[SilentFrequency]

I'd say... pretty much what @castleofargh
 did. Perhaps slightly different in inconsequential places.

Burn in makes sense from a physical standpoint... where the properties of a material that's exposed to constant changes in kinetic energy (in this case, the diaphragm) will change over time. Pretty much like a rock sitting in a river bed eventually gets worn away by the current. Though it may not take that long...

But the problem is... if someone never liked the tonal response of a headphone to begin with, then they would be much less inclined to like it again even after burn in. If they end up doing so, it's probably either a full moon, with the right mood, and some fine wine... or well, their taste in sound changed.

I'll cite myself as an example... I have heard the HD800 on many occasions... and I think I have heard one that is just fresh new out of the box, one that has been in use for years (note: more than 250 hours), one that has been modded, etc... and... I still don't quite end up liking it by that much. The change in my preference for the HD800 is probably proportional to the change in its sound due to burn in, which is pretty minimal.

Maybe what you refer to there is not what somebody may regard as "burn in" but rather normal wear and tear, which by its own opens another question that could be, what is the time span of a headphone diaphragm before past its best?

And as you example the hd800 (which I own personally and think is great) then if the "erosion" is slow over a period of time then the user is maybe less inclined to be aware of this change occurring in the first place whereas if "burn in" as is currently thought by some to actually exist in new products then they would almost certainly be aware of such a change?

And this is why I personally think "burn in" is maybe incorrect as it does neither the manufacturer or the consumer any favours.

 

[logwed]

I've been burning in my own body from the day i was born,but I've reached a point where not much is getting better with time ^_^.

 

 
Let us move on to Tyll Hertsen's fascinating set of articles on the subject! 1, 2, 3, last page for those who hate reading

The fact that Tyll was able to reliably identify the headphone with more playtime is pretty convincing evidence that there are perceivable changes, to me at least. But that will vary with your opinion on Tyll, and on his ability to set up a scientific test (read the articles, he's mad thorough). Maybe he rubbed the crap out of a rabbit's foot and managed to luck his way into getting it right 13/15 times! I wish that he'd done all 30 trials, 15 doesn't sound like all that many... He admits that the difference is very subtle, and being that he's an extremely well-trained listener, it's pretty clear that burn-in believers are either subject to psychological effects or are massively overstating what they are hearing. 

As far as Tyll's measurements go, if you want to interpret the data yourself, read the articles. I will rely on his interpretations because I have more faith in his ability than mine. He was unable to find a clear sign of any trend when measuring THD, frequency response, or in the CSD plots. However, when measuring IMD, there is a small downward trend with time. Impedance also showed a consistent change with time, but that doesn't really lend itself to a sonic interpretation.

Something that I think is worth noting, if Tyll had found an observable trend in the frequency response or CSD plots of the headphones, that would really mess up people's idea of burn-in. There is no one on head-fi who will tell you that burn-in makes a headphone sound worse. I dare you to find me the post! I don't think that anyone will disagree with me if I say that different people prefer different headphones, it's one of those damned matters of opinion. The CSD plot and its pathetic bro, the frequency response chart, are the best tools we have to show us what we like about different sounds (warm, bright, like a virgin touched for the very first time, blah blah blah). If there was a measurable difference in those plots, wouldn't you think that some people would hate how burn in makes their headphones sound? If we assume that people tend to like their burned in headphones more than when they were brand new, we should not see a significant change in CSD/freq response charts. However, one thing essentially all audiophiles hate is distortion! So, if headphones exhibit lower intermodulation distortion with time, it is conceivable that a headphone would sound better to pretty much anyone after it has been played for a time long enough to decrease the IMD by a perceivable increment. WARNING: I AM NOT SAYING THAT WHAT THE LISTENER HEARS AFTER BURN-IN IS PRIMARILY DUE TO PHYSICAL CHANGES IN THE HEADPHONE. 

So, if you accept Tyll's conclusion that there is a measurable difference between Q701s at t=0 and at some time in the future, it's minor and isn't really worth worrying about. Notice that fluctuations in test conditions (most likely air temps) had a more pronounced effect than anything else he brought up. 
 
Sorry if I cursed at all in here, I posted this on a more normal forum first

 

[Happy Camper]

The problem with the Science forum is it is highly unlikely that the hobbyist has the professional credentials or the lab to establish the proof asked of them. Any comments are immediately challenged with the same result. The title asks for an opinion in a proof forum.

 

[Head Injury]

  The fact that Tyll was able to reliably identify the headphone with more playtime is pretty convincing evidence that there are perceivable changes, to me at least. But that will vary with your opinion on Tyll, and on his ability to set up a scientific test (read the articles, he's mad thorough). Maybe he rubbed the crap out of a rabbit's foot and managed to luck his way into getting it right 13/15 times! I wish that he'd done all 30 trials, 15 doesn't sound like all that many... He admits that the difference is very subtle, and being that he's an extremely well-trained listener, it's pretty clear that burn-in believers are either subject to psychological effects or are massively overstating what they are hearing.

