The new iPhone G3 has a flush mount headphone jack and that is a good thing. The original iPhone had a resessed headphone jack that made it inconvenient to say the least. I constantly grab a pair of headphones and have to slice off a bit of the plug to allow it to fit into the iPhone. But that only gives me good listening and doesn't provide a microphone.

There are a few companies making iPhone headphones with built in mics, but what I wanted was a microphone that allowed me to also plug in a pair of headphones. Monster Cable makes the Monster iSoicTalk Microphone Headphone Adapter for iPhone which has a fatal flaw. Take a look at what plugs into the iPhone:

You see that large section that plugs into the phone. Well, as the phone is in your pocket that part bends back and forth. And for me it finally failed. So I opened it up:

One of the connections got pulled loose from the TRRS connector.

TRS vs. TRSS

Headphone connectors are known as 1/8" phono connectors. But I like to use the name 3.5mm TRS. Tip-Ring-Sleeve is the type of connector while 3.5mm is the diameter. The iPhone uses a 2.5mm Tip-Ring-Ring-Sleeve (TRRS) for it's headphone + microphone. And the jack is compatible with a 3.5mm TRS stereo plug like most headphones have, assuming that you have cut down the outer width of the plug shell. So here is the "pin-out" of the iPhone plug:

• Tip = Left Audio
• Ring _a = Right Audio
• Ring _b = Ground
• Sleeve = Microphone.

So, I de-soldered the TRRS rod and added a length of cable. I used shrink tubing and tape to put together the larger bit and used a cork to make a mold for epoxying the end that plugs into the iPhone. It isn't pretty, but it works.

By the way, you know how the iPhone stops playing when you pull out the 3.5mm TTRS (headphone jack) out? Well, that is because when you short out the microphone (the sleeve) to the ground ( Ring _b ) you can pause the audio. The switch built into this Monster and into the original iPhone headphones does just that, it shorts out the microphone and ground. So, when you pull the jack out, the connector inside shorts and pauses playback. Quite a feature in my book.

[Correction on 2009-04-05: Thanks to an email it was brought to my attention that I was using 2.5mm throughout this blog post. The headphone jack for the iPhone has a 3.5mm diameter. I have corrected this mistake above.]