-PHONE CONNECTORS-

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-as of [6 SEPTEMBER 2024]

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-OUR [PHONE CONNECTORS]-

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*2.5 MM*
(MONO)

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*3.5 MM*
(MONO/STEREO)

-STANDARD HEADPHONES JACK-

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*6.35 MM*
(STEREO)

(aka ‘1/4 inch’)

*GUITAR CABLES*

*PRE-AMPS*

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___*AKA*___

‘phone jack’

‘audio jack’

‘headphone jack’

‘jack plug’

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-a [phone connector] is a [family] of [electrical connectors] typically used for [analog audio signals]-

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The standard is that a plug (described as the male connector) will connect with a jack (described as female).

The phone connector was invented for use in telephone switchboards in the 19th century and is still widely used

The phone connector is cylindrical in shape, with a grooved tip to retain it.

In its original audio configuration, it typically has two, three, four or, occasionally, five contacts.

Three-contact versions are known as TRS connectors, where T stands for “tip”, R stands for “ring” and S stands for “sleeve”.

Ring contacts are typically the same diameter as the sleeve, the long shank.

Similarly, two-, four- and five- contact versions are called TS, TRRS and TRRRS connectors respectively.

The outside diameter of the “sleeve” conductor is 6.35 millimetres (1⁄4 inch).

The “mini” connector has a diameter of 3.5 mm (0.14 in) and the “sub-mini” connector has a diameter of 2.5 mm (0.098 in). The “mini” connector has a length of 14 millimetres (0.55 in)

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Other terms

Specific models, and connectors used in specific applications, may be termed e.g. stereo plug, headphone jack, microphone jack, aux input, etc.

The 3.5 mm versions are commonly called mini-phone, mini-stereo, mini jack, etc

In the UK, the terms jack plug and jack socket are commonly used for the respective male and female phone connectors

In the US, a stationary (more fixed) electrical connector is called a “jack”

The terms phone plug and phone jack sometimes refer to different genders of phone connectors,[5] but also sometimes refer to the RJ11 and older telephone plugs and corresponding jacks that connect wired telephones to wall outlets.

Phone plugs and jacks are not to be confused with the similar terms phono plug and phono jack (or in the UK, phono socket) which refer to RCA connectors common in consumer hi-fi and audiovisual equipment. The 3.5 mm connector is, however, sometimes—but counter to the connector manufacturers’ nomenclature[6]—referred to as mini phono.[7]

Historical development[edit]

Phone connectors:

2.5 mm (1⁄10 in) mono (TS)
3.5 mm (1⁄8 in) mono (TS)
3.5 mm (1⁄8 in) stereo (TRS)
6.35 mm (1⁄4 in) stereo (TRS)
Quarter-inch size[edit]
Modern phone connectors are available in three standard sizes. The original 1⁄4 inch (6.35 mm) version descends from as early as 1877, when the first-ever telephone switchboard was installed at 109 Court Street in Boston in a building owned by Charles Williams, Jr.;[8][9] or 1878, when an early switchboard was used for the first commercial manual telephone exchange[10][11] in New Haven, Connecticut created by George W. Coy.[12][13] The 1877 switchboard was last known to be located in the lobby of 185 Franklin Street, Boston.[8]

In February 1884, C. E. Scribner was issued US Patent 293,198[14] for a “jack-knife” connector that is the origin of calling the receptacle a “jack”.[15] Scribner was issued U.S. Patents 262,701,[16] 305,021,[17] and 489,570 relating to an improved design that more closely resembles the modern plug.[18] The current form of the switchboard-plug was patented prior to 1902, when Henry P. Clausen received a patent on an improved design.[19] It is today still used on mainstream musical equipment, especially on electric guitars.

Western Electric was the manufacturing arm of the Bell System, and thus originated or refined most of the engineering designs, including the telephone jacks and plugs which were later adopted by other industries, including the U.S. military.

By 1907, Western Electric had designed a number of models for different purposes, including:[20]

Code No. 47 2-conductor plugs for use with type 3, 91, 99, 102, 103, 108, and 124 jacks—used for switchboards
Code No. 85 3-conductor plugs for use with type 77 jacks—used for the operator’s head telephone
Code No. 103 twin 2-conductor plugs for use with type 91, and type 99 jacks—used for the operator’s head telephone and chest transmitter (microphone)
Code No. 109 3-conductor plugs for use with jack 92 on telephone switchboards (with the same basic shape as the modern Bantam plugs)
Code No. 110, 3-conductor plug for use with jacks 49, 117, 118, 140, and 141 on switchboards
Code No. 112, twin 2-conductor plug for use with jacks 91 and 99—used for the operator’s head telephone and chest, with a transmitter cutout key (microphone mute)
Code No. 116, 1-conductor plug for use with cordless jack boxes
Code No. 126, 3-conductor plug for use with type 132 and type 309 jacks on portable street railway sets
By 1950, the two main plug designs were:

WE-309 (compatible with 3⁄16-inch jacks, such as 246 jack), for use on high-density jack panels such as the 608A
WE-310 (compatible with 1⁄4-inch jacks, such as the 242)
Several modern designs have descended from those earlier versions:

B-Gauge standard BPO316 (not compatible with EIA RS-453)
EIA RS-453: Dimensional, Mechanical and Electrical Characteristics Defining Phone Plugs & Jacks standard of 0.206 in (5.2 mm) diameter, also found in IEC 60603-11:1992 Connectors for frequencies below 3 MHz for use with printed boards – Part 11: Detail specification for concentric connectors (dimensions for free connectors and fixed connectors).
Military variants[edit]
U.S. military versions of the Western Electric plugs were initially specified in Amendment No.1, MIL-P-642, and included:

M642/1-1
M642/1-2
M642/2-1
M642/2-2
M642/4-1
M642/4-2
MIL-P-642/2, also known as PJ-051. (Similar to Western Electric WE-310, and thus not compatible with EIA RS-453)
MIL-P-642/5A: Plug, Telephone (TYPE PJ-068) and Accessory Screws (1973),[21] and MIL-DTL-642F: Plugs, Telephone, and Accessory Screws (2015),[22] with 0.206 in (5.2 mm) diameter, also known by the earlier Signal Corps PL-68 designation. These are commonly used as the microphone jack for aviation radios, and on Collins S-line and many Drake amateur radios. MIL-DTL-642F states, “This specification covers telephone plugs used in telephone (including telephone switchboard consoles), telegraph, and teletype circuits, and for connecting headsets, handsets, and microphones into communications circuits.”
Miniature size[edit]
The 3.5 mm or miniature size was originally designed in the 1950s as two-conductor connectors for earpieces on transistor radios, and remains a standard still used today.[23] This roughly half-sized version of the original, popularized by the Sony EFM-117J radio (released in 1964),[24][25][failed verification] is still commonly used in portable applications. The three-conductor version became very popular with its application on the Walkman in 1979, as unlike earlier transistor radios, these devices had no speaker of their own; the usual way to listen to them was to plug in headphones. There is also an EIA standard for 0.141-inch miniature phone jacks.

The 2.5 mm or sub-miniature sizes were similarly popularized on small portable electronics. They often appeared next to a 3.5 mm microphone jack for a remote control on-off switch on early portable tape recorders; the microphone provided with such machines had the on-off switch and used a two-pronged connector with both the 3.5 and 2.5 mm plugs. They were also used for low-voltage DC power input from wall adapters. In the latter role they were soon replaced by coaxial DC power connectors. 2.5 mm phone jacks have also been used as the headset jacks on mobile telephones (see § PDAs and mobile phones).

