[93EXCivic]

Obviously in a perfect world headphones would match left to right perfectly but in a practical world what is the human ability to pick up on a difference in level from left to right? I would assume it would also be frequency dependent.

 

[pinnahertz]

  Obviously in a perfect world headphones would match left to right perfectly but in a practical world what is the human ability to pick up on a difference in level from left to right? I would assume it would also be frequency dependent.

It's something that never appears in specifications, so even if you had a nice single figure of merit, what would you do with it?
 
On the other hand, here is a reference:
 
http://www.feilding.net/sfuad/musi3012-01/html/lectures/008_hearing_III.htm#IID
 
See figure 2.31.  Looks like an apparent 10 degree shift in source location is caused by less than .5dB level differential.  One would expect good headphones to be less than that, hopefully 0.1dB.  Makes you wonder why it's not spec'd...but then, headphone specs are particularly sketchy, even the $4000 ones.  Nobody even specifies frequency response because of the target curve problem.  

 

[castleofargh]

the best manufacturers do for headphones as far as I know is to check for +/-1db in a given audio range(not even full 20hz-20khz). and almost all the other headphones have more than 1db variations somewhere, unless we get that one fine headphone that statistical randomness is bound to create from time to time.
but while this probably has a lot of psycho acoustic consequences, detecting channel imbalance with music isn't as easy as it seems. at least it isn't for me^_^.  even knowing how much and where some variations occur after measuring them, I'm still not always sure I could tell by ear(with music!!!!!!!!).

 

[pinnahertz]

  the best manufacturers do for headphones as far as I know is to check for +/-1db in a given audio range(not even full 20hz-20khz). and almost all the other headphones have more than 1db variations somewhere....

How do you know this?

 

[castleofargh]

from the few who care and advertise it like sennheiser for their TOTL headphone over the years(650, 800 then 800s), but I'm not sure about the frequency range measured. for IEMs, etymotic does the same +/-1db for something like 200hz-10khz.
as for knowing headphones/IEMs with more than 1db variation, well, measurements. can't say I'm 100% trusting online stuff, but the few things I measured myself rarely have less than 1db even will all the care I could muster to try and get a matching FR on purpose(removing pads or tips, marking the position, taking pictures...).
 
I don't know of any headphone brand certifying better than 1db for channel matching. I entertain the candid idea that if anybody was doing it, they would make everybody fully aware of it.

 

[pinnahertz]

  from the few who care and advertise it like sennheiser for their TOTL headphone over the years(650, 800 then 800s), but I'm not sure about the frequency range measured. for IEMs, etymotic does the same +/-1db for something like 200hz-10khz.
as for knowing headphones/IEMs with more than 1db variation, well, measurements. can't say I'm 100% trusting online stuff, but the few things I measured myself rarely have less than 1db even will all the care I could muster to try and get a matching FR on purpose(removing pads or tips, marking the position, taking pictures...).
 
I don't know of any headphone brand certifying better than 1db for channel matching. I entertain the candid idea that if anybody was doing it, they would make everybody fully aware of it.

I'd be curious to see where a manufacturer actually states channel level match.  I did check Sennheiser, Hifiman, Audeze and a few others before I stated that it wasn't specified, just checked again.  Etymotic doesn't spec it currently either. I was hoping you had your own test data, thanks for that.  

 

[castleofargh]

Senn and etymotic definitely do follow such rules. the matching for left and right is done on the driver for Senn, where they measure them and put them by pairs with the most affinity within a batch, and they simply discard stuff along the way when it isn't to whatever specs they decided upon(but then they make the driver themselves so it's a logical step anyway). I remember someone saying that you could ask Sennheiser for the FR graph of your very own hd800 or hd800s because they not only make those measurements as part of their quality control, they also keep them with the serial number.
 
for etymotic it's the same idea but they actually deliver what they call a certificate of performance with the latest er4sr and er4xr, but the channel matching care was already a thing with the late er4 series.
 
both focus on that and tolerate more of the inevitable variations from pair to pair, but try to get left and right in one pair as close as possible with an active selection of the drivers.
 
 
now I am positive that I'm not making that stuff up, but I have to admit that I also have a hard time finding it written on the web. for confirmation and information about etymotic it's easy, some cool Ety dudes are active on the dedicated er4 topic.
for Senn, I don't happen to have Axel grell's phone number, mostly because he doesn't have a clue that I even exist, but aside from that we're BFF in my head. ^_^ seriously I'm not sure where to find the information.
https://en-us.sennheiser.com/high-quality-headphones-around-ear-audio-surround-hd-650  here they mention

Systems with narrow tolerances (± 1 dB), hand-picked in pairs

but that's about all I can seem to find right now.
 
 
I do have my own measurements for a bunch of IEMs, but it's one pair of each measured by a noob on cheap gears. my pair of er4sr shows better matching than any other IEM I've measured but I wouldn't call that conclusive.
 
 
 
edit: found this
http://www.head-fi.org/t/538615/if-you-still-love-etymotic-er4-this-is-the-thread-for-you/9810#post_13016243

 

[Arpiben]

Other manufacturers keep a low profile when providing specifications:
 
"Matched drivers: +/- 1.5 dB between 30 and 5,000Hz (tentative)."
 
Well like any other specifications in different domains we  would expect :

1. typical values,
2. guaranted values

(The difference between both can reach several dB.)
 
Dealing with headphones in the price range of HD800, I am not expecting mass production units. Therefore, unfortunately I am only expecting a best possible pairing.
A fair approach would be to have the drivers` curves provided by default whatever results are. Apparently, it is not a common practice, since potentially it can raise more issues

I have short experience but, I have never seen any guaranted value either.

 

[Eric LeClair]

"Matched drivers: +/- 1.5 dB between 30 and 5,000Hz (tentative)."

Yeah I want to know more about this as well. I have these Edifier H840s but they sound like I hear more on the right. Great clear and crisp sound (Price was fantastic!) but I'm getting more on the right. I hope I'm not loosing hearing in my left - ha! Similar to the pain I had in my teeth the other day. Wish I could get a good dentist for it. The last thing I need is pain in my ears and my teeth at the same time. I already had a dental bridge and it hurt a lot.

 

[Whitigir]

How closely is the left and right of your ears have to be matched would be my question....