Jack plug

from Wikipedia, the free encyclopedia
Angled stereo jack plug, 3.5 mm diameter, with molded handle and kink protection
6.35 mm jack socket with mechanical locking in high quality design

Jack plugs , also known as line plugs in communication technology for headphones , are two-pole and multi-pole coaxial connectors that are widespread worldwide for the transmission of small electrical signals and high power levels for power amplifiers in stage technology or pure AC or DC voltage in the low voltage range . The tip and the sleeve of the two-pole jack plug correspond to the inner conductor (core) and the outer conductor ( shield , ground ) of the coaxial cable . With multi-pole plugs, each ring corresponds to a further concentric inner cylinder and contact. In English, the three-pin connector is referred to as the TRS connector for tip , ring and sleeve, multi- pin connector as TRRS , etc. - also known colloquially as audio plug or audio jack .

Some designs are standardized by the EIA as RS-453 and by the IEC as 60603-11.

The advantages are the ease of use. the quick release connection and the space-saving design. Disadvantages are the non-safe contacts, the risk of short circuits when handling under voltage and the contact defects when the spring tension decreases.

The contact load on the 6.35 mm sockets and couplings is up to 10 A. Depending on the application and product quality, many thousands of cycles are possible.


The name comes from the latching or snapping into the contact springs of the socket or coupling that hold the plug. When automatic attendant services did not exist, operator telephones were hand-connected. Their lines were on the handles of a switch cabinet . The connections were made with plugs and cords.


Left to right:
2.5mm mono; 3.5mm mono; 3.5mm stereo; 6.35 mm stereo

Jack plugs are manufactured with different shaft diameters:

2.5 mm
for particularly small devices such as headsets for cell phones. It is also used for data transmission on some pocket calculators or for cable releases on cameras. Also used in stereo systems to synchronize CD player and tape deck. This plug size is known as a micro-jack.
3.5 mm
mostly on portable devices (smartphones, MP3 players , Discman ), sound cards and small headphones; also called mini-jack or small jack .
4.4 mm
is used in professional recording studios. This jack plug, also known as the bantam plug or Tiny Telephone (TT), comes from telephone technology and has the advantage over normal jack plugs that the different diameters of the tip and ring prevent short circuits when plugging in.
5.23 mm
Also called pilot jack with the designation MIL-P-642/5 or PJ-068 is used in aviation radio devices with a headset to connect the microphone. The headphones are connected using a 6.35 mm jack. and the different diameters ensure the correct connection of the equipment.
6.35 mm
14 inch, on stereo systems and almost all devices used in music production , such as mixers , effects units , synthesizers , keyboards , electric pianos , electric guitars and guitar amplifiers . They are mechanically and electrically sufficiently resilient and have a large contact area; also called large jack or post connector , the latter due to the use of this format in old telephone exchanges.
7.13 mm
used in civil helicopters as well as in military aviation; also called NATO plug .
Connector structure:
1. Shaft: Ground
2. Ring: Right channel for stereo plugs, negative polarity for balanced connections
3. Tip : Left channel for stereo plugs, positive polarity for balanced connections, signal (" hot ") for mono plugs
4. Isolators
Circuit symbol:
A socket, two-pole,
B socket three-pole, sleeve grounded,
C socket three-pole with insulated 2 × three-pole switch,
D socket three-pole with 2 × two-pole switch, NC contact

There are jack plugs in versions with zero (optical), two (mono), three (stereo), four (stereo + additional) and five (stereo + stereo additional) contacts.

English name

There are different names for jack plugs in English: phone connector , phone jack (not to be confused with phono jack ), audio jack , headphone jack and jack plug . Plug is the general term for a plug and a socket is called a jack or socket , depending on the context .

Names of two- to five-pin jack plugs in the USA
Bez. Derived from translation Use for
TS Tip + sleeve Tip + shaft Mono plug
TRS Tip + ring + sleeve Tip + ring + shaft Stereo plug or single-channel balanced signal transmission
TRRS Tip + ring + ring + sleeve Tip + ring + ring + shaft Plug with additional contact (typically: microphone or video)
TRRRS Tip + Ring + Ring + Ring + Sleeve Tip + ring + ring + ring + shaft Plug with additional contact (typical: anti-noise )

Mono plug (two-pole)

3.5mm jack plug 2.svg
SIG (Sound) signal
GND Ground (return)

The mono plug carries the signal at the top and the shielding and return line (" ground ") at the rear part - the sleeve . The transmission is therefore asymmetrical .

