TRS connector
Encyclopedia
Analog signal
An analog or analogue signal is any continuous signal for which the time varying feature of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal. It differs from a digital signal in terms of small fluctuations in the signal which are...
s including audio
Audio
Audio is an electrical or other representation of sound.Audio may also refer to:*Audio, audible content in media production and publishing*AUDIO , an American R&B band of 5 brothers formerly known as TNT Boyz and as B5...
. It is cylindrical in shape, typically with three contacts, although sometimes with two (a TS connector) or four (a TRRS connector). It is also called an audio jack, phone jack, phone plug, and jack plug. Specific models are known as stereo plug, mini-jack, mini-stereo, headphone jack, tiny telephone connector and Bantam plug.
The TRS connector was invented for use in telephone switchboard
Telephone switchboard
A switchboard was a device used to connect a group of telephones manually to one another or to an outside connection, within and between telephone exchanges or private branch exchanges . The user was typically known as an operator...
s in the 20th century and is still widely used, both in its original in (exactly 6.35 mm) size and in miniaturized versions: 3.5 mm (approx. in) and 2.5 mm (approx. in). The connector's name is an initialism derived from the names of three conducting parts of the plug: Tip, Ring, and Sleeve – hence, TRS.
In the UK, the terms jack plug and jack socket are commonly used for the respectively male and female TRS connectors.
In the US, a stationary (more fixed) connector is called a jack
Jack (connector)
In electronics and electrical assemblies, the term jack commonly refers to a surface-mounted connector, often, but not always, with the female electrical contact or socket, and is the "more fixed" connector of a connector pair...
. The terms phone plug and phone jack are sometimes used to refer to TRS connectors, but are also sometimes used colloquially to refer to RJ11 and older telephone plug
Telephone plug
A telephone plug is a type of male connector used to connect a telephone to the telephone wiring in a home or business, and in turn to a local telephone network. It is inserted into its female counterpart, a telephone "jack", commonly affixed to a wall or baseboard...
s and the corresponding jacks that connect wired telephones to wall outlets (the similar terms phono plug and phono jack refer to RCA connector
RCA connector
An RCA connector, sometimes called a phono connector or cinch connector, is a type of electrical connector commonly used to carry audio and video signals...
s though both plug types are used in tandem when a computer
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
or MP3 player connects to a stereo). In conversation, the diameter is often added to specify which size: quarter-inch phone plug or 3.5 mm phone jack for the unbalanced two-channel three-contact version, and balanced TRS jack or TRS phone plug for the balanced one-channel three-contact version.
Modern connectors
Telephone switchboard
A switchboard was a device used to connect a group of telephones manually to one another or to an outside connection, within and between telephone exchanges or private branch exchanges . The user was typically known as an operator...
—making it possibly the oldest electrical connector standard still in use. The 3.5 mm or miniature and 2.5 mm or sub-miniature sizes were originally designed as two-conductor connectors for earpieces on transistor radio
Transistor radio
A transistor radio is a small portable radio receiver using transistor-based circuitry. Following their development in 1954 they became the most popular electronic communication device in history, with billions manufactured during the 1960s and 1970s...
s. The 3.5 mm and 2.5 mm sizes are also referred to as in and in respectively in the United States, though those dimensions are only approximations. All three sizes are now readily available in two-conductor (unbalanced mono) and three-conductor (balanced
Balanced audio
Balanced audio is a method of interconnecting audio equipment using impedance-balanced lines. This type of connection is very important in sound recording and production because it allows for the use of long cables while reducing susceptibility to external noise.Balanced connections use...
mono or unbalanced stereo
Stereophonic sound
The term Stereophonic, commonly called stereo, sound refers to any method of sound reproduction in which an attempt is made to create an illusion of directionality and audible perspective...
) versions.
Four- and five-conductor versions of the 3.5 mm plug are used for certain applications. A four-conductor version is often used in compact camcorder
Camcorder
A camcorder is an electronic device that combines a video camera and a video recorder into one unit. Equipment manufacturers do not seem to have strict guidelines for the term usage...
s and portable media players, and sometimes also in laptop
Laptop
A laptop, also called a notebook, is a personal computer for mobile use. A laptop integrates most of the typical components of a desktop computer, including a display, a keyboard, a pointing device and speakers into a single unit...
computer
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
s and smartphones, providing stereo sound plus a video signal. Proprietary interfaces using both four- and five-conductor versions exist, where the extra conductors are used to supply power for accessories. The four-conductor 3.5 mm plug is also used as a speaker-microphone connector on handheld amateur radio
Amateur radio
Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...
transceivers from Yaesu
Yaesu (brand)
Yaesu is an international brand of commercial and amateur radio equipment.It was founded as in 1959 by a Japanese radio amateur Sako Hasegawa with callsign JA1MP in the Tokyo neighborhood of Yaesu...
and on some mobile phones.