The 3.5 mm and 2.5 mm sizes are sometimes called 1⁄8 in and 3⁄32 in respectively in the United States, though those dimensions are only approximations.[26] All sizes are now readily available in two-conductor (unbalanced mono) and three-conductor (balanced mono or unbalanced stereo) versions.

Four-conductor versions of the 3.5 mm plug and jack are used for certain applications. A four-conductor version is often used in compact camcorders and portable media players, providing stereo sound and composite analog video. It is also used for a combination of stereo audio, a microphone, and controlling media playback, calls, volume and/or a virtual assistant on some laptop computers and most mobile phones,[27] and some handheld amateur radio transceivers from Yaesu.[28] Some headphone amplifiers have used it to connect “balanced” stereo headphones, which require two conductors per audio channel as the channels do not share a common ground.[29]

Broadcast usage[edit]
By the 1940s, broadcast radio stations were using Western Electric Code No. 103 plugs and matching jacks for patching audio throughout studios. This connector was used because of its use in AT&T’s Long Line circuits for distribution of audio programs over the radio networks’ leased telephone lines.[citation needed] Because of the large amount of space these patch panels required, the industry began switching to 3-conductor plugs and jacks in the late 1940s, using the WE Type 291 plug with WE type 239 jacks. The type 291 plug was used instead of the standard type 110 switchboard plug because the location of the large bulb shape on this TRS plug would have resulted in both audio signal connections being shorted together for a brief moment while the plug is being inserted and removed. The Type 291 plug avoids this by having a shorter tip.[30][page needed]

Patch bay connectors[edit]
Professional audio and the telecommunication industry use a 0.173 in (4.4 mm) diameter plug, associated with trademarked names including Bantam, TT, Tini-Telephone, and Tini-Tel. They are not compatible with standard EIA RS-453/IEC 60603-11 1/4-inch jacks. In addition to a slightly smaller diameter, they have a slightly different geometry.[31] The three-conductor TRS versions are capable of handling balanced line signals and are used in professional audio installations. Though unable to handle as much power, and less reliable than a 6.35 mm (0.250 in) jack,[32] Bantam connectors are used for professional console and outboard patchbays in recording studio and live sound applications, where large numbers of patch points are needed in a limited space.[31] The slightly different shape of Bantam plugs is also less likely to cause shorting as they are plugged in.[citation needed]

Less common[edit]

A dual 310 patch cable, two-pin phone plug

A two-pin version, known to the telecom industry as a “310 connector”, consists of two 1⁄4-inch phone plugs at a centre spacing of 5⁄8 inch (16 mm). The socket versions of these can be used with normal phone plugs provided the plug bodies are not too large, but the plug version will only mate with two sockets at 5⁄8 inches centre spacing, or with line sockets, again with sufficiently small bodies. These connectors are still 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 in-flight entertainment system. Plugging a stereo plug into one of the two mono jacks typically results in the audio coming into only one ear. Adapters are available.

A short-barrelled version of the phone plug was used for 20th century high-impedance mono headphones, and in particular those used in World War II aircraft. These have become rare. 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.

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 0.210-inch (5.3 mm) inside diameter jacks for fire safety communication in public buildings.[a]

Aviation and US military connectors[edit]
US military phone connectors include both 0.25-in. (6.35 mm) and 0.21-in. (5.34 mm) diameter plugs, which both mate with the M641-series open frame jacks, exemplified by Switchcraft C11 and C12 series jacks. Military specifications and standards relating to phone connectors include MIL-STD 202, MIL-P-642/*, and MIL-J-641.

Commercial and general aviation (GA) civil airplane headset plugs are similar, but not identical. A standard 1⁄4-in. monaural plug, type PL-55[34] (both two-conductor phone plugs, also called PJ-055B, which mate with JK-24 and JK-34A jacks) is used for headphones. On many newer GA aircraft the headphone jack is a standard 1⁄4-in. phone connector wired in the standard unbalanced stereo configuration instead of the PJ-055 to allow stereo music sources to be reproduced.

Aviation headphones are paired with special tip-ring-sleeve, 3/16-in (0.206 in)/5.23-mm diameter plug,[citation needed] type PJ-068 (PL-68), for the microphone. The PJ-068 mates with a JK-33 jack (Switchcraft C-12B), and is similar to the Western Electric plug WE-109. In the microphone plug the Ring is used for the microphone hot and the sleeve is ground. The extra (tip) connection in the microphone plug is often left unconnected but is also sometimes used for various functions, most commonly an optional push-to-talk switch, but on some aircraft it carries headphone audio and on others a DC supply.[citation needed]

Aviation plug type U-174/U or Nexus TP120, commonly used on military aircraft and civil helicopters

Military aircraft and civil helicopters have another type termed a U-174/U; These are also known as NATO plugs or Nexus TP120[35] phone plugs. They are similar to 1⁄4-in. (6.35 mm) plug, but with a 7.10 mm (0.280 in) diameter short shaft with an extra ring, i.e. four conductors in total, allowing two for the headphones (mono), and two for the microphone. There is a confusingly similar four conductor British connector with a slightly smaller diameter and a different wiring configuration used for headsets in many UK Military aircraft and often also referred to as a NATO or UK NATO connector.

Mono and stereo compatibility[edit]

Old-style male tip-sleeve connectors. The leftmost plug has three conductors; the others have two. At the top is a three-conductor panel jack.

Modern profile 2-conductor male

1⁄4 in TS connectors

The original application for the 6.35 mm (1⁄4 in) phone jack was in manual telephone exchanges.[36] Many different configurations of these phone plugs 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 microphones, electric guitars, headphones, loudspeakers, and other audio equipment.

When a three-conductor version of the 6.35 mm plug was introduced for use with stereo headphones, it was given a sharper tip profile in order to make it possible to manufacture jacks that would accept only stereo plugs, to avoid short-circuiting the right channel of the amplifier. This attempt has long been abandoned, and now the convention is that all plugs fit all sockets of the same size, regardless of whether they are balanced or unbalanced, mono or stereo. Most 6.35 mm plugs, mono or stereo, now have the profile of the original stereo plug, although a few rounded mono plugs are still produced. The profiles of stereo miniature and sub-miniature 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 is inserted into 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.[specify] However, if equipment is not designed for such a use, grounding the right channel causes a short circuit which has the potential to damage an audio amplifier channel. In any case, any signal from the right channel is naturally lost in this scenario.
If a three-conductor plug is connected to a two-conductor socket, normally the result is to leave the ring of the plug unconnected. This open circuit is potentially dangerous to equipment utilizing vacuum tubes, but most solid-state devices will tolerate an open condition well. A three-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.
Because of a lack of standardization in the past regarding the dimensions (length) given to the ring conductor and the insulating portions on either side of it in 6.35 mm (1⁄4 in) phone connectors and the width of the conductors in different brands and generations of sockets, there are occasional issues with compatibility between differing brands of plug and socket. This can result in a contact in the socket bridging (shorting) the ring and sleeve contacts on a phone connector.

