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k280 restoration

post #1 of 23
Thread Starter 

I recently acquired these cans from an ebay auction claiming they were in good condition although used. Having bought a k240 and k340 around the same time of which one seemed to be NOS (still bagged with all foils and plastic covering still attached) and the other in a excellent state although a bit smelly, I was hoping this would be another little jewel.

 

Oh how I was wrong...

 

They only arrived today after some shipping problems and I started the fun job of cleaning them.

I immediately noticed ( appart from smoke particles..) glue marks around the right cup together with what seemed to be cut marks from prying them open.

 

Long story short, someone obviously had "repaired" them and didn't do a really solid job to say the least :

 

P1000494.JPG

 

They ruined the outer cup and cover, outer headband 'wings' and the wiring & rubber bands which are easily replaceable.

It seemed the right side was effectively wired with a single strand to the wings over to the other side with the general idea of more solder is better.

 

So, I'm looking for an address, phone number, email or anything of the like of a company selling spare parts in Europe. I've read several topics where the general person to contact seemed to be Mark in the US. But since those are a few years old..

 

Items I would need are according to the service manual :

 

1040Z0903 cover
2058Z0503 cup
2040m0209 outer headband
2381m1101 cover complete
2073z1502 foam ring (are these really needed? they seem to have no real use as far as i can see)

 

Lets continue.

On the inside of the cups there are ... well, picture is a 1000 words so :

 

P1000501.JPG

 

these things (the platform sticking out). The foam seemed to have died of or damaged. Can I repair these with a litle bit of DIY or should I just order a complete new set of these? Or do these wholes effect the sound in no way at all?

 

In the end, I am wondering if it is still worth restoring these... Should I just try to find another set on ebay and forget about these? I have really no idea how rare these are or are becoming in EU.

 

foet.

post #2 of 23

I just gave a seller my first ever negative feedback for selling headphones where they made no mention of and photographed them obscuring damage. As for yours, I cannot help re the wiring, but the driver and pad should look like this....

 

4815506542_ca7b759097_z.jpg

 

 

4815505998_11accd53b4_z.jpg

 

As for the foam ring, if you mean the very thin almost fabric ring underneath the pads I don't see what it does either.


Edited by Prog Rock Man - 8/23/10 at 9:17am
post #3 of 23

I think the main reason the foam ring is there is to lift pads a bit so your ears wan't touch the baffle - I simply cutted new ones from 3mm foam, they don't seems to have any influence on sound.

post #4 of 23

Well mine was so flat it did not feel like foam any more. I cut up some Grado bowl pads and fitted them under the AKG pads.

 

Foet, have you had any joy with the cables/connections or any feedback from the seller?

post #5 of 23

Where are you located in the UK I used fullers Electronics (phone number 01728 746500). I found these by emailing AKG and they gave me my nearest agent.

post #6 of 23
Thread Starter 

Thanks for the pictures Prog Rock Man, at least I have an idea now how these are supposed to look in normal condition. The foam I was mentioning was indeed the small cutout circle underneath the pads. I'll just cut some out of random foam I can find since they appear to be a spacefiller only.

 

The wiring inside the cup is apparently left alone, or should I say, the part just up untill the drivers are clean. So I'll just remove the whole bal of shit, glue and solder and "fixed" wiring and make them dual entry. I'll replace the inner wiring with some single wires from a canare mini starquad or some silver plated hookup wire. This way I'll avoid any problems with the headband in the future and make sure they are wired properly.

 

I haven't heard a peep from the guy (or girl) since. But since I got these very cheap (say - €30 inc shipping) I'm not gonna start a war over them. And since I opened them sending them back will probably be a no go.

 

I'm not actually located in the UK FLee5. Belgium is where my stella stands.. I'll check out Fullers Electronics and give AKG a mail.

 

There is another pair of them on ebay atm, so if they end up going similarly low i'll just buy those and use these pairs for spare parts. Whats left of them anyways . Would be rediculous spending 50 smthing on restoring them while I could buy a hopefully good condition for less.

 

Will keep you posted! Either with pictures of a new one or with some tricky repairing.

 

 

// edit - this is the mail I send to the seller regarding the status of the phones.

 

Dearest

I recieved the headphones yesterday and immediatly noticed something very odd. the right cup was glued together and had a lot of damaging and cut marks on the outside.

When opening the headphones I noticed the wiring had been "fixed" with some very bad soldering and the whole cup was glued back together instead of just screwing and clicking it close.

The 2 wires inside the cup were also shortcutting themselves since the amount of solder was so large and the wires lay loose, they would just rub against each other the whole time.

Normally I wouldn't make a fuss about this, but since you advertised these as in good condition and fully working I feel tricked.

The repair of these would take quite a bit of money : new outer headband (since the connection inside the cup is totally gone, replaced with glue for that reason apparently), new bands, new outer cup, new closing cup ...