Handsfree
Handsfree is an adjective describing equipment that can be used without the use of hands or, in a wider sense, equipment which needs only limited use of hands, or for which the controls are positioned so that the hands are able to occupy themselves with another task without needing to hunt far...
headsets, providing mono (three conductor) or stereo (four conductor) sound and a microphone input. Common stereo headphones with the 2.5 mm plug are often not compatible with this type of socket. A 3.5 mm version of this plug is now commonly available on mobile telephones as well. A 3.5 mm stereo-plus-mic jack is available that is compatible with standard 3.5 mm stereo headphones, e.g. Nokia
Nokia
Nokia Corporation is a Finnish multinational communications corporation that is headquartered in Keilaniemi, Espoo, a city neighbouring Finland's capital Helsinki...
has been widely using TRRS connectors with 3.5 mm diameter since 2006. The selected pin assignment, with ground on the sleeve, is as well standardized in OMTP and has been accepted as a national Chinese standard YDT 1885-2009.
TRRS plugs do not work properly with a TRS stereo jack if the ground contact in the jack connects to the microphone contact on the plug. It is therefore a good practice to implement new TRS headphone jacks using a TRRS mechanical jack and connecting ground to sleeve as well as the second ring contact. This way such jacks will provide better compatibility with different TRRS cell phone headsets.
Although relatively unknown in modern consumer electronics, the professional audio world and the telecommunication industry has used tiny telephone (TT) connectors in patch bays which are mid-size phone plugs with a 4.4 mm (0.173-inch) diameter shaft. In the telecom world, this is known as a "bantam" plug. Though unable to handle as much power and not as reliable
Reliability engineering
Reliability engineering is an engineering field, that deals with the study, evaluation, and life-cycle management of reliability: the ability of a system or component to perform its required functions under stated conditions for a specified period of time. It is often measured as a probability of...
as a 6.35 mm (0.25-inch) jack, TTs have been used for professional console and outboard patchbays in studio
Studio
A studio is an artist's or worker's workroom, or the catchall term for an artist and his or her employees who work within that studio. This can be for the purpose of architecture, painting, pottery , sculpture, scrapbooking, photography, graphic design, filmmaking, animation, radio or television...
s and live sound applications, in which a single patch panel
Patch panel
A patch panel or patch bay is a panel, typically rackmounted, that houses cable connections. One typically shorter patch cable will plug into the front side, whereas the back holds the connection of a much longer and more permanent cable...
requires hundreds of patch points in a limited space. The TRS versions of TT connectors are capable of handling balanced line
Balanced line
In telecommunications and professional audio, a balanced line or balanced signal pair is a transmission line consisting of two conductors of the same type, each of which have equal impedances along their lengths and equal impedances to ground and to other circuits. The chief advantage of the...
signals and have been employed in pro audio installations. Recently, all-in-one digital audio switching matrices and digital signal processors have reduced the need for physical patching and extensive patch bays.
The most common arrangement remains to have the male plug on the cable and the female socket mounted in a piece of equipment: the original intention of the design. A considerable variety of line plugs and panel sockets is available, including plugs suiting various cable sizes, right angle plugs, and both plugs and sockets in a variety of price ranges and with current capacities up to 15 ampere
Ampere
The ampere , often shortened to amp, is the SI unit of electric current and is one of the seven SI base units. It is named after André-Marie Ampère , French mathematician and physicist, considered the father of electrodynamics...
s for certain heavy duty in versions.
Less commonly used sizes, both diameters and lengths, are also available from some manufacturers, and are used when it is desired to restrict the availability of matching connectors, such as .210 inch inside diameter jacks for fire safety communication jacks in public buildings, the same size found in vintage 16 mm projector speaker jacks.
- A two-pin version, known to the telecom industry as a "310 connector" consists of two TRS 6.35 mm jack plugs at a centre spacing of .625 inches. The socket versions of these can be used with normal jack plugs provided the plug bodies are not too large, but the plug version will only mate with two jack sockets at .625 inches centre spacing, or with line sockets, again with sufficiently small bodies. These connectors are still widely used today in telephone company central offices on "DSX" patch panels for DS1 circuits. A similar type of 3.5 mm connector is often used in the armrests of older aircraft, as part of the on-board entertainment system. Plugging a stereo plug into one of the two mono jacks typically results in the audio coming into only one ear. Adaptors are available.
- A short-barrelled version also exists, once used on high-impedance mono headphones, and in particular those used in World War IIWorld War IIWorld War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
aircraft. It is physically possible to use a normal plug in a short socket, but a short plug will neither lock into a normal socket nor complete the tip circuit. These are still manufactured but are now regarded as a non-standard size.
Combined TRS and optical connectors
A miniature optical connector used on portable and miniaturised equipment for TOSLINKTOSLINK
TOSLINK is a standardized optical fiber connection system. Also known generically as an "optical audio cable," its most common use is in consumer audio equipment , where it carries a digital audio stream from components such as MiniDisc, CD and DVD players, DAT recorders, computers, and modern...
in place of the larger standard square connector is the same size as a 3.5 mm TRS socket. There are sockets that combine a mechanical 3.5 mm TRS socket with a miniature TOSLINK connection (only one can be used at at time).