General use[edit]

A 3.5 mm 4-conductor TRRS phone connector

A 3.5 mm 5-conductor TRRRS phone connector

In the most common arrangement, consistent with the original intention of the design, the male plug is connected to a cable, and the female socket is mounted in a piece of equipment

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 amperes for certain heavy-duty 1⁄4 in versions intended for loudspeaker connections

Common uses of phone plugs and their matching sockets includeHeadphone and earphone jacks on a wide range of equipment. 6.35 mm (1⁄4 in) plugs are common on home and professional component equipment, while 3.5 mm plugs are nearly universal for portable audio equipment and headphones. 2.5 mm plugs are not as common, but are used on communication equipment such as cordless phones, mobile phones, and two-way radios, especially in the earliest years of the 21st century before the 3.5 mm became standard on mobile phones. The use of headphone jacks in smartphones is declining as of 2020 in favor of USB-C connectors and wireless Bluetooth solutions.
Consumer electronics devices such as digital cameras, camcorders, and portable DVD players use 3.5 mm connectors for composite video and audio output. Typically, a TRS connection is used for mono unbalanced audio plus video, and a TRRS connection for stereo unbalanced audio plus video. Cables designed for this use are often terminated with RCA connectors on the other end. Sony also used this style of connection as the TV-Out on some models of Vaio laptop.
Hands-free sets and headsets often use 3.5 mm or 2.5 mm connectors. TRS connectors are used for mono audio out and an unbalanced microphone (with a shared ground). Four-conductor TRRS phone connectors add an additional audio channel for stereo output. TRRS connectors used for this purpose are sometimes interoperable with TRS connectors, depending on how the contacts are used.[citation needed]
Microphone 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 points) on a wide range of equipment.
Personal computers, sometimes using a sound card plugged into the computer. Stereo 3.5 mm jacks are used for:[b]
Line in (stereo)
Line out (stereo)
Headphones and loudspeaker out (stereo)
Microphone input (mono, usually with 5 V power available on the ring.[c])
Older laptop computers generally have one jack for headphones and one mono jack for a microphone at microphone level.[d]
LCD monitors with built-in speakers will need a cable with 3.5 mm male TRS plugs on each end to connect to the sound card.
Devices designed for surround output may use multiple jacks for paired channels (e.g. TRS for front left and right; TRRS for front center, rear center, and subwoofer; and TRS for surround left and right).[e]
Eurorack, Moog and other modular synthesizers
Almost all electric guitars use a 1⁄4 in mono jack as their output connector. Some makes (such as Shergold) use a stereo jack instead for stereo output, or a second stereo jack, in addition to a mono jack (as with Rickenbacker).
Instrument amplifiers for guitars, basses and similar amplified musical instruments. 1⁄4 in jacks are overwhelmingly the most common connectors for:
Inputs. A shielded cable with a mono 1⁄4 in phone plug on each end is commonly termed a guitar cable or a patch cable, the first name reflecting this usage, the second the history of the phone plug’s development for use in manual telephone exchanges.
Loudspeaker outputs
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 keyboards use jacks for a similar range of uses to guitars and amplifiers, and in addition:
Sustain pedals
Expression pedals
Electronic drums use jacks to connect sensor pads to the synthesizer module or MIDI encoder. In this usage, a change in voltage on the wire indicates a drum stroke.
TRS jacks are sometimes used for balanced connections for instance in compact or economy audio mixing desks for balanced microphone inputs.

In some audio equipment, a TRS connection may be offered in addition to an XLR balanced line connector

Loudspeaker connections for older or consumer sound reinforcement equipment.

Speakon connectors are used in modern professional systems as they mate with greater contact area and thus carry higher current, lock in place and do not risk shorting out the amplifier upon insertion or disconnection

Some professional loudspeakers carry both Speakon and TRS connectors for compatibility. Heavy-duty 1⁄4 in loudspeaker jacks are rated at 15 A maximum which limits them to applications involving less than 1,800 watts.
Modular synthesizers commonly use monophonic cables for creating patches.
Quarter-inch phone connectors are widely used to connect external processing devices to insert points on mixing consoles. Two- or three-conductor phone connectors might be used in pairs as separate send and return jacks, or a single three-conductor phone jack might serve as both send and return, in which case the signals are unbalanced. The one unbalanced combination send/return TRS insert jack saves both panel space and component complexity, but the unbalanced connection may introduce a slight buzz. Insert points on mixing consoles may 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 phone jack as a DC power connector.
Some photographic studio strobes have 1⁄4 in or 3.5 mm jacks for the flash synchronization input. A camera’s electrical flash output (PC socket or hot shoe adapter) is cabled to the strobe light’s sync input jacks.
Some cameras 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 jacks as serial port connectors for data transfer and unit programming. This technique is particularly common on graphing calculators, such as the TI-83 series, and some types of amateur and two-way radio. In more modern equipment USB mini-B connectors are provided in addition to or instead of jack connectors. The second-generation iPod Shuffle from Apple has one TRRS jack which serves as headphone, USB, or power supply, depending on the connected plug.
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 9 V 500 mA DC power.
The Apple Lisa personal computer used a three-conductor TRS phone connector for its keyboard.
The Sangean DCR-200 radio uses a wire aerial terminating with a 2.5 mm phone connector.
Computer sound[edit]

3.5 mm jacks for microphone, audio out, and line-level audio in

A 3.5 mm plug for computer audio

A 3.5 mm headphone socket (TRS) on a computer

Personal computer sound cards, such as Creative Labs’ Sound Blaster line, use a 3.5 mm phone connector as a mono microphone input, and deliver a 5 V bias voltage on the ring to power the FET preamplifier built into electret microphones. Adjustmes may be required to achieve compatibility between different manufacturers.[38]

The Apple PlainTalk microphone jack used on some older Macintosh systems is designed to accept an extended 3.5 mm three-conductor phone connector; in this case, the tip carries power for a preamplifier inside the microphone. It cannot accept a standard microphone without a preamp. If a PlainTalk-compatible microphone is not available, the jack can accept a line-level sound input.

Normally, 3.5 mm three-conductor sockets are used in computer sound cards for stereo output. Thus, for a sound card with 5.1 output, there will be three sockets to accommodate six channels: front left and right; surround left and right; and center and subwoofer. 6.1 and 7.1 channel sound cards from Creative Labs, however, use a single three-conductor socket (for the front speakers) and two four-conductor sockets.[f] This is to accommodate rear-center (6.1) or rear left and right (7.1) channels without the need for additional sockets on the sound card.

Some portable computers have a combined 3.5 mm TRS-TOSLINK jack, supporting stereo audio output using a TRS connector, or TOSLINK (stereo or 5.1 Dolby Digital/DTS) digital output using a suitable optical adapter. Most iMac computers have this digital/analog combo output feature as standard, with early MacBooks having two ports, one for analog/digital audio input and other for output. Support for input was dropped on various later models[39][40]

Some newer computers, such as Lenovo laptops, have 3.5 mm TRRS headset sockets, which are compatible with phone headsets and may be distinguished by a headset icon instead of the usual headphones or microphone icons. These are particularly used for voice over IP.

Video[edit]

Different length 3.5 mm TRRS connectors

Equipment requiring video with stereo audio input/output sometimes uses 3.5 mm TRRS connectors. Two incompatible variants exist, of 15 millimetres (0.59 in) and 17 mm (0.67 in) length, and using the wrong variant may either simply not work, or could cause physical damage.

Attempting to fully insert the longer (17 mm) plug into a receptacle designed for the shorter (15 mm) plug may damage the receptacle, and may damage any electronics located immediately behind the receptacle. However, partially inserting the plug will work as the tip/ring/ring distances are the same for both variants.

Using the shorter plug in a socket designed for the longer connector will result in the plug not ‘locking in’, and may additionally result in wrong signal routing and/or a short circuit inside the equipment (e.g. the plug tip may cause the contacts inside the receptacle – tip/ring 1, etc. – to short together).

