braid, which serves to strengthen it. They also make a double spiral braid, which is more reliable than a single one, and covers a slightly larger area of ​​wires.

Types of cable connectors

Typically, for live sound devices, six types of cable connectors are used: TRS and XLR - for balanced connection and TS, RCA, banana and Speakon- for asymmetrical.

Connectors are divided into sockets (in English they are also called " female", And in Russian -" mom ") and plugs (in English they are also called" male", And in Russian -" dad "). While this division is obvious for jack connectors, in the case of XLR connectors, for example, the part of the connector with pins is a plug, and the mating part of the connector with holes is a jack.

TS phone 1/4 "(TS quarter-inch jack) - The most common connector for transmitting audio signals, it can be found on unbalanced patch cables, instrument cables, and speaker cables. The abbreviation "TS" stands for: T - Tip, which means "tip" and S - Sleeve, which can be translated as "sleeve". It is from these two parts that this connector consists. When using a two-pin connector, contact Tip(2) connects to the signal wire, and the contact Sleeve(1) - with common or earth conductor, for example, braided shield. 4 - insulation.	TRS phone jack (eng. Tip,Ring,Sleeve - which translates as Tip, Ring, Sleeve) looks like TS phone 1/4 ", with the only exception that it has an additional segment of the shaft called" ring "." Tip "," ring "and" sleeve "allow you to connect two wires, as well as use the ground. as follows: pin 1 ( Sleeve) connects to a common conductor. Pin 2 ( Tip) is designed to transmit a signal in phase. In this case, it is called " hot”,“ Plus ”,“ phase ”,“ phase plus ”or“ hot ”. Contact 3 is intended for signal transmission in antiphase. He's called " cold"," Minus "," antiphase "," phase minus "or" cold ". With two-channel transmission, pin 1 ( Sleeve) is used to connect to a common conductor, and pins 2 ( Tip) and 3 ( Ring) - for signal conductors of the first and second channels, respectively. A special case of two-channel transmission is the transmission of a stereo signal. Headphones are a prime example of this. For stereo transmission, pin 1 ( Sleeve) - common, contact 2 ( Tip) carries the left channel signal and pin 3 ( Ring) - right. Another use of two-way jacks is for bi-directional audio signals. A striking example of this is the gap connector ( insert) channel on the mixing console. As elsewhere, pin 1 is common, but there is no wiring standard for the second and third contacts. One of the two remaining contacts is the output and the other is the input.
XLR connectors(sometimes called " Switchcraft», « Cannon"And" canon ") is what you usually see at the ends of a microphone cable (both female and male connectors). These connectors can have three, four, five or more contacts. Three-pin XLR connectors are the most common in audio equipment. They are used for the balanced transmission of analogue mic / line level signals, digital signals, and sync signals. Three-pin XLR connectors are used on balanced patch cables to send the signal from the mixing console to the speakers, and from the DMX controller to the lighting equipment. XLR connectors with more than three pins are used in tube and stereo microphones.	RCA connectors - most commonly used on consumer stereo equipment, CD players and turntables. RCA cables are usually a pair of wires molded together so that only the ends are separated. Many mixing consoles have RCA inputs for connecting a stereo CD player to PA system and some remotes also have RCA outputs for connecting to recording devices.
Banana plugs is a reversible connector used on speaker- cables, often only at the end of the amplifier, or at both ends when the amplifiers are provided with an appropriate jack. The main advantage of the banana connector is that the wires are not soldered. The ends of the wires slip into the hole and are held in place with a set screw. This simple design allows the necessary repairs to be carried out on the spot, literally on the fly.	Speakon connectors used to connect speakers, more and more often used to connect speakers in PA systems. They are needed here because they are quite reliable and cannot be accidentally pulled out of the socket, which happens with banana plugs or TRS phone jacks. Connectors Speakon designed for high currents, they provide protection against human contact with live parts, which is important for powerful amplifiers. There are three types of connectors: two-pin, four-pin and eight-pin. The most commonly used four-pin connectors.
Minijack(1/8" mini jack ) - connector with a diameter of 3.5 mm, widely known for household equipment. In professional equipment, it is most often used to connect headphones, and even then - in small sound modules, portable equipment and other devices where the size of the jack is important. The minijack has become more widespread in multimedia equipment. The connectors can be either TS or TRS.	Connectors type D-Sub (multi-pin connector D-Subminiatur e) - more often seen on computers. In audio equipment, it is used to transmit analog signals at microphone and line levels, as well as for some audio digital interfaces, such as TDIF. In addition, the connector D-Subminiature used in various RS interfaces. D-Sub connectors are 9 -, 15 -, 25 -, 37 and 50-pin. DB25 D-Sub size is commonly used by some audio brands ( Tascam etc.) for analog / digital I / O. Mixers Mackie use DB25 to connect to interface Firewire... DB25 connectors are also used with some multichannel cables ( multicore) for analog connections, in particular those using the standard Tascam.

