Phase cancellation problem - diyAudio
Go Back   Home > Forums > Amplifiers > Headphone Systems
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Headphone Systems Everything to do with Headphones

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 16th June 2010, 01:55 AM   #1
Fonic is offline Fonic  Canada
diyAudio Member
Join Date: Jun 2009
Question Phase cancellation problem

I've got some Sennheiser MX51 earbuds that have some strange issues (I know these are hardly hi-fi, but I'm a broke student and this is about as close as it gets for me.)

At one point, the jack quit working. I tried fixing it myself - I bought a 90-degree jack at a local electronics store and soldered it on. After this I was getting center cancellation when I using it on my iPod or my computer, but not when I tried miscellaneous other headphone things. I eventually figured out that the jack was slightly longer than normal, so in some plugs the ground connection must be connecting to the ring instead of the sleeve.

I then tried a different jack that, as far I can tell, is a normal size. It worked great for about 2 weeks, then it started center-cancelling again. If I pull the jack out slightly, I get only one channel coming in-phase out of both sides. I figured it had to be a wiring problem since it worked fine for 2 weeks before crapping out. But I just took a look at them now, and from what I can tell, the wiring is fine. This time, it only has problems on the iPod. The weirdest part is I measured the headphones' resistances and got around 70 ohms from right to ground and left to ground, and about 140 ohms between right and left, which seems to make sense to me. I also tried this while connected to the iPod (since the iPod jack itself seems to be what is shorting it) and got approximately the same readings - which seems to indicate nothing is shorting. And it's not a busted iPod jack; I tried a different pair of headphones (which, as far as I can tell from eyeballing it, have the same size of jack) and it worked fine.

Anybody have any idea what would cause this, or more importantly how to fix it? I don't really want to just buy new headphones because I don't want ones any cheaper than this, but I'm also a job-less student and so I don't really want to buy ones better than this either.
  Reply With Quote
Old 16th June 2010, 02:42 AM   #2
diyAudio Member
Join Date: May 2009
Location: New Zealand
"Centre cancellation" implies that the ground connection (sleeve) of the headphone jack isn't making contact with the ground connection in the iPod socket.

- Bad match between the jack and the socket. Fix: Change the jack or the iPod.

- Poor quality jack. The connections between the solder tabs and the jack components are often only riveted, and the heat of soldering loosens the rivet. Fix: Change the jack.

- Break in the shield wire in the cable, near the jack. This is the usual cause of the original jack failure. Fix: Cut a couple of inches off the end of the cable and re-solder.
  Reply With Quote


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
driver and port phase/bass cancellation domtw Full Range 6 26th February 2010 03:14 PM
Cathodyne Phase splitter simulation problem? wildswan Tubes / Valves 6 29th June 2009 10:33 PM
Playback problem with terratec phase 22 zoranaudio Everything Else 0 27th October 2008 05:28 PM
Leach150 phase margin problem!!! mclarenpingu Solid State 27 3rd March 2008 08:44 AM

New To Site? Need Help?

All times are GMT. The time now is 05:46 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2