As you can see this does not meet the good condition at all.

kind regards,

foet


Edited by foet - 8/24/10 at 10:52am
post #7 of 23

Nice response foet. I sent the sellers who failed to declare or show damage a 'I am disappointed, but will not make a fuss' e-mail, to hopefully make them feel guilty. You are right, no point in starting a war.

 

I got mine, in very good condition without a box for £22 and a boxed, declared perfect pair went recently for £78 on UK ebay. The only fault is the elastics are very lose. I cheated and screwed the L and R bits tight so it is now fixed in position for me. Well you don't think I will let anyone else near my babies did you

post #8 of 23
Thread Starter 

" hides the fake foam copies behind his back " What, I wouldn't dare!

 

Well, the buyer apologized today and offered to take the items back. But since I would loose more money in shipping them back then actually keeping them as spare parts I'll hang on to them. Hopefully with a decent pair to accompany them soon :).

post #9 of 23

Hi everybody,
 

The poor K280 in foet's posting looks disgusting. How on earth can you treat such a great quality (and, back in the day, expensive) headphone like that? Not everybody has to like these phones (although I do... a lot), but at least treat them with respect and maybe sell them to somebody who appreciates a product that you can still order most replacement parts for after all those years.

 

(skip this part if you're not interested in my K280/eBay story and read on where the bold text starts)
 

Well anyway... if you're interested in my story, I bought two K280s on German eBay some years ago.

The first one was from a lady who used them for home recording and stated in the description that the cable was bad and she was selling it because of that. I won the headphones (I think I paid around € 30,- for them) and they were basically in mint condition. I couldn't find the fault in the cable and, in fact, I haven't noticed it during the several years I've been using the phones now. I almost felt a bit sorry for the seller who was very friendly and seemed to like the phones but sold them because of a fault that could have been fixed very easily even if it had been there in the first place.

I bought another one around the same time and it was advertised as being in a good, working state but it had earpads in terrible condition, a loose wire in one earcup, smelled bad and was full of dirt and lots of disgusting yellow particles, even on the capsules' diaphragms. I think I'd rather not know what the yellow stuff was... earwax, potato chips, something worse? I think the price was around € 30,- as well.

I clearly didn't trust the seller so I wasn't willing to send them back (and maybe lose the money *and* the phones) so I offered him not to take legal action if he refunded half the price. Apparently he feared the trouble or he felt guilty so he refunded not only half the price but also half of the shipping cost (which I hadn't asked for).

As for the phones... I took them apart and put all the plastic parts into hot water with dish detergent and then scrubbed them which removed the crud nicely.


With the capsules, I knew I wouldn't leave the goo on the diaphragms, so I took a chance and removed the capsules from their "cups" and sprayed them with electronics cleaner which was supposed not to "damage the most common construction materials" (whatever that means). It seems it did not, in fact, do any damage and removed the dirt quite effectively without me having to touch the delicate diaphragms.

When I had put the phones back together, I couldn't detect a real sonic difference compared to my "mint" pair. So for € 15,- and some cleaning work, they were probably not too bad deal. My sister has been using them for some years now and seems to be quite happy with them.

 

I wish I still had the pictures of the phones in their dirty state, but they're on a hard drive that died on me some years ago. But then, they wouldn't have been that exciting compared to the photos above :-)

 

I guess it is slightly ironic. I got one supposedly "broken" pair that was in fantastic shape and one supposedly "ok" pair that was in terrible shape.

 

 

Now I've had to replace the cable on the formerly disgusting phones and I've ordered some new earpads as well. The foam rings that sit underneath the earpad were disintegrating but replacements are not available any more. As a solution, I took the K240-style foam pads and cut holes in them. Since the ring was a bit too small in diameter, I put them on the neck of a coke bottle for a while in order to stretch them a bit which seems to have worked reasonably well.


There is one thing that is still bugging me. As you can tell from foet's second photo, the "disk" that holds the capsules has two sets of "vents" that are covered with some kind of felt: the round holes and the openings in the weird "nose".

 

The felt on the "nose" looks very worn, has some rips and is now a yucky green as opposed to the original dark grey. Also, I couldn't really clean it thoroughly when I had the phones apart since I would have destroyed it. While this doesn't seem to hurt much acoustically, I'd still like to replace it because it's disgusting and looks terrible.

 

As a solution, it should be easy enough to get some felt or other fabric, cut a suitable piece out of it and glue it on, but I'm not really sure what material would be best. I wonder if the cloth has any dampening characteristics like a controlled leak in a loudspeaker enclosure (Dynaudio used to call them "variovents") or if it's supposed to alter or shape the frequency response.

 

Would the kind of (more or less) "acoustically transparent" fabric used for loudspeaker grilles be a good choice or would I want something denser with a greater "air resistance"?

