[Zombie_X]

Yes it is odd. I wonder how this could have happened...
 
I ran his for about 75 hours after I put the new cable on but the sound has not changed. They are already on their way back to him. We'll see.
 
I still don't understand how his got the 32Ohm strain. Like I said he ordered them from the Manufaktur service and selected 600Ohm.

 

[Zombie_X]

Guys gots a head up for you.
 
My friend Puck Ja, who had the driver's without the diodes installed, contacted beyerdynamic and got an answer about the drivers. Their QC guys said it was part of a batch that did not have the diodes installed, so it was a QC issue. He also said that there were a few other more batches that did not have them besides the batch Puck's came from. The diodes do affect the sound/performance from my understanding, but I'm not that tech smart.
 
I urge you guys to check your drivers out because he is replacing Puck's free of charge. The driver's without the diodes are supposed to perform differently and also sound differently.
 
If they are willing to send you replacement driver's I could install them for you guys for free. 

 

[dukja]

While I do appreciate Zombie-X's help to discover the "missing resistor" issue and swap the driver, I would like to clarify some details.
 
1. Officially the Beydynamic-USA did not admit that it is QC issue.  They just say there was a period of time that the driver came without the resistor.  The contact person, who also put my DT880 together, plans to contact Beyer at Germany to find out why the resistor was missing and what the impact would be.  I will update you guys when I got information back from him.  Before that, we probably should not speculate too much.
 
2. SQ-wise, it "seems" quite different to me with and without that resistor.  Long ago I was quite surprised the tonal difference (fuller & smoother high with thicker mid vs. thinner but crispier high and tighter mid) between my two DT880/600ohm when I just got them, but I always thought the difference was due to the recable (one with mogami wire).  Since Z-X has lots of experience with different DT880/600 but with the his same cable, he must be able to detect the difference easily.  However, one could prefer one sound to the other, and that was the reason why I did not jump the gun earlier.  I also listened to the recabled "resistor-missing" DT880 sent back from Z-X.  The recabling does minimize the difference by smoothing the high freq but the difference was still there.  I also noticed the soundstage was closer comparing to my the other DT880/600ohm with mogami.  I believed that close stage was more due to the "resistor-missing" driver and that's why I decided to ask Beyer for the new driver since I prefer a farther stage.

 

[apatN]

Again, it's not a resistor but a diode. Sorry to nitpick but it's a completely different thing. Fortunately my drivers are okay.

 

[Skylab]

And at least in theory, the diode should have no sonic impact whatsoever.

 

[dukja]

The confusion of resistor or diode is not out of ignorance but from Beyer's information.  I mentioned diode but the person at Beyer correct me as resistor.
 
The terminology isn't so confusing for many EE engineers or scientists here. 

  Just open to possibilities since I have not opened and seen one yet.
Quote:

Again, it's not a resistor but a diode. Sorry to nitpick but it's a completely different thing. Fortunately my drivers are okay.

 

[nickchen]

Quote:

The confusion of resistor or diode is not out of ignorance but from Beyer's information.  I mentioned diode but the person at Beyer correct me as resistor.
 

You've been talking to a salesman then (proper collection of ties, company car and other privileges, no clue of anything)

 

 

[cfcubed]

I'd expect a true diode to have a large negative affect on any audio wave.  Audio is a form of AC and diodes "chop" at AC waves:
 
http://www.allaboutcircuits.com/vol_3/chpt_3/4.html
 
Betting it's a resistor if anything.
Quote:

And at least in theory, the diode should have no sonic impact whatsoever.

 

[nikongod]

the point of the diodes is to form a hard upper limit to the voltage swing seen by the drivers. A diode clipping off the tops of the signal wave>>driver damage.
 
(formerly) my DT770/600 had protection diodes across the drivers. 
 
My formerly functional Ultrastoned HFI-780 had protection diodes too. Apparently the ultrastoned drivers actually need protection. Oops. They sounded better with the 32ohm SFI-ortho drivers anyways.
 
Considering the turn on/off transients that an OTL tube amp (and some hybrids) can put out and the fact that turn-on-delay relays are seldom used its not such a bad idea to add protection diodes to the headphones.
 
If your amp cant drive the additional capacitance from protection diodes cleanly thats a funny joke. On you.

 

[cfcubed]

Ooo.    Thanks for pointing out what should have been obvious to me 
Only had a couple/few cans open and, never having seen extra electro bits in them, didn't know how diodes could be put to use there.  Not in series (duh on me). 
More like "You tryin' something funny with me you headamp?...Take that!"

 
Quote:

<snip>
(formerly) my DT770/600 had protection diodes across the drivers.

 

[dukja]

That is a possibility.  But at lease he knows how to solder driver to the cable. 

 
Quote:

You've been talking to a salesman then (proper collection of ties, company car and other privileges, no clue of anything)

 

And thanks to the explanation.  So the diode is for protection purpose.  That will make a lot of sense than just putting a resistor there.  So maybe this diode attenuating some high freq. unintentionally that the one with diode sounds smoother?  And its inevitably not-flat freq response shapes the final SQ to be more pleasant?  That is interesting idea to EQ the sound.  Maybe I should opt to not swap the driver to hear the "truer" driver sound.

(But this is my speculation.)
 
Quote:

the point of the diodes is to form a hard upper limit to the voltage swing seen by the drivers. A diode clipping off the tops of the signal wave>>driver damage.
 
(formerly) my DT770/600 had protection diodes across the drivers. 
 
My formerly functional Ultrastoned HFI-780 had protection diodes too. Apparently the ultrastoned drivers actually need protection. Oops. They sounded better with the 32ohm SFI-ortho drivers anyways.
 