Stereo plug (three-pin)

3.5mm jack plug 3 norm.svg
L. Left acoustic signal
R. Right beep
GND common ground (return line)

The stereo plug is the further development of the mono plug. To accommodate the third contact for the second channel, a ring was removed from the sleeve.

The tip is assigned the signal for the left channel, the ring behind the tip with the signal for the right channel. The rear part, the sleeve, is covered with the shielding and return line as with the mono plug. This type of signal transmission is also asymmetrical.

Mono plug with symmetrical connection (three-pin)

3.5mm jack plug 3 sym.svg
+ Line for audio signal, forward line for phantom power
- Line for audio signal with reverse polarity, forward line for phantom power
GND Screen for audio signal, return line for phantom power

In professional audio technology, symmetrical connections are mostly used, in which the signal is transmitted separately from the shielding and the ground potential via two equivalent lines - one with positive polarity ( hot ) and one with negative polarity ( cold ). Since disturbances caused by stray interference usually affect both conductors equally, the receiver can eliminate them by calculating the difference between the two signals. The rear part, the sleeve, is covered with the shield as with the mono plug. If you plug a mono plug into a symmetrically wired socket, you short-circuit the negatively polarized line to ground, which, depending on the circuit design, can lead to damage. XLR plugs are often used for balanced connections , but for reasons of space or cost, the same jack plugs are often used as for stereo connections.

To provide phantom power for microphones , the receiver (amplifier, mixer) has both signal lines connected to the same positive potential to ground (mostly 12 to 48 volts).

Stereo plug with additional function (four-pole)

Four-pole jack plug
3.5mm jack plug 4.svg
3.5mm jack plug 4i.svg
L. Left acoustic signal
R. Right beep
AUX Additional signal, e.g. B. Microphone
GND common ground (return line)

The stereo plug with additional function is a variant of the stereo plug in which an additional ring has been separated from the sleeve and a total of four contacts are available. Stereo plugs with additional functions are mainly used on cell phones and smartphones to connect headsets. Two different pin assignment variants are used to transmit stereo audio and a mono microphone channel. Both variants use the tip to transmit the left audio channel and the first ring to transmit the right audio channel. With the variant of the Open Mobile Terminal Platform (OMTP), the microphone channel is transmitted to the second ring and ground is on the third ring or the socket. In the variant of the Cellular Telecommunications Industry Association (CTIA), also known as the inverted variant, the assignment of the microphone channel and the ground are swapped so that the ground is on the second ring and the microphone channel on the socket.

Both variants allow normal headphones with a three-pin jack plug in a four-pin socket to be used without any problems, since the pin assignment of the tip and the first ring corresponds to that of the three-pin plug. The microphone channel is then short-circuited directly to ground by the plug. The variant makes a difference when connecting a headset to a three-pin socket with a dedicated contact spring for ground (but without a contact ring for the shaft), as used in MP3 players or computers, for example. If a four-pin plug is plugged into such a three-pin socket, the contact for ground is on the second ring. With the variant of the OMTP, the microphone channel is located here, so that a headset with a pin assignment according to the variant of the OMTP in a three-pin socket cannot be used. A headset with the pin assignment according to the CTIA variant, on the other hand, can be used in three-pole sockets without any problems, since here the ground is on the second ring and is correctly contacted by the socket. In this case, the microphone channel is without contact and inevitably has no function.

Adapter between OMTP and CTIA.

The pin assignment according to the OMTP variant is used by older cell phones from Nokia, Samsung and Sony Ericsson; the CTIA version from Apple ( iPhone , iPad , iPod and MacBook ), AVM, Blackberry, Xbox One Stereo Headset Adapter, HTC and newer Nokia, Samsung and Sony cell phones. It is also used in some notebooks from HP, Lenovo and Dell as well as in other devices. For some, especially older, cell phones, the pin assignment may differ from the variants described above. Standard accessories can then only be used with the help of adapters.

The microphone is bridged with resistors to control the audio player. The following resistance values ​​are used:

button resistance
Play / pause <70 Ω
Vol + 210-290 Ω
Vol- 360-680 Ω
(reserved for voice control) 110-180 Ω

Special applications of the four-pole jack plug

TRRS-to-USB adapter for the MP 9200WP MP3 player from SEG

In addition to being used to connect headsets, four-pole jack plugs are also used to transmit multi-channel sound, audio, video and USB signals. On an MP3 player, the four-pole jack plug offers the option of connecting the MP3 player to the PC using an adapter via USB, which means that there is no need for a further plug connection for USB.

