Denon AH-MM400
Sep 25, 2015 at 9:32 AM Post #766 of 1,435
For what it's worth, I've had a crackling earcup in another pair of headphones caused by a hair pressed right up against the driver in that earcup. Once I removed it there weren't any more problems. Just something you could possibly check before sending them away!
Haven't sent them away yet so I will definitely try to look for something like that. It's not something I even considered. By the way, while I wait for Denon (QualiFi) to come back to me on what options they can provide me here locally, do you know of any good headphone or audio repair shops in Sydney? I'm weighing up the costs of sending them back to Japan for repair under warranty, getting them fixed interstate if QualiFi come back with a favourable response or getting them rectified by any technician in Sydney who can source the genuine parts, which would then completely void my warranty.
 
Sep 25, 2015 at 12:16 PM Post #767 of 1,435
For what it's worth, I've had a crackling earcup in another pair of headphones caused by a hair pressed right up against the driver in that earcup. Once I removed it there weren't any more problems. Just something you could possibly check before sending them away!
So I thought it was going to be rocket science for the earpads to come off. A gentle pull and they were off. I got to see the driver in the flesh for the first time. Even the workmanship on the inside is spot on.

So I managed to verify a few things. There is definitely no rip in the driver. There is definitely no wire protruding in front of the driver. I found a hair indeed (even though it was on the outside of the earpads). In addition to that, close to the location of the hair, I managed to locate a hair thin piece of plastic, half the size and thickness of a toothpick, again on the outside of the earpad. Where the hell it came from, I have no idea. I also noticed that the sponge material is visible on one side of the earpad but not the other on the inside. I don't know if that's normal or whether that opening could also be a source of the vibration. If anyone has taken their earpads off, I'd love to know.

I hope I just avoided sending my beloved headphones away. If the problem returns, that's the first thing I'm checking next time to prove it's in fact the cause. Thanks Bark Snarly.
 
Sep 26, 2015 at 8:03 AM Post #768 of 1,435
Hope that turned out to be the fix, Romani! Would be nice if you didn't have to send them off at all. Keep us updated if the crackling has indeed stopped or not.
 
I'm kind of curious to see what the drivers look like myself now too. I haven't actually taken the earpads off these before...
 
Sep 26, 2015 at 9:35 AM Post #769 of 1,435
  Hope that turned out to be the fix, Romani! Would be nice if you didn't have to send them off at all. Keep us updated if the crackling has indeed stopped or not.
 
I'm kind of curious to see what the drivers look like myself now too. I haven't actually taken the earpads off these before...

I hope so too mate. Considering that hair and mega thin piece of plastic were on the outside of the earpad as opposed to being on the driver itself, I am not hopeful this was root cause to be honest. However, I have a feeling it has more to do with the earpads and how secure they are on the earcup. If you do end up taking the earpads off, please let me know whether the green cushion material is visible or whether is it out of view all the way around the earpad. That could be my problem. In either case, there hasn't been a re-occurrence, but then again, this issue rears its ugly head up every couple of months.
 
Sep 26, 2015 at 10:05 AM Post #770 of 1,435
... I also noticed that the sponge material is visible on one side of the earpad but not the other on the inside. I don't know if that's normal or whether that opening could also be a source of the vibration. If anyone has taken their earpads off, I'd love to know. ...

 
I would love to help you out on this one, I just do not understand what your asking.
 
Bark Snarly obviously put thinks in more understandable terms than me, because an inspections for things like hair, dust, or loose objects, is just what I meant. We had this little metal thing on these, that vibrates given enough base, so any loose piece, or any foreign object of any kind, will behave just like that metal thing.
 
  Anyone else try this cable?
 
http://www.ebay.co.uk/itm/251944630020?_trksid=p2060353.m2749.l2649&var=550815680185&ssPageName=STRK%3AMEBIDX%3AIT
 
I just got mine (after a month and a half) and it seems to make the left speaker much louder than the right. 
 
I can't tell if it is a fit issue or a cable issue. 

 
I really do not like the sound of both these issues. All I can do is just speculate and share my experiences from my past.
 
It could be the same issue, and to me, that would hint to the female 3.5mm jack. Given the assumption that soldering and cables are fine, that would break down to basicly two issues: Mechanical or dirt.
 
As for mechanical, that probably need some repair work or tinkering. It could be an alignment issue, and it could be third party jacks being of slight different dimensions, messing things up. I simply do not know.
 
In my experience, these things hardly ever breaks. What has happened to me, is that the soldering gets broken from fatigue. I have fixed some of these in the past, like in walkmans, simply by redoing the soldering of the female. Actually, the print board that these female jack terminators are soldered to, usually breaks on me, prior to the terminator itself. I actually have redone the wiring a couple of times, as to fix broken print boards.
 
