[jaddie]

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Why not, instead of arguing, create and run some experiments? I've been trying to arrange to actually do this with some headphones at least.

Great idea.  Non-trivial assignment.  
 
Experiments would need:
 
1. a stable measurement jig (possibly a head/pinna, but at least something head-sized for proper seal)
2. good resolution measurement equipment, calibrated mic, etc.
3. equipment to measure and log environmental parameters (temperature, humidity, barometric pressure)
4. method to verify stability of the above measurement equipment
5. two samples of each model to be tested, one as a DUT, the other as a control.  That gets you two samples of each, left and right
6. A carefully designed test regimen, measurement intervals, burn-in signal type and level, verification of level (SPL at the ear)
 
You need to do at least this.  If you do less, there's not enough to avoid the arguments. 

 

[jaycee1]

Whatever. My headphones sound better after burn in. Yours don't. You mad?
Quote:

No, your anecdote describes what you perceive as reality including illusions and the results of wishful thinking and cognitive biases. I do not understand why it's so hard to get that. You seem to be completely devoid of the idea of bias.
You also shouldn't be using words like dogma you obviously don't know the meaning of.
 
So you do not care about the technical reasons. Well, then we can stop the discussion here since the value of your anecdote has already been "assessed".
 
There's far more to it than frequency response graphs, which you'd know if you had read my previous posts, but since you're not interested in technical reasons I won't even try..
 
I agree. For example, of the small changes that were measured over at IF a tiny part could be attributed to the surround changing slightly or the diaphragm losing a bit of its stiffness (which is bad actually). But look at the post I quoted above. "Dramatic" differences were heard and reports of "day/night" differences using the same headphone as was measured at IF are not rare either.
When specific things (like driver burn-in) are really tiny compared to the overall perceived differences I rather simplify and say they are negligible or non-existent than reinforcing wrong ideas.
Your mass also increases if you run vs. standing still due to the kinetic energy but for all intents and purposes it doesn't change. Saying driver burn-in exists in such specific case would be equivalent to saying that jogging makes you heavier.
 
That sounds nice. Biggest problem is controlling all the variables, some of which you probably don't even have control over, like manufacturing accuracy.
Whenever I make claims I do try to make experiments to back them up.
 
 
 

 

[jaycee1]

I've just burned in a pair of koss ktxpro1's for about 60 hours now. 
 
Initially, they sounded slightly dark with a bit of high frequency sparkle. Unfortunately the highs were marred by very sloppy reproduction, esp. of percussion and snare drums. It's that weird uneven sound of low bit rate digital. Now, the highs are far cleaner. These are very balanced headphones, and very clean, esp. compared to my first listen or two. 
 
I have about a half dozen test tracks/favorite songs I almost always cycle through, so the volume and test tracks have not varied much at all. 
 
Anyway, I can now advocate a 60 hour break in period. If that doesn't help, you might not have very good headphones.
 
I am exceptionally pleased with these koss headphones. 

 

[jaycee1]

Quote:

My breakfast cereal tastes better on Tuesdays.

My grado and koss headphones sound better after 60+ hours of break in. 

 

[jaddie]

Quote:

My grado and koss headphones sound better after 60+ hours of break in. 

Next time you buy a new pair of headphones, buy two pairs (you can return one of them).  Have a friend blind-fold you.  Temporarily tag one pair, then playing them both, have your friend swap them for you.  Your job is to see if you can tell them apart.  If not (that's pretty important here) go ahead and burn-in one pair.  After your 6/60/600 hours of burn-in with your favorite exotic conditioning signal, have your friend blind-fold you again, and go ahead and identify the burned-in pair by playing them both, and having your friend swap randomly them for you.  After about 20 trials, see if how you "scored" and let us know.  Then box up the pair you don't like, and send them back for refund, or sell them here as "like-new" or "pre-conditioned".  
 
You'll do yourself, and readers here a favor by providing useful data rather than single-trial anecdote.  And what you will be providing will be basic statistical data for a single model with a burn-in signal of unknown average power and spectrum. 
 
Then, when you say "My headphones sound better after 60+ hours of break in", you'll also be able to relate the above trial and results.  Still not great, or universally conclusive, but better than what's going on here now, which frankly, is pointless. 
 
K?
 
Thanks!  
 
Hey, Currawong, how's that for an experiment?

 

[ktm]

Quote:

I discussed this a bit in my first thread after joining. IMO, I think "burn-in" should be applied to tubes, and not necessarily to headphones or solid state devices.
 
I spent nearly 15 years of my life making vacuum tubes. I can attest with certainty that with respect to tubes, burn-in is a very real phenomenon. The higher quality the tube, the longer the burn-in required. Glass vacuum tubes used in our headphone amps (or ancient TV's) burn in rather quickly (on the order of hours, or perhaps a few days at most). The active surface in a vacuum tube that emits electrons (and the target of those emissions), also "out gas", and this unwanted matter needs to be absorbed into a special component within the device. The vast majority of out gassing occurs fairly quickly, although it continues for a while. Tubes wear out because the surfaces that emit electrons, simply run out of electrons to emit. That's why tubes need replacing after a while.
 

 

Tube do change a lot over the 1st few hours, then flatten out, and then roll off and die.That's in their nature.
Cables? I believe cables make a difference, but i haven't spend too much $$. That can turn into a rat hole fast.
Cable burn in, not really buying it.
Mechanical devices like speakers and headphones, to some degree I'll go with. All my speakers and headphones
were bought used, other that a set of JBL L100's I bought back in the 1970's. So I don't have much to go on there.
All the equipment I currently have here is used, so it isn't a factor. Best of all, it's a lot cheaper!