The shorter 15 mm TRRS variant is more common and fully physically compatible with ‘standard’ 3.5 mm TRS and TS connectors.

Recording equipment[edit]

Stereo devices which use “plug-in power”: the electret capsules are wired in this way.

Many small video cameras, laptops, 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 unpowered microphone: usually a cheap dynamic or piezoelectric microphone. The microphone generates its own voltage, and needs no 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 FET amplifier. These provide a good quality signal, in a very small microphone. However, the internal FET needs 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. In the converse case (recorder provides no power; microphone needs 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.[citation needed]

PDAs and mobile phones[edit]

All iPhone models from the first generation to the 6S and SE use a four-conductor (TRRS) phone connector (center) for a wired headset.

Three- or four-conductor (TRS or TRRS) 2.5 mm and 3.5 mm sockets are common on older cell phones and newer smartphones respectively, providing mono (three conductor) or stereo (four conductor) sound and a microphone input, together with signaling (e.g., push a button to answer a call). These are used both for handsfree headsets (esp. mono audio plus mic, also stereo audio plus mic, plus signaling for call handling) and for (stereo) headphones (stereo audio, no mic). Wireless (connectorless) headsets or headphones usually use the Bluetooth protocol.

3.5 mm TRRS (stereo-plus-mic) sockets became particularly common on smartphones, and have been used e.g. by Nokia since 2006; they are often compatible with standard 3.5 mm stereo headphones. Some computers now also include a TRRS headset socket, compatible with headsets intended for smartphones.

There are multiple conflicting standards for TRRS connectors and their compatibility with three conductor TRS. The four conductors of a TRRS connector are assigned to different purposes by different manufacturers. Any 3.5 mm plug can be plugged mechanically into any socket, but many combinations are electrically incompatible. For example, plugging TRRS headphones into a TRS headset socket (or vice versa) or plugging TRRS headphones from one manufacturer into a TRRS socket from another may not function correctly, or at all. Mono audio will usually work, but stereo audio or microphone may not work, depending on wiring. Signaling compatibility depends both on wiring compatibility and the signals sent by the hands-free/headphones controller being correctly interpreted by the phone.[original research?] Adapters that are wired for headsets will not work for stereo headphones and conversely.[dubious – discuss] Further, as TTY/TDDs are wired as headsets, TTY adapters can also connect a 2.5 mm headset to a phone.

TRRS standards[edit]
Two different forms are frequently found, both of which place left audio on the tip and right audio on the first ring (for compatibility with stereo connectors). Where they differ is in the placement of the microphone and return contacts:

The first, which places the ground return on the sleeve and the microphone on the second ring, is standardized in OMTP[41] and has been accepted as a national Chinese standard YDT 1885–2009. It is mostly used on older devices, such as older Nokia mobiles, older Samsung smartphones, and some Sony Ericsson phones,[42] and products meant for the Chinese market.[43][44] Headsets using this wiring may be indicated by black plastic separators between the rings.[45][44]

The second, which reverses these contacts, with the microphone on the sleeve, is used by Apple’s iPhone line, and has become the de facto TRRS standard, to maintain compatibility with these products.[46][47][48] It is now used by HTC devices, recent Samsung, Nokia, and Sony phones, among others. This is referred to as CTIA/AHJ, and has the disadvantage that the mic will be shorted to ground if the body of the device is metal and the sleeve has a flange that contacts it. Headsets using this wiring may be indicated by white plastic separators between the rings.[45][44]

If a CTIA headset is connected to a mobile phone with OMTP interface, the missing ground will effectively connect speakers in out-of-phase series, resulting in no voice on typical popular music recordings where the singers are in the center; in this case, if the main microphone button is held down, shorting across the microphone and restoring ground, the correct sound may be audible.[44]

Standard Tip Ring 1 Ring 2 Sleeve Devices using this standard
CTIA, AHJ Left audio Right audio Ground Microphone Most Android devices.[49] Apple, HTC, LG, BlackBerry, latest Nokia (including 1st generation Lumia as well as later models[clarification needed]), latest Samsung, Jolla, Microsoft (including Surface, and Xbox One controller), Sony Playstation 4 (DualShock 4[50])
CTIA-style AV[51] Left audio Right audio Ground CVBS video Apple iPod (up to 6th generation), Raspberry Pi (2014 onwards), Xbox 360 E, Zune (defunct), some older mobile phones (including Nokia N93, Nokia N95,[52] Samsung Galaxy S GT-I9000,[53] T-Mobile Sidekick 4G)
OMTP Left audio Right audio Microphone Ground Old Nokia and also Lumia starting from the 2nd generation),[54] old Samsung (2012 Chromebooks), some old Sony Ericsson smartphones (2010 and 2011 Xperias),[55] Sony (PlayStation Vita), OnePlus One.
OMTP-style radios Speaker Clone Microphone / PTT Ground Yaesu FT-60R amateur radio hand-held.[56][57][58]
Video/audio 1 Left audio CVBS video Ground Right audio Sony and Panasonic camcorders. On some early Sony camcorders, this socket doubled up as a headphone socket. When a headphone plug was inserted, ring 2 was shorted to the sleeve contact and the camcorder output the right audio on ring 1.[59]
Video/audio 2 CVBS video Left audio Right audio Ground Unknown camcorders, portable VCD and DVD players, Western Digital TV live!, some newer LG TVs.
Video/audio 3 CVBS video Left audio Ground Right audio Toshiba TVs
The 4-pole 3.5 mm connector is defined by the Japanese standard JEITA/EIAJ RC-5325A, “4-Pole miniature concentric plugs and jacks”, originally published in 1993.[60] 3-pole 3.5 mm TRS connectors are defined in JIS C 6560. See also JIS C 5401 and IEC 60130-8.

Interoperability[edit]
The USB Type-C Cable and Connector Specification Revision 1.1 specifies a mapping from a USB-C jack to a 4-pole TRRS jack, for the use of headsets, and supports both CTIA and OMTP (YD/T 1885–2009) modes. See Audio Adapter Accessory Mode (Appendix A). Some devices transparently handle many jack standards,[61][62] and there are hardware implementations of this available as components.[63]

Some devices apply voltage to the sleeve and second ring to detect the wiring, and switch the last two conductors to allow a device made to one standard to be used with a headset made to the other.[64]

TRRRS standards[edit]
New TRRRS standard for 3.5 mm connectors was developed and recently approved by ITU-T.[65] The new standard, called P.382 (formerly P.MMIC), outlines technical requirements and test methods for a 5-pole socket and plug configuration. Compared to the legacy TRRS standard, TRRRS provides one extra line that can be used for connecting a second microphone or external power to/from the audio accessory.

P.382 requires compliant sockets and plugs to be backwards compatible with legacy TRRS and TRS connectors. Therefore, P.382 compliant TRRRS connectors should allow for seamless integration when used on new products. TRRRS connectors enable following audio applications: active noise cancelling, binaural recording and others, where dual analogue microphone lines can be directly connected to a host device. It was commonly found on Sony phones starting with the Xperia Z1-XZ1 and Xperia 1 II.

Switch contacts[edit]

Miniature phone plugs and jacks. All are 3.5 mm except the gold-plated plug, which is 2.5 mm. One of the 3.5 mm jacks is two-conductor and the others are three conductor. In this collection the tan-colored jacks have normally-closed switches.

