A
TRS connector (tip, ring, sleeve) also called an
audio jack,
phone plug,
jack plug,
stereo plug,
mini-jack, or
mini-stereo, and more recently
MP3 jack is a common audio connector. It is cylindrical in shape, typically with three contacts, although sometimes with two (a
TS connector) or four (a
TRRS connector).
It was invented for use in
telephone switchboardA 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 19th century and is still widely used, both in its original 1/4″ (6.3 mm) size and in miniaturized versions 1/8″ (3.5 mm) and 3/32″ (2.5 mm). 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 U.S., a stationary (more fixed) connector is called a
jackIn electronics and electrical assemblies, the term jack commonly refers to a surface-mounted connector, often 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 commonly used to refer to TRS connectors, but are also sometimes used colloquially to refer to RJ11 and older
telephone plugA 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 fixed 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 connectorAn RCA connector, sometimes called cinch plug or lotus plug, is a type of electrical connector that is commonly used in the audio/video market...
s though both plug types are used in tandem when a
computerA computer is a machine that manipulates data according to a set of instructions.Although mechanical examples of computers have existed through much of recorded human history, the first electronic computers were developed in the mid-20th century . These were the size of a large room, consuming as...
or MP3 player connects to a stereo.) To unambiguously refer to the connectors described here, the diameter or other qualifier is often added, e.g.
quarter-inch phone plug, 3.5 mm phone jack, and
balanced TRS jack or
stereo phone plug for the most common uses of the three-contact version.
Modern connectors
Modern TS and TRS connectors are available in three standard sizes. The original 1/4″ (6.35 mm) version dates from 1878, for use in
manual telephone exchangesA 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 1/8″ (3.5 mm) or
miniature and 3/32″ (2.5 mm) or
sub-miniature sizes were originally designed as two-conductor connectors for earpieces on
transistor radioA transistor radio is a small transistor-based radio receiver.-History:Bell Laboratories demonstrated the first transistor on December 23, 1947. After obtaining patent protection, the company held a news conference on June 30, 1948, at which a prototype transistor radio was demonstrated...
s. The 1/8″ and 3/32″ sizes are also referred to as 1/8″ and 3/32″ 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 (
balancedBalanced 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
stereoStereophonic sound, commonly called stereo, is the reproduction of sound using two or more independent audio channels through a symmetrical configuration of loudspeakers in such a way as to create the impression of sound heard from various directions, as in natural hearing...
) versions.
Four and five conductor versions of the 1/8″ plug are used for certain applications. A four conductor version is becoming a de facto standard output connector for compact
camcorderA camcorder is an electronic device that combines a video camera and a video recorder into one unit.In order to differentiate it from other devices that are capable of recording video, like cell phones and compact digital cameras, a camcorder is generally identified as a portable device primarily...
s, providing stereo sound plus a video signal. This interface is also seen on some
laptopA laptop is a personal computer designed for mobile use and small and light enough to sit on one's lap while in use. A laptop integrates most of the typical components of a desktop computer, including a display, a keyboard, a pointing device , speakers, and often including a battery, into a single...
computerA computer is a machine that manipulates data according to a set of instructions.Although mechanical examples of computers have existed through much of recorded human history, the first electronic computers were developed in the mid-20th century . These were the size of a large room, consuming as...
s and on the second-generation
iPod ShuffleThe iPod Shuffle is a digital audio player designed and marketed by Apple Inc. It is the budget model in Apple's iPod family. It was announced at the Macworld Conference & Expo on January 11, 2005, using the tagline "life is random". Instead of storing data on a hard disk, it was the first iPod to...
. Proprietary interfaces using both four and five conductor versions exist, where the extra conductors were used to supply power for accessories. The four conductor 1/8" plug is also used as a speaker-microphone connector on handheld
amateur radioAmateur radio, often called ham radio, is both a hobby and a service in which participants, called "hams," use various types of radio communications equipment to communicate with other radio amateurs for public service, recreation and self-training....
transceivers from
YaesuYaesu is an international brand of amateur radio equipment.It was founded as in 1959 by Sako Hasegawa in the Tokyo neighborhood of Yaesu. The initial intent seemed to have been to develop and manufacture amateur radio transmitters for the Japanese market but by 1964 there were sales agreements...
