Headphone Repair, Audio Quality and Wearing Comfort

the headset

my current headset is about 9 years old. it’s a half-open on-ear sennheiser pc 151 and i think it was 50 €. it’s very light and comfortable and the audio quality is alright i think (but not the microphone audio quality). like 6 years ago the microphone stopped working, so i replaced it with a standalone microphone of higher quality that is much better for my very quiet voice. i don’t know since when but for many years i’ve been having issues with the volume wheel integrated into the headset’s cable. whenever something touches the wheel i get quieter sound on one or both ears or no sound at all, and i have to keep fiddling with the wheel to make the sound go through as it should again. but apart from that it works well, and it’s really comfortable to wear. until a few weeks ago when i suddenly completely stopped getting sound in my left ear and no amount of fiddling with the wheel changed anything. but eventually i figured out that i could bend the cable right where it comes out of the earpiece to get sound again. and i figured out a way to wrap the cable around the earpiece once in a way that made it work without having to use my hands. but it was still unreliable and eventually that stopped working as well.

had the time come to finally replace the headset? the idea of having a pair of headphones with (relatively) high audio quality definitely sounds tempting. i’m an enjoyer of listening to and making music after all. but especially good ones would be expensive. and i don’t like replacing the headset when only the cable is damaged. and most of all: the current one is very comfortable to wear, in case i haven’t mentioned that yet.

audio quality

my dad lent me his pair of headphones that he doesn’t need often so that i had something to use until i had a working one of my own again. it was a sony one that apparently cost about 300 € when it was new. so extremely high audio quality, at least compared to what i’m used to. that makes it the third pair of 100+ € closed-back headphones from other people i’ve tried out in the last years. with all of them i’ve made the same observations regarding audio quality and wearing comfort. the audio quality definitely sounds different compared to my comparatively cheap headset, i can hear a lot more details which takes some getting used to but is great. but the thing is, they all somehow sound and feel very dull to me, not as in boring but as in i felt like deep tones were dominating everything else and making it sound kind of muffled. it felt like i was holding tin cans to my ears or like there were a wall between me and the otherwise very high-quality and detailed audio source. when i listened to the 2-hour zelda concert, it reminded me of the one time in recent years i’ve been on a concert. experiencing the “audio quality” of an actual orchestra with actual instruments was absolutely overwhelming and brought tears to my eyes. i think the only other time i had been to some concert was when i was a child but i was only dragged along and didn’t care about it and remember nothing. that star trek tng episode of spock’s dad crying at the concert reminded me of my incredible concert experience.

back to the headphones: listening to the zelda concert felt like i was in that concert hall again, but with an invisible wall between me and the orchestra that makes it sound dull. and it feels the exact same way on all 3 of these headphones. it’s not the same way in all songs, some don’t make me notice it much and others very much. there was also me wanting to listen to the latest technology connections video without even thinking about audio quality and as soon as he started talking i thought to myself “what is this audio feel? i can’t listen like this”. i’m not sure what this is. am i just too used to 50-€-headsets and i would have to wear good headphones for longer to get used to hearing things as they are supposed to sound? but even this time as i was wearing my dad’s headphones every day for 2 weeks or something, it only got less intense but was still very much there. i even tried finding videos of other people trying out high-quality headphones for the first time and hearing what they have to say but there was only awe like me at the concert and none of what i experience with these headphones. is it because all 3 of these headphones are closed-back? i guess that could explain a feeling and sound like closed tin cans on my ears. but if it’s this bad, why would people use closed-back headphones for quiet at-home use? and would open-back headphones really make this much of a difference? i should probably find some way to try some out some time.

