How do I convert a pair of aeroplane headphones to be used with a normal 3.5mm jack?

The pair of headphones are from QANTAS business class. They have 3 prongs: 2 x 3.5mm and one 2.5mm The two 3.5mm prongs are for left and right sound but the 2.5mm is (i think) for power for the headphones and the noise cancelling ability. I'm not sure how to incorporate the 2.5mm prong into a normal jack or whether it's even possible. I want to use these on an mp3 player or if the power needed is too big then on a laptop. Your help or ideas is appreciated! Cheers, Tal

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kelseymh6 years ago
For the left and right speakers, you can easily wire those to a 3.5mm stereo (3 pin) lead, and it sounds like you already know how to do that. I think you may be out of luck for the noise-cancellation power lead. But wait.... You are out of luck with an MP3 player, but I think you could do something to work on a laptop. Take the two wires for the 2.5mm lead, and hook them up to the power leads on a USB male connector. Then you can plug that line in to your laptop's USB jack (just like a USB lamp or coffe mug warmer :-), while you use the 3.5mm stereo plug (above) in the regular headphone output.
talco92 (author)  kelseymh6 years ago
Thanks man I'll try it out and let u know how it goes
Please be sure to take pictures along the way, so you can put up an Instructable when you're done :-) Even if the noise-cancelling part doesn't work, the rest of the conversion will still be interesting to people. Good luck!
talco92 (author)  kelseymh6 years ago
sorry for the late reply. it works! although the noise-cancelling feature is non-existant. Your usb idea was great. I forgot to document it but my friend also has a pair of these headphones and if I get around to modding his ones then I'll be sure to take photos ;) cheers
jfkendall6 years ago
Hi. What is most likely is that you have two mono plugs -- one for each speaker for each ear and one dummy plug that gives stability to the others or makes a better ground. I find it unlikely that it is a power plug unless there is amplification built into the headphones and that would increase the cost to the airline prohibitively. You can cut the wires and resolder on a new jack but, before you do, try going to a good dollar store and see if you can get a Y adapter. This will allow you to plug in each mono plug into a mono jack that is then prewired to a stereo plug. If you want a larger 1/4 inch stereo plug, you can buy an adapter that will allow you to plug in the 3.5 stereo pug into a 3.5 jack and use it as you would a pair of headphones with a 1/4 stereo plug. The other end of the adapter is a 1/4 inch stereo plug. Hope that this helps.
They are powered and the 2.5mm pin supplies the required power to effect the noise canceling feature.
FrereOP3 years ago
OK, here is the definitive answer.

They are active noise canceling headphones and are a special version of the commercially available LPE-880NC headsets made by Long Prosper Enterprise Company ( LPE ) (http://www.longprosper.com). They WILL NOT work without power and power is normally supplied from the socket in the seat.

Using simple components from Jaycar you can make a power supply in a small box with input sockets for the 2 x 3.5mm mono audio pins and the 1 x 2.5mm power pin. The audio inputs should be connected to a stereo 3.5mm socket (tip -L, ring - R, sleave - common) which will allow you to connect your audio source (MP3, iPod, FM Radio etc) using a 3.5mm stereo plug. They work with full noise canceling function.

Briefly, looking at the 3-pin plug FROM THE BACK with the pins facing AWAY from you, and the 2.5 mm pin at the TOP, the function of each pin is as follows:-

Top (2.5mm pin) - Power with tip connected to the positive terminal of the supply and sleave connected to the negative terminal of the supply.

Bottom Left (3.5mm pin) - Left Hand Channel with signal on the tip.
Bottom Right (3.5mm pin) - Right Hand Channel with signal on the tip.

The sleave of all pins (including the power and the stereo input socket) should be connected to the negative terminal of the power supply by connecting the sleave terminals of the sockets themselves.

I have made them work using a 3.0 V supply by connecting 2 x AAA batteries in series in a small battery box. Make sure you put a small on/off switch in the power supply line and only turn it on when you are listening otherwise it will be on all the time and you will drain your batteries. An enhancement would be the addition a low power indicator LED to show when it is switched on if you wish.
fatdoggydog5 years ago
Hi All... In case anyone is still wondering about this. I've found that if you just get one of the standard 2 pin connectors (i.e. join the L and R pins into a stereo jack), and then connect a battery jack and fix (as per photo) to the remaining shorter power pin you can get the full benefit of the noise cancellation!

Works very well... Not sure how long the battery lasts though and you have to remember to disconnect when not in use!

Hope this helps.

Hi Barry

What was the polarity of the power jack? Also the operating voltage for the noise-cancelling unit to function correctly.


JMS SEVEN5 years ago
I bought a splitter: 1 male to 2 female.  But this splits 1 stereo output to 2 stereo output.  Effectively, using this splitter, you will get mono output out of both ears since the left channel is shorted to the GND while the right channel is coneted to both signals. 

What is really needed is a stereo to dual mono splitter. So I opened up the splitter with an exacto knife (be careful not to cut yourself).  I cut off the left connector for the right side, and the right connector on the left side (they are pieces of copper).  Then I bend the left connector on the left side so it connects with the tip of the left side.  This works very well - much better than I expected.
beastboy6 years ago
I have a same headphone and open it. There is a a broad attached. Remove it and you will be able to use it after reconnected to a 3.5 jack in mp3 without using power.
talco92 (author)  beastboy6 years ago
"There is a a broad attached" what do you mean by that? cheers
In the left earphone, there is a ckt broad for amplify and it needs power. In order to use it in MP3, remove the wires and rewire to L, G and R. Hope this help.
BOOM56016 years ago
I'm guessing they won't make any noise until you supply the correct voltage for the built-in noise-canceling electronics. If the necessary voltage isn't marked on the headphones, and you can't find anything useful by googling, I'd disassemble them and identify the chip(s) inside. Then, find data sheets for those chips and determine the supply voltage required.
duck_tape_6 years ago
Do the two 3.5 mm jacks have a black line in the middle like the picture. If they do, just follow what other people have said. IF they don't have any lines in it the 3rd pron is probably the negative terminal for both other jacks. In this case if you cut the wire just before the jacks, there will probably only be three wires. You can just solder them to a standard 3.5 mm stereo jack.
mono jack.JPG
akosin6 years ago
use a splitter from radioshack or best buy!
sboy3656 years ago
cut off the jack, so that there is wires, then buy 3.5mm jack out of Maplin or radio shack, and wire up. hope this helps.
Laknight1176 years ago
splice the ends into a regular headphone cord and wire the power into a AA battery it might work/ or just buy a cheap pair of sound cancelling head phones for 5 bucks and replace the connections to the speakers the power inside the headphones