There's one complication with the blind test worth mentioning. Testing two different headphones, while unavoidable, introduces manufacturer variance into the test. No two headphones even within the same product line will measure exactly the same. Take a look at the two K701 samples he measured: A and B. The differences in frequency response here are larger than the ones found while burning the Q701 in. I don't doubt he heard a difference between the headphones, but it's hard to say the difference is from burn-in.
 
The only way to isolate burn-in changes for listening that I can think of would be to record a song played by a fresh headphone, then record it again after burn-in, and ABX the results. This has its own complications though, notably environmental changes.

 

[SilentFrequency]

Maybe brain burn in is for real and not equipment?

But I guess that is not possible to measure scientifically so it's subjective?

 

[logwed]

  There's one complication with the blind test worth mentioning. Testing two different headphones, while unavoidable, introduces manufacturer variance into the test. No two headphones even within the same product line will measure exactly the same. Take a look at the two K701 samples he measured: A and B. The differences in frequency response here are larger than the ones found while burning the Q701 in. I don't doubt he heard a difference between the headphones, but it's hard to say the difference is from burn-in.
 
The only way to isolate burn-in changes for listening that I can think of would be to record a song played by a fresh headphone, then record it again after burn-in, and ABX the results. This has its own complications though, notably environmental changes.

 
Tr00

 

[Bill-P]

Maybe what you refer to there is not what somebody may regard as "burn in" but rather normal wear and tear, which by its own opens another question that could be, what is the time span of a headphone diaphragm before past its best?

And as you example the hd800 (which I own personally and think is great) then if the "erosion" is slow over a period of time then the user is maybe less inclined to be aware of this change occurring in the first place whereas if "burn in" as is currently thought by some to actually exist in new products then they would almost certainly be aware of such a change?

And this is why I personally think "burn in" is maybe incorrect as it does neither the manufacturer or the consumer any favours.

Well, wear and tear is a natural physical phenomenon.
 
And a diaphragm may end up changing very little after an initial spur... the change can be a curve, too, and after a certain time frame, it could flat line, which means the diaphragm will end up lasting a super long time. But that's a study that I think will be done at a much later time.
 
Going back to that, if the change is a curve, that would explain why it doesn't change a lot at first, then it will change a lot during a certain time frame, and then it will simply stay there. It's not the first time I have seen that happen with a material.
 
Whether it is intended, though, well, you got me. It could be freak accident for all we know, and yeah, it may not do the manufacturer or consumer any good, but if it causes a positive effect, at least to your ears, then it should still be good.
 
Now the other question that I think you meant to ask would be... if it does exist, then are manufacturers aware of it? And I'll expand: why don't they spend the time at their factories to burn it in before hand?
 
I think some manufacturers are aware of burn-in. Especially high-profile companies like Beyerdynamic and Sennheiser. I am sure their engineers are good enough to realize the material they are using for the diaphragm will undergo some changes over time.
 
As for why they don't burn in, I think a part of it is due to the amount of resources it would take for that to happen. They would have to monitor the changes of each individual diaphragm pretty closely to make sure they are about the same, they would have to spend a long time (250+ hours if some burn-in claims are to be believed), and they would have to spare the expenses for the manpower, electricity, etc... so I can see why they would not want to do that in an effort to save costs.

 

[SilentFrequency]

Well, wear and tear is a natural physical phenomenon.

And a diaphragm may end up changing very little after an initial spur... the change can be a curve, too, and after a certain time frame, it could flat line, which means the diaphragm will end up lasting a super long time. But that's a study that I think will be done at a much later time.

Going back to that, if the change is a curve, that would explain why it doesn't change a lot at first, then it will change a lot during a certain time frame, and then it will simply stay there. It's not the first time I have seen that happen with a material.

Whether it is intended, though, well, you got me. It could be freak accident for all we know, and yeah, it may not do the manufacturer or consumer any good, but if it causes a positive effect, at least to your ears, then it should still be good.

Now the other question that I think you meant to ask would be... if it does exist, then are manufacturers aware of it? And I'll expand: why don't they spend the time at their factories to burn it in before hand?

I think some manufacturers are aware of burn-in. Especially high-profile companies like Beyerdynamic and Sennheiser. I am sure their engineers are good enough to realize the material they are using for the diaphragm will undergo some changes over time.

As for why they don't burn in, I think a part of it is due to the amount of resources it would take for that to happen. They would have to monitor the changes of each individual diaphragm pretty closely to make sure they are about the same, they would have to spend a long time (250+ hours if some burn-in claims are to be believed), and they would have to spare the expenses for the manpower, electricity, etc... so I can see why they would not want to do that in an effort to save costs.

Thank you!