Adapters

After cables and connectors, adapters are the most common switching devices. As you add hardware, you may find yourself needing a cable with an unusual set of connectors. Here adapters will come to the rescue.

These devices are designed to interconnect devices with different types of input and output connectors. The adapters have a small, often cylindrical body with different types of connectors at the ends. The most common are XLR-to-3-pin quarter-inch jack adapters and RCA-to-2-pin quarter-inch jack adapters. Often there are (mainly for use with headphones) adapters from a three-pin minijack to a three-pin quarter-inch jack. There are adapters with other combinations of connectors.

The use of such adapters is possible only if the input and output parameters of the devices match, that is, the inputs and outputs must have the same nominal signal level (for example, linear), transmit the signal in one way (balanced or unbalanced) and approach each other by input and output resistances ( impedances). If these conditions are not met, the signal transmission may be of poor quality. So, if the nominal levels of the input and output signals do not match, sound distortion or an increase in the noise level may occur, and if the input and output impedances do not match, signal loss may occur. A classic example of misapplication of adapters is connecting an electric guitar with passive pickups with a relatively high output impedance (5-25 kOhm) to the line input of a device with an XLR input connector and a relatively low input impedance of 10 kOhm using an XLR-jack adapter. There are several errors in this connection, the main one of which is the discrepancy between the input impedance of the device and the output impedance of the guitar (in this case, the input impedance should be much higher than the output impedance, at least ten times). Other special devices are responsible for this, with the help of which such connections can be made. These are matching devices.

Matching devices

These devices are designed to connect devices that, for some reason, cannot be connected directly using cables and adapters. The reasons for the impossibility of direct connection of devices may be a mismatch in nominal levels, inappropriate input and output resistances, an unequal method of signal transmission, or mismatch in characteristic impedances. All matching devices can be divided into four groups: level matching devices, impedance matching devices, signal transmission method matching devices, and decoupling devices.

In addition, there are devices that use several matching methods at the same time. Many of these devices provide electrical isolation while performing, for example, impedance conversion or level matching.

Splitters

These devices are designed to split the audio signal in order to distribute it to multiple receiving devices. Perhaps, they are most often used in concert activities, separating the signal for the main and monitor mixers. There are single-channel and multi-channel splitters. Almost all splitters have transformer-isolated outputs, that is, there is no galvanic connection between their outputs and the input. As a result, the influence on each other of devices connected to the splitter outputs is eliminated. In addition, there are buttons on the splitters Ground / Lift, with the help of which it is possible to disconnect the ground contact of the output connector from the common ground of the channel.

The Rolls MS 20, for example, is a single channel microphone splitter. The unit has a balanced microphone input on XLR connectors and two transformer decoupled balanced mic outputs on XLR connectors. In addition to the connectors, there is a Ground / Lift switch that disconnects the ground pins of the output connectors from the input ground.

Switches

If splitters split the input signal into several outputs simultaneously, then the switches allow you to send the signal from the input to the selected output, or vice versa - send the signal from the selected input to the output. They are used to switch the path of the audio signal when, for example, you need to route the sound to one or another effect processor.

The simplest switch is the so-called A-B Box. It allows you to route the signal from the input to one of the two outputs, or connect one of the two signal sources to one receiver. For example, the A-B Box DOD 270 is capable of feeding one output from one of two sources, or sending an input signal to one of two receivers. All three connectors (A, B, Com) for connecting sources and receivers are jacks. Switching is carried out by pressing the pedal button.

