TRRS plug to two TRS jack headset adapters

Android smartphones and PC use TRRS headset connectors. You can find details on that interface on my Telephone handset to smart phone and laptop posting. Ealier PCs used two TRS plugs (mic and headphones) for headsets. Because both connection types are still in use, sometimes adapters are needed.

Here are some details of those adapters.

The first suspect is  not very good types

The problem with those has been that 3.5 mm jacks are so close to each other that many 3.5 mm jacks do not fit in well.  Other issue is that the 3.5 mm jacks and the cable are not very durable. The connectors became loose quite quickly and cable failed on one of the unit. I also had some compatibility problems with some headsets (not detected correctly by smart phone and/or no mic sound).

Second better one is this 3.5MM 1 Male To 2 Dual Female Earphone Microphone Y Splitter Audio Cable Adapter



  1. Tomi Engdahl says:

    3.5 mm Headset: Accessory Specification

    This article specifies requirements for 3.5 mm plug headsets to function uniformly across the Android ecosystem.

    CTIA pinout for a 4-segment plug.

  2. Tomi Engdahl says: says
    “Mic DC resistance 1000 ohms or higher”

    There is some upper limit on what is the allowed maximum mic DC resistance, because if the mic circuit is completely open circuit, devices do not seem to detect that there is mic connected. The second adapter has 10 kohms resistor, that makes sure that when this adapter is connected to smart phone or suitable PC, it the device will think there is mic connected (no matter if actual mic is plugged in or not).

    Another note:
    Be careful what is the mic impedance you plug in. The interface is designed for electret microphones. If you plug in for example dynamic microphone, you it will not work correctly. Dynamic microphones typically have less than 1000 ohms DC impledance, which is too little for mic use. Several lower than 1000 ohms impedance levels are used to signal if buttons on certain headsets are pressed. So if you plug in wrong type of mic, the smart phone can think those buttons are pressed. Plugging in dynamic mic can cause for example phone to think volume- is pressed (has happened to me). I have also had one electret mic that was randomly detected as button presses…

    Control resistance values according to

    0 ohms [Function A] Play/Pause/Hook (required)
    240 ohms [Function B] Vol+ (optional)
    470 ohms [Function C] Vol- (optional)
    135 ohms [Function D] Reserved (optional) (Nexus devices use for voice commands)

    Function A supported operations:
    Play/pause/hook (Short Press), Trigger Assist (Long Press), Next (Double Press)

    CTIA pinout order (LRGM) is required in Android devices to be supported (this is what the adapters here are designed for)
    OMTP pinout order (LRMG) is optional (some regions have legal requirements for OMTP pinout)

    Ear speaker impedance should be 16 ohms or higher: Recommend 32 – 300 ohms

  3. Tomi Engdahl says:

    Mic charateristics from

    5.4.1. Raw Audio Capture

    If device implementations declare android.hardware.microphone, they:

    [C-1-1] MUST allow capture of raw audio content with the following characteristics:
    Format: Linear PCM, 16-bit
    Sampling rates: 8000, 11025, 16000, 44100 Hz
    Channels: Mono
    [C-1-2] MUST capture at above sample rates without up-sampling.
    [C-1-3] MUST include an appropriate anti-aliasing filter when the sample rates given above are captured with down-sampling.

    5.4.2. Capture for Voice Recognition
    If device implementations declare android.hardware.microphone, they:
    [C-1-1] MUST capture audio source at one of the sampling rates, 44100 and 48000.
    [C-1-3] MUST, by default, disable any automatic gain control when recording an audio stream from the AudioSource.VOICE_RECOGNITION audio source.
    SHOULD record the voice recognition audio stream with approximately flat amplitude versus frequency characteristics: specifically, ±3 dB, from 100 Hz to 4000 Hz.
    SHOULD record the voice recognition audio stream with input sensitivity set such that a 90 dB sound power level (SPL) source at 1000 Hz yields RMS of 2500 for 16-bit samples.
    SHOULD record the voice recognition audio stream so that the PCM amplitude levels linearly track input SPL changes over at least a 30 dB range from -18 dB to +12 dB re 90 dB SPL at the microphone.
    SHOULD record the voice recognition audio stream with total harmonic distortion (THD) less than 1% for 1 kHz at 90 dB SPL input level at the microphone.

  4. Tomi Engdahl says:

    How does the phone detect if 3.5 mm jack circuit is closed?

    On Android phones, on iOS devices, and on HD Audio PCs, no mechanical switches in the socket are used. Instead, the headphone socket has 4 contacts instead of 3, and accepts both 4-contact headsets and 3-contact headphones. The sleeve of the 3-contact headphone audio jack connects two of the socket contacts together.

