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13 September 2005

The 2.5 mm headphone dilemma, and perhaps the best solution

Smartphones, like my Windows-based Orange C500 or the Palm-based Treo series, make lovely little mp3 players. The sound may not quite be in the iPod league, but they are, after all, telephones, PDAs, video players and a whole lot more besides, so it would be churlish to make too much of that. And to top it off, my Smartphone cost rather less than an iPod.

But one of the areas which holds the Smartphone back as a music player is the manufacturers’ decision to provide 2.5 mm headphone sockets. Like most ‘emerging standards’, this one is nigh on impossible to find at high street retailers, and trust me, you’ll want to upgrade from the standard headsets that come with your phone pretty quickly.

That leaves you with two obvious options. Either settle for a set of ‘phones with a 3.5 mm and use an adaptor, or begin the ‘holy grail’ quest for a 2.5 mm pair. The former path means you have a world of choice, but the size of the adaptors, the degradation in sound quality that they bring and the extra weight hanging off your phone’s fragile 2.5 mm socket may dissuade you.

As for purchasing options, you’ll find the odd combined headphone/microphone for use with phones at some mobile phone shops, but acoustically they’re probably no better than the unit which shipped with your phone. And although there’s no option that I know of from mainstream headphone manufacturers such as Sennheiser, Sony and so on, there are a few retracting cable designs available from specialist manufacturers of PDA and phone accessories such as Proporta and Boxwave. Boxwave’s offering is currently on my review bench and I will blog about it (quite favourably, I anticipate) within the next day.

But there’s one other option which doesn’t seem to get a mention elsewhere—cut off the 3.5 mm plug from a pair of normal headphones or earplugs and solder on a small 2.5 mm plug which you can pick up from your local electronic hobbyist store. It’s not rocket science, and may give you the best of all possible worlds.Go to eebahgum!

14 comments:

Anonymous said...

I tried exactly that. Yet to my dismay, I got no sound from my favorite headphones after doing so. I dont know why? Didnt figure it to be a big deal, yet I hear absolutely nothing from my headphones now that I soldered the 2.5mm end on. Just thought I might let you know. Have you done this yourself, and if so, might there be something i have done incorrectly? The big problem lies in that a 2.5mm is a 4-conductor, where a 3.5mm is a 3-conductor. This is also the reason most adaptors only give mono sound when used.

eebahgum! said...

Hi Anon,

Yes, I have tried similar things on several occasions though not yet with a 2.5 mm plug.

You say the 2.5 mm had four connectors, so I gather that was two insulated wires, each with a coaxial shield around it. So the insulated wires will be your L and R signal wires, and the shields are both -ve or ground. The 3.5 mm by the sounds of it would have the L and R wires separately insulated, but with one coaxial shield running around both.

The 2.5 mm plug surely only has three signal areas on the actual plug part, at the tip, sleeve and base?

Anonymous said...

Thanks for the response. Yes...apparently the difficult thing is that you have to carefully scrape away all the insulation on the seperate wires. I tried that, and apparently i was unsuccessful and that is my problem. I hear another way is to use the soldering iron to slowly get the insulation off the wires. This is a very difficult task, and perhaps one that might cause some to not want to go through all the trouble. I will get it done (eventually). But maybe this might be a lesson to those who might want to try this. It is not as simple as it seemed at first! However, for me, it is still the best solution ;) Thanks

Anonymous said...

Shure as in www.shure.com makes the i4c-t that is a high def IEM with mic and has a 4 conductor 2.5mm plug you should check out

Anonymous said...

I've always had a problem with that protective coating and generally take several attempts to scrape it off before I can get a good connection. But then it suddenly hit me, if the coating is of a plastic nature then it should burn right off. Sure enough, tale a lighter to the tips and the coating quickly burns off, then all you have to do is wipe the soot off and get to soldering. I just made a nice set of 2.5mm with volume control sony ear buds for my treo and my 2.5mm mp3/mp4 player.

Anonymous said...

i dont know if anyone will see this because this is an old post but if someone that already did this could show a detailed picture of what wires to solder to what

Dave said...

I am going to try this. I just ordered 4 2.5 mm plugs. Pictures of the process would be nice, or a very detailed explanation

hagsmich said...

I figured it out and was able to make a set of 2.5mm headphones from a 3.5mm set. I bought the L shaped 2.5mm plug at Radio Shack. I purchased a $20.00 pair of Sony Sports headphones (3.5mm). I cut the end off and split the wires. I removed the black rubber sheath from each wire and found two wires in each side (Four Total Wires). On one side was a Red wire and a copper wire. On the Other side was a Red Wire and a copper wire. You must remove the protective sheath buy burning it off with a lighter. Once you've removed the protective sheath, combine the two copper wires and solder them to the ground. Then solder the green one to the middle and the red one to the end. Then put the plug back together and it works. The only real trick is that when you put it back together you must move the plug all the way inside the outer sheath or you will only be able to hear one side. Pictures are the only way to really explain it. This should help. I am converting all of my headphones to 2.5mm

Anonymous said...

excellent idea to BURN away the insulation. I have been carefully scraping with a sharp knife, for many years, with varying degrees of success. I am excited to use flame on my next attempt. THANK YOU for sharing!

Anonymous said...

"excellent idea to BURN away the insulation. I have been carefully scraping with a sharp knife, for many years, with varying degrees of success. I am excited to use flame on my next attempt. THANK YOU for sharing!"

Did you really spend years trying to do this?

Jim Walker said...

What bothers me is that the Verizon store where I bought my Centro or the ATT, or the Radio Shack, which all sell Palm seemed to be surprised by the mismatch between the plug and the jack. Tossing in an adapter would cost Palm pennies and generate more loyalty. A company that sells Smartphones should act smart.

uk3s said...

I agree with Jim. Would it really be so much pain for a company to just follow industry standards and get on the 3.5mm bandwagon? I don't have the patience to solder this and reconnect that.
sigh... but i guess its what you get for getting the bargain buy.
- damn LG Bliss

Anonymous said...

reguarding the solder work. yes there are 2.5mm jacks that have 4 conductors 3 ring 1 tip. these are typically for applications that use microphones just like the set that comes with the phone. if you go to an electronics supplier like radioshack you can buy a 2.5mm connector with either 3 conductors or 4 conductors. if you just worried about adapting headphones than you only need the 3 conductor jack. as far as the actual wire that is used I have never actually seen any type of coaxial wire used in a headphone application typically there is one insulated wire wrapped with uninsulated copper per headphone the uninsulated copper serves as the negative or ground. you can twist both uninsulated copper wires together and solder them to the tip connector on the headphone jack. to make it easier be sure to read the packaging that your 2.5mm jack was in the tip and rings should be documented plainly. but most connectors I have worked on the tip is the solder point that is closest to the front of the connector. It should be pretty clear on how to do this to anyone who has encountered the internals of simple electronics before. some tips though for first timers. be sure you get low temp solder that has flux in it. and also helpful is a fine tip for your soldering iron. you may also invest in a solder helper. This is a lil device with 2 alligator clips that you can use to position your work. it's really difficult to position your work and hold the solder and the soldering iron with only two hands. good luck to everyone

B.S. Vijay Anand said...

Any know which is the best ear-canal earphones/headphones with 2.5mm jack around 1000 INR?