Video-audio adapter with four-pole jack plugs

This plug is used on some camcorders , digital cameras and TV HD receivers to enable playback in FBAS format and analog two-channel or stereo sound on a television set. The pin assignment is not standardized in these cases and is determined by the respective manufacturer of the device.

Stereo plug with additional function (five-pin)

3.5 mm jack plug with additional function (5-pin)

Developed by ITU-T and standardized as P.382, these plugs are mainly used for stereo headphones with integrated digital noise reduction (also " active noise compensation ", English Active Noise Reduction [ANR], Active Noise Cancellation [ANC] or Digital Noise Cancellation [ DNC]) and have so far been found in higher quality Sony smartphones. In contrast to four-pin plugs, in which two audio channels and only one microphone channel are transmitted, the five-pin version offers an additional microphone channel so that stereo audio and stereo microphone signals can be transmitted at the same time. Interfering signals can be recognized independently for both ears, and during a phone call with a noise- reducing headset , the second microphone remains to be used to reduce background noise.

Switching function

The socket or coupling can be equipped with additional switching contacts that are actuated by the plugging process. In devices with built-in loudspeakers, these are often muted as soon as a headphone plug is plugged into the corresponding connection. Another example is devices that pause when the headphone plug is removed from the socket. In some guitar sockets and effects devices there are switches that only turn on the built-in impedance converter when a cable is plugged in.

Optical jack plugs

Toslink jack plug

There are also jack plugs for the optical transmission of signals in TOSLINK format. These are mainly used on notebooks or PC sound cards . There are combined sockets that can contact electrical jack plugs as well as built-in optical transmitters or receivers.


There are adapters for many different combinations. The following are common:

Through the use of adapters to increase contact resistance as well as the likelihood of contact difficulties.

Many headphone manufacturers include an adapter with their products so that the headphones can be operated on devices with a 3.5 mm or 6.35 mm jack socket. If the headphones are mainly intended for use on portable devices or computers, a 3.5 mm plug is used on the cable, onto which an adapter plug to 6.35 mm can be plugged or screwed. Conversely, headphones that are only occasionally used on portable devices use a 6.35 mm plug with an adapter plug to 3.5 mm, but due to the greater leverage of the 6.35 mm plug, the 3.5 mm plug -Socket can be easily damaged. An adapter cable is better here, i.e. an adapter with a short piece of cable between the two plug-in elements. For operation on particularly compact devices, there are adapter plugs and adapter cables to connect a 3.5 mm plug to a 2.5 mm socket.


For the color coding of the plugs and sockets, see identification color if necessary .

Since simple jack plugs are mechanically not very robust, their field of application is more limited to small electronic devices (including portable ones such as smartphones ) and home electronics (including personal computers ). In professional recording studios ( sound engineering ) or in musical stage technology , XLR connectors are used more , only electric guitars are still often connected via 6.35 mm jack plugs.

There are also high-quality special designs with mechanical locking that can at least compete mechanically with XLR connectors.

Headphone jack

Three-pole stereo plugs in the 3.5 mm version have been the standard connector on the market for headphones for portable devices since the 1980s; miniature portable devices also use less than 2.5 mm plugs. In contrast, the 6.35 mm plug is used for high-quality, non-portable devices (e.g. hi-fi amplifiers) and in professional environments.

Various manufacturers also use four-pin 3.5 mm jack plugs, often for remote control of the device on portable devices using a small switch in the headphone cable. Usually the additional contact can be short-circuited to ground without any problems so that conventional headphones can also be connected.

The company Apple uses the fourth contact in some laptops to one where composite video signal can be output, so a TV with a single connector connected. Here, too, the additional contact can be short-circuited to ground without damage. Nokia offers this function on some smartphones (e.g. N95), so the mobile phone can be connected to the television. Even with some Sony - camcorders is led the composite video signal via the AUX contact.

Some manufacturers use a 3.5 mm jack socket on portable digital audio devices, which feeds an optical S / PDIF signal to the tip of the jack plug and, at the same time, a stereo signal to the conventional metal contacts. The headphone jack can be used as usual, but alternatively a jack plug made entirely of plastic ("zero-pin") can be plugged in, at the tip of which a light guide emerges to connect the device with an optical digital input, for example on a HiFi Amplifier to connect. The contacts in the socket only serve to hold the plug.