Cable Testers

If you have PA system, a large sound system that you regularly use for big concerts, then a cable tester is a very small but such an important investment. Cables can lead in or out periodically, and then it is the cable tester that can quickly tell where, in what place and what kind of problem it is.

DIGITAL cables and connectors

The cables and connectors described above are analog, used for PA systems, instrument hookups, and traditional studios. Today digital technology has added many types of connectors and cables that connect computer serial buses to various external devices such as printers, interfaces, digital recorders and processors, video equipment, and DJ equipment. The variety of cables, connectors and protocols reflects the constant changes in digital technology. New technologies are often accompanied by new protocols affecting computer hardware, software, and drivers. Below is a description of some of the most common connectors and cables currently in use. One important caveat: often the same type of connector is used to carry a digital signal as for analog (XLR and RCA connectors, for example), but cables are usually designed for different impedances and therefore are not interchangeable with similar analog cables.

MIDI- an abbreviation that stands for Musical Instrument Digital Interface(musical instrument digital interface). It is a protocol designed for connecting electronic instruments with external digital devices. It conveys all aspects of a musical performance other than sound - that is, which note is tuned, how long it lasts, the velocity of the strike, etc. - while the actual tone is generated by the plug-in sound module. MIDI can also pass control parameters to software and synthesizers, allowing you to actually turn knobs and move sliders using MIDI with remote control.	USB is a relatively new type of computer connection that has become the standard for connecting external devices such as printers, cameras, musical instruments, and digital audio devices. USB cables have type A or type B connectors on one end and the other connector specific to the device being plugged in on the other side. USB can also serve as a power source for a connected device. In the course of several years since its introduction, the specification has as a result been updated from the original 1.1 standard to the 2.0 standard, the main difference of the latter is that it can transfer data at a faster rate. USB 2.0 is backward compatible with 1.1. The third in a row, new USB-connector - USB minijack - can often be seen on MP3-players and on some of the company's devices Roland.
FireWire (IEEE 1394): a protocol first developed for video because it allows high-speed data transmission up to 800 Mbps. It is now widely used for audio applications. There are three types of FireWire connectors: 4-pin, 6-pin, and 9-pin. The 4- and 6-pin versions are known as the FW400. The 9-pin version is known as the FW800. 6-pin has the same baud rate as 4-pin, but can still supply power. A 9-pin can transfer power up to twice as fast as a 6 or 4. Adapters are available when you need to link devices that require different connectors. The FW800 is backward compatible with the other two, but not vice versa.	S / PDIF - abbreviation for Sony Philips Digital Interface Format... This format for digital audio uses either optical or coaxial cable for transmission. The coaxial version uses RCA plugs, but these cables are not interchangeable with analog RCA, as the S / PDIF version must be 75 ohms. The optical version uses TOSLINK, a standard fiber optic connection system developed by Toshiba. Both versions are capable of carrying two audio streams, usually a left and right stereo signal.
AES / EBU is a format for transmitting digital signals developed by Audio Engineering Society(AES) and European Broadcasting Union(EBU) in the early 1980s. It uses AES Type 1 cable - three conductors, 110 ohm cable and XLR connections. It transmits two channels over one connection and is the transmission protocol on which S / PDIF is based. Due to the difference in impedance, an XLR mic cable, although it has the same connectors, will not function as an AES / EBU cable.	Bnc-the connector is used to connect a thin coaxial cable with a wave impedance of 50 Ohm and a diameter of ~ 0.5 cm. Cables with BNC connectors are used to connect electronic devices (signal generators, oscilloscopes, etc.), as well as to build networks Ethernet 10BASE2 standard. This connector is of the type « "bayonet" is often found on cables that carry clock signals between digital studio components. They are also found on video equipment and audio testing devices.
Optical cables and connectors: fiber optic technology is often used in digital devices to transmit data. Optical cables allow information to be transmitted over longer distances with a higher data transmission rate, based on the principle of light transmission, and absolutely do not create any noise. Many modern digital devices have two ports, one coaxial and the other optical. One of the important optical protocols is ADAT Lightpipe... It transmits eight channels of digital audio over a dedicated cable with a specially designed Alesis ADAT connector.	TDIF (Tascam Digital Interface) is a proprietary format that uses a 25-pin D-Sub cable for transferring eight channels of digital audio between compatible devices. This enables bi-directional communication, which means that only one cable needs to be connected to link eight inputs and outputs from one device to another. The old version of TDIF-1 cannot send or receive synchronized information (this requires a separate Wordclock connection). The new TDIF-2 protocol can transmit and receive synchronization without additional cables.

