oscillating op-amp causing ear pain?

Jul 23, 2009 at 10:59 AM Thread Starter Post #1 of 9

leeperry

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hi there, I've done quite a lot of recabling on this DT770...like this one : http://www.head-fi.org/forums/f6/rec...0-done-425937/

but now, I think my left driver is slightly out of phase or possibly foobared
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the stock cable doesn't have any plastic shielding on the 3 inner wires, but they're insulated w/ some vernish.

when I check the impedance of the 2 drivers, it's more or less identical....even though they used to give 622 on both sides when I bought them, then later on 628 on one side and 622 on the other.....and now they both give 624
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I initially thought that my new soundcard was faulty, because I started having pain in my left ear right after buying it(which went away when forcing crossfeed in foobar
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)

can an out-of-phase driver give pain to the inner ear
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if I play mono, the sound is very much on the right side...and so is a sinetone in sinegen..ah well, it's really getting on my nerves at this point
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right now I'm on the mobo onboard chip, and the left channel still sounds slightly out-of-phase...so my Asus soundcard is more or less ruled out. I guess it's time to recable everything again, put a furutech 1/4" plug and switch the drivers
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if the sound is left centered afterwards, I guess the right driver is indeed busted....I won't be caught on recabling ever again, I can tell you that
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Jul 23, 2009 at 3:15 PM Post #2 of 9
Phase is different than what you're describing. Your headphone is just out of balance. One side is louder than the other, not producing sounds at a different phase.

If you wear the headphones backwards does the sound move to the other side?

You're also probably measuring resistance in the drivers, not their impedance. I'm assuming you're using an ohm meter. Resistance might clue you in if there is something wonky, but it's no sure sign.

I'd find it hard to believe your ears would hurt from a misbalanced driver. It may give you a headache though, since everything is always shifted and it's bothering you.
 
Jul 23, 2009 at 3:54 PM Post #3 of 9
well I've got an appointment w/ my otologist in 10 mins
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all the problems started when I switched from the STX to the ST, and mine has a totally oxydated I/V DIP8 socket...

this is how the DIP8 sockets should look like : http://www.eal.gr/Scan48.jpg

this is how the bottom right socket looks like on my ST : http://img30.imageshack.us/img30/9601/dscn1662c.jpg

as I said, if I enabled crossfeed in foobar the pain disappeared
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anyway, I've checked w/ another pair of headphones and they're still balanced on the right....as I said none of this ever happened w/ the STX
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I don't really know what damage an oscillating op-amp can do, or maybe I'm allergic to the uber-low jitter of the ST
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how could I check the drivers? yes I did measure their resistance w/ a multimeter on the jack plug.

thanks for your help!
 
Jul 23, 2009 at 5:21 PM Post #4 of 9
Sounds like something is wrong somewhere. Can you test other cans with the card?
Also test your current headphone on another device.
Try and isolate the issue, to the cans or the source.
 
Jul 23, 2009 at 5:53 PM Post #5 of 9
It depends on what frequency it's oscillating. If the opamp is oscillating just above hearing frequency it could cause your ear to hurt as you may be able to "sense" the sound even though you're not really hearing it.

I get that with super high frequencies... We have a sonic welder at the other end of our office... it's so loud it hurts, but it only bothers me and one other person who can manage to hear that high.

It's possible it's oscillating on one channel and you're hearing it... but they usually oscillate at VERY high frequencies... but you never know, it depends on the design.

I'd stop using the card... it seems like it has some issues.
 
Jul 23, 2009 at 6:43 PM Post #6 of 9
yes, that sounds about right...I'm pretty new w/ dealing w/ op-amps...but it's more of a physical pain than a stricly auditive one
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I just went to the otologist, he said that I got a FR lack at 6000 and 8000Hz on the left ear...that's the "cotton in the ear" symptom I'm experiencing atm, and that always comes when I don't enable crossfeed in foobar on this card
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I will send back the card for RMA, and hopefully the new one will have pristine DIP8 sockets.

OTOH, the doctor said that you're REALLY not supposed to use headphones for +10H/day...even specialist in army corps don't work for so long
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I dunno what's a safe figure, but anything less than 6H sounds more like it.

what really sucks is that the STX didn't cause me any pain, it's right when I switched to the ST(w/ its uber-low jitter and much better soundstage) that problems arose
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either it is -as you said- that the freakin op-amp is oscillating at a non-audible freq....or maybe it's the uber-accurate stereo image of the ST that makes by brain dizzy..

I will take it easy until I get a new replacement card, hopefully in the meantime the cotton I got in my left ear will vanish.....and I will not use the new card for more than 6H/day, and only at very low volume w/ crossfeed enabled
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ahhhhhhh, freakin' upgraditis and inexistent chinese factory QA killed the cat I guess...

PS: I'll rename the thread title.
 
Jul 23, 2009 at 7:52 PM Post #7 of 9
Quote:

I just went to the otologist, he said that I got a FR lack at 6000 and 8000Hz on the left ear...that's the "cotton in the ear" symptom I'm experiencing atm, and that always comes when I don't enable crossfeed in foobar on this card


Did they give you a graph?
I know my ears are bad I have tinnitus in both but I am also lacking is HF specifically in my left ear. I got the graph IE 6db down at 4kHz, 12db down by 12kHz...and did some eq to help match the deficiency. Works pretty good. Also cross feed is a necessity necessity for me to listen through headphones.
Did they elaborate on why extended sessions were bad?
 
Jul 23, 2009 at 8:04 PM Post #8 of 9
ah good point, anyway I'll take it easy for a while...and next time I might just ask him for a copy of the FR curves indeed
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this card has already given me that "cotton in the left ear" symptom several times, it goes away after a few days eventually
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anyway, this otologist is an expert that works at courts, and he's also an otoplasty surgeon...so he know his business. he told me that pain in the outer ear is never much to worry about, still my left ear hurts as hell atm...and he checked everything he could using several machines, my outer ear is perfectly fine!

the best theory I got is that there's something foobared w/ that soundcard...I'll stop listening to HP for a few days, and hopefully everything will go back to normal when I get a new replacement working card
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well, he told me that your brain is not supposed to analyze dual mono audio for so long so often...I've been expecting way too much from my brain. we're not quite cyborgs yet, and headphones are a very unnatural mean of listening to audio...at least crossfeed makes it more "human-compliant"(by sending a very low copy of the opposite channel w/ a very slight delay...something like 15%/1ms, which my brain happens to crave for on this card!)
 
Jul 28, 2009 at 5:02 PM Post #9 of 9
just a small update, it looks like my sinusitis got into my Eustachian tube....and was increasing the pressure in the left middle ear, causing pain and that feeling of cotton in the ear(like when you take a plane)
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http://www.sinusinfectionhelp.com/eu...sfunction.html

anyway, my current treatment seems be fixing the glitch...the doc called me an uber-nitpicker, word to that!
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PS: now, where is that "I canz Hear!" lolcat when you need it
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