[xfinrodx]

Hey guys, I recently acquired a set of AKG K550 headphones.  Upon receiving them I noticed that the volume in the two cans was significantly unbalanced.  I figured I'd need to position them correctly, but no matter what I tried there was no improvement.  I began to suspect my left can was blown. 
 
I'm not an audio master, so don't read into my words too much.  I speak as a layman only; I am unsure how to meaningfully quantify concepts such as "imaging" and "positioning," so I am relying on simple English to try to convey the matter plainly

.
 
Testing was as follows:
 

1. Reproduction steps:
   1. Go to http://www.audiocheck.net/audiotests_frequencychecklow.php
   2. Click the play button.
   3. Observe right can is audible at 20hz and maintains reasonably flat response through the frequency rise to 200hz.
   4. Observe left can is not audible until 90hz and never matches the right can's output.  Left can also has nearly complete drop out pits at ~112-114hz and 170hz, as well as many smaller pits at other points all along the spectrum.
    
2. Reproduction steps (alternate a)
   1. Go to http://onlinetonegenerator.com/
   2. Press play at 440hz.
   3. Observe left can is significantly quieter than right can.
    
3. Reproduction steps (alternate b)
   1. Go to http://onlinetonegenerator.com/
   2. Press play at 114hz.
   3. Observe left can is significantly quieter than right can.  If the observer has perfect pitch observer may notice that left can is perhaps 1/4hz flat compared to right can.
    
4. Reproduction steps (alternate c)
   1. Go to https://www.facebook.com/noisia?sk=app_282344925171463
   2. Select "Noisia - Alpha Centauri (Excision & Datsik Remix)" (currently track 12)
   3. Observe specifically around 0:45 and later.
   4. Observe left can almost completely misses bass line while right can dutifully and proudly follows perfectly.  (Very striking test.  Many other songs fit in this one's stead:  Anything with a prominent and deep bass line will be very noticeable.)
    
5. Expected: A given monaural tone is played with reasonably equal volume in each can.
6. Expected B: A given stereo track will play reasonably similarly regardless of whether the left channel drives the left or right speaker and regardless of whether the right channel drives the right or left speaker.
7. Observed: A monaural tone is significantly quieter in the left can regardless of ear observing or left/right amp channel driving the left can for the same input.  Left can is specifically incapable of generating sound pressure at frequencies below 100hz.  Volume at frequencies higher than 100hz are significantly softer on left can compared to right can.  This is repeatable across sources and amplifiers.
8. Observed B: No matter if the output channels are swapped, the left can almost completely misses bass, completely misses deep bass, and plays all tones and musical content significantly more quietly compared with the right can.  This is repeatable across sources and amplifiers.

 
 
I welcome any input and especially any potential fixes that might avoid the need for an RMA or refund.
 
Thanks guys,
 
Kenny
 
Edit: Resolution pending RMA.  This should not be needed anymore.
Edit2: AKG replaced broken headphones.  Do not buy from ulogin if you want working headphones.

 

[xfinrodx]

*bump

 

[xfinrodx]

Come folks, help save me from RMA!  They're taking their dear sweet time getting back to me about it, so I'm pursuing a "natural cure" in the mean-time.
 
Bump2 - Electric Boogaloo.

 

[Katun]

The OP is a bit confusing and intimidating, which is perhaps why you haven't got any responses yet.
 
But regarding the problem, assuming the earpads are attached correctly and evenly, I think you just got a lemon. It happens.
 
Also, did you buy used or refurbished? It's definitely possible to partially damage one driver and not the other.

 

[xfinrodx]

Thanks for the reply, Katun!  I was only trying to be very clear...  I am happy to restructure it to be less confusing/intimidating.  I work in software QA and this is the form that we use for clarity and comprehension in bug reports.  It's the best way I know how to present an issue with related testing performed.  I could make it more wordy and less structured if you think it might be helpful. 
 
I went around the pads and they seem perfectly uniform, unfortunately, exactly the same as the right side.
 
I did buy used, from a good, respectable & experienced member on the board.  Extremely unlikely he would have knowingly sent me a bum set, so I'm hoping there's a silver bullet somewhere else for this.  That, and I know RMA's often take weeks.
 
 
Simplest way possible to say it is that the left can has no bass and is significantly quieter than the right can at all frequencies.

 

[Katun]

Well, all that was really needed was the top two segments, which was exact what I read before replying. But it's never a bad thing to go into extreme detail, but sometimes it can scare people away.

 
Not that it's any of my business, but I can't seem to find the classified. I'm guessing you did a private sale? I just find it slightly odd that they would sound unbalanced on arrival, unless you were previously informed.

 

[xfinrodx]

This is the classified.  I thought it odd as well, but yeah.  Should have bought new I guess!  If you can think of anything to try (nondestructive of course) I'd love to hear it...

 

[jadawgis732]

Yeah, I dealt with the same seller, who incidentally ripped me off by refunding me $28 less than the price I paid, and not reimbursing me for shipping a mod back to him. That guy is an awful seller, and looking at his feedback it seems that I have some company lately.
 