. There is also an optical connector used for
TOSLINKTOSLINK or Optical Cable is a standardized optical fiber connection system. Its most common use is in consumer audio equipment , where it carries a digital audio stream between components such as MiniDisc and CD players and DAT recorders...
(mainly on things like portable equipment; hi-fi separates and similar tend to use the standard square connector) that is the same size as a 1/8″ jack. Sockets exist that can make either an optical connection to such a plug or an electrical connection to a stereo jack plug. These combination electrical/optical output jacks are present on all Apple Macbook, Macbook Pro and Intel iMac computers.
A three- or four-conductor version of the 3/32″ (2.5 mm) plug is widely used on cell phone
handsfreeHandsfree 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 3/32″ plug are often not compatible with this type of socket. A 1/8″ (3.5 mm) version of this plug is now commonly available on mobile telephones as well. A 1/8″ stereo-plus-mic plug is available that is compatible with standard 1/8″ stereo headphones.
Although relatively unknown in modern electronics, the professional audio world and the telecommunication industry rely heavily on
tiny telephone (
TT) connectors which use 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. Due to their compactness and
reliabilityReliability engineering is an engineering field, that deals with the study of reliability: the ability of a system or component to perform its required functions under stated conditions for a specified period of time...
, TTs are often used for professional console and outboard patchbays in
studioA studio is an artist's or worker's workroom, or 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, cinematography, animation, radio or television broadcasting or the...
s and live sound applications, in which a single
patch panelA 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...
may require hundreds of patch points in a limited space. The TRS versions of TT connectors are capable of handling
balanced lineIn 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 are preferred in pro audio installations.
Both two-conductor and three-conductor versions of the three standard sizes are readily available in
male and femaleIn electrical and mechanical trades and manufacturing, each of a pair of mating connectors or fasteners is conventionally assigned the designation male or female. The "female" connector is generally a receptacle that connects to and holds the "male" connector...
inline versions, and panel-mounting female versions. Panel-mounting male versions of these also exist but are rare, as they are vulnerable to mechanical damage and therefore unreliable. Female inline versions are also notoriously unreliable and are avoided by many users.
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
ampereThe ampere is the SI unit of electric current. The ampere, in practice often shortened to amp, is an SI base unit, and is named after André-Marie Ampère, one of the main discoverers of electromagnetism....
s for certain heavy duty 1/4″ 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 6.3 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 1/8″ 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 II
World War II, or the Second World War , was a global military conflict which involved a majority of the world's nations, including all great powers, organized into 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.
Mono and stereo compatibility
In the original application in manual telephone exchanges, many different configurations of 1/4″ jack plug were used, some accommodating five or more conductors, with several tip profiles. Of these many varieties, only the two-conductor version with a rounded tip profile was compatible between different manufacturers, and this was the design that was at first adopted for use with
microphoneA microphone, colloquially called a mic or mike , is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal. In 1876, Emile Berliner invented the first microphone used as a telephone voice transmitter...
s,
electric guitarAn electric guitar is a guitar that uses pickups to convert the vibration of its steel-cored strings into an electrical current, which is made louder with an instrument amplifier and a speaker. The signal that comes from the guitar is sometimes electronically altered with guitar effects such as...
s,
headphonesHeadphones are a pair of small loudspeakers, or less commonly a single speaker, with a way of holding them close to a user's ears and a means of connecting them to a signal source such as an audio amplifier, radio or CD player. They are also known as earphones, earbuds, stereophones, headsets or,...
,
loudspeakerA loudspeaker is an electroacoustic transducer that converts an electrical signal into sound. The speaker pulses in accordance with the variations of an electrical signal and causes sound waves to propagate through a medium such as air or water.Loudspeakers are the most variable elements in a...
s, and many other items of audio equipment.
