1395Views15Replies

Author Options:

Converting digital headset to analogic one Answered

Hello! :D

Some time ago I have bought a Microsoft LifeChat LX-3000 digital, USB headset. Hmm...maybe it was not the best choice, but I want to convert it into an analogic one. In theory it is simple: I only have to remove the incorporated digital-analogic analogic-digital signal converter and connect the 2 wires of the headset to 2 Jack 3.5mm, one for the microphone and one for the speakers. Reason: my laptop's sound card is much better than the headset's built-in one.

I am pretty sure that this converter is located in the volume control box:
www.turbozone.ro/fotografii/Casti/Microsoft_JUG-00003.jpg

But things may not be as easy as they seem. Or are they?

As far as I have heard, the cable from the volume control unit and the headset consists in 2 wires. The cable of my old cheap analogic headset consists in 2 wires too. It shouldn't be complicated: the microphone wire get tied with the microphone wire and the speakers wire get tied with the speakers wire. But when I opened the old cheap analogic headset I noticed that each of the 2 wires branches out in 2 respectively 3 separate wires when they reach the headset: a blue one, a red one, a yellow one, a green one and a blue-yellow one. This is quite strange, isn't it? Or...do I have to worry about that?; should I simply tie the 4 wires together - old&cheap analogic speaker wire with LifeChat's speaker wire and old&cheap analogic microphone wire with LifeChat's microphone wire? I don't want to do somethig wrong.^^

Thanks in advance. :)

15 Replies

user
mitzoc (author)2010-02-23
user
gmoon (author)mitzoc2010-02-23

Sorry--if you don't use the "reply" button (at the bottom right of someone's msg), they may not see it when you bump the topic...

So--based on your feb 14 post, have you connected them to a a TRS plug? Tip to one headphone speaker, ring to the other speaker, shaft to the ground...

Select as Best AnswerUndo Best Answer

user
mitzoc (author)gmoon2010-02-24

Wow, I really did it!

Thanks a lot, gmoon! Now it only needs a few adjustments. A better connection is required, as the signal is losing from time to time.

Select as Best AnswerUndo Best Answer

user
gmoon (author)mitzoc2010-02-24

Cool--glad it worked!

You just successfully debugged and hacked your first electronic device. No stopping you now...

Select as Best AnswerUndo Best Answer

user
gmoon (author)gmoon2010-02-24

Oh--and buy a soldering iron. ;-)

Select as Best AnswerUndo Best Answer

user
mitzoc (author)2010-02-14

Wow.

I did how u said. One wire was the ground one (the ground of the headphones, not the ground that comes together with the green wire of the microphone). The other wire was the blue one. I heard a crackle in the left headphone. When I connected the red wire, I heard the crackle in the right headphone.

Hmm...what would that mean? That I have now a fully functional analogic  headset, that only needs 2 TRS connenctors (and a small volume controll unit)?

Select as Best AnswerUndo Best Answer

user
mitzoc (author)2010-02-07

Hmm... so I should connect a 3 V battery...but to which wires? Or should I connect it to the TRS connectors? ...and, would a 9V battery be too much and definately damage the headphones?

And...when I connect the battery, will I hear a crackling noise in the headphones? An instant noise or will the noise persist, until I take the battery out from the circuit?

Many thanks for your help. :)

Select as Best AnswerUndo Best Answer

user
gmoon (author)mitzoc2010-02-08

Disconnect the headphones from your current TRS connectors (the current wiring isn't correct anyway.)

I don't know which wires to connect--that's the challenge, to find the correct connections. One will be a ground that's common to both sides--my bet is that the bare copper shield is that GND wire...

Use a single 1.5V cell, instead of the 3V. I just tried it with a pair of analog headphones and the crackle is obvious. Yes, I think a 9V cell is too much.

The noise will be "instant" when you connect and disconnect the battery. It won't persist, and you might damage the phones if you leave the battery connected for long. Just quickly make-and-break the connection.