 

[xfinrodx]

Yeah, unfortunately I failed to read your review before the purchase.  As you can read, he did similar to me:  Gave me negative feedback because I was unsatisfied with broken headphones...  It's really unfortunate.  I was hoping to find a moderator or admin who might be willing to clear my good name on the matter with a presentation of facts related to the transaction, but I'm thinking it's unlikely.  Man, my first online negative.  Been trading in other forums for many years...  One transaction here and it all falls apart.
 
Anyway, on subject, they were blown.  AKG replaced them with a new set.

 

[deepshikhanc]

Haha - he did exactly the same to me too! I wonder if the headphone makers pass him off the defective items to sell on this site!  Luckily, I bought the Hifimans from him on ebay, or I would be out of 600$. One side was totally blown, but he claimed they were "perfect".
Once I gave him a negative feedback, he even threatened me to come to my work and extort the money out of me, because I live close by. Stalked my facebook profile as well! At least good to know I'm not the only one..lol. I am glad you got a replacement.

 

[jadawgis732]

Quote:

I was hoping to find a moderator or admin who might be willing to clear my good name on the matter with a presentation of facts related to the transaction, but I'm thinking it's unlikely.

I'll tell you the same thing I told deep: contact Currawong. If both of you are contacting him regarding ulogin, as I did a couple weeks ago, I think we could at least get the negatives removed. Same here, was my first negative anywhere. I'm like 24-0-0 on heatware, 16-0-0 on eBay, and 12-0-0 as an Amazon seller.
 
Also, good to hear that AKG replaced them. How do you like them, they are the nicest looking full size headphones besides the HD800, IMHO.
 
 
Quote:

Haha - he did exactly the same to me too! I wonder if the headphone makers pass him off the defective items to sell on this site! 
Once I gave him a negative feedback, he even threatened me to come to my work and extort the money out of me, because I live close by.

Oh man, that makes total sense, he seems to have an extraordinary amount of HiFiMan stuff (and broken stuff too). He even had them overnight a headband and earcups to me from China so I could mod a pair for him. BTW how did you owe him money?
 
 
 
 
 
 
 

 

[Currawong]

If you have an issue with a sale, please leave appropriate and factual feedback. 

 

[deepshikhanc]

I didn't. Because I bought the headphones on ebay, they gave me a full refund (including shipping) when I returned them. But this guy claimed that the headphones worked fine.  I got it tested by three other people and they all confirmed that one side was blown. However, he relisted the headphones on head-fi while they were still in transit and claimed that he 'restested' them. I feel bad for the guy who bought those cans from him again ! 
Next thing I know - I get an email from him with a link to my facebook account (thanks to google search) and a threat to come over to my workplace and get the money. (!!!!!) 

 

[jadawgis732]

Quote:

I didn't. Because I bought the headphones on ebay, they gave me a full refund (including shipping) when I returned them. But this guy claimed that the headphones worked fine.  I got it tested by three other people and they all confirmed that one side was blown. However, he relisted the headphones on head-fi while they were still in transit and claimed that he 'restested' them. I feel bad for the guy who bought those cans from him again ! 
Next thing I know - I get an email from him with a link to my facebook account (thanks to google search) and a threat to come over to my workplace and get the money. (!!!!!) 

 
Currawong, do you think that leaving feedback is the appropriate response when (1) a male seller is threatening to go to a female's place of business with the intent of extorting them and (2) stalking them on Facebook? What happens when a trader is so bad that feedback alone isn't enough?
 
P.S. Same thing happened to me. First he made me pay $28.70 (or refunded me $28.70 less) to mail the broken Fischer DBA-02s back to a seller (which is ludicrous). I could've lived with that. When I saw them for sale in the same thread two days later, I got really pissed.
 
 

 

[ulogin]

America has a culture of returning goods. Not sure if the culture is unique in America, but I have travelled enough to know that it is not cross-cultural. Take me as an example. I am rather “Americanized” in this regard. Several months ago I bought two shirts online from Hollister, and returned them just because I don’t like the color. And last week I bought several Polo shirts online from Ralph Lauren, and found that they even included a return shipping slip (and that is prepaid) inside the package.
 
I thought it could not get any worse than this—only to find out that used market in head-fi gears is. Not only do buyers want to return things because they don’t like it (which is easy for things as subjective as sound signature). They also want to return things, when they managed to find cheaper alternatives. The worst part is that they start to think that you are Hollister or Ralph Lauren or Amazon, when they see the seller has a lot of stuffs put up for sale.
 
Well, I am not Hollister, nor Ralph Lauren, nor Amazon, and I don’t like people returning stuffs (although I think I should let you guys know when my HD800 and HP1000 get "blown" drivers). So I won’t refund just because buyers don’t like the sound, or just because buyers find another one for cheap. But I do issue refund, and the policy is clearly stated in my classified advertisements: I will issue a refund, but only if the problem that the buyer claim is verified by a third party—which is any Headphone Supremus of the buyer’s choice.
Enough said. If not, I won’t mind posting details about the three buyers in the following posts.