When a three-conductor version of the 1/4″ jack was introduced for use with
stereoStereophonic sound, commonly called stereo, is the reproduction of sound using two or more independent audio channels through a symmetrical configuration of loudspeakers in such a way as to create the impression of sound heard from various directions, as in natural hearing...
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 1/4″ 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 circuit
A short circuit in an electrical circuit is one that allows a current to travel along a different path from the one originally intended....
the output of the right channel amplifierGenerally, an amplifier or simply amp, is any device that changes, usually increases, the amplitude of a signal. The relationship of the input to the output of an amplifier—usually expressed as a function of the input frequency—is called the transfer function of the amplifier, and the magnitude of...
. 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 tube
In electronics, a vacuum tube, electron tube , thermionic valve, or valve is a device used to amplify, switch, otherwise modify, or create an electrical signal by controlling the movement of electrons in a low-pressure space...
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. 1/4″ plugs are common on home and professional component equipment, while 1/8″ plugs are nearly universal for portable audio equipment. 3/32″ plugs are not as common, but are used on communication equipment such as cordless phones, mobile phone
A mobile phone or mobile is a long-range, electronic device used for mobile telecommunications...
s, and two-way radioA two-way radio is a radio that can both transmit and receive , unlike a broadcast receiver which only receives content.Two-way radios are available in mobile, stationary base and hand-held portable configurations. Hand-held radios are often called walkie-talkies or handie-talkies...
s.
- Consumer electronics devices such as digital cameras, camcorders, and portable DVD player
Portable DVD Player is the name given to any portable device in which its primary function is the playing of DVDs.-History:...
s use 1/8″ 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.
- Microphone
A microphone, colloquially called a mic or mike , is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal. In 1876, 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.
- Patching points (insert points
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 card
A sound card is a computer expansion card that facilitates the input and output of audio signals to and from a computer under control of computer programs. Typical uses of sound cards include providing the audio component for multimedia applications such as music composition, editing video or...
plugged into the computer. Stereo 1/8″ jacks are used for:
- Line in (stereo)
- Line out (stereo)
- Headphones/loudspeaker out (stereo)
- Microphone input (mono, usually with 5 volt 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 level
Line level is a term used to denote the strength of an audio signal used to transmit analog sound information 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 connectorThe XLR connector is an electrical connector design. XLR plugs and sockets are used mostly in professional audio and video electronics cabling applications, often for microphones. Home audio and video electronics normally use RCA connectors for line level signals generated by a preamplifier...
, 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 1/8″ male-male cable from the sound card.
- Note: Higher end sound cards sometimes sport a breakout panel which supports 1/4″ 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 guitar
An electric guitar is a guitar that uses pickups to convert the vibration of its steel-cored strings into an electrical current, which is made louder with an instrument amplifier and a speaker. The signal that comes from the guitar is sometimes electronically altered with guitar effects such as...
s. Almost all electric guitars use a 1/4″ mono jack (socket) as their output connector. Some makes (such as ShergoldShergold 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 RickenbackerRickenbacker International Corporation, also known as Rickenbacker ), is an electric guitar manufacturer, notable for putting the world's first electric guitars into general production in 1932...
).
- Instrument amplifier
An 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 instrumentA musical instrument is an object constructed or used for the purpose of making the sounds of music. In principle, anything that produces sound can serve as a musical instrument. The history of musical instruments dates back to the beginnings of human culture...
s. 1/4″ jacks are overwhelmingly the most common connectors for:
- Inputs. A shielded cable with a mono 1/4″ 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.