wearing comfort

the worst thing about these other headphones, which also includes the headset i had for a very short time before my current one (someone threw it to the floor and broke it and i was actually happy that i could get a new one), is the wearing comfort. after just a short amount of time they hurt the top of my head, my ears and the sides of my head so bad that i have to take them off again. the first two were quite heavy and over-ear so i thought those were the reasons (which is unfortunate because all high-quality ones seem to be over-ear and on-ear seems to be dying out nowadays), but my brother’s headphones allegedly are only 120 g which makes them slightly lighter than my beloved sennheiser 151 and on-ear like mine as well. the top padding is quite hard though and the earpieces apply very much tension at the ears, so maybe that’s the reason. but when i tried them again after like a year and the earpieces had lost its strong clamping force, it only reduced the ear pain but the pain at the top of the head was just as bad. even with bad padding, how could something as light as 120 g make the area where the padding touches my head hurt so badly? my headset on the other hand is so comfortable. it’s very loose, it slides off if i tilt my head forward but it doesn’t hurt my hears at all, and neither the top of my head thanks to its better padding. i can barely feel it at all. so maybe the main issue is top padding and i could make potential new headphones comfortable if i add softer padding?

but headphones made for good audio quality seem to weigh at least 250 g. that’s the same range as the other headphones i tried, including the 2 full weeks with my dad’s over-ear headphones. those hurt everywhere despite having seemingly good padding. it was horrible, i could prolong wearing a bit by constantly moving the top back and forth to hurt a different part of my head until the pain there gets too strong too, but generally i didn’t wear them much, i avoided it as much as possible. eventually i tried to improve the padding by putting my (relatively) fluffy winter pajama top in its folded closet state on my head like a hat and the headphones on top. that made the top pain bearable, although not completely gone, so 250 g seems to be the maximum acceptable weight for me even with tons of padding. am i the princess from the princess and the pea? but the top pain being gone and being able to wear it longer meant that the side pain could unleash its full potential. i think it was mostly the ears itself and not the sides of my head with this pair of headphones, but that pain alone also became strong enough that i couldn’t wear it for long. am i just destined to always use cheap headphones? at least that would be good for my wallet.

with audio quality and especially wearing comfort making any other pair of headphones seemingly unusable to me, and acceptable light on-ear headphones seemingly not available for purchase anymore, i not only wanted to try repairing my old headphones, i absolutely had to do it. my audio life depended on it.

the repair process

i thought that i might be able to repair it if i could just cut off a bit of the cable slightly below where it comes out of the left earpiece since that’s where i had to bend the cable during the last days. and if that fails, maybe i could replace the entire cable. that would also get rid of the volume wheel issue. it’s really unfortunate that this pair of headphones doesn’t have cables with plugs on both sides that are entirely and easily replaceable like on the high-quality headphones i tried out. i tried finding replacement cables that have a 3.5 mm jack on one side and open wires on the other, but i could only really find like one of those on amazon (which i try to avoid), otherwise it’s only really just a replaceable jack without cable because apparently that’s usually what fails in audio cables. i gave up trying to find a cable and wanted to try cutting off the potentially damaged piece of my cable first, if that worked i could save myself the trouble of finding a replacement cable. i barely knew anything about soldering, i had just seen it some time ago online when i was watching someone who builds their own keyboards. soldering looked interesting and fascinating. melting tiny bits of flowy metal to connect two other metal things? feels delicious and satisfying. but also dangerous, which i’m less fond of.

i remember my dad soldering when i was like 5, along with using a hot glue gun that was also fascinating (and dangerous). so i told him about my broken headset and asked him if he happened to be able to provide me with the equipment and knowledge needed to re-solder the cable. but he said he only soldered a few times many years ago and doesn’t really know anything about it, he just somehow managed to solder when he had to and the result wasn’t pretty but functional, and he didn’t have soldering stuff anymore.

