[MrTechAgent]

  Oh and about the channel imbalance, just replace the cable. The cable is almost always the culprit in these kinds of things. If it was not the cable, but for instance a misaligned voice coil, it would be very unlikely that 1 side would only sound more quiet, without distortion or alterations in frequency range. Recabling is very easy with the DT48, so long as you're not unscrewing the caps on which the cable ends are soldered on, because that would destroy the headphones, like so many things can.

Perhaps it would help but...
The DT48A that KBI gave me has the same imbalance issue, my right cup is quieter. 
Before jumping to the conclusion that re-cabling is the solution, I considered Voice Coil tolerances but that didn't sound too convincing because even in the range of 2-5Ohms + or -, it wouldn't be audible. Then did a test re-cable to see if it helped with the imbalance and NO. It didn't. This seems to be very common, KBI's DT480 had a similar imbalance. My DT480 doesn't have it. Jeff's (maniacal71) suggestion may sound dubious but I think he put in some thought before suggesting it here. (Waiting for his extra input)

Also, my DT48A with the imbalance has no abnormalities, its in phase and hence my imaging is not disturbed, just quieter. I found the right Channel setting to keep everything as cohesive as possible.

 

[Aizura]

  Perhaps it would help but...
The DT48A that KBI gave me has the same imbalance issue, my right cup is quieter. 
Before jumping to the conclusion that re-cabling is the solution, I considered Voice Coil tolerances but that didn't sound too convincing because even in the range of 2-5Ohms + or -, it wouldn't be audible. Then did a test re-cable to see if it helped with the imbalance and NO. It didn't. This seems to be very common, KBI's DT480 had a similar imbalance. My DT480 doesn't have it. Jeff's (maniacal71) suggestion may sound dubious but I think he put in some thought before suggesting it here. (Waiting for his extra input)

Also, my DT48A with the imbalance has no abnormalities, its in phase and hence my imaging is not disturbed, just quieter. I found the right Channel setting to keep everything as cohesive as possible.

 
Well, the chance that something is technically wrong with the tranducers is pretty small so I wouldn't mess with them before doing some more tests.
It may sound stupid, but are you sure that you are wearing the headphones symmetrically? As in, having both earcups adjusted to the same length relative to the headband? I've seen a LOT of lopsided DT48's for sale where the previous owner adjusted only 1 side in order to fit their head, instead of both sides, probably because people don't want to bother with having to unscrew more than 1 bolt.
 
I bought 2 pairs of DT48 second hand where this was the case, and when i first tried them, 1 side also sounded louder than the other. Once I adjusted the cups to be symmetrical, the balance was restored.
 
I feel that the DT48 is more sensitive to this sort of thing than other headphones. The sound they produce seems very directional. You really have to make sure that both tranducers are placed exactly the same relative to the ear canals, or it sounds noticably imbalanced. I find this issue a lot more pronounced with the over-ear pads than the on-ear ones.

 

[MrTechAgent]

   
Well, the chance that something is technically wrong with the tranducers is pretty small so I wouldn't mess with them before doing some more tests.
It may sound stupid, but are you sure that you are wearing the headphones symmetrically? As in, having both earcups adjusted to the same length relative to the headband? I've seen a LOT of lopsided DT48's for sale where the previous owner adjusted only 1 side in order to fit their head, instead of both sides, probably because people don't want to bother with having to unscrew more than 1 bolt.
 
I bought 2 pairs of DT48 second hand where this was the case, and when i first tried them, 1 side also sounded louder than the other. Once I adjusted the cups to be symmetrical, the balance was restored.
 
I feel that the DT48 is more sensitive to this sort of thing than other headphones. The sound they produce seems very directional. You really have to make sure that both tranducers are placed exactly the same relative to the ear canals, or it sounds noticably imbalanced. I find this issue a lot more pronounced with the over-ear pads than the on-ear ones.

Well, the DT48A that I have has the franken headband, same as the Berlin.
So it took me a long time to find the right fitting. Even I thought it was a sealing issue because I have E pads on it and I lost some articulation because of the baffle touching the headband. As you can see..


I'll try to get new EDT48R pads but the way I hear it. I don't think it would really help, its a very noticeable system imbalance.

 

[takato14]

Okay.
 
Finally found my multimeter and tested the DT48S. 
 
Cable impedance measures at .3 ohms on both channels. Left driver is 5.3 ohms, right driver is a whopping 33.5 ohms. DeepFunk mentioned that extra gain tends to "wake up" the drivers, so I listened to them at excessive volumes for a bit, snapping my phone's volume control up and down rapidly to try and incur something in the right channel. At first... the result was very frightening. It freaked out a little, cutting into full volume and out completely, to finally settle on zero... no measurable impedance after this.
 