- Loudspeaker
A loudspeaker is an electroacoustic transducer that converts an electrical signal into sound. The speaker pulses in accordance with the variations of an electrical signal and causes sound waves to propagate through a medium such as air or water.Loudspeakers are the most variable elements in a...
outputs, especially on low-end equipment. Speakon connectors are generally considered superior and so are usually preferred on higher-end equipment, although it is not uncommon to find both provided for compatibility. Heavy-duty 1/4″ loudspeaker jacks are rated at 15A maximum which limits them to applications involving less than 1,800 watts. 1/4″ 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 keyboard
An electronic keyboard or digital keyboard is a sample-based keyboard instrument. Its sound is generated or amplified by one or more electronic devices....
s use jacks for a similar range of uses to guitars and amplifiers, and in addition
- Sustain pedals.
- Expression pedals.
- Electronic drum
An electronic drum is a percussion instrument in which the sound is generated by an electronic waveform generator or sampler instead of by acoustic vibration.-How electronic drums work:...
s use jacks to connect sensor pads to the synthesizerA synthesizer is an electronic instrument that is capable of producing a variety of sounds by generating and combining signals of different frequencies...
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 1/4″ unbalanced line connector alongside (or in a few cases in the middle of!) and as an alternative to an XLR
The XLR connector is an electrical connector design. XLR plugs and sockets are used mostly in professional audio and video electronics cabling applications, often for microphones. Home audio and video electronics normally use RCA connectors for line level signals generated by a preamplifier...
balanced line connector.
- Modular synthesizer
The 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 patchesA patch, in terms of music synthesizers, is a sound setting. For example, a synthesizer may have patches for a piano sound, a guitar sound, etc.Modular synthesizers, the first synthesizers, used cables to patch the different sound modules together...
.
- ¼ in connectors are widely used to connect external processing devices to mixing console
In professional audio, a mixing console, or audio mixer, also called a sound board or soundboard, 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)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 1/8″ or 3/32″ jack as a DC power connector
A DC connector is an electrical connector for supplying direct current power. DC connectors are poorly standardized, compared to domestic AC power plugs and sockets. DC plug is a common name used for one common type of cylindrical two-conductor plug available in a range of sizes and used to power...
.
- Some photographic studio strobe lights have 1/4″ or 1/8″ jacks for the flash synchronization
In 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 shoethumb|200px|[[Canon EOS 350D]] Hot shoeA hot shoe is a mounting point on the top of a camera to attach a flash unit. 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...
adapter) is cabled to the strobe light's sync input jacks. Some examples: Calumet Travelite, and Speedotron use a 1/4″ mono jack as the sync input; White Lightning uses 1/4″ stereo jacks; Pocket Wizard (radio trigger) and Alien Bees use 1/8″ mono jacks.
- Some cameras (for example, Canon, Sigma, and Pentax DSLRs) use the 3/32″ 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 3/32″ or 1/8″ jack plugs as serial port
In 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 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 radio, often called ham radio, is both a hobby and a service in which participants, called "hams," use various types of radio communications equipment to communicate with other radio amateurs for public service, recreation and self-training....
and two-way radioA two-way radio is a radio that can both transmit and receive , unlike a broadcast receiver which only receives content.Two-way radios are available in mobile, stationary base and hand-held portable configurations. Hand-held radios are often called walkie-talkies or handie-talkies...
, though in some more modern equipment USB mini-BUSB is a way of setting up communication between a computer and peripheral devices. USB is intended to replace many varieties of serial and parallel ports. USB can connect computer peripherals such as mice, keyboards, PDAs, gamepads and joysticks, scanners, digital cameras, printers, personal...
connectors are provided in addition to or instead of jack connectors. The second-generation iPod ShuffleThe iPod Shuffle is a digital audio player designed and marketed by Apple Inc. It is the budget model in Apple's iPod family. It was announced at the Macworld Conference & Expo on January 11, 2005, using the tagline "life is random". Instead of storing data on a hard disk, it was the first iPod to...
from Apple has a single TRS jack which serves as headphone, USB, or power supply, depending on the connected plug.
- On CCTV
Closed-circuit television is the use of video cameras to transmit a signal to a specific place, on a limited set of monitors.It differs from broadcast television in that the signal is not openly transmitted, though it may employ point to point wireless links...