Select as Best AnswerUndo Best Answer

user
mitzoc (author)2010-02-07

Ok, the work proceeded. But it didn't have a happy end. :(

I sectioned the LifeChat Headset's wire (between the headphones and the digital-analog&analog-digital converter) and it is identical to the wire of my cheap analogic headset. A perfect match. So I just tied the wires together: red wire with red wire, blue wire with blue wire and so on. But when I plugged in the 2 TRS connectors, I could hear no sound. And the microphone was not functioning either. :'(

I don't know where the problem may lay: bad connection (I might have not tied the wires well), short circuit (I might have damaged the insulation of some wires), different materials (the metal of LifeChat's wire is different from the metal of the cheap analogic headset, I suppose) or more seriously, what I did is a stupid thing which nobody does (some things are not to be mixed together). So feel free to laugh at me.

Some photos:

Select as Best AnswerUndo Best Answer

user
gmoon (author)mitzoc2010-02-07

No one is laughing.

Unfortunately, there's no wire coloring standard. Just connecting red-to-red, blue-to-blue, etc. is no guarantee.

I'd suggest you test the headphone wiring. Use a 3V battery, carefully connecting it momentarily, then severing the connection (headphones will only respond to DC voltage when you make or break the connection. Leaving the DC connected for long could cause damage.) You should hear a crackle, once you stumble on the right wires.

Buy some alligator-clip jumpers for this purpose.

There's at least a 50-50 chance the bare copper shield wire is the ground (-) for the headphones.

All this assumes that there is no active circuitry within the headphones themselves (which I intimated before: "We can't know if there's any circuitry in the Lifechat cans beyond the control box"-- "cans" being each ear cup.)

Select as Best AnswerUndo Best Answer

user
mitzoc (author)2009-12-18

Hi!

I'm back. I have managed to open up the small volume control box. There is a whole electronic system inside, which makes me think that the digital-analog analog-digital converter is located there. Moreover, 5 wires branch out from the wire that ties the headphones with the volume control box, two of them being coloured in red, respectively blue. The other 3 wires (with the black, green and blue isolation) have no colour. So...5 wires vs 5 wires ... seems tieable.^^

Some pictures:
img696.imageshack.us/img696/4941/dsc02959.jpg
img689.imageshack.us/img689/6160/dsc02966o.jpg
img14.imageshack.us/img14/286/dsc02969eo.jpg

Select as Best AnswerUndo Best Answer

user
mitzoc (author)2009-12-13

Hello and thanks for helping me. :)

Here is a scheme of the electric circuit of my old and cheap analogic headphones.

Note:
Casca dreapta = right speaker
Casca stanga = left speaker
Microfon = microphone

As you have said, there are 2 channels, one for microphone and one for the speakers. But...the green wire is connected to the left speaker too. Note: There is NO intersection between the green wire and the blue-orange wire.

And for the time being, I am quite afraid to cut the wire of the LifeChat Lx-3000 too.^^ There is a saying around here: measure 10 times and cut once.:D

Select as Best AnswerUndo Best Answer

user
gmoon (author)mitzoc2009-12-13

You'll get more information by examining the plug end. After all, most headphone / mic combos can be used without the microphone--correct? Any computer audio output is wired as I noted; see this trs (tip/ring/sleeve) connector reference. I'd expect to see two plugs--one for the headphones, one for the mic.

So if the three conductor wire has a a TRS plug at the end, it's right, left, and ground.

Otherwise, I don't think your old headphones are much help here. We can't know if there's any circuitry in the Lifechat cans beyond the control box...unless you disassemble it.

Sometimes complete destruction is the cost of hardware hacking.

Select as Best AnswerUndo Best Answer

user
gmoon (author)2009-12-12

It's really difficult to say without any documentation or access to the device, but here's a guess:

Stereo headphones are typically fed with three wires-- one for left, one for right, and a common ground. The ground wire functions both as a signal path, and as a shield--the outer sheath of the cable.

It's likely the microphone has a separate shielded cable. The ground is probably shared at the control box, but the mic and headphones would likely NOT be encased together within the same same shielded cable (after all, grouping them together would defeat the purpose of the shield.)

Without dismantling the headphones, try a continuity test between wires in the other "branch"--are any two wires in the different branches connected? (0 ohms) They would likely be the ground wires... also for any wire connected to an outer sheath.

It's possible the microphone is isolated and doesn't share the same ground, but in any case the group of three wires is likely the headphones.

This looks to be a voice headset, primarily. Don't know if you'll ever get good audio response from the thing.

Select as Best AnswerUndo Best Answer

user
Kiteman (author)2009-12-12

(Bumped to front page for the attention of those that can help.)

Select as Best AnswerUndo Best Answer