Improper rolling of the connecting cables is bound to cause problems sooner or later. In accordance with Murphy's laws, a badly folded roll at the most inopportune time and in the most inappropriate place will surely fall apart, get tangled and make you put off everything in order to unravel it. To avoid such situations, it is better to fold it right from the very beginning.

ROLLING AND INSTALLATION OF CONNECTING CABLES

First, never wrap the jumper wires around your arm or elbow. There are several ways to roll cables that can be used to roll the cable more neatly. For example, one of them.

Holding the cable in this place with the thumb and forefinger of your left hand, intercept it in the same place with your right hand so that you get a ring

Take the beginning of the connecting cable in your right hand with the connector facing you so that it hangs down slightly.

Now grasp the cable with your left hand near where you are holding it with your right hand and, while grasping the beginning of the cable with your right hand, move your left hand to the side about one meter.

With your right hand grasping this ring, make another loop.
This method of coiling the cable is simple and very widely used. Once you see how it is performed, you will immediately understand how to use it and why you need to start coiling the cable from the beginning, and not from the end.

After all the cable is in your right hand, slide the end of the cable into the ring from the outside with your left hand so that a small loop forms, and then thread the end of the cable through this loop.
After that, tighten the resulting knot.

The connecting cable folded in this way is easy to unwind and will not get tangled during transportation.

LAYING THE MULTI-WIRE CONNECTING CABLE

A multi-wire connecting cable or braid is used to connect external sources and receivers of signals with the input and output circuits of the mixing console. The reliability of the whole concert complex depends on the condition of this cable, so you need to handle it carefully, lay it in the most natural way for it, without kinks and kinks. When folding and unrolling a multi-wire connecting cable, you need to keep in mind that the presence of breaks in any of its lines is most often detected when it is connected. When folding the multi-wire connecting cable in the manner described above, consider the switch box its end, and the group of connectors used to connect to the console as the beginning. The diameter of the loops should be as large as possible. If this diameter turns out to be larger than the dimensions of the box in which the cable is to be stored, then it can be folded into the box in eights, carefully making sure that the cable is laid flat and not twisted. In this case, the installation must be started from the end. Never try to wrap the stranded connection cable around your hand, it weighs too much.

Laying the stranded connecting cable in the box.

Although the multi-conductor patch cable looks thick and sturdy, it is made up of a large number of very thin ordinary patch cables tightly tied together. When bending a multi-wire jumper cable, these wires not only bend, but also compress and stretch, so they can break if bent too much. Since a multi-conductor patch cable contains 12 to 32 symmetrical cables in a dense plastic sheath, the tension inside the cable can be very strong.

Multi-conductor connection cable device

The ends of the balanced cables of the multi-conductor interconnect cable can be connected either to the control box or to the multi-pin connector through which the multi-conductor cable can be connected to the control box located on the stage. This solution prevents tangling of the connected terminals of the multi-wire cable when connected to the stage control box and avoids excessive tension.

On the other end of a multi-lead connecting cable, there are usually separate connectors, most often XLR type, that make connections to the input channels of the mixing console. When making these connections, the weight of the stranded cable must be taken into account. It is unacceptable that the entire load falls on one connector, since the weight of the cable can simply tear it off.

Preparation of a bundle of connecting cables for laying in the hall. To avoid contamination or damage to the multi-conductor cable connectors during storage and installation, it is useful to place them in a special bag attached to the end of the cable.

When folding the stranded connecting cable after a gig, never yank on it if it snags on something. You could accidentally pry the connector off the leg of a chair or table. Once the cable is rolled up, it is a good idea to place the connectors in a special bag or bag by tying it at the end of the cable. This will keep you protected from dust and accidental damage.