Mono and stereo compatibility
Microphone
A microphone is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal. In 1877, Emile Berliner invented the first microphone used as a telephone voice transmitter...
s, electric guitar
Electric guitar
An electric guitar is a guitar that uses the principle of direct electromagnetic induction to convert vibrations of its metal strings into electric audio signals. The signal generated by an electric guitar is too weak to drive a loudspeaker, so it is amplified before sending it to a loudspeaker...
s, headphones
Headphones
Headphones are a pair of small loudspeakers, or less commonly a single speaker, held close to a user's ears and connected to a signal source such as an audio amplifier, radio, CD player or portable Media Player. They are also known as stereophones, headsets or, colloquially, cans. The in-ear...
, loudspeaker
Loudspeaker
A loudspeaker is an electroacoustic transducer that produces sound in response to an electrical audio signal input. Non-electrical loudspeakers were developed as accessories to telephone systems, but electronic amplification by vacuum tube made loudspeakers more generally useful...
s, and many other items of audio equipment.
When a three-conductor version of the in jack was introduced for use with stereo
Stereophonic sound
The term Stereophonic, commonly called stereo, sound refers to any method of sound reproduction in which an attempt is made to create an illusion of directionality and audible perspective...
headphones, it was given a sharper tip profile in order to make it possible to manufacture jacks (sockets) that would accept only stereo plugs, to avoid short-circuiting the right channel amplifier. This attempt has long been abandoned, and now the normal convention is that all plugs fit all sockets of the same size, regardless of whether they are balanced mono, unbalanced mono or stereo. Most in plugs, mono or stereo, now have the profile of the original stereo plug, although a few rounded mono plugs are also still produced. The profiles of stereo miniature and subminiature plugs have always been identical to the mono plugs of the same size.
The results of this physical compatibility are:
- If a two-conductor plug of the same size is connected to a three-conductor socket, the result is that the ring (right channel) of the socket is grounded. This property is deliberately used in several applications, see "tip ring sleeve", below. However, grounding one channel may also be dangerous to the equipment if the result is to short circuitShort circuitA short circuit in an electrical circuit that allows a current to travel along an unintended path, often where essentially no electrical impedance is encountered....
the output of the right channel amplifierAmplifierGenerally, an amplifier or simply amp, is a device for increasing the power of a signal.In popular use, the term usually describes an electronic amplifier, in which the input "signal" is usually a voltage or a current. In audio applications, amplifiers drive the loudspeakers used in PA systems to...
. In any case, any signal from the right channel is naturally lost. - If a three-conductor plug is connected to a two-conductor socket, normally the result is to leave the ring of the plug unconnected (open circuit). In the days of vacuum tubeVacuum tubeIn electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...
s this was also potentially dangerous to equipment but most solid state devices tolerate this condition well. A 3-conductor socket could be wired as an unbalanced mono socket to ground the ring in this situation, but the more conventional wiring is to leave the ring unconnected, exactly simulating a mono socket.
Uses
Some common uses of jack plugs and their matching sockets are:- Headphone and earphone jacks on a wide range of equipment. in plugs are common on home and professional component equipment, while 3.5 mm plugs are nearly universal for portable audio equipment. 2.5 mm plugs are not as common, but are used on communication equipment such as cordless phones, mobile phoneMobile phoneA mobile phone is a device which can make and receive telephone calls over a radio link whilst moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile network operator...
s, and two-way radioTwo-way radioA two-way radio is a radio that can both transmit and receive , unlike a broadcast receiver which only receives content. The term refers to a personal radio transceiver that allows the operator to have a two-way conversation with other similar radios operating on the same radio frequency...
s. - Consumer electronics devices such as digital cameras, camcorders, and portable DVD playerPortable DVD PlayerPortable DVD Player is the name given to any portable device whose primary function is the playing of DVDs.-History:...
s use 3.5 mm connectors for composite video and audio output. Typically, a TRS connection is used for mono audio plus video, and a TRRS connection for stereo audio plus video. Cables designed for this use are often terminated with RCA connectors on the other end. - Hands-free sets and headsets often use 3.5 mm or 2.5 mm connectors. TRS connectors are used for mono audio out + an unbalanced microphone (with a shared ground). TRRS connectors are are used to add an additional audio-out channel (i.e. stereo out + microphone).
- MicrophoneMicrophoneA microphone is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal. In 1877, Emile Berliner invented the first microphone used as a telephone voice transmitter...
inputs on tape and cassette recorders, sometimes with remote control switching on the ring, on early, monaural cassette recorders mostly a dual-pin version consisting of a 3.5 mm TS for the microphone and a 2.5 mm TS for remote control which switches the recorder's power supply. - Patching points (insert pointsInsert (effects processing)In audio processing and sound reinforcement, an insert is an access point built into the mixing console, allowing the user to add external line level devices into the signal flow between the microphone preamplifier and the mix bus....