Panel-mounting jacks are often provided with switch contacts. Most commonly, a mono jack is provided with one 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 point.

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.

Design[edit]

Examples of jack configurations, oriented so the plug ‘enters’ from the right. The most common circuit configurations are the simple mono and stereo jacks (A and B); however there are a great number of variants manufactured.[66]

A two-conductor TS phone connector. 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.
A three-conductor TRS phone connector. 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.
This three-conductor jack has two isolated SPDT switches. 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.
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.

Sleeve: usually ground
Ring: Right-hand channel for stereo signals, negative polarity for balanced mono signals, power supply for power-using mono signal sources
Tip: Left-hand channel for stereo signals, positive polarity for balanced mono signals, signal line for unbalanced mono signals
Insulating rings
Pin Unbalanced mono Balanced mono
in/out67 Unbalanced
stereo
In/out (simplex) Insert[68]
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
Notes
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.[69][70]
Early QSC amplifiers used a tip negative, ring positive input wiring scheme.[71]
Whirlwind Line Balancer/Splitters do not use the sleeve as a conductor on their unbalanced 6.35 mm/1⁄4 in TRS phone input. Tip and ring are wired to the transformer’s two terminals; the sleeve is not connected.[72]
Balanced audio[edit]
When a phone connector is used to make a balanced connection, the two active conductors are both used for a monaural 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 connectors. Another advantage offered by TRS phone connectors used for balanced microphone inputs is that a standard unbalanced signal lead using a TS phone jack 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.

A disadvantage of using phone connectors for balanced audio connections is that the ground mates last and the socket grounds the plug tip and ring when inserting or disconnecting 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.

This problem does not occur when using the ‘gauge B’ (BPO) phone connector (PO 316)[73] which although it is of 0.25 in (6.35 mm) diameter has a smaller tip and a recessed ring so that the ground contact of the socket never touches the tip or ring of the plug. This type was designed for balanced audio use, being the original telephone ‘switchboard’ connector and is still common in broadcast, telecommunications and many professional audio applications where it is vital that permanent circuits being monitored (bridged) are not interrupted by the insertion or removal of connectors. This same tapered shape used in the ‘gauge B’ (BPO) plug can be seen also in aviation and military applications on various diameters of jack connector including the PJ-068 and ‘bantam’ plugs. The more common straight-sided profile used in domestic and commercial applications and discussed in most of this article is known as ‘gauge A’.

XLR connectors used in much professional audio equipment mate the ground signal on pin 1 first.

Unbalanced audio[edit]
Phone connectors with three conductors 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 phone plug correctly grounds the input. In the same fashion, use of a “tip return” insert style allows a mono phone 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 in TRS connectors in this way is seen in very many professional and semi-professional audio mixing desks, because it halves the space needed for insert jack fields which would otherwise need 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 three-conductor TRS phone inserts, the concept is extended by using specially designed phone jacks that will accept a mono phone plug partly inserted to the first click and will then connect the tip to the signal path without breaking it. Most standard phone connectors 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. 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 phone connectors are used as patch points.

Some sound recording devices use a three-conductor phone connector as a mono microphone input, using the tip as the signal path and the ring to connect a standby switch on the microphone.

Poor connections[edit]
Connectors that are tarnished, or that were not manufactured within tight tolerances, are prone to cause poor connections.[75] Depending upon the surface material of the connectors, tarnished ones can be cleaned with a burnishing agent (for solid brass contacts typical) or contact cleaner (for plated contacts).[75]

See also[edit]

Banana connector

Coaxial power connector

Notes[edit]

^ 0.210 inch inside diameter jacks are also found in discontinued Bell & Howell 16 mm projector speakers.[33]

^ Some higher-end sound cards provide a breakout panel that supports 1⁄4 in plug devices as well.

^ The traditional use of a stereo plug for a mono microphone for balanced output is incompatible with this configuration.

^ An attenuating cable can convert line level or use a signal from an XLR connector, but is not designed to record from a stereo device such as a radio or music player. Newer computers may feature a single TRRS female jack (See § Computer sound).

^ Circuitry on the sound device may be used to switch between traditional Line In/Line Out/Mic functions and surround output.

^ Creative’s documentation uses the word pole instead of conductor to describe connector contacts.

References[edit]

^ International Library of Technology: … Principles of Telephony … International Textbook Company, Scranton, PA. 1907. p. 36. tip ring sleeve 0-1922.

^ Robert McLeish (2005). Radio Production. Newnes. ISBN 0-240-51972-8.

^ Standard Reference Designations for Electrical and Electronics Parts and Equipments: IEEE 200-1975 (Reaffirmed 1988): Section 4.1.5.3. IEEE and ANSI, New York, NY. 1975.

^ Reference Designations for Electrical and Electronics Parts and Equipment: ASME Y14.44-2008 (Replaced IEEE 200-1975): Section 2.1.5.3. ASME, Fairfield, NJ. 2008. Archived from the original on 2010-03-13.

^ Gary D. Davis and Ralph Jones (1989). The Sound Reinforcement Handbook. Hal Leonard. ISBN 0-88188-900-8.

^

“Barrel – Audio Connectors”. Digi-Key catalog.

“Audio-Video Connectors”. Mouser Electronics catalog.

“Jacks & Plugs”. Switchcraft catalog.

“Definition of: mini-phone connector”. PC Magazine Encyclopedia. Also called a 3.5 mm or 1/8″ connector, it is a plug and socket widely used for analog audio signals in portable devices.

“Mini Phone Plug Adapters”. RAM Electronics online catalog. (e.g.) 3.5mm female stereo mini phone jack to 1/4″ male Stereo phone plug Adapter

^

Lewallen, Dale (1993). This Old PC. Ziff-Davis Press. p. 362. ISBN 978-1-56276-108-0. Retrieved September 8, 2016. Remember that sound cards use the smaller 1/8-inch mini-phono plug…

“Connect your Mac to a home stereo, iPod, iPad, musical instruments, or speakers”. Apple.com. Apple Inc. Retrieved September 8, 2016. 1/8-inch stereo mini-phono plug adapter.

“Glossary”. Monoprice. Retrieved September 8, 2016. 3.5 mm Plug/Jack: Also referred to as a 1/8 inch, auxiliary input, mini stereo, and mini phono.

“Beckman Coulter Automatic Temperature Compensation (ATC) Probe” (PDF). Beckman Coulter. 2008. p. 1. Archived from the original (PDF) on September 16, 2016. Retrieved September 8, 2016. The 3.5mm mini-phono plug connector of the ATC Probe plugs into the 3.5mm mini-phono jack on the pH meter.

Divine, John (September 7, 2016). “Apple’s iPhone 7 and its 10 Flashy Features Won’t Move AAPL Stock”. USNews.com. U.S. News & World Report. Retrieved September 8, 2016. …instead of the headphone jack…. There will be a lightning-to-mini phono adapter included as well.

^ Jump up to: a b “Birthplace of the Telephone”.

^ Frank Lewis Dyer. Edison: His Life And Inventions, p. 71.

^ “When Phone Operators Were Unruly Teenage Boys”. 19 September 2014. Retrieved 2017-10-25.

^ “Chapter 3 Local Manual Systems” (PDF).

^ “First Commercial Telephone Exchange – Today in History: January 28”. 28 January 2020.

^ “A Brief History of the Telephone”.

^ “US Patent 293,198: Telephone Switch”.

^ Chapuis, Robert J. (2003). 100 Years of Telephone Switching. Amsterdam, The Netherlands: IOS Press. p. 51. ISBN 9784274906114.