Considering the turn on/off transients that an OTL tube amp (and some hybrids) can put out and the fact that turn-on-delay relays are seldom used its not such a bad idea to add protection diodes to the headphones.
 
If your amp cant drive the additional capacitance from protection diodes cleanly thats a funny joke. On you.

 

[coryloew]

Ok, so I just received my new 6J1P-EV tubes yesterday.  Installed them into my Little Dot MKIII headphone amp.  With the DT880 600 ohm headphones, there is a slight increase in bass over my Mullard driver tubes.  And I mean slight.  I'm a little confused when certain people describe changing driver tubes as resulting in drastic sonic changes.  This is my 3rd variety of tubes that I've tried with the headphone amp, I supposedly have one of the more revealing headphones out there, and I hear all of these tube changes as slightly altering the sound characteristics.  There may be a small percentage of the audiophile community that can easily pick out these changes, and then they may describe these changes as "much increased bass", or "sound stage increased by 20 feet in width",etc.  Compared to all my friends and family, I have the most discerning ear (that may or not mean anything), and have typically been highly critical when things are not balanced well.  I still don't hear these large changes in sound characteristics that supposedly should be happening.  Who knows, maybe my ears are somewhat flawed.  According to my latest hearing test, all is good. 
 
The odd thing is that my DT880 600 ohm phones have shown me how much I love my lowly SR60 cans.  With the new tubes in my LDMKIII, the Grados have noticeably more slam and bass than they did with the Mullard tubes.  Odd that I noticed the difference in tubes more with my cheap Grados than the DT880's.  Even more odd is that people told me that I would not notice the changes in tubes with my lowly SR60's.  I know what many of you are thinking...the DT880's are not a rock or techno headphone and I should not expect them to be bass heavy.  I don't want them to be bass heavy.  So far my experience with the DT880's has been mixed.  I would describe them as having a very airy and delicate sound.  Highly detailed.  To my ears, the top end is too hot.  Everything has too sharp of an edge to it.  To my ears, even live music doesn't sound this sharp-edged.  They also seem to lack any form of warmth.  The DT880's really help me to analyze music, but I don't know if it helps me to enjoy the music and get into it.  To me, music always needs to be heard and felt (a little).  Maybe I'm finding I don't want music to sound airy and delicate with copious amounts of detail.  I'm not going to give up yet.  Perhaps I will adjust to this and end up loving it.  That or maybe I just need to get a good EQ.  I hope this doesn't come across as too negative of a post.  Just thought I'd add my experience.

 

[Zombie_X]

Ok, my misunderstanding then dukja. I misread your e-mail (was half awake when it was read). Thank's for clearing that up.
 
I just wanted to give everyone a head-up on it just in case it was QC issue, so perhaps I jumped the gun a bit...
 
And like I stated earlier, my DT880/600 and dukja's DT880/600 both sound different. I've also heard like 30 or so other DT880/600's and they all sounded like mine, but dukja's was different. His had a thinner sound to if with a more confined soundstage. It sounded closer to the 250Ohm version than the 600Ohm version, but only in tone It retained all of the 600Ohm's refined trebles/mids/bass, just it was not as thick sounding as mine.
 

 
Quote:

While I do appreciate Zombie-X's help to discover the "missing resistor" issue and swap the driver, I would like to clarify some details.
 
1. Officially the Beydynamic-USA did not admit that it is QC issue.  They just say there was a period of time that the driver came without the resistor.  The contact person, who also put my DT880 together, plans to contact Beyer at Germany to find out why the resistor was missing and what the impact would be.  I will update you guys when I got information back from him.  Before that, we probably should not speculate too much.
 
2. SQ-wise, it "seems" quite different to me with and without that resistor.  Long ago I was quite surprised the tonal difference (fuller & smoother high with thicker mid vs. thinner but crispier high and tighter mid) between my two DT880/600ohm when I just got them, but I always thought the difference was due to the recable (one with mogami wire).  Since Z-X has lots of experience with different DT880/600 but with the his same cable, he must be able to detect the difference easily.  However, one could prefer one sound to the other, and that was the reason why I did not jump the gun earlier.  I also listened to the recabled "resistor-missing" DT880 sent back from Z-X.  The recabling does minimize the difference by smoothing the high freq but the difference was still there.  I also noticed the soundstage was closer comparing to my the other DT880/600ohm with mogami.  I believed that close stage was more due to the "resistor-missing" driver and that's why I decided to ask Beyer for the new driver since I prefer a farther stage.

 

[dukja]

Z-X you are a great guy!  No problem at all.
 
It is just that I told the person at Beyer-USA that I will not speculate until I heard back from him. So some clarification wouldn't hurt.
 
And I do appreciate that more knowledge person can chime in on the detail of this diode.  It helps a lot!
 
Quote:

Ok, my misunderstanding then dukja. I misread your e-mail (was half awake when it was read). Thank's for clearing that up.
 
I just wanted to give everyone a head-up on it just in case it was QC issue, so perhaps I jumped the gun a bit...
 
And like I stated earlier, my DT880/600 and dukja's DT880/600 both sound different. I've also heard like 30 or so other DT880/600's and they all sounded like mine, but dukja's was different. His had a thinner sound to if with a more confined soundstage. It sounded closer to the 250Ohm version than the 600Ohm version, but only in tone It retained all of the 600Ohm's refined trebles/mids/bass, just it was not as thick sounding as mine.

 

[nikongod]

I found this while looking for a schematic of a limiter (not a schematic):
Beyerdynamic web article on SPL limiting
 
Interestingly, my current DT770pro (80ohms) have no protection diodes, even though the article lists it as an option. Perhaps they are serious about the "optional" part.
 
Figure 5 example a is what I believe was in my old DT770/600. 
Headwize article on the subject