[jwolfeld]

I don't have an iPhone, but I have a Lenovo laptop which has the same kind of audio jack as an iPhone: 4 conductor, tip-ring-ring-sleeve (TRRS) style. I would like to buy an over-ear MONO headset with boom microphone for it, but those devices usually have 3 conductor TRS style plugs. Are they nevertheless compatible? I worry that the sleeve will short-circuit the left and right ear conductors to each other, or will short-circuit it to ground.

Do iPhone users who want an over-ear mono headset microphone have to buy something specially iPhone compatible, or will one designed for a laptop work as well?

Thanks.

[Spheric Harlot]

The sleeve will short-circuit the mic.

Left and right phones will work fine.

Having somebody solder an adapter to make the mic work and kill one side of audio is trivial, though.

[jwolfeld]

Thanks. I found a great blog which shows the pinout for this plug: iPhone Headset Plug | GeekSpeak
I can now clearly see why the mic will be shorted out, as you say. Both Monster and HeadsetBuddy offer adapters which tap off the microphone conductor onto a separate jack.

However, even though you indicated that the left and right phones will work fine, I'm still unsure about them. I found this quote in the TRS Connector entry on Wikipedia: "However, grounding one channel may also be dangerous to the equipment if the result is to short circuit the output of the right channel amplifier." This is what I'm afraid of. I guess what I really need to build is a TRRS plug to TRS jack adapter, wired like this:

Left: Plug tip to Jack tip
Right: Plug Ring A to nothing
Ground: Plug Ring B to Jack Ring
Mic: Plug Sleeve to Jack Sleeve

Does that make sense? Or am I worrying too much?

[Spheric Harlot]

The phones will work fine. Tip and ring are left and right, respectively, and have been for forty years.

[jwolfeld]

Trying to figure out why I don't seem to be able to understand your answers... Did you miss the fact that I'm using a MONO headset? There is no distinct left and right channel on the plug from a mono headset. If I'm not mistaken, the plug has ground on the first (and only) ring. That will ground the right output channel, won't it?

[Phileas]

All the cable adapters you'll ever need: http://kvconnection.com
This is the page you're looking for: http://www.kvconnection.com/iPhone-Adapters-s/8388.htm

We frequently use our iPhones to shoot video, to use external mikes you'll need an adapter.

[jwolfeld]

Thanks, Phileas. Is that your site? You're right, it has really everything I'll ever need. I believe this one is exactly what I'm looking for:
2.5 mm TRS headset to iPhone adapter - 3.5mm 4 conductor TRRS Male to 2.5mm TRS Female

The price is a bit steep, though, so I'm going to test my (ancient) soldering skills first. If it doesn't work, I'll be back.

[Spheric Harlot]

No. 2.5 mm jacks are those stupid miniature jacks that showed up on a couple cellphones, and nowhere else.

[jwolfeld]

True, but 2.5mm to 3.5mm TRS adapters are easy to come by, and the mono headset I have just happens to have one of those stupid 2.5mm plugs on it :-).