CONNECTORS

In order to ensure the compatibility of the input and output connections of various devices, standard types of plug connections are used. One of the most commonly used connector types are the XLR 3-pin connectors from Cannon, Sweet-chcraft, Neutric and many others.

The detachable connection consists of two parts - a connector and a detachable socket. For XLR type plug connections, there is an individual standard for input and output plug connections. The input jacks of XLR-type connectors always have holes that accept the pins of the connectors. The input sockets of this type of connection are made with pins, so the output connection must have holes.

The XLR plug-in part that supplies the signal has pins, and the plug-in part that receives the signal has holes.

Microphone jacks always have pins, and the input jacks these microphones plug into are holes. The mixer output jacks are also pronged, and the multi-wire input jacks are also drilled. This principle is maintained throughout the chain from start to finish.

Sometimes you can find devices with both types of jacks installed at the input. This is no exception to the rule. This is done in cases where there is a need to connect the inputs of several devices into a common parallel circuit, so to speak, the input of one of the devices is the output for the other.

Let's give an example. Let's say you have two stereo amplifiers and you want to use them to amplify the signal of one of the channels of your sound reproduction system. To do this, you must connect all the inputs of these amplifiers using standard connecting cables, and connect their outputs to the four groups of loudspeakers of the section of one of the channels.

Combining the inputs of power amplifiers.

The standard input and output connectors are convenient for extending cables. You can take several short cables and, by connecting their connectors together in a common circuit, get one long one. No additional adapters are required.

A SERIOUS EXCEPTION TO THE RULE - CONNECTING SPEAKERS

The USA, Japan and Australia use the output jacks as the speaker input jacks. This is done in order to prevent accidental connection of the output cables of power amplifiers, the output voltage of which is very high, to the input of any other device. However, special interconnect cables are required to connect the loudspeakers in this way, so this exception is not common in the UK and Europe.

Marking

It is a good idea to pre-label and label all connectors on a multi-wire patch cable by attaching channel numbers and instrument names to them. The presence of marks speeds up the work during setup of the mixing console, facilitating orientation in the circuits connected to it. Attach the labels with the words “Bass. drum "," Hat "," Volume 1 "" Volume 2 ", etc. The conclusions left unused, just number. By using these markings, you can save a ton of valuable work time, of course, if you don't try to apply the tags during the concert.

Mark the connecting cables in advance, before you lay them and bundle them in one bundle.

If you often have to assemble the same concert complex, then its assembly will be simplified if you label all the connecting cables of this complex. Then you do not have to keep in mind the details of its assembly and spend time fixing erroneous switching instead of using it for sound tuning or relaxation.

SYMMETRICAL AND UNYMMETRICAL CABLES

An unbalanced insulated cable is an ordinary insulated wire placed in a braided shield, also covered with insulation.

Unbalanced insulated cable device.

A balanced insulated cable differs from an unbalanced cable only in that it contains not one, but two insulated wires inside.

Symmetrical insulated cable device.

And in fact, and in another case, the shielding braid is designed for the same purpose - to weaken the interference produced by external alternating magnetic fields.

All electrical signals are two-phase and require two wires for their transmission. In order to distinguish these phases from each other, one of the phases is considered positive and the other negative. With an unbalanced connection, the conductor serving as the negative phase is the braided shield of the cable. In this case, the center wire of the cable is called the signal wire, and the shield braid is called the zero wire.

When connected symmetrically, the positive and negative phases of the signal are transmitted through the two inner wires, and the braided shield is used to electrically connect all metal shield surfaces. In order for this wire to be grounded without risking causing a short circuit, its potential must be zero. For this reason, it is called neutral, body, common wire or ground.

Purpose of conductors of unbalanced and balanced cables.

The goal of a balanced connection is to achieve the lowest possible interference.

