Since P = V^2/R,

Make V^2 = 10 arbitrarily and use 10/20.8 and 10/18.7, the difference in power will be a lot less. e.g. 5% or so. Add the inaccuracies of your measurement and I think it comes out in the wash.

Is it that simple?
Everyone agrees with Keepitsim...?

I mean, I know a difference between left headphone 18.6 ohm and right headphone 18.1 ohm wouldn't make a difference, but in my case it's 19 ohm vs 21 ohm, they're not that close.

 

You missed the point you could be off some in how you hold the leads from the dmm and it close taking everything into account.

 

I'm getting pretty solid and stable measures of ohms for each speaker, it's not that it's measuring 18, then jumps to 19, then to 22, then down to 16...

Anyway, supposing my measurements are accurate (which I think they really are):

What happens if you use a 13 ohm left headphone and a 23 ohm right headphone?

I was searching this on Google but I couldn't find much information. So say it doesn't matter, as an stereo amplifier is actually 2 different amplifiers in one box.

 

What happens if you use a 13 ohm left headphone and a 23 ohm right headphone?

So, add resistances in an external box and use your SPL meter and check.

I was searching this on Google but I couldn't find much information. So say it doesn't matter, as an stereo amplifier is actually 2 different amplifiers in one box.

True enough. I built my power amp with mostly 1% resistors, but that is very unheard of. 5% probably. Gains of transistors are all over the map and the bias circuits are supposed to stabilize them. I've done so many amplifier repairs and none had internal gain or balance controls you had to set.

 

So, add resistances in an external box and use your SPL meter and check.

Hahaha, no, I meant that what would happen if you have one headphone with 13 ohm and another with 22 ohm. One louder than other?

 

T

Hahaha, no, I meant that what would happen if you have one headphone with 13 ohm and another with 22 ohm. One louder than other?

to be that far off, new headphone would likely have twice as many wraps of wire on the voice coil and some careful calculations would have to be made because there is a multi-level interaction. More turns means more resistance (because longer wire) but it also means higher magnetic field because of more turns but current falls because of higher DC resistance so less magnetic field. That is for the electrical portion. If there is so much variability from headphone to headphone, there must be terrible quality problems with the headphone maker or the upstream suppliers. In that case, you would also have to look at the permanent magnets and understand how lower strength magnets make the speaker less efficient than one with higher field strength.

In the end, your question is a non-issue because a difference that big means so many other quality issues are present that their is no way to assume how the two headphones compare. If they are within 15% or so, then you have nothing to worry about since your ear will not likely notice that difference (it takes 10x the power to double the perceived loudness. A 15% difference is nothing.

 

So, I bought a TRRS audio jack to repair the headphones I had broken. This is how it looks:


First question... is there a guide or something to do this properly?
Everything is so annoyingly tiny that is so easy to create a short circuit between the terminals in that cylinder thing.

This is my finished job:


Don't ask me how I managed it, but there're no short circuits anywhere. Yeah, I'm shocked too that's happening.
But hey, the actual job is not as messed up as it look in the photos, it's the quality of my phone's camera. In this last picture, the black area where the 3 connectors are soldered is not that messy . Oh, and I pressed with pliers those clamps, so those cables are not moving at all, even if you pull hardly from the cable.

These are the measurements:
Ground to left: 18.6 ohm
Ground to right: 18.3 ohm
Ground to microphone: infinite ohm unless I press the mic button in the cable, then it is 2.8 ohm
Left to right: 35 ohm
Left/Right to microphone: infinite ohm

So, as you can see, the audio jack connector use the standard OMTP configuration. You can clearly see it because the large pin in the back is the ground. So one question came to my mind...

Second question... would it be alright if I soldered the cables using the standard CTIA configuration?
I could solder the microphone cable in the back large pin and the ground cable to the cylinder of the left, where it's the microphone now, so that would give me a CTIA configuration.

I don't know, I can only see the ground being soldered where it is right now, in the back large pin.