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 1/8″ TS (two conductor) jack for 9V(?) DC power.
Switch contacts
Panel-mounting jacks are often provided with switch contacts. Most commonly, a mono jack is provided with a single normally closed (NC) contact, which is connected to the tip (live) connection when no plug is in the socket, and disconnected when a plug is inserted. Stereo sockets commonly provide two such NC contacts, one for the tip (left channel live) and one for the ring or collar (right channel live). Some designs of jack also have such a connection on the sleeve, as this contact is usually ground it is not much use for signal switching but could be used to indicate to electronic circuitry that the socket was in use.
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 pointIn 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 1/8″ or 3/32″ 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 three-conductor signal input socket is used on some battery-powered guitar effects pedals to eliminate the need for a separate power switch. When the user plugs in a two-conductor guitar or microphone lead, the resulting short-circuit between earth 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 side effect is the risk of inadvertently discharging the battery if the lead is not removed after use, for example if equipment is left connected overnight.
Tip/ring/sleeve terminology
In
twisted pairTwisted 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. This appears to have originated with the use of
TRS jacks by
switchboardA 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...
operators with the
tip and ring"Tip" and "Ring" are common terms in the telephone service industry referring to the two wires or sides of an ordinary telephone line. Tip is the ground side and Ring is the battery side of a phone circuit. In the UK these are referred to as the 'A' and 'B' wires...
wires attached to the corresponding parts of the jack. Originally, the
hot and
ground were reversed, but often the metallic desktops of the switch boards were scarred by the discharge from the tips and the system was reversed to the present usage.
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 Output | Unbalanced Input | Unbalanced Insert | Balanced | Stereo |
|---|
| Tip |
Signal |
Signal |
Send or Return signal |
Positive/"Hot" |
Left channel |
| Ring |
Ground or No Connection |
Ground or No Connection |
Return or Send signal |
Negative/"Cold" |
Right channel |
| Sleeve |
Ground |
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 QSC
QSC Audio Products, LLC is an American manufacturer of professional audio products. QSC's products are targeted to the requirements of audio professionals in concert, installation, portable entertainment and cinema applications...
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 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 connectorThe XLR connector is an electrical connector design. XLR plugs and sockets are used mostly in professional audio and video electronics cabling applications, often for microphones. Home audio and video electronics normally use RCA connectors for line level signals generated by a preamplifier...
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 1/4″ 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 computerA 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 cardA sound card is a computer expansion card that facilitates the input and output of audio signals to and from a computer under control of computer programs. Typical uses of sound cards include providing the audio component for multimedia applications such as music composition, editing video or...
s from Creative Labs,
Sound BlasterThe 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 1/8″ TRS as a mono microphone input, and deliver a 5 V polarising voltage on the ring to power
electretElectret is a dielectric material that has a quasi-permanent electric charge or dipole polarisation. An electret generates internal and external electric fields, and is the electrostatic equivalent of a permanent magnet. Oliver Heaviside coined this term in 1885...
microphones from the card manufacturer. Sometimes called
phantom power, this is not a suitable power source for microphones designed for true
phantom powerPhantom power is a method that sends a DC electrical 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 [transistor] built into the electret microphone can.) Compatibility between different manufacturers is unreliable.
Normally, 1/8″ 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. But the 6.1 and 7.1 channel soundcards from Creative Labs are equipped with 1 and 2 sockets of 1/8″ 4-conductor sockets respectively. This is to accommodate rear-center (6.1) or rear left & right (7.1) channels without additional sockets on the sound card. But speaker have normal 3-conductor sockets. In Creative's documentation, the word "pole" is used instead of "conductor".
The
AppleApple Inc. is an American multinational corporation that designs and manufactures consumer electronics and computer software products. The company's best-known hardware products include Macintosh computers, the iPod and the iPhone...
PlainTalkPlainTalk 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 1/8″ TRS; in this case, the tip carries power for a
preamplifierA preamplifier , or control amp in some parts of the world, is an electronic amplifier which precedes another amplifier to prepare an electronic signal for further amplification or processing...
