Really confusing channel imbalance

Discussion in 'Advice Threads' started by not_root, Aug 30, 2021.

  1. not_root

    not_root New

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    I've been experiencing a channel imbalance issue that defies explanation. My previous stack (Modi 3, Asgard 3, one of [HD600, DT880, Elleven Acoustica woodie, PortaPros) would consistently have a right channel that was louder/bassier than the left. As a sanity check, I tried several things:
    - Used a mono recording and swapped the DAC and amp interconnects, which made no difference.
    - Used different RCA interconnects to verify that the cables were not defective.
    - Physically reversed the headphones on my head to verify that the imbalance was indeed real and not a result of my hearing.
    - Turned the volpot to the maximum position and changed the volume digitally to make sure it wasn't a pot imbalance. To confirm, I used a multimeter, which indicated that the amp was outputting 2.00V when the digital volume was set to 0dBFS.
    - Used each headphone and verified that the exact same imbalance was present.

    Since I thought it unlikely that all four of the headphones tested would have an audibly right-favoring imbalance, I figured that the issue must be with the amp, since switching the DAC channels made no difference (and would also eliminate any possible misconfiguration in the digital realm).

    I've since replaced the stack with a Geshelli J2 and a Lake People G111 and the issue remains - I have repeated most of the steps above and the channel imbalance is indeed audible and basically the same.

    This is driving me insane - am I missing something incredibly obvious? Thanks in advance, any help wouuld be much appreciated.
     
  2. Lyander

    Lyander Official SBAF Equitable Empathizer

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    Even with digital volume set to max there have been times when I've caught myself with my face up my butt and there was a slight 2db or so skew in favour of one channel over the other in Windows settings. That aside it seems you've quite thoroughly accounted for everything besides the source (i.e. CDT or computer that feeds into the DAC) so perhaps finding something else to play out of might give a hint as to a plan of action?

    One more thing is that ambient noise can very much skew perception. When my AC or fan are running (or both on really hot days) I fully expect center image to waver a bit when I'm using the HP-3s as they're a bit more pinpoint with staging than the HD600s. Is your listening room entirely silent during these instances or is there perhaps air conditioning or similar running?

    P.S.
    There is the all purpose advice thread still but I guess enough people might have similar problems, haha.
     
  3. not_root

    not_root New

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    Switching the DAC cables left/right should account for any digital source discrepancy, right? And reversing the headphones on my ears seems like it would isolate the issue independent of ambient noise (ie, if the channel imbalance favored the right channel, the left would be louder when reversed).

    Thanks for responding, and apologies if this didn't warrant a new thread - it felt too oddly specific for the general thread.
     
  4. fastfwd

    fastfwd Friend

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    You swapped only one end of the DAC-to-amp interconnects, right? In other words, you connected DAC-left to amp-right, and DAC-right to amp-left?

    If so, and if "made no difference" means that the right channel was still louder, then the problem is between the amp end of the interconnects and your ears. So you can rule out the interconnects and everything behind them, including the source.

    Since all four headphones exhibit the same imbalance, you can probably rule out the headphones and their cables, but only if each has its own cable. Anything shared among the headphones (like a 3.5mm-to-1/4" adapter, or an extension cable) would still be suspect.

    Ok, so if there's only an amp between the interconnects and the headphone cable, then you're right: It's a mystery.

    But if there IS a termination adapter (or anything else) between the interconnects and the amp, or between the amp and the headphone cable, then it's that thing.
     
    Last edited: Aug 31, 2021
  5. Lyander

    Lyander Official SBAF Equitable Empathizer

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    ARGH, my brain was absolutely out of order there, I somehow understood it to be that when you swapped the headphones it was still the same channel being louder but somehow missed that you'd already ruled out it being hearing-related. Also missed that you swapped the DAC interconnects between L and R channels since I skimmed.

    This does seem to defy any sort of rational explanation given how much work has gone into troubleshooting. Just to confirm you've tried playing a mono track and flipping the headphones backwards to check that it would then move to LEFT channel, then swapping interconnects to see if that persisted?
     