) on a wide range of equipment. - Personal computers, sometimes using a sound cardSound cardA sound card is an internal computer expansion card that facilitates the input and output of audio signals to and from a computer under control of computer programs. The term sound card is also applied to external audio interfaces that use software to generate sound, as opposed to using hardware...
plugged into the computer. Stereo 3.5 mm jacks are used for:- Line in (stereo)
- Line out (stereo)
- Headphones/loudspeaker out (stereo)
- Microphone input (mono, usually with 5 V power available on the ring. Note that traditional, incompatible, use of a stereo plug for a mono microphone is for balanced output)
- Laptop computers generally have one line levelLine levelLine level is a term used to denote the strength of an audio signal used to transmit analog sound between audio components such as CD and DVD players, TVs, audio amplifiers, and mixing consoles, and sometimes MP3 players....
jack for headphones and one mono jack for a microphone at microphone level. You can use an attenuating cable to convert line level or use a signal from an XLR connectorXLR connectorThe XLR connector is a style of electrical connector, primarily found on professional audio, video, and stage lighting equipment. The connectors are circular in design and have between 3 and 7 pins...
, but it is not designed to record from a stereo device such as a radio or music player. - LCD monitors with built-in speakers will require a 3.5 mm male-male cable from the sound card.
- Note: Higher end sound cards sometimes sport a breakout panel which supports in plug devices as well.
- Devices designed for surround output may use multiple jacks for paired channels (ex. TRS for front left and right; TRRS for front center, rear center, and subwoofer; and TRS for surround left and right). Circuitry on the sound device may be used to switch between traditional Line In/Line Out/Mic functions and surround output.
- Electric guitarElectric guitarAn electric guitar is a guitar that uses the principle of direct electromagnetic induction to convert vibrations of its metal strings into electric audio signals. The signal generated by an electric guitar is too weak to drive a loudspeaker, so it is amplified before sending it to a loudspeaker...
s. Almost all electric guitars use a in mono jack (socket) as their output connector. Some makes (such as ShergoldShergoldShergold Guitars, or Shergold Woodcrafts Limited, was established in October 1967 by former Burns London employees Jack Golder and Norman Houlder...
) use a stereo jack instead for stereo output, or a second stereo jack, in addition to a mono jack (as with RickenbackerRickenbackerRickenbacker International Corporation, also known as Rickenbacker, is an electric and bass guitar manufacturer based in Santa Ana, California...
). - Instrument amplifierInstrument amplifierAn instrument amplifier is an electronic amplifier that converts the often barely audible or purely electronic signal from musical instruments such as an electric guitar, an electric bass, or an electric keyboard into an electronic signal capable of driving a loudspeaker that can be heard by the...
s for guitars, basses and similar amplified musical instrumentMusical instrumentA musical instrument is a device created or adapted for the purpose of making musical sounds. In principle, any object that produces sound can serve as a musical instrument—it is through purpose that the object becomes a musical instrument. The history of musical instruments dates back to the...
s. in jacks are overwhelmingly the most common connectors for:- Inputs. A shielded cable with a mono in jack plug on each end is commonly called a guitar cord or a patching cord, the first name reflecting this usage, the second the history of the jack plug's development for use in manual telephone exchanges.
- LoudspeakerLoudspeakerA loudspeaker is an electroacoustic transducer that produces sound in response to an electrical audio signal input. Non-electrical loudspeakers were developed as accessories to telephone systems, but electronic amplification by vacuum tube made loudspeakers more generally useful...
outputs, especially on low-end equipment. On professional loudspeakers, Speakon connectors carry higher current, mate with greater contact area, lock in place and do not short out the amplifier upon insertion or disconnection. However, some professional loudspeakers carry both Speakon and TRS connectors for compatibility. Heavy-duty in loudspeaker jacks are rated at 15 A maximum which limits them to applications involving less than 1,800 watts. in loudspeaker jacks commonly aren't rigged to lock the plug in place and will short out the amplifier's output circuitry if connected or disconnected when the amplifier is live. - Line outputs.
- Foot switches and effects pedals. Stereo plugs are used for double switches (for example by Fender). There is little compatibility between makers.
- Effects loops, which are normally wired as patch points.
- Electronic keyboardElectronic keyboardAn electronic keyboard is an electronic or digital keyboard instrument.The major components of a typical modern electronic keyboard are:...
s use jacks for a similar range of uses to guitars and amplifiers, and in addition- Sustain pedals.
- Expression pedals.
- Electronic drumElectronic drumAn electronic drum is an electronic synthesizer which mimics an acoustic drum kit.The electronic drum usually consists of a set of pads mounted on a stand in a disposition similar to an acoustic drum kit. The pads are discs with a rubber or cloth-like coating. Each pad has a sensor which generates...
s use jacks to connect sensor pads to the synthesizerSynthesizerA synthesizer is an electronic instrument capable of producing sounds by generating electrical signals of different frequencies. These electrical signals are played through a loudspeaker or set of headphones...
module or MIDI encoder. In this usage, a change in voltage on the wire indicates a drum stroke. - Some compact and/or economy model audio mixing desks use stereo jacks for balanced microphone inputs.
