DAI Euro port schematics

I would like to connect a Phonax Roger X with DAI connector to a Bernafon Soundgate 3 stereo input jack: a female DAI (3 holes) to stereo connector. There are connectors for stereo to DAI, e.g. here, which allow you to connect for example your mp3-player to your hearing aid. But unfortunately I haven’t been able to find female DAI to stereo connectors (Three holes—wire—stereo jack).

The solution is to build it myself or hack the male DAI-to-stereo connectors.

Does anyone know the schematics of the DAI Euro port connector? Does anyone know what the pinout is?

DAI stands for Direct Audio Access.
Euro port refers to the 3 pin connector that allows to plug in audio devices into your hearing-aid or streamer.

Picture of connector: All sizes | P1010252 | Flickr - Photo Sharing!
Picture of pinout: http://l-userpic.livejournal.com/30460700/6554328
Discussion of DAI cables: http://hearingaidhacks.livejournal.com/53103.html

At the risk of just talking to myself here is the summary of some input from the German forum microcontroller.net:
I’d connect it like this:

DAI Connector TRS Connector

GND ----------------------------------- SLEEVE (ground)

VCC - leave unconnected

OUT ---------------------±-[ 1 K ]---- RING (right channel)
|
±-[ 1 K ]---- TIP (left channel)

To have it documented here, the pinout of DAI according to
http://l-userpic.livejournal.com/30460700/6554328:

GND VCC OUT +-+ | | +--+ | | +-+ ) ( | | ) ( | | | | | | +------------+ | |

Re: Was ist das für ein Stecker?

Autor: Zulde Z. ([zulde_z](http://www.mikrocontroller.net/user/show/zulde_z)) Datum: 18.03.2015 17:53

I think that this would work for cables from a device (e.g. mobile
phone) to a 3pin euro port.

However, since the Roger X actually needs its power to work and generate
an output, I can’t leave the center pin unconnected. Rather I am
thinking to connect GRD and center to a hearing aid battery, GRD to the
2nd ring, --some older TSSR’s have GRD at the sleeve, but modern ones
apparently use it for the microphone of the headset according to a wiki,
– and OUT to top and 1st ring.

What are those --[1K]-- in your scheme? Resistors? Those will work to
attenuate the signal from a mobile phone to my hearing aids. However,
the Soundgate 3 expects a mobile phone level, while it will be getting a
microphone level. So I am likely to have the reverse problem of
amplifying the signal. Can I simply put a battery between OUT and top to
amplify?

So my main problems are:

  • Will the Roger X be able to handle the battery or is it too much
    voltage?
  • How can I amplify the signal if needed?
  • Is it correct that the GRD is minus and center is positive voltage?

Tried it with a 312 battery, which generated 1.245V between the Roger X GRD and V_DD(+), and a 500 Ohm resistor at the OUT before the split to tip and ring of a common stereo jack. Checked whether the GRD of the jack was not connected to the tip and ring.

Results:

  • Roger Pen doesn’t connects with the Roger X.
  • Roger X doesn’t generate any sound, nor indication beeps.

Further experiments:

  • Could try it with a TSSR jack.
  • Could check what the voltage is of the Octicon Streamer Pro battery, before changing the voltage.