 

[Greenleaf7]

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My grado and koss headphones sound better after 60+ hours of break in. 

Did breaking in open up the sound stage and remove the veil?

 

[esldude]

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Did breaking in open up the sound stage and remove the veil?

I've heard things do exactly that!  How did you know?
 

 

[Greenleaf7]

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I've heard things do exactly that!  How did you know?
 

I don't that's why I'm asking jaycee1. I wonder if the veil on his headphones got lifted somehow.
 
This is a video about veils, synergy and portable rigs
 
http://www.youtube.com/watch?v=w7Rqo8jI8dk

 

[ssrock64]

The problem with multi-headphones trials, especially of lower-end models (those that you're most likely to buy two pairs of for the sake of testing) is production variance, regardless of burn-in. It's not a proper test to use just two different pairs of the same headphones, because one may sound different from the other regardless of burn-in. In addition, the test proposed a few posts up doesn't go anywhere to prove mechanical burn-in, because it could easily just be driver heating or pad wear responsible.
 
 
My form of the test would have at least five of the same headphones, preferably a higher-end model from a company known for great QC, at different stages of burn-in. To avoid some outliers, every single one of them would have brand-new earpads at the time of the test and would all have had at least one hour of burn-in to simply "warm the drivers" because that's another issue of certain controversy.

 

[jaddie]

Quote:

The problem with multi-headphones trials, especially of lower-end models (those that you're most likely to buy two pairs of for the sake of testing) is production variance, regardless of burn-in. It's not a proper test to use just two different pairs of the same headphones, because one may sound different from the other regardless of burn-in.

If you look at what I suggested, that would be determined in the initial comparison of both non-burned-in pairs. If they were already detectably different, the test could just stop there.
Quote:

. In addition, the test proposed a few posts up doesn't go anywhere to prove mechanical burn-in, because it could easily just be driver heating or pad wear responsible.

Pretty sure proponents of burn-in don't care exactly what is happening, only that there's a positive change.  Determining what causes it is outside the scope of both tests I suggested, but would be the logical next step.
Quote:

My form of the test would have at least five of the same headphones, preferably a higher-end model from a company known for great QC, at different stages of burn-in. To avoid some outliers, every single one of them would have brand-new earpads at the time of the test and would all have had at least one hour of burn-in to simply "warm the drivers" because that's another issue of certain controversy.

Yes, that would be ideal.  And also so impractical that it will never be done on more than perhaps a very few models.  So far it seems that people with at least some resources don't seem to be interested in doing a test with even two copies of each.  Assuming manufacturers wouldn't just offer five test samples of their $1000 headphones, samples would have to be bought, and now you've got a project with a significant budget. Without a wide cross-section of the market, we couldn't discern the effect of general burn-in. 
 
I have another suggestion...but it's not fully cooked yet.  Stay tuned.

 

[fatcat28037]

Quote:

 
Stax run-in their drivers for two weeks before assembling them into headphones. They stated that the vast majority of any changes will occur during that period. It was interesting. My experience of these things has been considerably varied. Symphones Magnums drivers very distinctly change with use -- the bass is boomy at first. I need to check with Rhydon how much he tests the drivers before sending them out.
 
With electronics, discreet OPAMs seemed to go all weird sonically for the first 350 hours before settling down. Some tests without music playing suggested this was purely due to heat. Some DACs I've owned sounded harsh at first but not so much after 2 weeks of being left switched on. Many other headphones and other equipment I didn't notice any changes with them.  It would definitely be interesting to measure the IMD of the components where I felt I observed something before, during and after a couple of hundred hours of use. It would also be interesting to see if any manufacturers would be willing to talk, even off the record, about how much run-in their equipment is given.
 
I definitely don't think it is something it's a case of something existing or not but something that has to be considered per-component alongside measurements and an understanding of what is going on, if anything.

Interesting Currawong, thanks for the post, I'll keep this in mind.

 

[xnor]

Yeah I wondered if this info is from the Stax website, or some interview? Is there any data on these changes that occur during that period?
On the Symphones: maybe their special coating material behaves similarly as the epoxy I described before, i.e. small cracks develop that reduce the stiffness of the diaphragm after some stress? That would be ironic since: "A newly developed coating material was created to address unwanted bending modes within the diaphragm surface."
 
Discrete op-amps: I doubt it but shouldn't be too hard to measure.

 

[jaycee1]

Quote:

Did breaking in open up the sound stage and remove the veil?

With igrado's no. The highs were far too harsh initially, meaning, right out of the box. They remained that way after about 20+ and 40+ hours of burn in. I listened to them again at around the 60+ hour mark, and the highs had become far less harsh, and as a result, the sound signature was quite balanced overall. There was a bit of sparkle remaining, which was musical and pleasant.
 
I've broken in koss ktxpro1's for a similar amount of time. Again, after around the 60 hour mark, the sound signature had changed. In this case, the weird percussion smearing had smoothed out. Again, now I have something close to a neutral sound signature with a bit of pleasing high frequency sparkle. 
 
No changes in sound stage. If I want a broad soundstage, I listen to speakers. 
 
Also, I find that an amp is really nice for allowing headphones to shine, particularly in the highs. 
 
I just don't find any consistent effect of burn-in. All I can say is, in a couple of cases, burn in has allowed the headphones to reach their potential. In the majority of cases, the changes if any, are slight to unnoticeable. 

 

[jaycee1]

My experiences mirror those of currawong: burn in varies on a case by case basis. There is no consistent effect, and sometimes none.