the next days i tried to open up the headphones to see how the innards look like and if it looked possible to cut off and re-solder the cable. just opening it was already very difficult. i had to violently pull apart the halves of the earpieces which i hate doing because i worry about breaking things if i use too much force. that allowed me to take off and clean the ear paddings for the very first time. you probably don’t want to know what they looked like. it also exposed one cable each coming out of the still attached halves of the earpieces and going to a tiny pcb on each speaker where two wires each were soldered on. interesting, but i wanted to get to the part where the main cable goes into the left earpiece. there was one obvious screw slightly above the earpiece on the headband thing but that didn’t make the earpiece come off at all. it took me a long time to figure out that there are 3 more screws underneath each earpiece that can only barely be reached by sticking a screwdriver through some of the holes in the back side of the half earpieces, and even then the screwdriver is still at quite an inconvenient angle. i could get two of them out but the third was nearly impossible. but eventually i got that one out too and finally got to the important bits: a bigger tiny pcb with 5 wires coming from the main cable and 3 other cables with 2 wires each going to each earpiece and the microphone. just getting here was already really difficult, these headphones were definitely not made to be repairable.

in the meantime, my dad, eager to help, had surprised me by picking up soldering gear for me at a store he was driving past on his way to pick up my brother for a part of the summer holidays. he didn’t have the knowledge for me but he could provide me with the gear after all. and once i had finally opened the headphones, i was ready to attempt the actual repair.

to get a feeling for the soldering iron, i took an old frayed iphone 4 cable i still have in my collection of cables, cut it in half, got a bit of the wires out and tried to solder them together. opening the cable was already very interesting and surprising. the wires weren’t simply small wires like what i had seen in the keyboard soldering sessions online. they consisted of tons of tiny wires each, like plant fibres or something. in a tutorial of how to solder two wires together i had seen something like this but it looked more like each wire just consisted of maybe a few smaller wires that had to be twisted between your fingers to keep them together, not like a paintbrush with thousands of bristles to beat the devil out of. but apparently this is what cables look like inside. fascinating.

soldering the twisted wires made out of twisted bristles seemed to have worked alright. turning on the soldering iron for the first time felt a little scary because it’s a very hot potentially very dangerous tool, and so my hands were shaking a little that first time. i tried to put a bit of solder on the tip first as i’ve read that that’s important to do and called tinning, but that didn’t really work the way i had imagined. it created more like a wrinkly solder blob hanging off the side.

next i made the fateful cut to the real headphone cable. the tiny pcb being so tiny and the soldering spots on it being so tiny and close together didn’t make it look easy. since i don’t need the microphone, i planned to just connect the 3 wires that were labelled as belonging to the headphone part to make it easier. maybe i could even repair the microphone too this way some day. so i freed a bit of the wires from the cable and cut away the two microphone wires to get them out of the way. those were very brush-like too and one of them was contained in a cable-like plastic sheath with the other wrapped around it, and unlike the other 3 wires that seemed to have coloured insulation on them, these looked uninsulated, which reinforced my decision not to solder these two wires to the pcb because i don’t think i could get them to not touch each other and be cleanly separated. i had some trouble getting the 3 important wires to stay in the correct order because they’re arranged in a different order inside the cable compared to the spots they have to be soldered to. two of the wires kept wanting to switch places. it seemed very finicky and my optimism after finally getting the headphones open started to wane. i could barely even get the tips of the wires to be in the right position without the hot soldering iron in my other hand, and of course without touching the three wires coming out of the cable themselves.

so i turned on the soldering iron again and tried to remove the old wires from the pcb with desoldering wick. which i didn’t know existed, i imagined that i could just heat the old solder and pull off the old cable and that’s that, but fortunately the wick was included. absorbing the old solder with the wick didn’t feel like it worked as well as i would have expected but it worked more or less. next i wanted to try applying a bit of solder to the tips of the wires because i thought that would make it easier to solder them to the tiny pcb instead of holding the solder directly to the pcb where i imagine it would very easily touch the neighbouring contact because they were so close together. but that didn’t really work, the wires didn’t soak up the solder as i saw in a video, they kind of just became a mess of wrinkly solder with dark soot all over or even broke off. so i cut that part off, freed another bit of wire and tried again but this time soldering the wires directly to the pcb instead, but that was just as sooty and not working. and the tip and the solder on the tip also started getting soot all over, all solder just became completely unusable wrinkly blobs and especially the tip of the tip but also the rest of the tip started getting darker or even blue. i stopped my attempts and went back to research.

