[Intensecure]

For @VocaloidDude, although it isn't evidence, just to get another informed opinion from someone who should know.. I asked Dan Wiggins of PeriodicAudio who make a new line of IEMs about his opinion of "burn-in" and I quote.
"IMHO, there is no burn-in needed. The excursion of your IEM is so low that it breaks in literally in a few minutes of use. If you hear "burn in" of your IEM, it's most likely your own psychoacoustic shift in preference. Short-to-long term FR/THD/IMD/Z measurements show no measurable changes - and I am also a firm believer that we can measure to a much higher level of accuracy than we can hear.
Dan Wiggins. Periodic Audio.

He knows his stuff, I'd take his opinion over any subjective "audiophile" but that's my choice.

 

[saidentary]

Absence of proof is not proof of absence. But in the absence of proof, the null hypothesis is generally considered to be the best default.

Incontrovertible, empirical evidence? No. Anecdotal accounts, including my own? Yes.

Someone (smart about audio) has told me that there are certain chemical residues from the manufacturing process of copper wire that "burn off" over time, because the wires heat up when used in stereo system cables. There is also some phenomenon wherein a cable's dielectric changes with "burn in." There is also almost certainly a psychoacoustic component with respect to perception of "burn in" and in my opinion this is likely to be the largest contributing factor.

It's interesting to me how much contentious debate centers on this topic, and how correspondingly little (to absent) controlled (preferably blinded) empiric and/or experimental testing seems to have been done--by anyone.

 

[sonitus mirus]

Someone (smart about audio) has told me that there are certain chemical residues from the manufacturing process of copper wire that "burn off" over time, because the wires heat up when used in stereo system cables. There is also some phenomenon wherein a cable's dielectric changes with "burn in."

I can understand where the mechanical motion of a transducer might measurably change over time with use, though how much this might translate into any audible differences is where this topic might take root and provide some room for a discussion.

What I quoted from you above; however, and without any additional information provided, I'd say there already is solid empirical evidence to suggest that an audio signal would not be influenced in any meaningful way that would allow for an audible difference to be identified.

 

[Niouke]

I've been shopping for speakers and an amp recently (went for Klipsch RP-250F's and a Yamaha A-S701 if you want to know), and the burn in/break in syndrome is real over there! Following that lead I found this article which talks about dynamic drivers in speakers, I believe it applies to IEM's as well. There is a burn in process applied at the factory, but it lasts only a few seconds with no observable change on the long term:

http://www.audioholics.com/loudspea...ction/speaker-break-in-fact-or-fiction-page-2

 

[Speedskater]

Unless your system has 1000 Watt amplifier's and you play them at full volume, the cables don't heat up as much as they do when the sun shines on them thru the window. Whether there are residues on the surface or not, it doesn't matter the audio signal is in the copper. Now at GHz frequencies the surface is important.
Reasonable changes in the cable's dielectric will not affect an audio signal.

 

[sarge7359]

For @VocaloidDude, although it isn't evidence, just to get another informed opinion from someone who should know.. I asked Dan Wiggins of PeriodicAudio who make a new line of IEMs about his opinion of "burn-in" and I quote.
"IMHO, there is no burn-in needed. The excursion of your IEM is so low that it breaks in literally in a few minutes of use. If you hear "burn in" of your IEM, it's most likely your own psychoacoustic shift in preference. Short-to-long term FR/THD/IMD/Z measurements show no measurable changes - and I am also a firm believer that we can measure to a much higher level of accuracy than we can hear.
Dan Wiggins. Periodic Audio.

He knows his stuff, I'd take his opinion over any subjective "audiophile" but that's my choice.

I just want to point out this is IEMs explicitly. The items that have significant excursion (speakers, full size headphones) are possible for burn in to matter because of the actual physical characteristics of the materials.
Burn in of cables still smells like BS tho. Do enough to verify you didn't get defective item.

 

[Slaphead]

This is one subject that's going to run & run & run.

