As per this picture top to bottom = MIC at the Top, GND, Right, with Left at the bottom = CTIA
I will refer to them a Top, 2nd, 3rd, Btm respectively.
also the measurements I show are from a RIG 300HX (xbox version, Xbox is known to be CTIA, so plugging in and testing your headset(gaming) on an xbox controller may also prove it.
Using a good multimeter, choosing the best range on your meter, for each connection, to find the most accurate answer for each measure.
measure: Top-->2nd = MIC ohm might equal 50-20000 ohms
- for me:
- Top-->2nd = 8000 ohms
now measure 3rd-->Btm
- for me:
- 3rd-->Btm = 320 ohms,
- each ear (L&R) should be half, or 160 ohms in my case.
at this point we still do not know which is ground, but what we do have is the total impedance
so now you will do 2 measurements
whichever is equal to half of 3rd-->Btm
- = (3rd-->Btm)/2
- will be the GND
In my case:
- 2nd-->Btm = 160 ohms
- so 2nd=GND meaning I have CTIA
if Top-->Btm = (3rd-->Btm)/2, then you have OMTP
Here are my measurements:
- MIC-->GND = 8000 ohms
- L-->MIC-->R = 320 ohms
- GND-->L = 160 ohms
- GND-->R = 160 ohms
- MIC-->GND-->L = 8160 ohms
MIC-->GND-->L means because MIC is connected to GND internal and so to is GND to Left/Right speaker, when can measure across MIC-->L/R to get a max reading.
Your readings may vary, but apply the same math and you should be fine.