it looked so easy in the keyboard building and headphone repair videos i had seen, and most videos just show the main soldering part but not what happens before and after holding the soldering iron to the parts. and all videos, complete processes or not, seem to do it differently and use different tools. from what i had gathered my issues may had been caused by oxidation of the tip, which happened because of improper tinning, which in turn possibly happened because of one piece of equipment that everyone but me seemed to have: a sponge to wipe the tip. i had seen some strange round shiny thing that the keyboard builder kept dipping their soldering iron into and i was fascinated by how it looks, not being able to identify what it’s even made out of and having no idea what it’s doing. but it seemed like i may need that and it could solve my issues.

after getting a brass sponge i tried again. i melted the first bit of solder as soon as the iron was hot enough, wiped it off in the brass sponge… and the tip looked mostly silver and shiny just as it always does in videos and photos! after a few more re-tins all of the soot was gone and i tried soldering again but i couldn’t really get the solder to properly melt and flow onto the contact. and getting the wire to stay in the right position was almost impossible even with an in this case not so helpful helping hand. and then the same thing happened again, wrinkly solder and soot and re-tinning didn’t help. eventually i came to the conclusion that the soldering iron may be getting too hot. it doesn’t have any temperature regulation and it says 80 w on it which is apparently quite a lot i think.

when i started the next attempt, another day later, i again kept touching the solder to the iron to know when it’s hot enough and start as soon as possible before it gets too hot, and just a bit after reaching the minimum temperature i shut it off so it wouldn’t get too hot. since the soldering techniques that seem to be good practice didn’t really work for me and i was starting to really lose patience and hope, i decided to just try the apparently bad-practice thing of melting solder to the tip and then putting that solder on the contact. that would at least allow me to use my other hand to more carefully manoeuvre (that word looks funny) the wires. and doing it this way actually worked. the solder became more like a high cp_badlands spire with a flat top instead of a small volcano because more solder kept being pulled off the iron tip as i moved it away, it was almost like drawing in 3d. and it didn’t really work like in the videos i had watched anyway because those all threaded a wire through a hole in a pcb while this pcb had no holes, it had to be connected to the flat surface. i was worried that the solder spires might make a bad connection because the flux core didn’t get to clean the contacts and all that stuff but i was just going to try it like this now since it at least worked in some way. but right after the first connection the solder stopped melting because the iron had already cooled off too much. i turned it on again and very quickly, before i was able to connect the second wire, it appeared to have exceeded the upper temperature limit that makes the solder wrinkly and probably the flux burn to soot, and potentially also burn away or break the wires. so i let it cool again and tried once again later, trying to be as quick as possible while attempting to keep the temperature in the usable range. i got all 3 wires to connect, finally.

with shaking hands, partly from being excited and partly from worrying that i might have done something wrong and i will now set fire to the kitchen but not by cooking, i plugged the cable into the pinephone and put music on. nothing had exploded yet and sound seemed to come from the headphones, so i carefully held the still disassembled parts to my ears. and i heard flower garden from yoshi’s island, coming out of both ears! my excitement went through the roof. i actually did it! now i just have to properly thread the cable through the places it’s supposed to be threaded through and put the earpiece back together. but i had a bit of a weird feeling about the song i had just heard. i compared the song with my dad’s headphones and found a left-right stereo test on youtube and tried listening to that. after some experiments it turned out that the situation was the following: sound playing on the left channel came out of both sides, sound playing on the right channel came out of the right side and sound playing equally on both channels was louder on the left side. i compared the wires to the photo of the original wires once again as i had done many times before the final solder attempt and i noticed that the wires L and − were swapped, even though i had paid such close attention to them being in the right order. but these two are the ones that i mentioned before, they’re in the wrong order inside the cable and kept wanting to get back into that wrong order after i moved them. so i must have not noticed them swapping places again during the final soldering process. i was very focussed on the soldering part so it makes sense.