    One of the contacts is responsible for microphone and usually feeds 1.5-3.3v of voltage through a current limiting resistor (2-10 kOhm), which is necessary to bias a JFET transistor in the microphone capsule of a headset. DC resistance measurement between the microphone pin and the ground pin of the socket can be used to detect the kind of device plugged in – it will be 0 Ohm for a headphone, infinitely high for no device connected, and about 2 kOhm thereabouts for a headset with microphone.

    There have been quite a few answers on this, but still some additional clarifications may be helpful:

    yes, quite a few headset jacks include still an insert detect switch, which may also be a signal switch for simple (mono) headsets.

    when the insertion is detected by some means, the headphone amplifier may enter a detection mode (see e.g. WO 2006045617 A3 patent application) where the host device detects what is connected (stereo headphones, mono headset with mic, stereo headset with mic, video connector, etc.) and in which order the ground and microphone wires are. This is included in the latest revision of the OMTP headset standard. This kind of detection wouldn’t be fooled by a non-connected plug in the original question.

    Apple 3.5 mm jacks employ a proprietary device identification chip connected across the microphone line.

    Most jack sockets include a switch that is opened when a jack is inserted.

  5. Tomi Engdahl says:

    Just to complicate things, TRRS plugs come in two different types, with the mic connection being in a different place. The original Nokia standard for GSM was called OMTP (Open Mobile Terminal Platform), while the newer one is called AHJ (American Headset Jack). I note that Nokia switched to AHJ when it launched its Lumia phones, and it has also been used by HTC and other Android manufacturers. Apple uses an AHJ layout with non-standard signalling and controls: it’s sometimes referred to as CTIA. Software may be able to handle some of the differences.

    It’s true that smartphones can be very convenient for recording audio, and it’s also true that an external mic will improve the quality of the recordings.


  6. Tomi Engdahl says:

    How to Use XLR Microphone on iPhone – Connect XLR Mic to iPad and Apple Devices

    XLR to iPhone DIY adapter

    Easy to build adapter for dynamik and self powered XLR microphones and iPhone. Works with Macbook Air.

    Sometimes iPhone or iPad does not recognize external mic so the solution I have found is to use a small resistor between pin 2 (mic in) and pin 1 or 3 (ground) if u use a XLR. The small load will act like a pull down resistor and the ext mic will be recognized by the iOS. I have tried different resistor between 1 k and 10 k and they all work good. I did not use any resistor in series with pin 1 from my rode mic pro as the audio level seemed just fine

  7. Tomi Engdahl says:

    SESCOM IPHONE-MIC-1 XLR to TRRS Adapter Test and Review

    A test and review of the IPHONE-MIC-1 XLR to TRRS audio adapter on an HTC One M9 using the ATR2100-USB microphone by Audio-Technica. Find out how to record high-quality audio on your mobile device!

  8. Tomi Engdahl says:

    Best Way to Connect a Phone (iPhone, Android) to a Mixer.

    DIY iRig Guitar to iPhone Interface

    IRig Guitar Input (DIY)

    diy iphone guitar input / line output?

    Universal iRig for iPhone and the Android the hands or we save 30 euros

  9. Tomi Engdahl says:

    Build a Line Level to Microphone Adapter – Record from your Phone to Computer or Camera

    Here’s a simple box to solve a common problem – recording audio from your phone or stereo to your computer or camera, when the recording device only has a stereo microphone jack.

  10. Tomi Engdahl says:

    How to Use XLR Microphone on Android Phone – Connect XLR Mic to Android Devices and Tablets

    External Mic on Galaxy Devices

    A typical handheld mic like the Shure SM57 or SM58 has a step up transformer inside to 150 ohms nominal.
    The actual measured impedance might be more like 200 ohms.

    In days of old, a microphone was actually run into an input terminated in a 150 ohm transformer.
    Nowadays they go into a transformer-less unterminated input.

    I tried with a 4 conductor plug, a 0.1 µF cap and a Shure SM58.
    Note: A much larger capacitor (~100 µF) is really needed for decent bass response.
    It needed a good 30 dB in Audacity to make a reasonable level.

  11. Tomi Engdahl says:

    XLR to iPhone DIY adapter

    Easy to build adapter for dynamik and self powered XLR microphones and iPhone. Works with Macbook Air.


    Sometimes iPhone or iPad does not recognize external mic so the solution I have found is to use a small resistor between pin 2 (mic in) and pin 1 or 3 (ground) if u use a XLR. The small load will act like a pull down resistor and the ext mic will be recognized by the iOS. I have tried different resistor between 1 k and 10 k and they all work good. I did not use any resistor in series with pin 1 from my rode mic pro as the audio level seemed just fine. I hope it helps. Thanks for your nice vid.