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.
Generally, all of Apple's computers now have combination electric/optical 1/8″ TRS jacks for both input and output. This allows for conventional stereo input and output with electrical connections, or 5.1 digital input and output with a mini-
ToslinkTOSLINK or Optical Cable is a standardized optical fiber connection system. Its most common use is in consumer audio equipment , where it carries a digital audio stream between components such as MiniDisc and CD players and DAT recorders...
cable.
Plug-in power
( from: http://www.epanorama.net/circuits/microphone_powering.html )
Recording equipment
Many small video cameras, laptops,
MinidiscA MiniDisc is a magneto-optical disc-based data storage device initially intended for storage of up to 80 minutes of digitized audio...
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 (usually of the "toy" variety), which use an un-powered microphone: usually a cheap dynamic or piezo microphone. The microphone generates its own voltage, and does not require power.
- Devices (usually very expensive recorders, for hi-fi or broadcast use) which use a self-powered microphone: usually an expensive dynamic microphone with internal battery-powered amplifier.
- Devices (most consumer equipment) which use a "plug-in powered" microphone: an electret microphone containing an internal FET 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 it could destroy a broadcast-type microphone.
Aircraft headsets
Commercial and
general aviationGeneral aviation is one of two categories of civil aviation. It refers to all flights other than military and scheduled airline 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 1/4″ 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 1/4″ (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 for a pair of monaural headphones, a microphone, a push-to-talk switch and a common ground conductor.
Some mobile phones such as the
Nokia N95The Nokia N95 is a smartphone produced by Nokia as part of their Nseries line of portable devices. The N95 runs Symbian OS v9.2, with a S60 3rd Edition user interface...
, the Apple
iPhoneThe iPhone is an Internet and multimedia enabled smartphone designed and marketed by Apple Inc. Because its minimal hardware interface lacks a physical keyboard, the multi-touch screen renders a virtual keyboard when necessary...
and the HP
IPAQiPAQ presently refers to a Pocket PC and personal digital assistant first unveiled by Compaq in April 2000; the name was borrowed from Compaq's earlier iPAQ Desktop Personal Computers. Since Hewlett-Packard's acquisition of Compaq, the product has been marketed by HP...
500 Voice Messenger also use a similarly-wired plug for their
headsetHeadset may refer to:*Headphones , this refers to a set of headphones including a microphone attachment*Headset *Headset *Headset , an electronica / hip-hop group...
.
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
switchIn electronics, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another. The most familiar form of switch is a manually operated electromechanical device with one or more sets of electrical contacts...
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.
Color Codes
These codes were standardized by
MicrosoftMicrosoft Corporation is a multinational computer technology corporation that develops, manufactures, licenses, and supports a wide range of software products for computing devices...
and Intel in 1999 for computers as part of the PC99 standard.
See: PCxx Standards.
| green TRS 1/8″ |
stereo output, front channels or headphones |
| black TRS 1/8″ |
stereo output, rear channels |
| grey TRS 1/8″ |
stereo output, side channels |
| gold TRS 1/8″ |
dual output, center and subwoofer A subwoofer is a woofer, or a complete loudspeaker, dedicated to the reproduction of bass audio frequencies, from 80 Hz down as far as 20 Hz, or in rare cases, lower. Also known as "subs", these are used to augment the low frequency performance of main loudspeakers. Subwoofers are...
|
| blue TRS 1/8″ |
stereo input, line level Line level is a term used to denote the strength of an audio signal used to transmit analog sound information between audio components such as CD and DVD players, TVs, audio amplifiers, and mixing consoles, and sometimes MP3 players....
|
| pink TRS 1/8″ |
mono or stereo microphoneA microphone, colloquially called a mic or mike , is an acoustic-to-electric transducer or sensor that converts sound into an electrical signal. In 1876, Emile Berliner invented the first microphone used as a telephone voice transmitter...
input |
External links