ericj
Headphoneus Supremus
- Joined
- Aug 2, 2005
- Posts
- 8,270
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- 169
The typical dynamic diaphragm has a dome in the middle and a ring around the edge, and the ring usually has ridges. There are notable exceptions like the K701 series, but they usually have ridges.
If something has crushed the driver, that's bad, and most people would suspect that there is nothing they can do about it.
And sometimes they are right, but, there are things you can try.
A few days ago i bought a pair of HD580 in fairly rough condition and already disassembled on ebay. I had no idea how rough. The seller said the drivers were carefully packed separately, and that turned out to mean that they wrapped them in bubble wrap instead of doing something sensible like sandwiching them against a piece of rigid cardboard since the domes don't extend further than the mounting ring.
But hey maybe they were already crushed when packed. Probably were. And one of them has a broken lead so it probably can't ever be repaired, though some heroes have successfully removed an entire diaphragm to allow them to unwind the voice coil a loop or two.
So if you got some HD580/600/650 drivers, eh, I'm interested. I would complain to the seller if i didn't suspect i broke that lead myself. And i think at least one of the diaphragms is actually torn. I dunno. maybe i complain about the crushing and see if i can get a partial refund because i can kinda argue that all i got was an amazingly filthy HD580 chasses and some wrecked drivers.
Anyway, if you think it's probably trash anyway, or if you know you just have a couple crushed ridges, here's what to do.
Here's what i started with.
So, not good. And this is after i gently brushed away some of the rotted foam and other debris.
Un-crushing the dome - if you have access to the dome from behind, it's probably best to use a wood or plastic device to gently push it back up from behind.
You can also blow on it from behind, or as some grado fans suggest, suck on it from the front, but that involves getting your mouth on this thing.
Suck or blow, that can be the only thing that works. The hazard is that the position of the voice coil relative to the magnet structure can get pushed too forward which will greatly decrease the sensitivity. More on that later.
One way to un-crush those ridges is with a bit of sticky substance on the end of a toothpick. Some people use a bit of tape, maybe the goo from duct tape. I'm using partially cured butyl speaker cement.
The idea is to get a little booger of cement to stick gently to the diaphragm material and then gently pull it away, which will cause the material to snap back to it's original position. And sometimes it snaps right back to crushed. So you may have to try several times.
Only attempt this sort of thing when you have a cool head. If you start to feel agitated or impatient, put it down and go do something else for a while. Watchmakers keep a lot of small containers and things like bell jars and wine glasses around so that they can cover or put away the delicate work at any moment when there's a risk of getting too rough with it.
Of course, one problem may be that the driver is greasy. It happens.
If you have reason to believe that the driver was doped with something at the factory, such as some beyerdynamic drivers that are actually sticky, you might want to just keep refreshing your little booger of cement until it finally sticks to the plastic.
If you're pretty sure that the diaphragm isn't doped with anything but ear sweat, go ahead and clean it.
Fluff out the tip of a cotton swab and put a little isopropyl alcohol on it and use that to wipe up the grime.
Refresh as needed.
let the alcohol evaporate and try again. Be patient. you may have to come at a dimple from a few different angles until it stays where you want it.
When you have the really bad damaged reversed, you can gently warm the diaphragm to sort of re-set it. I can't guarantee that this won't adversely affect the driver. But I mean we're talking about a crushed driver anyway, right? If the creases were bad enough or set long enough maybe the first time you try to use the driver the creases and dimples snap back into place, and that sure as heck changes the sound.
So if it's this or give up, i find it generally works.
I set my chinese "858D" hot air wand to 115-120c, turn the air flow down to about 2, install like an 8mm nozzle, and give the driver face just a light warming, I move the want in a spiral around the dome and roll for maybe 2 seconds.
Could you use a hair dryer? I dunno, maybe? How hot is your hair dryer? Be careful.
Anyway, a couple seconds of hot air took these drivers from this:
to this:
Some of the additional clarity is from plastic (PET?) that has been stressed beyond it's maximum elasticity relaxing back to it's un-stressed state. Some of it is probably, uh, from re-melting head grease. ew.
Might be hard to see but i suspect that the diaphragm is actually torn at about 11:00. There are still some dents at 3:00 or so, and i might take another pass at un-denting those dents. or i might not, since it looks like maybe it's torn.
Here's another angle, easier to see the remaining damage, and you can see that there are still some deformations in the dome, but i don't think they will wreck the sound quality.
I don't think i'd recommend warming the diaphragm if there are still bad creases. it might make those creases worse.
If you have sucked or blown on the driver and caused it to move out from the magnet structure, that can be fixed.
What I've done in the past is take a small piece of paper and roll it into a tube roughly the same diameter of the voice coil and use that to press down gently on the voice coil while i give the roll another second or so of hot air. Seems to work.