  6. Tachikoma

    Tachikoma Almost "Made"

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    There is one more component you haven't mentioned - the actual digital source. If its a computer... check the volume mixer's balance setting?
     
  7. Riotvan

    Riotvan Snoofer in the Woofer

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    Yeah might be a windows mixer problem, try using wasapi or asio. Even better put a linux distro(Ubuntu or something) on an usb stick and try the sound in that live environment to bypass windows all together.
     
  8. not_root

    not_root New

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    Yeah, there's nothing shared between the headphones - all of them use different cables/adapters.
    Yup, exactly.
    I use ALSA on Linux and WASAPI on Windows, so this shouldn't be an issue. In any case, swapping the interconnects between channels verified that this isn't an issue.

    Thanks for all the replies - I have checked this to make sure I've not gone crazy and this isn't all just in my head.
     
  9. Tachikoma

    Tachikoma Almost "Made"

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    Well, try running the headphones straight out of your PC, I guess. Maybe, just maybe, your previous amp had a DC offset that left permanent damage on all of your headphones.
     
  10. not_root

    not_root New

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    I think you might unfortunately be right. I ran the headphones out of my laptop's HP out, and the same imbalance is present. I realized that, like an idiot, I've switched the Asgard 3's gain setting (many times) while the headphones were plugged in. My multimeter says that when the switch is flipped, at the peak around 70mV of DC offset is sent to the output. Looks like through a combination of my amp and some boneheadedness, I've totaled my electrodynamic headphone collection. :(

    EDIT: Is it normal for gain switches to generally be that dangerous? My (admittedly flawed thinking) was that since it's a front panel control, it should be safe enough.
     
    Last edited: Aug 31, 2021
  11. mitochondrium

    mitochondrium Friend

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    Condolences
     
  12. Riotvan

    Riotvan Snoofer in the Woofer

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    Damn that’s very sad to hear. Which headphones have been affected? Driver replacements might be available.

    Is there anything in the manual about this? Sounds to me your amp was defective and caused damage.
     
  13. not_root

    not_root New

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    Each one I've used with the A3, so the HD600, DT880, PortaPros, my customs
    Nope, nothing in the manual. I imagine it's difficult to confirm that this is the root cause - I don't want to accuse Schiit of anything, especially prematurely.
     
  14. Riotvan

    Riotvan Snoofer in the Woofer

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    Yeah don’t go throwing blame around but definitely contact @schiit they might want to take a look at it.
     
  15. Tachikoma

    Tachikoma Almost "Made"

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    My tube speaker amp makes a loud pop when I switch between NFB and no-NFB (gain switches usually work by changing the amount of NFB being used), but I wouldn't expect a headphone amp to do that.
     
  16. not_root

    not_root New

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    I've sent them an email - I still find this very strange - even 70-100 mV shouldn't necessarily affect each headphone and in the same way. Thanks all for the replies, I'll update if I get a useful response.
     
  17. bilboda

    bilboda Florida boomer

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    You can swap the drivers in the HD 600. That would allow you to check your hypothesis that one might be damaged. I once ordered a single driver for my HD 650 due to an all thumbs approach to a mod.
     
  18. not_root

    not_root New

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    Just confirmed by switching the L/R cables on the HD600.
     
  19. Lyander

    Lyander Official SBAF Equitable Empathizer

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    Crap, genuinely sorry to hear. You can easily (with some degree of care, cough) swap the diaphragms on the HD600 between capsules to see if that's all you'll need to replace, but last I checked they only really sold whole capsule assemblies unless you find some random dude who happens to have a spare driver kicking around from being a sausage-fingered hippo.

    (flashbacks intensify)
     
  20. not_root

    not_root New

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    It's been more than a week since I contacted Schiit, using both their form and directly emailing [email protected] as listed in the manual, and I haven't yet received a reply. Is this expected?
     

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