- The majority of professional audio equipment uses mono jacks as the standard unbalanced input or output connector, often providing a in unbalanced line connector alongside (or in a few cases in the middle of!) and as an alternative to an XLRXLR connectorThe XLR connector is a style of electrical connector, primarily found on professional audio, video, and stage lighting equipment. The connectors are circular in design and have between 3 and 7 pins...
balanced line connector. - Modular synthesizerModular synthesizerThe modular synthesizer is a type of synthesizer consisting of separate specialized modules connected by wires to create a so-called patch. Every output generates a signal – an electric voltage of variable strength...
s commonly use monophonic cables for creating patches. - ¼ in connectors are widely used to connect external processing devices to mixing consoleMixing consoleIn professional audio, a mixing console, or audio mixer, also called a sound board, mixing desk, or mixer is an electronic device for combining , routing, and changing the level, timbre and/or dynamics of audio signals. A mixer can mix analog or digital signals, depending on the type of mixer...
s' insert points (see Insert (effects processing)Insert (effects processing)In audio processing and sound reinforcement, an insert is an access point built into the mixing console, allowing the user to add external line level devices into the signal flow between the microphone preamplifier and the mix bus....
). TRS or TS connectors might be used in pairs as separate Send and Return jacks or a single TRS jack might be employed for both Send and Return in which case the signals are unbalanced. The single unbalanced combination Send/Return TRS insert jack saves both panel space and component complexity. Note that mixing console insert points can also be XLR, RCA or Bantam TT (tiny telephone) jacks, depending on the make and model. - Some small electronic devices such as audio cassette players, especially in the cheaper price brackets, use a two-conductor 3.5 mm or 2.5 mm jack as a DC power connectorDC connectorA DC connector is an electrical connector for supplying direct current power. Unlike domestic AC power plugs and sockets, DC connectors are not generally standardized....
. - Some photographic studio strobe lights have in or 3.5 mm jacks for the flash synchronizationFlash synchronizationIn a camera, flash synchronization is defined as the firing of a photographic flash coinciding with the shutter admitting light to photographic film or electronic image sensor. It is often shortened to flash sync or flash synch....
input. A camera's electrical flash output (PC socket or hot shoeHot shoeA hot shoe is a mounting point on the top of a camera to attach a flash unit.- Design :The hot shoe is shaped somewhat like an inverted, squared-off "U" of metal. The matching adapter on the bottom of the flash unit slides in from the back of the camera and is sometimes secured by a clamping screw...
adapter) is cabled to the strobe light's sync input jacks. Some examples: Calumet Travelite, and Speedotron use a in mono jack as the sync input; White Lightning uses in stereo jacks; Pocket Wizard (radio trigger) and Alien Bees use 3.5 mm mono jacks. - Some cameras (for example, Canon, Sigma, and Pentax DSLRs) use the 2.5 mm stereo jack for the connector for the remote shutter release (and focus activation); examples are Canon's RS-60E3 remote switch and Sigma's CR-21 wired remote control.
- Some miniaturized electronic devices use 2.5 mm or 3.5 mm jack plugs as serial portSerial portIn computing, a serial port is a serial communication physical interface through which information transfers in or out one bit at a time...
connectors for data transfer and unit programming. This technique is particularly common on graphing calculators, such as the TI-83 seriesTI-83 seriesThe TI-83 series of graphing calculators is manufactured by Texas Instruments.The original TI-83 is itself an upgraded version of the TI-82. Released in 1996, it is one of the most used graphing calculators for students...
, and some types of amateurAmateur radioAmateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...
and two-way radioTwo-way radioA two-way radio is a radio that can both transmit and receive , unlike a broadcast receiver which only receives content. The term refers to a personal radio transceiver that allows the operator to have a two-way conversation with other similar radios operating on the same radio frequency...
, though in some more modern equipment USB mini-BUniversal Serial BusUSB is an industry standard developed in the mid-1990s that defines the cables, connectors and protocols used in a bus for connection, communication and power supply between computers and electronic devices....
connectors are provided in addition to or instead of jack connectors. The second-generation iPod ShuffleIPod shuffleThe iPod Shuffle is a digital audio player designed and marketed by Apple Inc. It is the smallest model in Apple's iPod family, and was the first to use flash memory...
from Apple has a single TRRS jack which serves as headphone, USB, or power supply, depending on the connected plug. - On CCTVClosed-circuit televisionClosed-circuit television is the use of video cameras to transmit a signal to a specific place, on a limited set of monitors....
cameras and video encoders, mono audio in (originating from a microphone in or near the camera) and mono audio out (destined to a speaker in or near the camera) are provided on a single three-conductor connector, where one signal is on the tip conductor and the other is on the ring conductor. - The Atari 2600 (Video Computer System), the first widely popular home video game console with interchangeable software programs, used a 3.5 mm TS (two conductor) jack for 9V(?) DC power.
- The Apple LisaApple LisaThe Apple Lisa—also known as the Lisa—is a :personal computer designed by Apple Computer, Inc. during the early 1980s....
personal computer used a TRS Jack for its keyboard.
Switch contacts
Less commonly, some jacks are provided with normally open (NO) or change-over contacts, and/or the switch contacts may be isolated from the connector.