Anyway, since i have some doubts about ever getting good music out of these drivers, especially the one with a broken lead, I hope someone gets some benefit from this.
If something has crushed the driver, that's bad, and most people would suspect that there is nothing they can do about it.
And sometimes they are right, but, there are things you can try.
A few days ago i bought a pair of HD580 in fairly rough condition and already disassembled on ebay. I had no idea how rough. The seller said the drivers were carefully packed separately, and that turned out to mean that they wrapped them in bubble wrap instead of doing something sensible like sandwiching them against a piece of rigid cardboard since the domes don't extend further than the mounting ring.
But hey maybe they were already crushed when packed. Probably were. And one of them has a broken lead so it probably can't ever be repaired, though some heroes have successfully removed an entire diaphragm to allow them to unwind the voice coil a loop or two.
So if you got some HD580/600/650 drivers, eh, I'm interested. I would complain to the seller if i didn't suspect i broke that lead myself. And i think at least one of the diaphragms is actually torn. I dunno. maybe i complain about the crushing and see if i can get a partial refund because i can kinda argue that all i got was an amazingly filthy HD580 chasses and some wrecked drivers.
Anyway, if you think it's probably trash anyway, or if you know you just have a couple crushed ridges, here's what to do.
Here's what i started with.
So, not good. And this is after i gently brushed away some of the rotted foam and other debris.
Un-crushing the dome - if you have access to the dome from behind, it's probably best to use a wood or plastic device to gently push it back up from behind.
You can also blow on it from behind, or as some grado fans suggest, suck on it from the front, but that involves getting your mouth on this thing.
Suck or blow, that can be the only thing that works. The hazard is that the position of the voice coil relative to the magnet structure can get pushed too forward which will greatly decrease the sensitivity. More on that later.
One way to un-crush those ridges is with a bit of sticky substance on the end of a toothpick. Some people use a bit of tape, maybe the goo from duct tape. I'm using partially cured butyl speaker cement.
The idea is to get a little booger of cement to stick gently to the diaphragm material and then gently pull it away, which will cause the material to snap back to it's original position. And sometimes it snaps right back to crushed. So you may have to try several times.
Only attempt this sort of thing when you have a cool head. If you start to feel agitated or impatient, put it down and go do something else for a while. Watchmakers keep a lot of small containers and things like bell jars and wine glasses around so that they can cover or put away the delicate work at any moment when there's a risk of getting too rough with it.
Of course, one problem may be that the driver is greasy. It happens.
If you have reason to believe that the driver was doped with something at the factory, such as some beyerdynamic drivers that are actually sticky, you might want to just keep refreshing your little booger of cement until it finally sticks to the plastic.
If you're pretty sure that the diaphragm isn't doped with anything but ear sweat, go ahead and clean it.
Fluff out the tip of a cotton swab and put a little isopropyl alcohol on it and use that to wipe up the grime.
Refresh as needed.
let the alcohol evaporate and try again. Be patient. you may have to come at a dimple from a few different angles until it stays where you want it.
When you have the really bad damaged reversed, you can gently warm the diaphragm to sort of re-set it. I can't guarantee that this won't adversely affect the driver. But I mean we're talking about a crushed driver anyway, right? If the creases were bad enough or set long enough maybe the first time you try to use the driver the creases and dimples snap back into place, and that sure as heck changes the sound.
So if it's this or give up, i find it generally works.
I set my chinese "858D" hot air wand to 115-120c, turn the air flow down to about 2, install like an 8mm nozzle, and give the driver face just a light warming, I move the want in a spiral around the dome and roll for maybe 2 seconds.
Could you use a hair dryer? I dunno, maybe? How hot is your hair dryer? Be careful.
Anyway, a couple seconds of hot air took these drivers from this:
to this:
Some of the additional clarity is from plastic (PET?) that has been stressed beyond it's maximum elasticity relaxing back to it's un-stressed state. Some of it is probably, uh, from re-melting head grease. ew.
Might be hard to see but i suspect that the diaphragm is actually torn at about 11:00. There are still some dents at 3:00 or so, and i might take another pass at un-denting those dents. or i might not, since it looks like maybe it's torn.
Here's another angle, easier to see the remaining damage, and you can see that there are still some deformations in the dome, but i don't think they will wreck the sound quality.
I don't think i'd recommend warming the diaphragm if there are still bad creases. it might make those creases worse.
If you have sucked or blown on the driver and caused it to move out from the magnet structure, that can be fixed.
What I've done in the past is take a small piece of paper and roll it into a tube roughly the same diameter of the voice coil and use that to press down gently on the voice coil while i give the roll another second or so of hot air. Seems to work.
Anyway, since i have some doubts about ever getting good music out of these drivers, especially the one with a broken lead, I hope someone gets some benefit from this.