^ “U.S. Patent 262,701: Circuits for multiple switch boards of telephone exchanges”.

^ “U.S. Patent 305,021, September 1884”.

^ Scribner, C. E. “U.S. Patent 489,570: Spring Jack Switch”.

^ “Telephone switchboard-plug. US 711556 A”.

^ “Western Electric Telephonic Apparatus and Supplies (1907)”.

^ “MIL-DTL-642/5B”. 3 March 2021.

^ “MIL-DTL-642F: Plugs, Telephone, and Accessory Screws” (PDF).

^ “All-right jack: Simple but effective plug-in has endured for more than a century”. Retrieved 2016-09-11.

^ “Sony history 1960s”. Sony official website.

^ Description of 3.5 mm earphone jack in described model: “Vintage Sony 1960’S EFM-117J Radio”. WorthPoint. Retrieved 2016-01-25.

^ 3.5 mm Stereo Plug, CUI Devices, retrieved 2021-09-01

^ “3.5 mm Headset: Accessory Specification”. Android Open Source Project. Retrieved 2019-06-15.

^ “Build a Data Cable for the Yaesu VX-6”.

^ “Geek Out V2+ User Manual”.

^ Chinn, Howard (July 1947). “Single Jacks for Broadcast Application” (PDF). Audio Engineering. 31 (6).

^ Jump up to: a b “The Low-down On Analogue Interfacing -“. www.soundonsound.com. Retrieved 16 August 2018.

^ Gibson, Bill. (2007) The Ultimate Live Sound Operator’s Handbook, p. 202. Hal Leonard Corporation. ISBN 1-4234-1971-5

^ “Switchcraft Telephone Jack and Telephone Plug Mating Chart” (PDF). Archived from the original (PDF) on 2014-04-13. Retrieved 2013-06-24.

^ “PL-55”. Radionerds.com. Retrieved 17 August 2018.

^ “Item # TP-120, Telephone Plug”. Amphenol Nexus Technologies, Inc. Retrieved 2012-01-12.

^ Ranjan Parekh; Ranjan (2006). Principles of Multimedia. Tata McGraw-Hill Education. pp. 225–. ISBN 978-0-07-058833-2.

^ “Switchcraft Z15J 1/4″ High Power Speaker Jack”. Full Compass. Retrieved October 24, 2011. High power 2-conductor speaker jack carries 15A (continuous) audio speaker current levels.

^ “Computer microphones”. Retrieved 2021-12-11.

^ “Questions Answered 4: Optical Output on the Mac”.

^ “Audio input/output on Macbook computers.”.

^ “Wired Analogue Audio” (PDF). Retrieved 2012-06-01.

^ “MEElectronics – P version headset earphone compatibility”. Meelec.com. Archived from the original on 2010-12-27. Retrieved 2013-07-14.

^ “iphone – Why do Chinese EarPods not work with German MacBook Pro?”. Ask Different. Retrieved 2020-04-24.

^ Jump up to: a b c d “Linx:What is your mobile phone headset jack standard: OMTP or CTIA?-Headset OEM|Earphone Factory|Headphone Supplier —China LINX CO,.LTD”. www.headphonefactory.net. Retrieved 2020-04-24. In order to fit the Chinese national conditions, Apple China released Earpods with some changes, specifically for the Chinese market, to make it in line with the Chinese domestic OMTP standard. … Therefore, iPhone original headsets sod in China are different from Earpods sold in other regions.

^ Jump up to: a b “IPhone国行耳机不兼容问题 – Apple 社区”. discussionschinese.apple.com. Retrieved 2020-04-24.

^ “Headphone inline controls – how they differ on Apple iOS vs. Android/Nokia | Hacker News”. news.ycombinator.com. Retrieved 2020-04-24.

^ “Xiaomi In-Ear Headphones Pro HD (2 +1 Hybrid)”. Headphone Reviews and Discussion – Head-Fi.org. Retrieved 2020-04-24.

^ “Smartphone Headset Standards: Apple iPhone, AHJ (CTIA), & OMTP”. Headset Buddy Help. Retrieved 2020-04-24.

^ “3.5 mm Headset Jack: Device Specification”.

^ “Smartphone Headset Standards: Apple iPhone, AHJ (CTIA), & OMTP”. Retrieved 15 August 2021.

^ www.cablechick.com.au. “Understanding TRRS and Audio Jacks – Cable Chick Blog”. www.cablechick.com.au. Retrieved 16 August 2018.

^ “TV Out on the Nokia N95”. All About Symbian. Retrieved 6 October 2019.

^ “Singtel Group, first in the world to launch breakthrough Android 2.1 Samsung Galaxy S”. singtel.com. Retrieved 6 October 2019.

^ “Jays AB headset for Windows Phone and a note on headset standards”. Allaboutwindowsphone.com. Retrieved 26 March 2017.

^ “2012 Xperia range uses different 3.5mm headset standard | Xperia Blog”. www.xperiablog.net. 27 February 2012. Retrieved 2017-08-17.

^ Yaesu FT-60R Technical Supplement (PDF). VERTEX STANDARD CO., LTD. 2005. pp. 10, 13.

^ “Radio Wiring – ArgentWiki”. wiki.argentdata.com. Retrieved 2020-05-29.

^ “MH-37A4B wiring diagram”. www.qsl.net. Retrieved 2020-05-29.

^ Sony and Panasonic camcorder service manuals

^ “EIAJ RC-5325A”.

^ FAQ – What type of wired headsets can I use with my Nokia Lumia phone? – “Nokia Lumia 820 and 920 support both American Headset Jack (AHJ) headsets and standard Nokia OMTP headsets.”

^ Jays AB headset for Windows Phone and a note on headset standards – “Nokia’s Windows Phone 8 devices (Nokia Lumia 520, 521, 620, 720, 810, 820, 822, 920, 925, and 928) use a new universal connector, enabling the use of both AHJ and OMTP headsets.”

^ “TS3A227E Autonomous Audio Accessory Detection and Configuration Switch”.

^ Digital Silence (earphone manufacturer): explanation of TRRS connectors and availability of adapter.

^ “ITU-T Work Programme”. Retrieved 26 March 2017.

^ “Jack Schematics table” (PDF).

^ “Frequently Asked Questions”. Retrieved 2012-05-28.

^ “Diagrams” (PDF). Retrieved 2012-05-28.

^ Sweetwater (2000-01-13). “Sweetwater inSync”. Sweetwater.com. Retrieved 2013-07-14.

^ “Silent Way’s recording tricks- Mackie CR-1604 mixer”. Silentway.com. Retrieved 2013-07-14.

^ “QSC Audio Products. Frequently Asked Questions”.

^ [1] Archived November 10, 2006, at the Wayback Machine

^ “Neutrik mil-b-gauge-type plugs”.

^ “dbx 166XL compressor with balanced TRS tip send input and output jacks and one TRS ring send sidechain jack”.

^ Jump up to: a b “Q. What’s wrong with my patchbay? -“. www.soundonsound.com.

External links[edit]

The 19th Century plug that’s still being used—BBC News

“The Rise and Fall of the Headphone Jack”. CNBC. 2019-08-28. Archived from the original on 2021-11-04.

en.wikipedia.org /wiki/Phone_connector_(audio)
Phone connector (audio)
Contributors to Wikimedia projects53-67 minutes 7/3/2003
For the plugs for landline telephones, see Telephone plug. For the connector sometimes called a phono connector, see RCA connector.

