Integrating Telephone into W124 Audio System
 

I have a 1987 300E that came with the usual Becker audio system. It also came with an analog cell phone that was integrated nicely into the audio system: It has a microphone, audio was through the speakers, and one could dial through the radio preset buttons.

The analog cell phone has been removed, though I still have all of the parts. It just is not useful any longer.

How do I include this sort of phone system into a more modern radio/adapter/whatever? I am generally aware of bluetooth options, but those rely mostly on the cell phone to do the heavy lifting.

Is what I desire possible, or has technology passed this by?

Dialing through the radio isn't gonna happen, but assuming there's a way to manually switch over to the phone on the headunit somehow, you should be able to use the mic and speakers. If you can figure out the inputs wire it to a TRRS 3.5mm jack like so and plug into your phone.

http://i.imgur.com/Yt8ZpX5.jpg

I don't know how the audio system handled receiving calls, if it automatically muted the stereo and switched over to the phone or whatever.

Thanks for the reply!

I was thinking along the same lines. It was brought on by getting a Christmas gift: A wired headset for my iPhone. It works very well, and I much prefer the wired version to the Bluetooth ones, which always have sounded terrible to me. This one uses a single earpiece, but earbuds work, and I'm sure there are stereo earpiece/microphone units available.

So the hookup would be simple if there is an auxiliary port on the radio. I have seen some adapters advertised to connect iPods, iPhones and the like to Becker radios, but nothing is mentioned about the microphone line.

Is connecting a microphone in addition to the audio lines standard for all 3.5 mm cables/ports, or does one have to be careful? I've not found any pinouts yet to check.

You would be much better off using a Parrot bluetooth kit.

Becker in NJ can perform the auxiliary input modification to your head unit. You send the radio in and they send it back with a jack installed on a pigtail out the back of the radio.

If you indeed have the factory cell phone then the left front speaker was a special dual coil speaker. One half for the radio and one half for the cell phone.

I did this on my 1998 E300. I made a post for this about 4 years ago in this sub forum.

A Becker aux-in mod won't have a mic input. The audio will play through the speakers, but the phone mic will be used.


The diagram I posted is the correct pin-out for smartphones, but as jaybob says, it may or may not be feasible.

Thank you both for the replies!

I feared that the Becker modification would not use the existing microphone. They used to have more information on their web site, but I recall that they wired it through the tape deck. That would exclude use of the microphone without further effort. I'd think that this should be possible, but there may not be enough market demand to justify the effort.

Again, I've never had a call where the caller used Bluetooth that sounded good at all. Maybe they do exist, but I've not heard it personally. And a lot of friends and colleagues use Bluetooth connections in their cars.

If the Becker modification does not work (I will send them an email message), would a third-party radio be able to do what I seek? Or should I give up and start over completely?

A modern stereo with Bluetooth can work wonderfully. Mic placement is important. In my W201 I installed it where the driver a-pillar meets the dash, and I don't get any complaints about call quality.

My friend had his Becker modded. I forget where his mic is located, but it's kinda rough sounding sometimes. That could possibly be the service in his area though.

The way I did it in my W210: http://www.peachparts.com/shopforum/car-audio-multimedia/336476-analog-cell-phone-update-1998-w210.html

I used a Parrot kit to handle phone calls (handsfree profile) and streaming (A2DP profile).
The Parrot has a microphone and a small (approx. 10 W/ch) built in stereo amplifier, and a pair of line level outputs.

In a W210 the two dash speakers are dedicated to the cell phone. On the W124 the factory cell phone audio was shared via the dual coil speaker with the audio system on the left front dash speaker only.

If it was me (and I did plan to do this to my W124 wagon before I sold it) I would get another dual coil speaker from a W124 in the JY and put it on the right front to match the left front one. Use the Parrot amp to drive the second coils on these speakers. The primary coils continue to the audio amp.

Get the stock radio modified by Becker to obtain the aux input. They will send your radio back with a 1/8 inch jack interposed in the audio stream between the FM radio and the input to the power amplifier. The jack has switch contacts that when the plug is removed, the audio passes through. If a plug is inserted, the audio from the remote device replaces the audio coming from the FM tuner. This jack is on the end of a 4-conductor shielded cable.

You will want to remove this jack and use the 4 wires in conjunction with a relay to switch between normal radio operation and streaming. I was going to trigger the relay using the antenna control switch, placing the antenna in the 'down' position flips the relay to streaming operation mode.

The final piece of the puzzle is to trace out the muting lead from the factory cell phone controller into the radio. You will use this relay combined with an output of the Parrot to mute the radio while you're on the phone.

The Parrot model I used has a remote display head that I was able to integrate into the W210's built in cell phone controller. I think the W124 had a similar arrangement on the upper control panel. Not sure if you will have enough room to fit that display up there or not. The actual control device is a little remote that they expect you to strap to the steering wheel. I ended up using double stick tape to hold it to the lower control panel area in a blank spot, it almost looked factory.

Jay_bob,

That is impressive work and attention to detail! Well done!

I am considering replacing the radio with a Continental tr7412ub-or or its VDO equivalent. I've talked with Becker, and refurbishing the Grand Prix and installing the auxiliary port or Bluetooth costs a bit over $300. The above replacement radio costs $350 from Becker, or about $160 directly from Germany.

Stay tuned...

I found what adapter is required to install the radio with the existing wiring. However, it seems that an adapter for the antenna also is required (see
http://www.peachparts.com/shopforum/car-audio-multimedia/375208-continental-tr7412ub-anyone-have-one.html ).

It is not clear to me what antenna adapter is required -- can anyone give me a clue?