We are developing and manufacturing sound amplifier using ADAU1761.
We finished all designs and tests, then just start mass production.
There is a key problem at this time.
Our device has one microphone input + two earphone(stereo).
Microphone needs two lines(input(In+bias) & ground)
Earphone needs three lines(right & left & monoout pin)
Therefore, it needs 5 lines for earphone with microphone.
But it is not easy to find 5 pole phone jack and plug. (only order-base production, and no ready-made parts)
We tried to connect the microphone bias - earphone monoout, ground etc.
But the result was heavy noise, not satisfactory.
My question is "Are there any method which can use one microphone and two earphone(stereo) with 4 lines?"
Please, give me some advices for me.
Thanks very much.