  12. Tomi Engdahl says:

    Better Audio For Facebook Live: Using An iRig Pro Duo

    With the iRig Pro Duo, it’s now possible to get studio quality audio for live streaming for Facebook or Instagram on your smartphone. Today we look at the iK Multimedia iRig Pro Duo with a simple setup and a more complex setup!

  13. Tomi Engdahl says:

    IK Multimedia iRig Family

    Featuring an introduction to the IK Multimedia iRig Family by Derrick Floyd of IK Multimedia.

    Embracing the concept of bringing versatility and creative ease to both the education and professional fields of music, the IK Multimedia iRig Family offers musicians compact but loaded guitar interfaces to record ideas, work out parts or just plug in and jam with the band. All of this is done easily with a quick connection to your smart phone, multimedia or other supported device.

    The IK Multimedia iRig Family consists of: iRig2, iRigHD2, iRigPro and iRigProDuo.

  14. Tomi Engdahl says:

    Smallest Audio Interface Eva? IK Multimedia iRig PRO I/O

    Check out the brand new iRig PRO I/O by IK Multimedia. This may be the smallest interface, with the largest compatibility ever. From Android, to IOS, to Mac, to PC …

    IK Multimedia iRig Pro I/O Review

  15. Tomi Engdahl says:

    How to Use an External Mic or Microphone on Your iPhone or iPad

    Learn how to use an external microphone on your iPhone with a simple adapter cable which will allow you to hook any 1/8-inch or 3.5mm jack microphone into your iPhone, iPad, iPod Touch or even your MacBook. This cable is required because the iPhone and other Apple products are built using a TRRS type port which combines headset and microphone connects into one plug. You can’t simply plug a 3.5mm microphone straight into an iPhone or iPod and expect it work.

  16. Tomi Engdahl says:

    CTIA (international standard phone) and OMTP (domestic Chinese) connection formats

  17. Tomi Engdahl says:

    DIY iRig Test and schematic : homemade iRig (with impedance matcher) guitar to ipod, iphone, ipad

  18. Tomi Engdahl says:

    Saramonic SmartMixer for Camera or iPhone/Android

    Need more options for running sound on your camera or smartphone? The Saramonic Smartmixer gives you three microphone options for capturing sound.

    Saramonic Smart Mixer Review

    Audio mixer for your smartphones. Tired of bad audio for your smartphone videos?

  19. Tomi Engdahl says:

    Great $23 Budget Preamp for Video Shooters

    Today we look at using the Saramonic SmartRig XLR preamp with video cameras. This cheap $23 preamp is very impressive and offers 48v phantom power and level control with a knob.

    hack video for this preamp here:
    Hacking the $23 Saramonic Preamp For Video Use

    It still seems crazy to me that the preamp in a 23$ accessory is better than the internal preamps in most dslrs. Like seriously guys, get it together. Amazing video Caleb, love seeing you mod stuff.

  20. Tomi Engdahl says:

    Use Your Earbud’s Media Controls On Your Laptop With This Useful Dongle

    David] sends in his very nicely designed “Thumpware Media Controller” that lets your mobile phone headphones control the media playback on your PC.

    We realize that some PCs have support for the extra pins on cellphone earbuds, but at least some of us have experienced the frustration (however small) of habitually reaching up to touch the media controls on our earbuds only to hear the forlorn click of an inactive-button. This solves that, assuming you’re still holding on to those 3.5mm headphones, at least.

    The media controls are intercepted by a PIC16 and a small board splits and interprets the signals into a male 3.5mm and a USB port.

    Thumpware Media Controller
    Use your headphone buttons to control sound and video on your PC

  21. Tomi Engdahl says:

    How To “Convert” A Laptop Microphone Port To Line In

  22. Tomi Engdahl says:

    To create the DIY remote shutter button, [NirL] used a spare limit switch, resistor, and cannibalized an old set of earbuds for the cable and 4-conductor 3.5 mm audio plug. Most phones and camera apps trigger the shutter when they receive a Vol+ signal through the audio plug, which is done by connecting MIC and GND through a 240 Ohm resistor.

    When the user presses the selfie stick button to take a picture, the smartphone recognizes the change in resistance between Ring 2 and the Sleeve of the 4-pole audio jack plug

    Not sure but roughly 240Ω +/- 1% button resistance is called for imitating the volume up function. Note that the microphone segment of the headphone jack triggers a picture once the circuit is closed by short-circuiting the GND (G) and MIC (M) wires, provided the button resistor is in the correct resistance range (210-290Ω).

    More details

    Obviously, this trick works only for Android since Apple devices demand custom circuitry to enable such functionalities.


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