 

The only thing I would add to this is that you have to make the solder joint as quickly as possible and this is where pre-tinning of both terminal and wire really helps. If the soldering iron is in contact with the joint for too long the heat will travel up the wire and damage the insulation within the cable where you can't see it and that is a short circuit waiting to happen.

 

The only thing I would add to this is that you have to make the solder joint as quickly as possible and this is where pre-tinning of both terminal and wire really helps. If the soldering iron is in contact with the joint for too long the heat will travel up the wire and damage the insulation within the cable where you can't see it and that is a short circuit waiting to happen.

Yeah, I tried to do it as quickly as possible. Except the first time I tried to solder the middle cable. That time I left it for too long (actually not completely stuck there, but close enought to spread the heat and melt a little the black rings) and it's were all the little mess happened. I knew I had to be quick, and as you can see, I tinned the cables. That helped a lot.

 

OK, ok, ok, bad news!

The "expensive" headphones again have the same problem (the reason I created this post). Yesterday they were all right after I fixed it, but today again the left headphone stopped working. I'm measuring the resistance and this is what I get:
Ground to left: between 80 ohm and 150 ohm
Ground to right: 18.6 ohm

Does this mean the bad/broken joint is in the left headphone itself?
Or in the middle of the cable?

Oh, what a bad luck I have

 

Make semi-permanent connections. e.g. Use a jack, mini-grabbers or whatever.

And start slowly flexing with your meter attached. Cables USUALLY break at the ends, but not always.

 

If the broken connection is inside the left headphone (which by the way is really tiny), I can't fix it, right?

But I don't know, the headphones have a really nice cable without memoir effect, and the build quality of them is superb, except the jack connector who was utterly crap.

 

Not necessarily. You'll have to take some pics.

This http://www.simplyspeakers.com/speaker-repair-instructions.html shows some pretty difficult repairs of real speakers. A friend recently did two with kits from this company. Agreed, it's not headphones.

 

A- You're working with a PLUG. It mates with a "jack".

1- insufficient/improper tinning of conductors and connect points

1a- You are reading with a D.C. meter and circuit which includes an A.C. electromagnetic device (the speaker), and uses a very very small current and low voltage. Your readings will reflect that, and that includes very tiny stray wire strands (and "lead" particles as mentioned in other of your posts)
2- you crimp the tabs, or what should have been a split-sleeve, with a crimper sized for that sleeve diameter.
3- that tip looks like a lightly used tip should look.

Tinning is a vital step in soldering conductors, but I suspect you already read that somewhere. You may also have read of "cold joints" (if not, you have now), but I'm not that type of novelist, so I can't explain it to you,,,, Google or YouTube maybe.

 

There was nothing to do

After I tried it 3 times, and still was getting in the lefr headphone 80-150 ohm, I decided to rip off the cable from the left headphone (unattach it). And my thoughts were right. The problem was the left headphone. I've tested the continuity between the jack plug and the 2 cables in the end of the left headphone, and ground to ground were 1 ohm, as well as green to green. So the cable was not damaged anywhere, the problem was inside the left headphone, may be one of those 2 cables was not making good contact with the hardware inside the headphone.

So, I think I'll have to buy them again
It's $70... after all I've done...

 

Nope, not the connections neither. I've soldered them (after inevitably destroying the headphone case and structure) and again I got the 150 ohm. I think something inside the driver, like a tiny cable, may be from the coil, got broken.

I'm gonna get broken too after this purchase...