The original purpose of these contacts was for switching in telephone exchanges, for which there were many patterns. Two sets of change-over contacts, isolated from the connector contacts, were common. The more recent pattern of one NC contact for each signal path, internally attached to the connector contact, stems from their use as headphone jacks. In many amplifiers and equipment containing them, such as electronic organs, a headphone jack is provided that disconnects the loudspeakers when in use. This is done by means of these switch contacts. In other equipment, a dummy load is provided when the headphones are not connected. This is also easily provided by means of these NC contacts.
Other uses for these contacts have been found. One is to interrupt a signal path to enable other circuitry to be inserted. This is done by using one NC contact of a stereo jack to connect the tip and ring together when no plug is inserted. The tip is then made the output, and the ring the input (or vice versa), thus forming a patch point
Patch point
In electronic audio technology, a patch point is a connection that allows a signal to be withdrawn from a device, modified in some way, and returned. This can, for example, be done using a jack plug, using the tip of the plug for the outgoing mono signal, and the ring for the returning signal, a...
.
Another use is to provide alternative mono or stereo output facilities on some guitars and electronic organs. This is achieved by using two mono jacks, one for left channel and one for right, and wiring the NC contact on the right channel jack to the tip of the other, to connect the two connector tips together when the right channel output is not in use. This then mixes the signals so that the left channel jack doubles as a mono output.
Where a 3.5 mm or 2.5 mm jack is used as a DC power inlet connector, a switch contact may be used to disconnect an internal battery whenever an external power supply is connected, to prevent incorrect recharging of the battery.
A standard stereo jack is used on most battery-powered guitar effects pedals to eliminate the need for a separate power switch. In this configuration, the internal battery has its negative terminal wired to the sleeve contact of the jack. When the user plugs in a two-conductor (mono) guitar or microphone lead, the resulting short-circuit between sleeve and ring connects an internal battery to the unit's circuitry, ensuring that it powers up or down automatically whenever a signal lead is inserted or removed. A drawback of this design is the risk of inadvertently discharging the battery if the lead is not removed after use, such as if the equipment is left plugged in overnight.
Tip/ring/sleeve terminology
Twisted pair
Twisted pair cabling is a type of wiring in which two conductors are twisted together for the purposes of canceling out electromagnetic interference from external sources; for instance, electromagnetic radiation from unshielded twisted pair cables, and crosstalk between neighboring pairs...
wiring to this day, the non-inverting and/or "live" (or "hot") wire of each pair is known as the ring, while the inverting and/or "earthy" (or "neutral") wire is known as the tip, inherited from the traditional connection via the TRS connector in telephone systems. If the pair is shielded, or if the pair is accompanied by a dedicated earth wire, this third conductor is known as the sleeve. This usage corresponds to the connection to a three-connector jack plug in a manual telephone exchange.
The term tip ring sleeve is more common in some English-speaking countries than others. Outside of the USA the term stereo jack plug is probably more common, even for connectors not used for stereo. The modern profile three-conductor jack plug was originally designed for stereo signal connections, with left channel on the tip, right on the ring and common return on the body or sleeve. The term TRS is particularly appropriate to distinguish these three-conductor (stereo) plugs used in other than stereo applications.
| Unbalanced mono in/out | Unbalanced mono insert | Balanced mono in/out | Unbalanced stereo | |
|---|---|---|---|---|
| Tip | Signal | Send or Return signal | Positive/"Hot" | Left channel |
| Ring | Ground or No Connection | Return or Send signal | Negative/"Cold" | Right channel |
| Sleeve | Ground | Ground | Ground | Ground |
- Note that the first version of the popular Mackie 1604 mixer, the CR1604, used a Tip Negative, Ring Positive jack wiring scheme on the main left and right outputs.
- Note that early QSCQSC Audio ProductsQSC Audio Products, LLC is an American manufacturer of professional audio products. QSC's target markets are audio professionals in concert, installation, portable entertainment and cinema applications.-History:...
amplifiers used a tip negative, ring positive input jack wiring scheme.
-
- Whirlwind Line Balancer/Splitters do not use the Sleeve as a conductor on their unbalanced ¼ in TRS input. Tip and Ring are wired to the transformer's two terminals; Sleeve is not connected.
Audio
When a TRS is used to make a balanced connection, the two active conductors are both used for a monauralMonaural
Monaural or monophonic sound reproduction is single-channel. Typically there is only one microphone, one loudspeaker, or channels are fed from a common signal path...
signal. The ring, used for the right channel in stereo systems, is used instead for the inverting input. This is a common use in small audio mixing desks, where space is a premium and they offer a more compact alternative to XLR connector
XLR connector
The XLR connector is a style of electrical connector, primarily found on professional audio, video, and stage lighting equipment. The connectors are circular in design and have between 3 and 7 pins...
s. Another advantage offered by TRS connectors used for balanced microphone inputs is that a standard unbalanced signal lead using a mono jack plug can simply be plugged into such an input. The ring (right channel) contact then makes contact with the plug body, correctly grounding the inverting input.
The disadvantage of using TRS jacks for balanced audio connections is that the ground mates last and the socket grounds the plug tip and ring when inserting or pulling out the plug. This causes bursts of hum, cracks and pops and may stress some outputs as they will be short circuited briefly, or longer if the plug is left half in. Professional audio equipment uses XLR connectors which mate the ground signal on pin 1 first.
