[NimnuL]

 
They do not use the same driver. The impedance of the K612 is much higher than the K7xx series.

 
The difference in impedance can be (and I'm persistant to say that it is) caused by a different cable. 
Also, when you take a look at the graphs comparing K612 and K712/702 you'll see a lot of similarities. 
To my ears they sound alike with differences in stage. Details, clarity, fun ... if it's not the same, then it's so close that not worth the difference in money.
This reminds me a discussion over Sennheiser and its HD555 vs. HD595 (or now HD558 vs. HD598). They use the same drivers too, different cushions and design though. I'm sure many of you remembers the 'epic' HD555 mod with removing the rectangle foam from behind the drivers which made them almost-HD595
I'm awaiting for the shots of the drivers comparing the one from K612 and K702/712. I'm curious if I'm really wrong
I can take a pictures of K612, but I have no idea how to put them apart. There are no screws. 
 
 


 
I know that service documentation http://www.akg.com/media/media/download/9352 sugests that these cans can be dissasembled from behind, but I have no idea how ... 
 

 

[AUserName501]

Spoiler: Quote: NimnuL

   
The difference in impedance can be (and I'm persistant to say that it is) caused by a different cable. 
Also, when you take a look at the graphs comparing K612 and K712/702 you'll see a lot of similarities. 
To my ears they sound alike with differences in stage. Details, clarity, fun ... if it's not the same, then it's so close that not worth the difference in money.
This reminds me a discussion over Sennheiser and its HD555 vs. HD595 (or now HD558 vs. HD598). They use the same drivers too, different cushions and design though. I'm sure many of you remembers the 'epic' HD555 mod with removing the rectangle foam from behind the drivers which made them almost-HD595
I'm awaiting for the shots of the drivers comparing the one from K612 and K702/712. I'm curious if I'm really wrong
I can take a pictures of K612, but I have no idea how to put them apart. There are no screws. 
 
 


 
I know that service documentation http://www.akg.com/media/media/download/9352 sugests that these cans can be dissasembled from behind, but I have no idea how ... 
 

 

Check the product sheets on AKGs website and you'll see the driver number is different for the K7xx series and K6xx series.

 

[elwappo99]

 

 
They do not use the same driver. The impedance of the K612 is much higher than the K7xx series.

 
The difference in impedance can be (and I'm persistant to say that it is) caused by a different cable. 
Also, when you take a look at the graphs comparing K612 and K712/702 you'll see a lot of similarities. 
To my ears they sound alike with differences in stage. Details, clarity, fun ... if it's not the same, then it's so close that not worth the difference in money.
This reminds me a discussion over Sennheiser and its HD555 vs. HD595 (or now HD558 vs. HD598). They use the same drivers too, different cushions and design though. I'm sure many of you remembers the 'epic' HD555 mod with removing the rectangle foam from behind the drivers which made them almost-HD595
I'm awaiting for the shots of the drivers comparing the one from K612 and K702/712. I'm curious if I'm really wrong
I can take a pictures of K612, but I have no idea how to put them apart. There are no screws. 
 

 
I can tell you from personal experience measuring the exact impedance across the K601 and K701 drivers they do have different impedance. 
 
I don't think any manufacturer has produced a cable with resistors to change the impedance. It wouldn't make sense on a few levels. The only headphone that had resistors in it were the Sony F1 and MA900.

 

[NimnuL]

  Check the product sheets on AKGs website and you'll see the driver number is different for the K7xx series and K6xx series.

 
 

   
I can tell you from personal experience measuring the exact impedance across the K601 and K701 drivers they do have different impedance. 
 
I don't think any manufacturer has produced a cable with resistors to change the impedance. It wouldn't make sense on a few levels. The only headphone that had resistors in it were the Sony F1 and MA900.

 
 
Fair points gentelmans, thanks for clarification. The last thing I want to do is to multiply wrong knowledge  

 

[Andreas_D]

   
I know that service documentation http://www.akg.com/media/media/download/9352 sugests that these cans can be dissasembled from behind, but I have no idea how ... 
 
 

 
I think this applies to k612 too.
 
 
 
I received my k612 this weekend and I'm very excited to rediscover my ex k601 sound, but imho with a little construction quality drop. (made in china) . I'm wondering, how much burn in do they need?
 
I saw that Senn HD650 is a good combo with Burson and I'm tempted to pull the trigger on them, but I would like to know, besides the different sound signature, would it be a really upgrade from k612, in any terms?

 

[NimnuL]

   
I think this applies to k612 too.
 
 
 
I received my k612 this weekend and I'm very excited to rediscover my ex k601 sound, but imho with a little construction quality drop. (made in china) . I'm wondering, how much burn in do they need?
 
I saw that Senn HD650 is a good combo with Burson and I'm tempted to pull the trigger on them, but I would like to know, besides the different sound signature, would it be a really upgrade from k612, in any terms?

 
I burned mine for over 70 hours straight, I don't know if the sound changed enough to spot the difference though. 
 
'Made in China'? You mean your's aren't made in Austria? On mine there is a small sticker on the leather headband. And the sticker is rather a silly thing when we are talking about phones for 150EUR.  
 
By the way, the build quality isn't connected with geographical location of the factory. Standards are standards, eighter they are met or not, doesn't matter in which factory. 
HD600 are not easy to drive to my ears, depends on the source you have. I recon the K612 to be excellent cans for the money, HD600 are good too, but rather not so good looking and not so comfy. 
 
What serial number are your AKGs? 

 

[Andreas_D]

I also have that sticker, but with "made in china prc"

  002061 
 
When I say quality drop, I mean between K601 and k612. A K612 made in China and one made in Austria should be the same,

 

[kman1211]

  I also have that sticker, but with "made in china prc"

  002061 
 
When I say quality drop, I mean between K601 and k612. A K612 made in China and one made in Austria should be the same,

Interesting my K612 is 002175 and is made in Austria. I wonder if they are making them in both Austria and China at the same time.

 

[conquerator2]

 
Interesting my K612 is 002175 and is made in Austria. I wonder if they are making them in both Austria and China at the same time.

001212, China

 

[Punnisher]

There was a point in time, within the last five years or so, where AKG started assembling the majority of their lineup in China. Same parts, different assembly location. This excluded their flagship audiophile line, the K7XX series and up which are still made in Austria.
 
If there are 612s made in both locations, it might suggest another shift in manufacturing location. I'll do some searching and see what I can find. I'd love a pair of 612s made in Austria. Not that it really matters, but it's something different and unique about AKG that I like.

 

[kraken2109]

001266
Made in China

 

[appsmarsterx]

looks like mine is made in Austria?

 

[kman1211]

looks like mine is made in Austria?

Seems that way. Mine said it on the box and had a sticker on the bottom of the headband that said Made in Austria. The sticker fell off in a couple days though.
 

 

[NimnuL]

 
This would explain why they put a poor sticker on the K612 Pro, not a nice printing on the external earcup. Mine are 000360. 
 

 

[LowLatency]

Mine are also "Made In China" ordered from thomann, serial number 001189.
Sound superb though, more detailed all the way through than my HD 555's. Compliment everything I've thrown at it so far. Bass is there, tight and controlled on properly mastered tracks think Monolake. Amazing for funk/soul and jazz. Sound neutral all the way through with a slightly warm tint. 
 
Easy to power on my Pioneer A-109 amp, normal listening level around 9 on the dial, far too loud past 11. M-Audio 24/96 soundcard/dac.
 
Great cans for the price, can't really fault them.