Balanced Connection Assignment

The main reason for resorting to a balanced connection is that a balanced line has a higher noise immunity than an unbalanced one. The amplification of signals produced by the systems of the concert complex reaches enormous values. Therefore, despite the fact that the amplitude of the interference signal induced in the wire by external magnetic fields is insignificant, it can become quite noticeable at the output of the sound reproduction system. Add to this the fact that the number of wires that carry signals that require amplification is in the tens, and you will understand why you have to struggle with interference. The signal amplitude at the microphone output is several millivolts. In order to apply this signal to the input of the power amplifier, it must be increased to one volt. This requires an increase of almost 1000, and sometimes more, times. It is clear that with this gain, a multi-conductor interconnect cable that can be longer than 50 meters is capable of generating tremendous noise.

In the case of unbalanced cable, any interference signal attenuated by the braided shield is amplified by the preamplifier input circuits to the same extent as the signal. This is because both the noise and the audio signal are transmitted over the same wires. In a balanced cable, the interference signal is induced in both the positive and negative phases equally, since the interference potential difference captured by the cable is created between its inner conductors and the screening braid. Electrical oscillations induced in positive and negative phases by external fields will be in phase. The electrical vibrations created in the phases of the cable by the input signal are always antiphase. Since the input circuits of devices designed for balanced connection perceive only antiphase oscillations, they practically will not perceive the interference signal.

In general, if you want a low noise system, use a balanced connection for the connections. An unbalanced connection can only be used for transmitting instrument signals if the length of the connecting cable does not exceed 3-4 meters. Any longer connections, especially those made by multi-conductor connecting cables, must be symmetrical.

Matching an unbalanced connection with a balanced

Sometimes it may be necessary to connect a three-pin balanced input connector to a two-pin unbalanced output connector, or vice versa. This situation can occur when connecting musical instruments or sound processors. In this case, the positive phase of the balanced connector is used as the signal wire, and the negative phase and shield are connected together at the point where the neutral conductor of the unbalanced connector is connected. The cable used for this connection must be two-wire.


Wiring method for a two-wire cable when matching an unbalanced connection with a balanced

INTERNATIONAL STANDARDS

Three-pin cannon XLR / AXR connectors have an international standard for pin assignment and pin numbering. If the connector is designed for balanced connection, then pin 1 should be common, pin 2 should be positive, and pin 3 should be negative.

However, this standard is not always observed. Television and radio receivers, sound reinforcement equipment, measuring equipment, and sometimes entire studios, can have their own standards.

If the studio equipment uses a balanced connection, then you most likely will not have problems related to the connection standard. Typically, an incompatibility problem occurs when trying to negotiate mixed connection standards for balanced and unbalanced lines.

Imagine the following situation. A connecting cable designed to carry a signal from a balanced source to an unbalanced source involves connecting the signal wire to pin 3. Pins 1 and 2 in such a cable must be shorted. If you connect this cable to a balanced output that has pin 2 positive, the signal to a device that has an unbalanced input will be carried through the braided shield of the cable, causing a sharp increase in noise. To eliminate this mismatch, the phases of the balanced output must be reversed.

If you work with someone else's equipment and you do not have the opportunity to rewire the input and output connectors, then to change the phases, you can use special adapters that are connected to standard connecting cables. This adapter consists of two appropriately connected connectors, one of which must be input and the other output. The pins of these connectors are connected so that the positive and negative phases are reversed. Adapters that change the phases of a balanced signal are convenient to use when matching the phases of microphones, when the mixing console does not have phase change switches.

An adapter cable that reverses the phases of a balanced connection. Pin 3 of one connector connects to pin 2 of the other.
Always keep track of which phase you are using to transmit the signal. This will help you navigate correctly when connecting unfamiliar equipment.

RULES FOR HANDLING CONNECTING CABLES

All connections in the concert complex used to transmit audio signals must be balanced. An exception can be made only for those circuits whose signals are high and the length of the connecting cable is not too long.
On XLR connectors, pin 1 is for ground only. You can use pins 2 and 3 to connect the positive phase. This has no effect on the balanced connection cable. Therefore, when matching the inputs and outputs of various devices, the pin number you use to connect the positive phase must be remembered.
Prepare spare interconnect cables and connectors in advance.
The connectors on the cables must be handled with care. Pay particular attention to the connectors of the multi-conductor connecting cable.
XLR connectors and plugs with male connectors are outputs. The entrances always have holes.
The design principles of multi-pin connectors are given in the appendix.