TRS connectors are also commonly used as unbalanced audio patch points (or insert points, or simply inserts), with the output on many mixers found on the tip (left channel) and the input on the ring (right channel). This is often expressed as "tip send, ring return." Other mixers have unbalanced insert points with "ring send, tip return." One advantage of this system is that the switch contact within the panel socket, originally designed for other purposes, can be used to close the circuit when the patch point is not in use. An advantage of the "tip send" patch point is that if it is used as an output only, a 2-conductor mono jack plug correctly grounds the input. In the same fashion, use of a "tip return" insert style allows a mono jack plug to bring an unbalanced signal directly into the circuit, though in this case the output must be robust enough to withstand being grounded. Combining Send and Return functions via single in TRS connectors in this way is seen in very many professional and semi-professional audio mixing desks, due to the halving of space needed for insert jack fields which would otherwise require two jacks, one for Send and one for Return. The tradeoff is that unbalanced signals are more prone to buzz, hum and outside interference.
In some TRS inserts, the concept is extended by using specially designed TRS jacks that will accept a mono jack plug partly inserted "to the first click" and will then connect the tip to the signal path without breaking it. Most standard TRS jacks can also be used in this way with varying success, but neither the switch contact nor the tip contact can be relied upon unless the internal contacts have been designed with extra strength for holding the plug tip in place. Even with stronger contacts, an accidental mechanical movement of the inserted plug can interrupt signal within the circuit. For maximum reliability, any usage involving "first click" or "half-click" positions will instead rewire the plug to short Tip and Ring together and then insert this modified plug all the way into the jack.
The TRS Tip Return, Ring Send unbalanced insert configuration is mostly found on older mixers. This allowed for the insert jack to serve as a standard-wired mono line input that would bypass the mic preamp (and likely a resistive pad, as well as other circuitry, depending on the design), and thus improve sound quality. However tip send has become the generally accepted standard for mixer inserts since the early-to-mid 1990s. The TRS Ring Send configuration is still found on some compressor sidechain input jacks such as the dbx 166XL.
In some very compact equipment, 3.5 mm TRS jacks are used as patch points.
Some sound recording devices use a TRS as a mono microphone input, using the tip as the signal path and the ring to connect a standby switch on the microphone.
Computer sound
Personal computerPersonal computer
A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...
sound card
Sound card
A sound card is an internal computer expansion card that facilitates the input and output of audio signals to and from a computer under control of computer programs. The term sound card is also applied to external audio interfaces that use software to generate sound, as opposed to using hardware...
s from Creative Labs, Sound Blaster
Sound Blaster
The Sound Blaster family of sound cards was the de facto standard for consumer audio on the IBM PC compatible system platform, until the widespread transition to Microsoft Windows 95, which standardized the programming interface at application level , and the evolution in PC design led to onboard...
or compatible to these use a 3.5 mm TRS as a mono microphone input, and deliver a 5 V polarising voltage on the ring to power electret microphone
Electret microphone
An electret microphone is a type of condenser microphone, which eliminates the need for a polarizing power supply by using a permanently charged material....
s from the card manufacturer. Sometimes called phantom power, this is not a suitable power source for microphones designed for true phantom power
Phantom power
Phantom power, in the context of professional audio equipment, is a method for transmitting DC electric power through microphone cables to operate microphones that contain active electronic circuitry....
and is better called bias voltage. (Note that this is not a polarizing voltage for the condenser, as electrets by definition have an intrinsic voltage; it is power for a preamplifier FET
Fet
Fet is a municipality in Akershus county, Norway. It is part of the Romerike traditional region. The administrative centre of the municipality is the village of Fetsund.Fet was established as a municipality on 1 January 1838...
[transistor] built into the electret microphone can.) Compatibility between different manufacturers is unreliable.
Normally, 3.5 mm 3-conductor sockets are used in computer soundcards for stereo output. Thus, for a soundcard with 5.1 output, there will be 3 sockets to accommodate 6 channels—front left & right, surround left & right, and center & subwoofer. In the 6.1 and 7.1 channel soundcards from Creative Labs, however, there are two 3.5 mm, 4-conductor sockets. This is to accommodate rear-center (6.1) or rear left & right (7.1) channels without the need for additional sockets on the sound card. The other speaker outputs on these cards have normal 3-conductor sockets. In Creative's documentation, the word "pole" is used instead of "conductor".
The Apple
Apple Computer
Apple Inc. is an American multinational corporation that designs and markets consumer electronics, computer software, and personal computers. The company's best-known hardware products include the Macintosh line of computers, the iPod, the iPhone and the iPad...