With stereo, the ground contact (often also in the connected cable) is shared. This leads to an influence on the foreign channel, especially with low-impedance listeners. The crosstalk can no longer be neglected, especially since the contact resistances are typically critical. With the DIN square plugs , which are rare today , the mass was independent, the channels ideally separated.

Line level connection

The pin assignment is identical to the headphone connection, but the level is different and the external connection impedance is higher than with headphones. 3.5 mm stereo connectors are common on portable devices and on computers, as well as 6.35 mm connectors in mono and stereo in semi-professional environments and in devices for musicians.

High-quality devices often have a balanced 6.35 mm mono connection for each channel.

The headphone connection can be used as a line output. Depending on the source, it is possible that the headphone output has too low a level and cannot control the input sufficiently. A headphone output is adjustable in level. A line output, on the other hand, only has a rough level adjustment - if at all.

In the consumer sector, cinch connections are mostly used for line-level signals , sometimes - especially with older devices - DIN connectors are also used . 3.5 mm jack plugs are used in the PC sector.

Microphone connector

Stereo microphones

The pin assignment is identical to the headphone connection, albeit with a significantly lower level and different impedance.

Tip: left, ring: right, shaft: ground

Mono microphones

  • Two-pole plug: tip: signal, shaft: ground; if necessary with toner supply
  • Three-pin plug, 3.5 mm, asymmetrical, consumer variant (e.g. Soundblaster ): tip: signal, ring: supply (e.g. 1.5 V or 5 V), shaft: ground
  • Three-pin plug, 3.5 mm, unbalanced, variant of wireless microphones (e.g. Sennheiser): tip: signal with audio feed (e.g. 10V), ring: line input, shaft: ground
  • Three-pole plug, symmetrical : tip: +, ring: -, shaft: ground; possibly with phantom power

Professional microphones (with the exception of clip-on and neckband microphones) are usually not connected via jack, but via XLR connectors.

Guitar connector

Electric guitars and electro-acoustic guitars usually have a 6.35 mm mono socket and are connected to an amplifier input via a cable with a mono plug. The assignment is the same as for the microphone connection. There are also models that transmit a stereo signal through a stereo jack. With active pickup systems, a switch contact in the socket can be used to switch the power supply to the built-in impedance converter on and off.


The insert socket (e.g. on mixing consoles) is used to loop external effects devices into the signal path , namely before the fader (in simple mixing consoles directly after the input amplifier (gain), in larger consoles it can also be switched after the EQ). The internal signal path is interrupted by an isolating contact on the jack socket as soon as the jack plug is inserted. One contact of the three-pin jack plug (usually tip) picks up the signal, the other (usually ring) feeds it back. The signal routing is therefore unbalanced. A special insert cable is required to connect the effects devices. Usually only so-called dynamics (e.g. compressor) are looped into the insert, while delay effects such as reverb are integrated via aux send and return.

With a special cable, an insert socket can also be used as an (unbalanced) direct out. To do this, the contacts of the tip and ring of the insert plug must be connected in the connection cable.

Data transfer

Some manufacturers of pocket calculators use the jack standard to equip their devices with data transmission. Individual variables, but also entire programs, can be transmitted from pocket calculator to pocket calculator, but also from pocket calculator to PC (e.g. the TI-83 series from Texas Instruments).

The iPod shuffle (2nd generation) uses a four-pin jack plug to transmit a USB signal. The built-in battery is also charged by the 5 V voltage it contains.

In music electronics, pure switching signals, for example from a foot switch , are often transmitted using 6.35 mm jack plugs.

Sensors for, for example, the pulse on exercise bikes are often equipped with jack plugs. The lack of a mechanical lock is an advantage here. When the cable is stretched, the connector loosens without damaging the connection.

Jack plugs and sockets were also used to back up data on analog cassettes in older synthesizers .

Some older EKG devices had jack sockets from which the cables to the heart sensors came off.

The headphone connection of the Nexus 4 is also a UART connection .

