Audio Jack 2.5 mm

Jae Stutzman jaebird at
Mon Apr 30 22:16:13 CEST 2007

---------- Forwarded message ----------
From: Jae Stutzman <jaebird at>
Date: Mon, 30 Apr 2007 15:12:13 -0500
Subject: Re: Audio Jack 2.5 mm
To: Brad Midgley <bmidgley at>

My motorola E2 has a 3.5 mm jack. Same as the N800.

On 4/29/07, Brad Midgley <bmidgley at> wrote:
> Wolfgang
> Judging from the high-resolution picture on the wiki it looks like the
> > phone has a very special 2.5mm connector with 4 separate electrical
> > connections (instead of the more common 3-connection version).  If I'm
> > interpreting this correctly they are running both ground,
> > left-earphone, right-earphone and microphone in one plug.  To me, this
> > seems much more convenient than the 2x 3.5mm plug method used for
> > computer headphones.
> hopefully it is a 4-conductor connector. unfortunately there are two ways
> manufacturers commonly wire up the 4-conductor 2.5mm connector. I have a set
> that is wired for the palm way of doing it that I plan to try.
> Nokia ships 4-conductor 3.5mm stereo headphones w/mic with their n800. The
> jack is backward-compatible with 3-conductor headphones. It's the first time
> I've seen a 3.5mm plug that could work with a microphone. It just might take
> a while to catch on.
> On the a2dp front, we got some help from Nokia on our codec and now it's
> running nicely in (mostly) 32-bit ops. It should be pretty easy for the cpu
> to encode stereo audio on the fly, but there is still a delay that we need
> to accommodate.
> Brad

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