PlainTalk
PlainTalk
PlainTalk is the collective name for several speech synthesis and speech recognition technologies developed by Apple Inc.In 1990, Apple invested a lot of work and money in speech recognition technology, hiring many respected researchers in the field. The result was "PlainTalk", released with the...
microphone jack used on some older Macintosh systems is designed to accept an extended 3.5 mm TRS; in this case, the tip carries power for a preamplifier
Preamplifier
A preamplifier is an electronic amplifier that prepares a small electrical signal for further amplification or processing. A preamplifier is often placed close to the sensor to reduce the effects of noise and interference. It is used to boost the signal strength to drive the cable to the main...
inside the microphone. If a PlainTalk-compatible microphone is not available, the jack can accept a line-level sound input, though it cannot accept a standard microphone without a preamp.
Since they became available, Apple computer
Apple Computer
Apple Inc. is an American multinational corporation that designs and markets consumer electronics, computer software, and personal computers. The company's best-known hardware products include the Macintosh line of computers, the iPod, the iPhone and the iPad...
s have used combined 3.5 mm TRS-TOSLINK jacks for both input and output, supporting stereo input and output with electrical connections, or 5.1 TOSLINK digital input and output.
Plug-in power
( from: http://www.epanorama.net/circuits/microphone_powering.html )
Recording equipment
MiniDisc
The disc is permanently housed in a cartridge with a sliding door, similar to the casing of a 3.5" floppy disk. This shutter is opened automatically by a mechanism upon insertion. The audio discs can either be recordable or premastered. Recordable MiniDiscs use a magneto-optical system to record...
recorders and other consumer devices use a 3.5 mm microphone connector for attaching a (mono/stereo) microphone to the system.
These fall into three categories:
- Devices that use an un-powered microphone: usually a cheap dynamic or piezoelectric microphone. The microphone generates its own voltage, and does not require power.
- Devices that use a self-powered microphone: usually a condenser microphone with internal battery-powered amplifier.
- Devices that use a "plug-in powered" microphone: an electret microphone containing an internal FETField-effect transistorThe field-effect transistor is a transistor that relies on an electric field to control the shape and hence the conductivity of a channel of one type of charge carrier in a semiconductor material. FETs are sometimes called unipolar transistors to contrast their single-carrier-type operation with...
amplifier. These provide a good quality signal, in a very small microphone. However, the internal FET requires a DC power supply, which is provided as a bias voltage for an internal preamp transistor.
Plug-in power is supplied on the same line as the audio signal, using an RC filter. The DC bias voltage supplies the FET amplifier (at a low current), while the capacitor decouples the DC supply from the AC input to the recorder. Typically, V=1.5 V, R=1 kΩ, C=47 µF.
If a recorder provides plug-in power, and the microphone does not need it, everything will usually work ok, although the sound quality may be lower than expected. In the converse case (recorder provides no power; microphone requires power), no sound will be recorded. Neither misconfiguration will damage
consumer hardware, but providing power when none is needed could destroy a broadcast-type microphone.
Aircraft headsets
General aviation
General aviation is one of the two categories of civil aviation. It refers to all flights other than military and scheduled airline and regular cargo flights, both private and commercial. General aviation flights range from gliders and powered parachutes to large, non-scheduled cargo jet flights...
civil airplane headset plugs are similar, but with a difference. A standard in monaural plug, type PJ-055, is used for headphones, paired with special tip-ring-sleeve, 0.206 inch diameter plug, type PJ-068, for the microphone. The extra connection in the microphone plug is used by an optional push-to-talk switch.
Military aircraft and civil helicopters have another type known by the designation U-174/U. They are also known as Nexus TP120 telephone plugs. They are similar to a standard in (6.3 mm) stereo plug, but with a 7.1 mm (0.281") diameter short shaft with an extra sleeve. This provides four connections in one plug, allowing two for the headphones, and two for the microphone, the push-to-talk switch options is not included in this plug. it is separately wired, usually on one of the hand controls of the aircraft.
Configurations and schematic symbols
These examples are meant to illustrate each possible component of such jacks, but many other configurations using these basic components are available. All examples in the above figure are oriented so the plug 'enters' from the right.
A. A simple two-conductor jack. The connection to the sleeve is the rectangle towards the right, and the connection to the tip is the line with the notch. Wiring connections are illustrated as white circles.
B. A three-conductor, or TRS, jack. The upper connector is the tip, as it is farther away from the sleeve. The sleeve is shown connected directly to the chassis, a very common configuration. This is the typical configuration for a balanced connection. Some jacks have metal mounting connections (which would make this connection) and some have plastic, to isolate the sleeve from the chassis, and provide a separate sleeve connection point, as in A.
C. This three-conductor jack has two isolated SPDT switch
Switch
In electronics, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another....
es. They are activated by a plug going into the jack, which disconnects one throw and connects the other. The white arrowheads indicate a mechanical connection, while the black arrowheads indicate an electrical connection. This would be useful for a device that turns on when a plug is inserted, and off otherwise, with the power routed through the switches.
D. This three-conductor jack has two normally closed switches connected to the contacts themselves. This would be useful for a patch point, for instance, or for allowing another signal to feed the line until a plug is inserted. The switches open when a plug is inserted. A common use for this style of connector is a stereo headphone jack that shuts off the default output (speakers) when the connector is plugged in.
The most common circuit configurations are the simple mono and stereo jacks (A and B above), however there are a great number of variants manufactured.