 

I *could* probably order new "disks" with the vents on them, but I'd rather avoid ordering parts and try to fix this myself.

 

Any ideas would be appreciated.

 

Kind regards,

Stephan

post #10 of 23

*bump*

 

Any ideas how critical using the exact kind of fabric for the vents on the "nose" is and what material would be a good choice, anyone?

post #11 of 23

Quote:

Originally Posted by CptKlotz View Post

*bump*

 

Any ideas how critical using the exact kind of fabric for the vents on the "nose" is and what material would be a good choice, anyone?


Fitz probably will be able to answer that if he notices this thread.  You could PM Fitz if he doesn't, to find out for us.

 

Do you mean the fabric on the vents facing your head (on the plate with the drivers on it)? That fabric is very important to the sound.  Or do you mean the rear vents on the headphones facing out?  I think that's there just to keep dust and dirt out, but still let air in.  I think if you choose a fabric that doesn't allow the headphones to breath it'll probably make it sound more muffled.  This is a better question for Fitz.

post #12 of 23

Hi and thanks for your reply.

 

I mean the fabric on the disc the capsules are mounted on, specifically on the "nose" sitting in front of your ear.

 

 

k280.png

 

The flat and round vents still look ok, but the material on the "nose" looks pretty worn and has some little rips in it (not as bad as the one in foet's picture above, but a more disgusting colour).

 

I'm not sure I detect a sonic difference compared to the other K 280 that is still in great shape.

 

I have both a K270P and a K290 Surround that seem to use the very same disc, but they have a different material on the "nose" that looks less like felt and more like a kind of plastic mesh.

 

However, comparisons might be difficult. The K270 is a closed design and uses diffferent capsules. The K290 is essentially the same headphone as the K280 but with the earpiece rotated 90° and wired for surround. On the K280, one capsule's bass hole is closed with wax, whereas on the K290, they're both open. Thus, the K290 has significantly more bass when used in stereo mode (I prefer the K280's more neutral sound).

 

According to AKG's service documents (aren't those great?), the disc is the same on K280 and K290 (2381 Z 1101) but different on the K270 (2381 Z 0104). The ones on the K290 and K270 still look the same to me, but who knows...

 

To be honest, I'd like to replace the fabric because it's disgusting and looks bad. This is a used phone that was in terrible shape before I fixed and cleaned it.

 

I guess the question is what acoustic properties the felt stuff has.

 

Should it be as acoustically transparent as possible and just cover the holes? In that case, I could probably try the material used for many loudspeaker covers.

 

It probably becomes more difficult if it is supposed to have some dampening or frequency filtering characteristics in order to tune the bass response or filter out reflected midrange and treble or something.

 

Maybe I should ask this in AKG's own forum, but I'm not sure they are going to give me any advice other than "please buy a new disc" which is what I'm trying to avoid. I rather wouldn't want to buy two discs that probably cost at least € 10,- a piece for a headphone that I got for € 15,- if I don't have to.

post #13 of 23

The original material has a moderate acoustic resistance, that is to say it isn't acoustically transparent, but doesn't completely block the sound either. There's pretty much no chance you'll get the exact specifications of what to replace it with, and since slight differences in thickness or material type will affect it, you'll just have to experiment and see what sounds best to you. Maybe you'll even discover some common material that makes it sound even better than what AKG originally used. :)

post #14 of 23

Thanks, Fitz!

 

I'll have a look if I can find something that looks close to what AKG used and try it.

 

Kind regards,

Stephan

post #15 of 23

Ok, I tried something today.

 

I used a drinking straw to breathe through the felt material of my K 280 which is in good condition. It did offer some resistance. Then I tried the same through a tea filter and the resistance was at least similar.

 

Of course, the "frequency selective" properties may still be different, but of course, there's no way for me to tell, so I used the tea filter.

 

Since the tea filter is beige, I put it into the inkjet printer and printed it black and then cut out pieces that are the right shape for the "noses" on the headphone. I glued them on with a little superglue and then painted the spots where you could see the white colour of the dried glue black with a marker pen.

 

It doesn't look perfect, but at least the disgusting green stuff is gone.

 

Sonically, I still don't think I could tell the two K 280s apart. Maybe that is because the larger vents are on the other side of the earpiece anyway.

 

What actually makes me wonder is that many people seem to find the K 280 dark and "bassy". I think the two K 280s have *less* bass than my K 240 Monitor (which seems to be quite an old one, with the black and white vents in the place of the Sextett's passive radiators). I wonder if there are different versions of the K 280 around (maybe on some, the bass hole of one capsule per side isn't closed with wax (as the tech documents say it should be) which would make them sound closer to the K 290 which *is* a little bass-heavy). I would suspect that the average person would find these phones too flat or "boring" if anything.

 

 

Anyway, thanks for your input... Now we'll have to see how long my teabag solution is going to last :-)

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