Power supply

Adapter for universal plug-in power supplies

Jack plugs with a diameter of 2.0 mm, 2.5 mm and 3.5 mm are occasionally used for powering small devices. Since the contacts are exposed, these plugs can lead to a short circuit as soon as they are plugged in . The plug-in power supply unit used should therefore be short-circuit-proof. In most cases, barrel plugs (on the right in the picture) are used for the power supply . Neither the dimensions of the plugs nor the polarity of the contacts are standardized. Most of the time, the tip is connected to the positive pole and the shaft to the negative pole.

Loudspeaker connection

Instrument amplifiers in public address technology traditionally use jack connectors to connect internal and / or external speakers . Jack sockets and plugs are used, especially for devices in the low to medium price range, despite their disadvantages:

  • The contacts are not touch-safe. The SELV voltage limit value (25 volts alternating voltage) is easily exceeded.
  • High currents flow, which stress the jack connector system in limit areas. With a power of 500 watts and a loudspeaker impedance of 4 ohms, a current of more than 10 amps already flows.
  • When the plug is pushed into the loudspeaker box, the amplifier is short-circuited and can be destroyed when switched on.
  • Inputs and outputs of devices as well as switching inputs (all usually designed as 6.35 mm jack plugs) can be mixed up, which means that high electrical power can be fed into sensitive inputs or outputs can be connected in parallel in an impermissible manner.
  • Tube amplifiers must not be operated without speakers. If the plug contact comes loose, the amplifier can be destroyed.


In the aviation plugs are used in various sizes:

  • Civil aircraft (powered aircraft for general aviation and commercial aircraft with the exception of Airbus models using XLR connectors ):
    • Headphones ( headset ): 6.3 mm jack plug, two-pole and rarely also three-pole, referred to as PJ 055
    • Microphone (headset and hand-held microphone): 5.23 mm jack plug (0.206 inch) two-pin, designated as PJ 068
  • Helicopters and military aircraft (including fighter jets):
    • Headphones, microphone (headset): 7.13 mm jack plug (0.281 inch) with a total of four poles (tip plus two rings + shaft), designated as U174 / U , rarely as TP120 or colloquially as a NATO plug


Loose contacts

In particular, the smaller versions of the jack plug (3.5 mm and 2.5 mm) are mechanically not very stable, so that loose contacts can arise. Even with professional designs, the ground contact often does not have its own contact spring.

With many low-cost devices and cables in particular, the contacts in the sockets and on the plugs are of very poor quality. The contacts are bad even fresh from the factory, they can also oxidize, and an unfavorable mechanical design causes loose contacts. This often affects the ground contact, which can lead to hum and crosstalk between the two audio channels, especially with low-resistance loads ( headphones ). With mains-operated devices, it is a nuisance because a high resistance between the device grounds creates an interference voltage between the two points. If the ground connection is completely interrupted, the two sound converters of the headphones are connected in series with opposite polarity between the signal outputs. The mono component is eliminated and the stereo differences result in a typically low-bass, single-channel signal that is difficult to locate. When recording music, only a reverb remains from the vocals and central solo instruments.

In many mobile devices, the sockets are soldered directly to the circuit board and not attached to the housing. Leverage forces occur during use, which can break solder joints.

Short-circuit effects when plugging in

The jack plug first connects the signal lines and only then the ground line. During insertion, the tip (left channel) first comes into contact with ground, then with the contact spring of the right channel and finally with the contact spring of the left channel. Similarly, the ring for the right channel first comes into contact with ground before it rests against the contact spring of the right channel. This leads to noise at the moment of plugging in the signal source when the cable leads to the input of an amplifier. Conversely, a jack cable at the amplifier output will cause a short circuit when plugged into the signal load (e.g. loudspeaker). (For loudspeakers see SPK - speakON , for line / microphone see XLR .)

Depending on the design and manufacturing quality, with some connections the contact springs even bridge the insulation rings of the connector when they are inserted and thus lead to a temporary short circuit in individual channels. For example, the amplifier outputs of some headphone connections are short-circuited in a certain position when plugged in, as is the case with some power supplies with a jack plug. While headphone amplifiers are usually temporarily short-circuit proof, all other plug connections should therefore only be connected to devices that are switched off in order to avoid overloads caused by such short circuits. Inferior power packs or cables can become very hot and cause damage.

Short circuit effects due to mono plug, symmetrical connections

Mono and stereo jack connectors are electrically incompatible: mono plugs in stereo sockets short the right channel to ground, stereo plugs in mono sockets have no connection (open) for the right channel, or the right channel is shorted to ground. So this one remains silent.