A pair of phone connectors: A plug (right) is inserted in a socket (jack, left). Note the flat open contact spring parallel to and inside the tip contact spring.

When the plug is removed, those contacts close to connect a circuit;

such a connection is said to be “normal”.

Inserting the plug connects its tip to one part of that circuit instead

.

*’3.5 milli-meters’ = ‘0.14 inch’
(also referred to as ‘1/4 inch’)
(although that is just an approximiation)
(like my headphones)

.

(the next most common size…is ‘6.35 mm’)
(also referred to as ‘1/4 (inch)’)
(because it is exactly that)

(a ‘diameter difference’ of 2.85mm)

(bought 3.5mm’ –> ‘6.35mm’ adaptor)
(via ‘amazon’)
(5-pack)

$8.99

*AMAZON LINK*

.

“headphone jacks/plugs 101′
(‘HEADPHONESTY LINK’)

(‘rings’ are the spaces between the black ‘insulating bands’)

“headphone plug sizes” –>

0 RINGS –> ‘2 CONDUCTOR PLUG’
(TS CONNECTOR)

1 RING –> ‘3 CONDUCTOR PLUG’
(TRS CONNECTOR)

2 RINGS –> ‘4 CONDUCTOR PLUG’
(TRRS CONNECTOR)

3 RINGS –> ‘5 CONDUCTOR PLUG’
(TRRRS CONNECTOR)

.

(HEADPHONE PLUG DIAMETER…)

2.5MM

3.5MM

4.4MM

6.35MM

.

*’macbook’ has a pair of ‘3.5MM headphone jacks’*
(on left side)

.

.

You will never look at the headphone jack and plug the same way again.

Headphone jack is dead!

Apple has killed the headphone jack.

Sounds familiar?

Ever since Apple removed the headphone jack from the iPhone 7 in favor of a lightning port, other smartphone companies have quickly followed suit with the removal of the once omnipresent port.

“I am Jack’s complete lack of surprise.”

-Fight Club

There are still a few major companies like LG and Samsung who choose to release their flagships with the headphone jack, but I suspect that could change with the upcoming trend of true wireless headphones.

The truth is that most mainstream consumers don’t care for the headphones jack.

Good riddance, they say.

So, why should you care then?

Who Is This Guide For?

Do you want to enjoy audiophile headphones that only have a wired connection?

Are you looking to buy an amplifier for your headphones?

Are you looking to buy and upgrade your audio cable?

Do you want to try balanced audio?

If you answered yes to any of the above questions, this guide is for you

.

By the end of the guide, you will be comfortable with terms like:

3-pole mini

Stereo mini

3.5mm single-ended (or unbalanced) cable

2.5mm balanced cable

Difference between a Headphone Jack and Headphone Plug

.

The Sony TA-ZH1ES with many strange looking holes at the front

Do you see these sockets that the above Sony TA-ZH1ES have?

Those are headphones jacks.

It is where you insert the headphone plugs to receive audio signals.

A variety of headphone plugs

The headphone jack is a family of electrical connectors that are typically used for analog audio signals. I

t is also known by other names like phone jack, audio jack, aux input, etc.

There are cases where headphone jack are used for digital audio signals.

For example, the Google Chromecast can output either analog or digital signals off its single 3.5mm output jack

Female and male connectors

From Amazon. Male Connector (L) Female Connector (R)

In electrical and mechanical trades and manufacturing, each half of a pair of mating connectors or fasteners is conventionally assigned the designation male or female. – Wikipedia

Unfortunately, the audio industry has not unified in the way the electrical and mechanical trades have to describe the different gender of connectors.

You will often find the word “plug” used to describe the male connectors while “jack” used to describe the female connectors

.

Evolution of the Headphone Jack

Who is jack?

The origin of the term “jack” can be traced back to 1874 when C.E. Scribner patented, what he calls, a “jack-knife” connector.

Patent of C.E. Scribner

The earliest known jack was a ¼ inch (6.35mm) version and still has mainstream usages which we describe below.

Rounded to pointed tip profile

In the early development days, there were many different jack designs.

The rounded tip design was particularly popular because it was compatible with different manufacturers.

The rounded tip quickly gained traction as the de-facto tip profile for audio equipment.

But with the rise of stereo audio, a different tip profile was needed to prevent the old rounded tip from frying the circuit when inserted into incompatible equipment.

A pointed tip jack will prevent a rounded tip plug from being inserted fully, hence solving the problem

.

Anatomy of a Headphone Plug

Conductors

Regardless of the plug size, all headphone plugs have conductors.

Conductors are the contact points of the plugs that close the circuit.

A headphone plug has a minimum of 2 conductors and commonly up to 5.

If it has 3 conductors, it may be called a 3 conductor plug.

Some manufacturer uses pole to replace conductor.

Hence, it can also be called a 3 pole plug.

Identifying conductors.

Each conductor has a specific name:

Tip (T)

Ring (R)

Sleeve (S)

All plugs have at least a Tip and Sleeve. It is the number of Rings that differentiate them.

If the plug only has one ring, it is a 3 conductor plug or a TRS connector. If it has two rings, it is a 4 conductor plug or a TRRS connector.

Don’t mistake the black band as a ring. It is an insulating band. The band separates the parts of the plug from being shorted together.

Nomenclature of the Headphone Plug:

2 conductor, 2 pole, TS

3 conductor, 3 pole, TRS

4 conductor, 4 pole, TRRS

5 conductor, 5 pole, TRRRS

.

Different Plug Connectors configuration

Depending on available conductors, manufacturers can choose to configure jack and plug in various ways. Both must be complementary to each other.

2 conductor plug (TS)

Available Connectors: Only the tip and sleeve connectors are available.

Connectors Connection:

Pin Function
1 Ground
2 Signal
The connection is fairly straightforward here. One connector is used to carry the audio signal while the other acts as a return path and ground.

The ground acts as a reference point for the signal but it also picks up interference noises like an antenna. The longer the cable, the higher chance the more noise will be picked up.

Common Usage: You can find TS connectors mainly with guitars, instruments, and applications that do not require a long cable connection.

3 conductor plug (TRS)

Available Connectors: Aside from the tip and sleeve, there is an additional ring connector with two insulating bands around it.

Connectors Connection:

Pin Unbalanced Mono Balanced Mono Unbalanced Stereo
1 Ground Ground Ground
2 Optional (Mic etc) Signal – (Cold) Right Audio Channel
3 Signal Signal + (Hot) Left Audio Channel
With the addition of another conductor “R”, we open up different possibilities such as supporting balanced mono signals and unbalanced stereo signals.

As seen in the “Unbalanced Mono” column above, the engineer can choose to make use of the additional conductor to carry a microphone signal instead. In this case, where the audio is unbalanced, we may also sometimes refer to this as a single-ended plug.

TRS still cannot carry a balanced stereo signal. For that, see TRRRS connector below.

Common Usage: Most common form of jack connectors. You see these on the end of most stock headphone cables.

4 conductor plug (TRRS)

Available Connectors: With a 4 conductor plug, we have two additional rings with three insulating bands.

Connectors Connection:

Pin Function
1 Microphone
2 Ground
3 Right Audio Channel
4 Left Audio Channel
The above connection configuration follows the Cellular Telecommunications and Internet Association (CTIA) standards. Such a connection format is also called the CTIA TRRS jack connector format.

Common Usage: It is the most commonly adopted standard for modern smartphones and gaming consoles where the cable supports a microphone and stereo audio connection at the same time.