that meant that i had to start over again. which i did on yet another day, and getting it to stay in the right temperature range was again difficult, along with getting the wires to be in the right place and all that stuff. but i got it to work again with again the same suboptimal but apparently still functional solder spires. i tested the audio channels again, and voilà: everything came out of the proper side and at the proper and equal volume! so that was the issue. it took me a bit of thinking about the internal wiring layout as someone who has no idea how all of this works or even what ground/− is, but my theory of what happened is this: the wire for the left channel was connected to −. − goes to the pcb and then splits into two soldering spots with two wires, with one wire going to each earpiece. so that probably caused the left channel audio to come out of both sides, while the wire for the right channel correctly went to the R spot and therefore only to the right side. both channels playing at once being louder on the left side is a little more difficult to explain. the left earpiece is connected to the left channel wire on ground and the ground wire on L, so i guess that just changes the “direction” but doesn’t functionally make a difference? while the right ear got both the right channel signal on R as well as the left channel signal on ground, and maybe these possibly almost identical sound waves from the stereo test video partially negated each other and thereby made it sound quieter, like when inverted identical waves play at once in famitracker? as opposed to non-inverted identical waves making it louder? i guess that could make sense. or it’s completely wrong. i have no idea. but it was definitely interesting to see and think about how headphones work under the hood.

exhausted but happy that it finally worked, i prepared to put the left earpiece back together. then the next unfortunate thing happened. the earpiece is still connected to the side of the headband by the one small short cable with two wires that goes from the main pcb through a hole in the middle of the earpiece to the tinier pcb in the earpiece. this meant that the earpiece was always a little in the way and i had to be careful not to apply too much pull force on that cable. but in those final moments it happened: one of the two wires soldered to the earpiece side became loose. at least there was plenty of room this time, the wires were soldered to the pcb very far apart. just re-soldering this one connection was somehow very difficult again and this time it was way scarier because i only had that very short cable to work with whereas the main cable is 3 m long and i had plenty of cable that i could afford to cut away when i messed up. but the helping hand was useful this time and eventually i repaired this connection too, the sound still worked perfectly and i started carefully putting things back together.

putting the first screw i mentioned back was simple of course, but the other three are probably almost impossible. they were nearly impossible to reach to get out in the first place, there’s no way i could get them back in. so i just gave up because i wanted to be done. the left earpiece now hangs on by just one screw that is a little up the headband, so i can pull on the earpiece and lift it away from the headband a little, kind of like a wooden plank that is only nailed to the ground on one end instead of both, but as long as i don’t do that and treat it with care it’ll probably be fine. i finally plugged it into my pc again and had working audio with my beloved comfortable old headset. after using my dad’s headphones for like 2 weeks, even if not for long each day, i was a little disappointed by the lack of detail, clarity and “punch” in its sound, kind of like looking at a low-res jpg after looking at an uhd png, but the lack of that strange low dull sound feeling actually made it feel better to me overall. kind of as if the uhd png were in greyscale and the jpg only 720p but had incredible colours. the quality feels acceptable to me. it’s infinitely better than the 10 € wired earbuds i bought once for when we were doing runs in pe class and were allowed to listen to music, and way better than the 50 € waterproof bluetooth earbuds i use while doing annoying things like showering and vacuum cleaning. i can live with the audio quality of these headphones very well. and above all: i barely feel them while wearing them. but i still keep wondering what makes higher-quality ones sound so weird to me.

conclusion

this was quite the journey but i’m really happy that i succeeded in my repair attempt. take that, planned obsolescence! you’ll never take my beloved headphones alive! and it was also very educational, it made me understand and appreciate headphones and electronics and cables in general a little more, as well as making me treat them with more care. although i already do treat everything very carefully. except for the many times i keep rolling over the lower part of the headphone cable with my chair. it’s a miracle that that part is still undamaged. soldering was definitely way more difficult than the quick and simple “solder on and boom done” i had expected, but maybe it’s just my lack of experience and proper equipment. but i guess i still somehow managed to solder when i had to and the result wasn’t pretty but functional.