Audio wired Headset

joerg joerg.twinklephone at
Tue Mar 4 15:47:15 CET 2008

Am Di  4. März 2008 schrieb Gilles Casse:
> Hi all,
> I am a little bit embarrassed: my audio headset is lost, another one
> bought recently is not compatible (a 4 ring model for a Nokia, the
> resulting sound is too low, almost unusable).
> Is it possible to buy a new audio wired headset from
> Otherwise, where can we get one please (OpenMoko distributor?).
> The wiki mentions several models.
> "Analog wired Headset
> There's a four-ring 2.5mm stereo jack which provides connectivity to
> old-fashioned wired headsets.
> The headsets used by Motorola smartphones (A780,A1200, ...) and the V-360
> have a compatible configuration."

I can't help by selling headsets, but at least i may deliver exact pinout for 
the jack from diagrams, so you might check for compatibility.

base = ground 
speaker left  (internal impedance 33R) to ground. (+jackinsert detection)
speaker right (internal impedance 33R) to ground.
tip = mic electret condenser type, to ground. 
      bias (power for mic) 2K2 from +3.3v(wolfson codec) 
      (+HoldButton shortcircuit to ground)

Due to the internal 33R resistors, any low impedance headset will not work (or 
only low sound). I guess 40R should be minimum impedance for the speakers.


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