5 conductor plug (TRRRS)

Available Connectors: For a 5 conductor headphone plug, we have 3 ring connectors.

TRRRS connectors are used to support balanced stereo signal. You will find that XLR connectors (3 pin pairs, 4 pin, and 5 pin) are also a common choice for stereo balanced headphones. XLR connectors have been the standard balanced connector in the professional audio market for decades.

It is no surprise that when balanced headphone connections grew in popularity, the standard XLR became a go-to solution.

XLR5 Female (L) XLR5 Male (R)
Unlike TRS connectors, XLR connectors have pins instead of tips, rings, and sleeve. However, they work the same way. The XLR5 connector has 5 conductors just like a TRRRS connector.

Sony did make a TRRRS headphone jack – 4.4mm Pentaconn connector.

Penta means “5” and conn is short for connector.

Please be aware that the Pentaconn connectors are new and not adopted widely by the industry.

You either have to get an adapter to accommodate the 5 pole connector

or purchase a compatible Sony amplifier.

If you are looking to make your own DIY cable with the 4.4mm Pentaconn connector, check out moon audio store.

Schematic of a headphone jack and plug

From CUI DEVICES
If you are interested in the schematic of a headphones jack, you can hop on over here for a more detailed article.

Different sizes of headphone jacks/plugs

When we describe the size of the headphone jack or plugs, we are referring to the diameter of the connector.

6.35mm Connector
This is the largest connector among the jacks. It is otherwise known as the ¼ inch connector.

Name Size Conductors
UGREEN Stereo Audio Adapter 6.35mm Male to 3.5mm Female TRS
UGREEN Stereo Audio Cable 6.35mm to 3.5mm TRS
4.4mm Connector
Name Size Conductors
Yinyoo Upgrated 6 Cores Copper Stereo Earphone Cable 4.4mm to MMCX TRRRS
FiiO 8-Stranded High-Purity Monocrystalline Silver-Plated Copper Cable 4.4mm to MMCX TRRRS
Geekria Apollo Balanced Gold-Plated Adapter 4.4mm male to 3.5mm female TRRRS
3.5mm Connector
Known as the miniature size or mini for short. You can call it a ⅛ inch too.

Name Size Conductors
AmazonBasics 3.5mm Male to Male Stereo Audio Aux Cable 3.5mm to 3.5mm TRS
Zeskit Aux Audio Cable 3.5mm to 3.5mm TRRS
Nacodex Audio Cable 3.5mm to 2.5mm TRS
Kingtop Combo Audio Adapter Cable 3.5mm male to 3.5mm female TRRS
2.5mm Connector
Known as the sub-miniature or sub-mini for short.

Name Size Conductors
NewFantasia Replacement Cable with Remote and Mic 2.5mm to 3.5mm TRS
NewFantasia HiFi Cable Balanced Male 2.5mm to 2.5mm TRRS
Why does a headphone plug matter?
A headphone plug:

directly affects the audio signal it transmits.
indirectly affects the overall quality of sound.
tells us what the cable is capable or not capable of doing (mic, stereo support, etc).
Let us first understand two basic concepts with regards to the transmitted signal from the audio source to our headphones.

Mono VS Stereo Signal
Two types of signal can be transmitted from the audio source to the headphones

Monaural (Mono)
Stereophonic (Stereo)
A mono signal uses only 1 audio channel while a stereo signal uses two audio channels (left and right).

Stereo signal simulates “natural” hearing by creating the impression of sound coming from different directions. This is accomplished by the separate audio channels producing sound in two different speakers (or stereo headphones). You can call this the “surround-sound” effect.

As for mono signal, the sound reproduced is intended to be heard from one position.

Balanced VS Unbalanced Audio
Balanced audio is all about interconnecting audio equipment and transmitting signals in a “balanced” manner.

To do that, we need a combination of an audio source (amplifier) that can produce balanced output and a cable that is capable of carrying that balanced output.

From boxcast
A balanced output has two signal phases (or a hot and cold signal) per channel. Each phase has an equal impedance relative to ground, hence the name balanced.

A balanced mono cable typically has at least three conductors (TRS) to carry the signal to the headphones. A balanced stereo cable has at least five conductors (TRRRS).

Advantage of Balanced Audio

The advantage of balanced connections over unbalanced connections is the canceling of noise interference via a technique named Common Mode Rejection (CMR).

Any noise interference that hits the two balanced phases in the cable is imprinted equally on them. The receiving equipment (headphones in our case) only cares about the difference between the phases.

So, interference that adds equally to both phases creates no difference between them and is canceled out when they are recombined by the amplifier. This canceling process of noise while preserving the original sound is known as CMR.

This means that balanced cable can run longer than unbalanced cable and operate in noisier environments because it cancels any noise interference.

So when is audio unbalanced?

When the requirements to meet balanced audio are not met, the audio is considered unbalanced.

For example:

The audio source is unable to produce a balanced output.
The cable is not capable of carrying a balanced signal (TS, single-ended TRS connectors).
Plug is the key
With the above two concepts, you should know that you can send 4 types of signal from the output (amplifier for example) via a cable to a pair of headphones.

Unbalanced mono

Balanced mono

Unbalanced stereo

Balanced stereo

Whether a signal can be fully supported or even supported at all depends on the number of conductors found on the plug.

Output Signal Jack Connector Balanced Audio Connection

Balanced Mono TS N

Balanced Mono TRS Y

Unbalanced Stereo TRS Y

Balanced Stereo TRS N

Balanced Stereo TRRRS Y

Is it confusing?

It can be hard to digest if you are reading all this for the first time. The part where stereo uses two channels and balanced audio needing two copies of the same signal with reverse polarity tripped me up pretty good, too.

An easy way to understand is to first acknowledge that we need conductors to send and carry signals.

The more signals we need to send, the more conductors we need.

For example, if we want to send a balanced stereo signal, it needs to send

one right channel (R+),

one flipped right channel (R-),

one left channel audio (L+),

one flipped left channel audio (L-).

In total, it needs 4 signal wire and one ground wire which only a TRRRS connector can provide.

Thus, if a jack with an inadequate connector is used (like a TRS connector), the headphone doesn’t receive the complete set of signals to do the CMR. Hence, the whole audio connection becomes unbalanced.

Let’s Practice Our New Skill
Let’s see if we can put our new-found skill to good use.

Remember the “3 pole mini” term we mentioned right at the start of the article? What do you think it means?

3 Pole Mini

Ans: 3.5mm TRS jack

Stereo Mini

Ans: 3.5mm TRS jack (Bonus Qns: why do we think is TRS and not TS?)

3.5mm single-ended cable

Ans: 3.5mm TRS jack (Bonus Qns: Is this a balanced cable?)

2.5mm balanced cable

Ans: 2.5mm TRS jack that can carry balanced signals

From https://www.fiio.com/q5
Do you see that the FiiO Q5 had two outputs? One with a headphone logo, another with “BAL” sign.

Do you understand what that means?

Lastly, another practice question.

See if you can read the “Headphone Output” specifications of the Sony TA-ZH1ES and understand what they mean.

If you do, congratulations!

You just leveled up your audiophile knowledge.

Do you like this article?

Did we miss anything?

Let us know in the comment section below.

www.headphonesty.com /2019/04/headphone-jacks-plugs-explained/

Headphone Jack and Plugs: Everything You Need to Know

Chief Editor

13-17 minutes

(Last Updated On: February 9, 2020)

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