Answered Bad stereo separation / L&R channels spilling over...

Discussion in 'Headphones, Earphones & Portable Music' started by Maurice Chavez, Feb 11, 2019 at 7:13 PM.

  1. Maurice Chavez

    Maurice Chavez
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    Hi there,

    I have owned a pair of Sennheiser CX 3.00 for about 18 months. The other week I randomly decided to test them to make sure they're working OK. I did a stereo separation test and the audio is spilling over into the opposite channel....

    So if I play audio to the left channel I could hear it in the right earphone too, but it's slightly attenuated (lower volume).... and vice versa; if I played audio to the right channel only, I could hear it in the left earphone too, but slightly attenuated.

    So I sent them off to the manufacturer under warranty, and today I received a replacement pair of CX 300S (basically same earphone but with a mic for phone use)... Unfortunately these replacements are also exhibiting the exact same problem albeit to a lesser degree (for now, I'm guessing it gets worse over time).

    I've done the test on two Samsung phones, a tablet, two laptops, my PC, and my TV headphone socket via HDMI from PC.

    My questions are;
    Is this is normal for low end £35 earphones?
    Or is it normal for 3.5mm jacks on all devices? Are consumer devices just poorly wired and should I invest in a proper headphone amp with a digital input and a 6.3mm phone out?
    Will I get the same problem if I get a pair of £200 IEMs and plug them into random 3.5mm jacks around the house?
    Has anyone else tested their headphones for stereo separation?
    (I assume it's more difficult to perform this test on large headphones unless you can remove the speakers from the headband and wrap each one under a blanket or something.)
    Should I send this replacement unit back and tell them to improve their quality control?


    Thank you for reading.
     
  2. Best Answer:
    Post #15 by Maurice Chavez, Feb 15, 2019 at 3:27 AM (1 points)
  3. noiseboy72

    noiseboy72
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    You should get 100% separation and if you are not, there's an issue with the source in my experience.

    The drivers are wired to separate connections on the jack, so if you are getting cross talk it's probably due to some sort of effect being applied by the source - maybe a spacial or surround type effect - which all use phase inversion to apply some of the signal slightly out of phase to the other driver.

    I've just tried mine using a Denon test CD on my laptop playing into my AKG NC60s in wired mode - in both noise cancelling and standard mode and the left / right tones have not so much as a hint of cross talk. Even running from a test track on Spotify through my phone via bluetooth shows minimal cross talk. I can move the "active" side off my ear and hear nothing from the other.
     
  4. Maurice Chavez

    Maurice Chavez
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    Thank you for your response noiseboy!

    The thing is I've tried multiple sources, including devices which shouldn't be applying any fancy processing to the audio such as old MP3 players, an old iPod nano too. The Windows PCs also have all enhancements turned off. Even tried making my own test files using Audacity.

    Also if it was a source issue, Sennheiser should have returned my old pair of headphones and refused to replace them (unless they do no testing at all!).

    Also the issue was far more pronounced on the pair I sent back. It's still there on the replacement pair but less obvious.


    Hmm. I don't have any other earphones to test, I think the best thing to do is buy some cheap £10 Sonys just to test, and if they don't exhibit the same behaviour I will send this pair back to Sennheiser and ask them to send me a pair which have passed some sort of quality control.

    Thanks.
     
  5. dannnielll

    dannnielll
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    Noiseboy is correct. There is 100% separation between the audio channels in any headphones.. how ekel would they work. ? There are a variety of other effects which can cause blending. I have each if sennheiser cx5, momentun in ear and on ear and there is no crosstalk. Some people find that objectionable and many sound cards has dsp effects to blend lower frequency sounds
     
  6. dannnielll

    dannnielll
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    The almost certainly did not bother testing them... The cost of getting someone to do what woukd be nanual test woukd be disproportionate. I have muktiplm earphones abd they all work the same way. Senns are a very good brand.
     
