Earphones with Integrated Mics and Mobile Phones

Everyone knows the 3.5mm standard earphone/headphone connector. It's the one that looks like this:
Take a close look at that picture though and you'll notice those two are not the same. The white earphones have what looks like a standard 3.5mm stereo TRS connector. The black earphones however have a 3.5mm TRRS connector. TRRS connectors allow for stereo sound going to the earphones, but also for a microphone audio signal going from the earphones to the connected device. These are typically found in smartphone earphones such as the Klipsch Image S2m.
Not all TRRS connectors are the same though. The Motorola Droid for example uses the following pin layout (image courtesy of kvconnection.com):
So from left-to-right we have 4 white strips. These are for the left-audio signal, the right-audio signal, the microphone signal, and the ground. The iPhone on the other hand uses a different TRRS connector pin layout:
Here, the ground and microphone ports are switched. What this basically means is that earphones with an integrated microphone that works on an iPhone, will most likely not work on the Motorola Droid or other phones with the first TRRS layout (the microphone won't work, but the earphones should still be fine as the first two ports for audio out are the same).

Note also that some iPhone/iPad/iPod models support earphones with integrated volume controls along-side the microphone (e.g. Klipsch Image S4i). I believe* this works by the earphones being configured to send special signals down the microphone port when a button is pressed, which the iPhone can pick-up and interpret into corresponding software actions such as increasing the volume or skipping tracks. These signals are non-standard. An iPhone specific earphone such as the Klipsch S4i is unlikely to work with other devices unless those devices have copied and implemented the Apple signal codes (which could be copyrighter or patented). So even if the TRRS port on your earphones have the matching pin-layout for the phone you're using, don't expect volume controls or track skipping or take-call buttons to work as expected. (*can't find a source to prove this).

Knowing which pin-layout a phone uses is a bit hard to find as well. kvconnection.com have a partial list here. They also have many different styles of adapters that can convert between different pin-layouts, and even different connector types (although not cheap).

So the moral of this post is, if you want to use fancy earphones with integrated features, make sure your phone is on the compatibility list, or get someone to confirm they work with your specific phone model before you buy.

And also, if you're thinking of using your TRRS earphones on a desktop or laptop or other MP3 player, you may need an adapter to make it work. A standard 3.5mm TRS jack can sometimes be too short to fit a TRRS connector, which means you won't be able to plug your earphones all the way in, and the left/right audio out signals may not make correct contact with the jack, so you may either get no sound, or poor sound with noise, or only sound in on one side, etc.


  1. Really interesting !!!

  2. I bought headphones with mic and they had a really short wire, and the supplied extension didn't work - I lost the left audio channel. I bought other extension cords and they didn't work either. Tried matching both different extensions with the phones own headset, still the same. Tried both SGS2 and iPhone 3GS, same result. Same thing with usual TRS-headphones without mic. And yes, using said headphones or headset without the extensions gave crystal sound in stereo.

    The extensions' male connectors looked just as long as the headphones'. Of course I couldn't see inside the female connectors, but it just seems strange they would both be too deep coming from different manufacturers?

    Any guess?

  3. All the mobiles phones do not have same pin connector. Some are thick, thin, narrow etc in shapes. So you cannot use single headphones with all. Before buying the, you should know the type of pin.


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