I found your reply very interesting

Just so you know, I am pretty new to the audiophile world and my hd800's were gifted to me and they took me some time to get used to, plus I have no technical talk knowledge which means many threads here on Sound Science make no sense to me, so I appreciate you putting your reply to me in terms that the maybe average member here could understand and definitely for me ( I'm guessing your job is in sound technicalities?)

Where you mention a change in curve, what do you mean by "curve" ie a curve in data of a materials changing?

 

[Bill-P]

Thank you!

I found your reply very interesting

Just so you know, I am pretty new to the audiophile world and my hd800's were gifted to me and they took me some time to get used to, plus I have no technical talk knowledge which means many threads here on Sound Science make no sense to me, so I appreciate you putting your reply to me in terms that the maybe average member here could understand and definitely for me

( I'm guessing your job is in sound technicalities?)

Where you mention a change in curve, what do you mean by "curve" ie a curve in data of a materials changing?

 
Well, I don't claim to know everything. I'm just making guesses like everyone else. Although... I am pretty confident about that.
 
As for curve, I really mean... curve in a graph like this:
 


If the Y-axis is the amount of change, and the X axis counts the time, then after a certain time, there would just be no to very little change.
 
I'm just guessing that that's the case, though. There really is no basis for me to say this. If I have the time, I would conduct a study, but I suspect it will take... a long time. Or certainly longer than 250 hours.

 

[castleofargh]

oh I do believe in pads burn in !!!!!!
each time I get new ones I'm sad for a few days (both for comfort and because the sound isn't the same as what I had gotten used to on the crumbled old pads. to me this is very significant objectively and subjectively. the rest, as said, depending on the manufacturer, even left and right channels might have more differences than what a 200hours burn in change could do.
I think we all agree that very little things in the world stay as they are for eternity, so in that respect yes burn in does exist.
but does it matter? can we do much about it? will it turn a gear I don't like into one I like? I would have to answer no to all 3.

 

[SilentFrequency]

oh I do believe in pads burn in !!!!!!
each time I get new ones I'm sad for a few days (both for comfort and because the sound isn't the same as what I had gotten used to on the crumbled old pads. to me this is very significant objectively and subjectively. the rest, as said, depending on the manufacturer, even left and right channels might have more differences than what a 200hours burn in change could do.
I think we all agree that very little things in the world stay as they are for eternity, so in that respect yes burn in does exist.
but does it matter? can we do much about it? will it turn a gear I don't like into one I like? I would have to answer no to all 3.

How often do you change your headphone pads and for which headphones?

I do use my headphones quite a lot (about 1 hour every day) but the pads are still as good as new, but maybe I've not had them as long as other members here maybe?

 

[Head Injury]

How often do you change your headphone pads and for which headphones?

I do use my headphones quite a lot (about 1 hour every day) but the pads are still as good as new, but maybe I've not had them as long as other members here maybe?

I've used my LCD-2 an average of 6 hours a day or more for 3.5 years. I just ordered my first pair of replacement pads

 

[SilentFrequency]

I've used my LCD-2 an average of 6 hours a day or more for 3.5 years. I just ordered my first pair of replacement pads

:eek:

But I'm guessing you are joking

 

[castleofargh]

 

oh I do believe in pads burn in !!!!!!
each time I get new ones I'm sad for a few days (both for comfort and because the sound isn't the same as what I had gotten used to on the crumbled old pads. to me this is very significant objectively and subjectively. the rest, as said, depending on the manufacturer, even left and right channels might have more differences than what a 200hours burn in change could do.
I think we all agree that very little things in the world stay as they are for eternity, so in that respect yes burn in does exist.
but does it matter? can we do much about it? will it turn a gear I don't like into one I like? I would have to answer no to all 3.

How often do you change your headphone pads and for which headphones?

I do use my headphones quite a lot (about 1 hour every day) but the pads are still as good as new, but maybe I've not had them as long as other members here maybe?

hd650 so velvet stuff, and I use the default pads, didn't like the cheap ebay one.
I never shower and eat my cereals with the headphone as a giant spoon. that might speed up the need for new pads? ^_^
seriously I changed them after a year this time, but it's mainly because I think nothing should be stuck to my skin without being cleaned for that long. I had no comfort trouble with the old ones and didn't notice anything alive growing inside them ^_^.
with leather pads it's another story as you can clean them up nicely.

 

[SilentFrequency]

hd650 so velvet stuff, and I use the default pads, didn't like the cheap ebay one.
I never shower and eat my cereals with the headphone as a giant spoon. that might speed up the need for new pads? ^_^
seriously I changed them after a year this time, but it's mainly because I think nothing should be stuck to my skin without being cleaned for that long. I had no comfort trouble with the old ones and didn't notice anything alive growing inside them ^_^.
with leather pads it's another story as you can clean them up nicely.

But you have just sent my germs ocd into overdrive thinking of my hd800 pads! :eek:

I think cleaning them daily with bacterial wipes will be ok even if I shower twice daily?