I let them sit for a little, blowed into the magnet vents a little, and tried measuring them again. Back to 33.5 ohms, and the right driver is making sound again. I then decided to be a little more gentle and hooked it up to the O2. I let it run at a moderate volume, just above normal listening levels, for a few minutes.
 
Lo and behold: the right channel suddenly springs to life (and scares the **** out of me).
 
After this happens, it measures at 9.6 ohms. The volume is still imbalanced but not a fraction as much. If you were listening to the headphone when this happened, it will sound like it's at perfect balance afterwards. The channel balance remains perfect out of both of my computers, no matter the measured impedance.
 
I'm guessing that this is almost definitely a voice coil connection issue. How does one remedy this? I've seen several pictures of the DT48 drivers disassembled but no instructions for how to do it yourself...
 
I'm gonna leave them running at this volume level for a while and see what happens. Ironic that I'm the one currently relying on burn-in to fix this thing.

 

[Headzone]

why would someone push 20hz sine wave at headphones? especially the DT48 which dont play that much below 60hz anyway

 

[maniacal71]

My Kudelski doesn't have any problem below 20, I tested it and it reproduced 10hz on normal listening level, it's fitted with the soft vinyl pads. Keeps the ears very close to the drivers.Imbalance issues if not caused by cable imbalance, I washed them as described previously, although condensate is purer than water the dust accumulated could muck when mixed, the driver has no glue on that side, it's a concave air blown in a single piece, so it's safe and I've done that countless times.

 

[maniacal71]

The disassembly requires removal of the 2 soldered joints inside then screw out the driver, but unfortunately the voice coil itself is near impossible to unwind or glue back without affecting the flexibility of the diaphragm and strongly discourage that, alternatively you can measure the difference in resistance from the plug end, not forgetting to separate the grounds, adding a similar resistance on the lower resistance/higher volume should make them closer to balanced in terms of volume, another easier way is to get a player like rock boxed and balance the channels there.

 

[Headzone]

I tested it and it reproduced 10hz on normal listening level

you must have monkey hearing Considering human hearing is -30dB down at 10hz

 

[takato14]

The disassembly requires removal of the 2 soldered joints inside then screw out the driver, but unfortunately the voice coil itself is near impossible to unwind or glue back without affecting the flexibility of the diaphragm and strongly discourage that, alternatively you can measure the difference in resistance from the plug end, not forgetting to separate the grounds, adding a similar resistance on the lower resistance/higher volume should make them closer to balanced in terms of volume, another easier way is to get a player like rock boxed and balance the channels there.

Uh? I don't mean unwinding or ungluing the coil, jesus christ that'd destroy the transducer.
 
The way it's behaving clearly indicates some kind of connection issue somewhere between the solenoid and the cable, and actually now that I think about it someone may have recabled these ages ago and left a cold solder joint on the channel...

 

[MrTechAgent]

After a lot of back and forth with Beyer we have reached to an agreement. 
I'll be visiting Beyerdynamic HQ in Heilbronn in April (First Week). I confirmed with my friends at Beyer and they do have the two Berlins, the exact one's that KBI showed on his Facebook page. One with the Classic 4 Rod Spring Steel and the other one which is the same as the Franken but instead of the PVC we have a P-Leather band with foam which seems to be completely disintegrated.
I'm hoping to see a lot of DT48 Memorabilia there.

Also looking forward to meeting Wolfgang Luckhardt (CEO) and just Beyerdynamic's hand manufacturing. 
I have to admit, I'm getting goosebumps right now. Touching that Berlin is going to be surreal.

 

[Max Choiral]

Is this Beyerdynamic DT48 has something in common with Etymotic ER-4S?

 

[CJG888]

There are similarities in the tonal balance and midrange clarity.

 

[takato14]

There are similarities in the tonal balance and midrange clarity.

Are you kidding me? The ER-4 absolutely slaughters the DT48 in linearity and clarity. The DT48 sounds dark and grainy by comparison. 

 

[CJG888]

The midrange is clear - that's all I claimed! The bass and treble are both rolled off by modern standards (and there appears to be an odd coloration in the bass).

IMO, the DT48 driver could be a fantastic basis for a 3-way system

 

[Max Choiral]

Hmm, so this could be the only one competitive closed-back headphone. Damn, I regret not auditioning it when the production had been running on
 
Quote:

  Are you kidding me? The ER-4 absolutely slaughters the DT48 in linearity and clarity. The DT48 sounds dark and grainy by comparison. 

Wow, never have heard about it being dark