 

I continued reading this and some of the older posts and had the best time this morning. It was like a comic strip in a newspaper! I laughed and laughed. i really got tickled whenever one said"i had a tip last 20 years"! I can relate. I have a weller dad bought when i was 5 and now i'm 60 and i just retired it with a new one. i'll keep the old one handy just in case. I've been through a bunch of smaller irons. the cheaper the better.
Dad told me as i struggled with a joint that it was 90% cleaning,5% iron, 2% solder,2% flux and 1% brains. said i would be a master!
To the novices problems: whenever i bash my head too much it hurts-meaning only experience and reading /taking advice from other posts will make this magic happen. I see the crappy joints and wires hanging out but the one that really brought back memories was the puddle of solder on a circuit board that looked like mt.fuji ! been there.
I don't know if anyone referred to the clamp but i had a similar thing happen and working with those small wires is very delicate work. just crimping the wire would short it out inside. to overcome this i started applying hot glue at that crimp joint and out towards the headphones as i screwed the cover in place. touch up clean the excess glue off and let it cool til cold. hope that may help.

 

I continued reading this and some of the older posts and had the best time this morning. It was like a comic strip in a newspaper! I laughed and laughed. i really got tickled whenever one said"i had a tip last 20 years"! I can relate. I have a weller dad bought when i was 5 and now i'm 60 and i just retired it with a new one. i'll keep the old one handy just in case. I've been through a bunch of smaller irons. the cheaper the better.
Dad told me as i struggled with a joint that it was 90% cleaning,5% iron, 2% solder,2% flux and 1% brains. said i would be a master!
To the novices problems: whenever i bash my head too much it hurts-meaning only experience and reading /taking advice from other posts will make this magic happen. I see the crappy joints and wires hanging out but the one that really brought back memories was the puddle of solder on a circuit board that looked like mt.fuji ! been there.
I don't know if anyone referred to the clamp but i had a similar thing happen and working with those small wires is very delicate work. just crimping the wire would short it out inside. to overcome this i started applying hot glue at that crimp joint and out towards the headphones as i screwed the cover in place. touch up clean the excess glue off and let it cool til cold. hope that may help.

80℅cleaning, 12℅flux maybe??? Oh,,,,
flux cleans! 95℅cleaning!!

 

Be80be is correct. That wire is braided on the inside to ensure long life in the flexibility department. Don't take this badly, but that's the solder job you did (badly.) You can't solder those wires when they are connected as you'll probably burn stuff up. DON'T use an open flame, probably one of the worst things you can do.. It causes the copper (and other parts) to oxidize making soldering to them almost impossible.

My suggestion is take it back apart. If you have a junk pair of earphones then practice soldering on those... Tin the wires as the other have stated, make sure you flux them generously. Make a puddle of solder on your iron (even if it's on the underneath side) and heat ONE lead (in the solder blob) until it OBVIOUS it's completely soldered. By obvious I mean that it's solid feeling and you don't see any of the fine non-conductive parts. Wires will look 'soldered' not like the ones in your picture. If you complete this and you've created the 'hard' wires (as GopherT states), just carefully strip them back until you have the desired length. Don't strip them back until all wires are done, so they can be even.

The shield they were talking about is the 'ground' wires that you have mentioned. If you carefully open those cables, both have a woven shield around them which is your 'ground'. If you have to cut a chunk off to repair it, then take it apart and you'll know... Also the strain relief should be the crimped metal piece. I've always used needle nose pliers, and yes you have to be careful. You never want to use the ground braid as a stain relief. Also Don't forget to put the cover on the cable before you solder. Ensure there is enough clearance for the cover to attach without force.

Once you have this done, you can easily use minimal heat to attach them to the plug. And crimp to ensure mechanical strain relief.

It might be smart to check the impedance without the plug on, then you know what it should be.

Don't feel bad, these wires are the most difficult to solder and even me with decades of soldering different stuff screw them up now and then. You do this a couple hundred times you'll get the knack. I use Litz wire in my higher frequency projects and it's easier to solder than that headphone wire.

Now if you would have just followed GopherT suggest at the start, you'd be happily listening to them now.

Good luck...

Jack

 

Be80be is correct. That wire is braided on the inside to ensure long life in the flexibility department. Don't take this badly, but that's the solder job you did (badly.) You can't solder those wires when they are connected as you'll probably burn stuff up. DON'T use an open flame, probably one of the worst things you can do.. It causes the copper (and other parts) to oxidize making soldering to them almost impossible.