That said, the jack terminators pumping out of china these days, fits differently than any jacks I have ever used in my past. Some seems thicker. I try to avoid using these, as they as far as I can tell, weakens the female jack, and other male terminators fits more loosely after using these bigger ones. Still nothing has broken on me yet.
 
In my experience, I just never had to clean any female jack ever. That includes the mobile phone that lives in my pockets. Cleaning might be vacuuming, compressed air, or some alcohol. As for vacuuming that is an utterly no go with any electronics, use compressed air. Also, be careful as not to spill fluids like alcohol on the drivers. Applying some alcohol to a male jack, and give it some play, might be all that is needed. The alcohol itself will just vaporize, and will not be of any problem. Some windshield cleaner will do just fine, the blue fluid used in cars.
 
Once again, I hope these ramblings to to be helpful, and not just add to the problem. Issues of these kind, tend to foster a lot of wise comments, which of few turns up to pinpoint anything. You really need to trust your own gut guys.
 
Best of luck to both of you.
 
Sep 28, 2015 at 1:28 PM Post #772 of 1,435
Anyone else try this cable?

http://www.ebay.co.uk/itm/251944630020?_trksid=p2060353.m2749.l2649&var=550815680185&ssPageName=STRK%3AMEBIDX%3AIT

I just got mine (after a month and a half) and it seems to make the left speaker much louder than the right. 

I can't tell if it is a fit issue or a cable issue. 


The 3.5,mm jack on the headphone side should have 4 contact points, whereas the cable you show has only 3 (it has a common ground for both stereo channels instead of separate + and - for each channel).... so it's the wrong cable :frowning2:
 
Sep 28, 2015 at 1:56 PM Post #773 of 1,435
That makes sense. I assumed it'd work because other cables designed for the NC 800, etc. seem to work with the  AH-MM400.
 
The seller's agreed to pay for my return shipping so all's good.
 
I've ordered this now: http://www.ebay.co.uk/itm/201161650856?_trksid=p2060353.m2749.l2649&var=500336697755&ssPageName=STRK%3AMEBIDX%3AIT
 
I've seen people try it here so I assume it'll work, but how, in the future, would I tell if it has three or four contact points?
 
Thanks!
The 3.5,mm jack on the headphone side should have 4 contact points, whereas the cable you show has only 3 (it has a common ground for both stereo channels instead of separate + and - for each channel).... so it's the wrong cable :frowning2:

 
Sep 28, 2015 at 2:28 PM Post #774 of 1,435
The 3.5,mm jack on the headphone side should have 4 contact points, whereas the cable you show has only 3 (it has a common ground for both stereo channels instead of separate + and - for each channel).... so it's the wrong cable :frowning2:


Not sure that's right. I have a replacement cable wired like that one and it's fine (left, right, common ground).
 
Sep 28, 2015 at 8:41 PM Post #776 of 1,435
The 3.5,mm jack on the headphone side should have 4 contact points, whereas the cable you show has only 3 (it has a common ground for both stereo channels instead of separate + and - for each channel).... so it's the wrong cable :frowning2:



Not sure that's right. I have a replacement cable wired like that one and it's fine (left, right, common ground).


.... well there are 2 options coming to my mind:

1) inside the denon there could be an option of balanced connection with 4 pins. Now, even if there are 4 contacts on the headphone side, still the two separate ground contacts are "united" inside the cable to a common ground because on the amp side there is only 3 contacts. But inside the denon socket still are 4 "receiving" pins. 2 separate for ground. Normally just one receiving pin is used here for ground. This pin would sit comfortably in the middle of the ground contact (the one closest to the grip of the jack). Now this 2 pins of the denon use more space and come very close to the adjacent signal pin (right channel)....
2) the pin closest to the jack grip is used for mic purposes which somehow makes no sense because the 400 has no build-in mic.

Bot in both cases the contact points an their receiving pins are quite close to each other. So now in combination with the oval "socket-entrance" other cables might not have perfect fit, resulting in a ground pin touching the right signal contact and like that leading to such effect...
 
Sep 29, 2015 at 8:54 AM Post #780 of 1,435
How do the ear pads come off?  When I pull at them it seems like the leather is just going to pull out and I stop for fear of ruining them.
Go to the back edge and if you pull softly enough, you will find there is a lip that is tucked away into a trench surrounding the driver. As long as you aren't aggressive in your approach, there should be no possibility of tearing anything.
 

Users who are viewing this thread

Back
Top