If, in professional studio equipment, the cables for unbalanced audio signals with mono jacks are plugged into sockets for balanced connection (stereo sockets), this creates a short circuit in the complementary (inv) signal that is on the right pole (ring). The input or output and thus the connection act asymmetrically and thus naturally lose the advantage of a symmetrical data connection with a differential signal.

A symmetrical output reacts differently depending on the circuit. High quality servo / floating outputs behave like an unbalanced output with a mono jack without any problems. The complementary (inv) pole must be connected to ground for asymmetrical operation.

The more common ground-symmetrical outputs, on the other hand, with mono jacks can show not only the loss of the typical advantages of a symmetrical connection but also increased distortion and a heavy load on the electronics. In such amplifiers, the short circuit of the complementary (inv) pole must be avoided. If possible, a stereo jack should be used here, but the ring should not be connected to ground, even if problems are not always immediately obvious.

If possible, with semi- symmetrical connections, the cable should be symmetrical in two-pole pairs. The adaptation then takes place exclusively on the asymmetrical side. In the case of unbalanced 6.35 mm jack (mono) inputs, the adaptation takes place automatically and optimally in the device in many cases; this usually also applies to unbalanced mono jack outputs. With pure 6.35 mm connections, the wiring is exactly the same as with balanced connections. Otherwise, the cable and one side of the connector are constructed completely symmetrically, but the adaptation then takes place in the connector (or via an adapter) on the side to be connected asymmetrically (typically no 6.35 mm jack plug or no line connection). Some aspects of differential signal processing are still used. (In the case of cables to ground-symmetrical outputs, the second wire in the cable can be omitted, so a cheaper coaxial cable can be used. With such outputs, even with optimally adapted connections, no advantages of a differential coupling can be used.) Finished optimal cables are very rarely available for sale , optimal adapter also hardly.

In the case of jack cables, it should also be noted that stereo and symmetrical (mono) cables can hardly be differentiated from the outside and are usually not differentiated in retail. In the case of stereo cables, the two signal-carrying wires should be shielded separately, whereas in the case of symmetrical cables, they should be shielded in pairs. This also contributes to the uncertainty of cabling with a jack plug.

Likelihood of confusion

With jack plugs that are used for power supply, there is a risk of short circuits if the plug comes into contact with conductive objects. A long short circuit between the connector tip and the sleeve can destroy the power supply unit. If a jack plug connected to a power supply unit is plugged into a headphone, microphone or line connection, the audio device can be destroyed.

The contact assignment for audio signals (loudspeakers, headphones, etc.) documented above is used by all manufacturers. However, there is no agreement for power supplies. It is often stated on the devices or in the operating instructions which assignment is used. In the case of direct current, the negative pole is often on the sleeve and the positive pole on the tip.

Color coding

For the 3.5 mm connections on computer sound cards / mainboards , color coding of the inputs and outputs according to the PC99 specification has been established:

colour function
pink Microphone input ( mono ).
blue Line-in (stereo).
green Output for loudspeakers , line-out ( stereo )
black Rear speaker output (stereo)
silver Side speaker output (stereo)
orange Subwoofer output and center output.

Often switchable as an alternative to the digital output.

The exact colors may differ in hue and saturation. The color coding can also be found on jack plugs, headphones , CD players , MP3 players and MiniDisc players.

See also

Web links

Commons : Jack plug  - collection of pictures, videos and audio files
Wiktionary: Jack plug  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. IEC 60603-11 "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)"
  2. 4.4 mm Bantam miniature jack plug ( Memento from December 15, 2017 in the Internet Archive )
  3. NEUTRIK BANTAM JACK PLUGS - 4.4mm - Canford. Retrieved April 15, 2020 .
  4. elv.de: Electronics knowledge about: The jack plug
  5. Data sheet of a smartphone audio chip with an application example (PDF file; 474 kB)
  6. Overview of the compatibility of headsets with different cell phones and smartphones ( Memento from December 27, 2010 in the Internet Archive )
  7. Android Wired Audio Headset Specification
  8. PDF data sheets with manufacturer-specific pin assignments for 3.5 mm jack plugs
  9. Technical requirements and test methods for multi-microphone wired headset or headphone interfaces of digital wireless terminals
  10. EW Plug Pin configuration - Sennheiser UK Support. Retrieved October 15, 2019 .
  11. ^ Building a Nexus 4 UART Debug Cable