My suggestion is take it back apart. If you have a junk pair of earphones then practice soldering on those... Tin the wires as the other have stated, make sure you flux them generously. Make a puddle of solder on your iron (even if it's on the underneath side) and heat ONE lead (in the solder blob) until it OBVIOUS it's completely soldered. By obvious I mean that it's solid feeling and you don't see any of the fine non-conductive parts. Wires will look 'soldered' not like the ones in your picture. If you complete this and you've created the 'hard' wires (as GopherT states), just carefully strip them back until you have the desired length. Don't strip them back until all wires are done, so they can be even.

The shield they were talking about is the 'ground' wires that you have mentioned. If you carefully open those cables, both have a woven shield around them which is your 'ground'. If you have to cut a chunk off to repair it, then take it apart and you'll know... Also the strain relief should be the crimped metal piece. I've always used needle nose pliers, and yes you have to be careful. You never want to use the ground braid as a stain relief. Also Don't forget to put the cover on the cable before you solder. Ensure there is enough clearance for the cover to attach without force.

Once you have this done, you can easily use minimal heat to attach them to the plug. And crimp to ensure mechanical strain relief.

It might be smart to check the impedance without the plug on, then you know what it should be.

Don't feel bad, these wires are the most difficult to solder and even me with decades of soldering different stuff screw them up now and then. You do this a couple hundred times you'll get the knack. I use Litz wire in my higher frequency projects and it's easier to solder than that headphone wire.

Now if you would have just followed GopherT suggest at the start, you'd be happily listening to them now.

Good luck...

Jack

I don't know what you mean by braided. Can you send me some pictures of what cable do you think I have?

I'm looking at it right now and I see no braided cables at all. I strip like 1 cm and I see:
1. A cotton-like "cable", which I think it's for strength purposes. I burn it or cut it.
2. A copper colored wire. That copper color is an isolating coating and I have to burn it to remove it, so I can expose the raw copper cable that I must solder. The same with red cable and green cable.

If you think there's a better technique to remove the coating, please, tell me, as that's what guides I've read say I should do, use a lighter.

It's true that you can oxidize the copper cable inside the isolating coating when you burn the coating with a lighter. It turns black and it's more difficult to solder it, though not impossible (of course it depends on how burnt it is). Nevertheless, after some practice, I've learnt to burn the coating without damaging the bare copper cable. I know that because I leave a shiny copper cable exposed. I've measured continuity in that little segment of shiny copper wire and it's perfect. After tinning that segment, it's even more perfect. It's hard to master, but I think the way I do it exposes the bare copper wire properly.

Second, the pictures in the first post show my first attempt. The wires are not tinned, and it can be way better, but that joint did the job and it was working fine. As I explained later, the problem was not the connection there. My left headphone got broken. After re-soldering and repairing the jack 3 times, I gave up and opened the headphone (inevitably destroying it). I measured, directly on the little IC, the impedance of the headphone, and I was still getting those annoying 80-150 ohm. So, that means the headphone got broken, probably a broken part in the coil.

Third, I know my method of exposing the copper in the jack end of the cable works because once I opened the headphone and removed the soldered ground and green cable from there, I tested continuity in both cables. I touched with the multimeter leads the tinned exposed end I created and the end that was soldered to the IC, in the green cable, and it instantly measured 0 ohm. The same with ground.

What I still don't control at all is tinning those cables. I heat the cable with the iron soldering and try to melt the solder there, but it doesn't work. I tried what you said too, and it's the only thing that worked, but after waiting a lot. I create a solder bubble in the iron tip and then I put inside that solder bubble the exposed cable, but it's really, really hard to tin it. The solder just won't get stuck to the cable. Nevertheless, after, I'd say, 1 minute or so, trying it, I manage to do it.
I've tinned normal cables, and the process is instant. Nothing to do with what happens with these cables. I'd like to see a video of someone working with these cables and tinning them. If I see they tin them instantly, I'd say it's dark magic.

Thanks for replying.