My personal experience is that it perhaps can happen, but only with a few headphones/IEMs.

I have a bit of HP/IEM collection and up until I aquired one IEM I had heard no evidence of burn in at all.

The IEM in question is the RHA T20. When I first got them I found the treble practically unbearable, and the lower midrange was practically non existent. Putting on the bass filter on made them listenable, but still they were somewhat unabalanced to my ears. Nevetheless they had some good punchy qualites and with that I was happy to persevere with them.

After around a month of daily use (approx 1hr per day) use I noticed that the hard edge had disppeared from the treble and the midrange had filled out quite nicely. However I was more than prepared to put that down to getting used to them rather than any burn in effect as I didn't really believe in burn in.

Fast forward the best part of year and I decided to switch back to my HD25s for my daily drivers, which have remained in regular use for the last 3 or 4 months while the T20s have been lying in my bag.

Yesterday I forgot to bring my HD25s with me, so I used the T20s for the first time in months. I was expecting them to have the same harsh treble and the lacking lower midrange as I initially heard them. However they sounded just like they did when I stopped using them - No hard edge and a filled out midrange.

Obviously I can't discount that I'd built up a psyco-acoustic memory of them, but if not then this is the only time that I've experienced an obvious burn in effect. Plus I'm not the only person to experience this with an RHA product - What HiFi specifically mentions something very similar in their review of the MA750i.

So from my point of view I can't exclude the possibilty of burn in. However I suspect that it only affects a very few number of products, and then I think that it's effects in a good number of cases are vastly overstated.

 

[castleofargh]

-having a memory is not the same as the actual event.
-sighted listening shouldn't serve any purpose aside from deciding how much we enjoy ourselves. a sighted test is not evidence of anything because without proper controls and references, it can never be conclusive. it only shows how some people have way too much self confidence for their own good.
-subjective anecdotes serve no purpose aside from showing how people's logic is flawed as soon as they are involved in it, and how little evidence someone needs when the point is to agree with his own opinion.

even if those anecdotes came from proper testing and had objective records of each event, it would still be but an anecdote, like Rin Choi's measurements, Tyll's or even the limited stuff I measure myself. those are what might be accepted as proper anecdotes. and even then, the conditions of the measurements might come to be questioned. but of course most audiophiles don't need blind test, don't need repeatability to declare something law, don't have bias, aren't moved by emotions, can isolate their senses from one another, and have perfect memory. those are but a few things we have to take for granted if we are to consider random feedbacks all over the web as proving anything about burn in.
you guys are mostly discussing the possible conclusions, while I'm doing a triple facepalm just looking at the thought process that led somebody to decide he believes or doesn't believe in burn in. whatever it's actually supposed to encompass, because even that isn't defined properly.

 

[old tech]

In the manual that came with my active speakers it specifically says that no burn in is required. I forgot the exact text but it was worded in such a way that it could have been interpreted as a mocking of those in the audiophile world that believe in burn in.

 

[sonitus mirus]

In the manual that came with my active speakers it specifically says that no burn in is required. I forgot the exact text but it was worded in such a way that it could have been interpreted as a mocking of those in the audiophile world that believe in burn in.

My active speakers' manual for the KRK Rokit 8 (3rd generation) does mention, at the bottom of the 3rd page, that a modest break-in time is optimal.

http://www.krksys.com/manuals/rokit/RokitG3-Manual.pdf

NOTE - The studio monitors will take break-in time to achieve optimum sonic performance. Under moderate use, play a favorite album between 15 to 25 hours.

I just listened to them. I have no idea if there was any improvement or any difference. I certainly didn't purposefully attempt to break them in. The manufacturing process, along with the size and the material of the drivers, could warrant a break-in period.

 

[widgets]

My personal opinion side with ear adjustment. If I "Burn In" a headphone in a sealed box for hundreds of hours I get no improvement, but if I listen, for a few months my brain adjusts to the new sound signature and the alien way my favourite songs sounded when the headphone were new disappears. My take is that its all in your head... but not in a superficial way.