  7. GMC79

    GMC79
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    Just tested a few of mine including my old cx300 which I've had for many years since they were first released in what 2006?
    All fine.
     
  8. Maurice Chavez

    Maurice Chavez
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    Good morning and thank you all for the replies and information.

    So the consensus here is that it's more than likely my sources at fault here, and that all my devices seem to be applying some sort of DSP to send some audio into the opposite channel for reasons I cannot comprehend.

    Anyway, I've ordered a pair of cheap £8 Sony earphones which should be arriving later today, if I have the same problem with the Sonys then I know that about 30 different devices including friends and family's devices consisting of various phones, tablets, PCs and laptops, mp3 players, hifis and stereos, are all dodgy........

    And if the cheap Sonys don't have the same issue, then it will have to be another warranty claim sadly.
     
  9. John7

    John7
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  10. noiseboy72

    noiseboy72
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    Another thought...
    Is it either the way you are testing the headphones, or possibly your ears themselves?

    I know that sounds strange, but hear me out. How are you testing the earphones? The only real way is below:

    Play back a stereo file with audio on just the right channel. Create this yourself using Audacity, so that you know the right side has no audio whatsoever. Test files from the internet may not be as clean as you think they are.

    Listen to 1 ear at a time, with the other isolated - wrap it in a towel. The left channel should have audio and the right nothing at all.

    If you hear audio from the right hand earphone, either the playback device is applying an effect or there is a level of crosslinking between the headphones. This could be due to them not being plugged in all the way - so that the wrong contacts are being made on the plug.
     
  11. Maurice Chavez

    Maurice Chavez
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    Thanks noiseboy, yep that is exactly how I've been testing this.

    My cheaper Sonys have arrived and........

    ....they have exactly the same problem.

    Which now means about 30 different devices with a 3.5mm jack ALL have exactly the same problem. Thing is I haven't tested a proper external DAC. I think this is what i need to test moving forward.

    Overall sound quality from the Senns is still much better than the cheaper pair so at least that's all good.

    Thanks for all the help.
     
  12. JayCee

    JayCee
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    I find it odd that someone would “randomly” decide to “test” year and a half old headphones.
    What drove you to test them?
    Surely you would only check them if you had a problem with the sound?
     
  13. Steven

    Steven
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    How are you testing channel separation though? Duff units are a part of mass produced consumer electronics but having to write off thirty units is incredibly bad luck. The midi settings should allow adjustment of the channel balance or else look into free software like audacity
     
  14. dannnielll

    dannnielll
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    Maurice, there is something wrong here,and it is not the headphones.perhaps you should describe in detail the connector sequence etc.
     
  15. Maurice Chavez

    Maurice Chavez
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    Yes I have created two seperate files using Audacity.

    I open mp3, then select dropdown menu and select "split stereo track", then click mute on Left channel and save as "right.wav", then unmute left and mute right, save as "left.wav".

    These are the test files (i uploaded to multiple hosts so you can use whatever one you like):

    (Royalty Free Music from Bensound)

    LEFT

    left-bensound-happyrock.wav - Quick File Share
    left-bensound-happyrock
    Filebin


    RIGHT
    right-bensound-happyrock.wav - Quick File Share
    right-bensound-happyrock
    Filebin



    There is no connector sequence. headphones are being plugged directly into 3.5mm jack on all devices. Directly into PC sound card, directly into phone headphone jack. directly into laptop, directly into tablet, etc, etc.

    So far tested about 35 different devices belonging to friends and family. ALL spill stereo output into opposite channels.
     
    Last edited: Feb 15, 2019 at 3:47 AM
  16. Maurice Chavez

    Maurice Chavez
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    Best Answer
    I have found the answer.

    It's because 3.5mm jacks share a conductor for L and R channels.

    Huge thank you to everyone who tried helping.
     
    Last edited: Feb 15, 2019 at 4:05 AM

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