Is burn in real or placebo?

Discussion in 'Sound Science' started by hifi man, May 13, 2013.
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  1. Kdubbs82
    I agree. Some is psychology. But I’ve noticed the difference in my HD600s after 100 hours of burn in. They don’t sound as tight and relax a bit. I love them!

  2. liquidrats
    are we screwed by the manufacturers to have this burn-in period; in fact it's to retune our heads. But the tips helps a lot tho in the lower and upper region in the frequency band.
  3. Danamr
    What this comes down to is what piece of gear we are talking about too. Headphones from a major company, I suspect they are going to say no, you should not hear a change. $1000.00 power cables on the other hand need at least 500 hours of burn in to get the best out of them...(or whatever the max return period is in hours)
  4. castleofargh Contributor
    even within headphones, there are many designs. even just looking at dynamic drivers, think about all the materials and shapes used by manufacturers. it's obvious that different gears are simply different. trying to stick some global concept onto all that is a waste of time.
    I'm absolutely sure that the Sennheiser guys have run tests or at the very least simulations on hundreds if not thousands of coils and membranes and have measured the hell out of them over time. if only to check for stability and durability. they have the statistically significant results for their very specific model. I'd believe that kind of information if it was made public, no matter what it would say so long as I could see some measurements. even averages would do great.
    but average Joe talking from memory about that anecdote from uncontrolled listening, is that a joke? I don't trust my own experience under those conditions, I'd have to be on drug to consider such impressions to have any sort of factual relevance.
    how some can have a misplaced confidence in themselves is not helping. TBH anytime I read somebody saying that he's sure he heard a difference, that he has enough experience not to fall for placebo while sticking to sighted impressions, I instantly distrust anything coming from his mouth. I know that 1/ his testing method is unreliable so he doesn't have the means to back up his claims. and 2/ that he's a very bad judge of what is or isn't real.

    now I happen like Brooko to measure a few stuff from time to time, those are my anecdotes, and they don't tell me about any mystifying tendency for massive sound change. sometimes a battery needs a full charge or 2, freshly started gear might measure a little differently from when it's been working for some time and warmed up to a stable temperature. headphone pads have the most massive impact I know of on headphones over time. placement, shape, how well they get to conform with our skull, how over time we end up with the driver closer to the ear and all the changes coming from that. they're all very real and very significant changes. at this point I don't have a doubt that pad and bad memory are the 2 most significant causes of change over time on a headphone. so if I come with my large head, I get more clamping, so I need less hours for the pads to give in to pressure. is that still burn in if the size of my head and the headband setting and maybe glasses, determine how much and how fast the sound will change?
    for IEMs, dirty dampers(dust and earwax clogging them over time) is a reality, easy to measure, easy to change the dampers for new ones on a few IEMs and check in real time how much we get back at resonance frequencies and in the trebles. it can be many dBs so obviously it's audible. but now if how much ear wax the user generates is what dictates the amount of change, is it still the IEM burning in? ^_^ maybe that's why I'm not a big burn in believer? my body is pretty lazy at secreting anything, from sweat to saliva to earwax. maybe sweat on the pads accelerate changes in elasticity, maybe more earwax would get me to feel IEMs changing rapidly? I'm only half joking, it's kind of a reasonable hypothesis.
    shocks can also be unkind to gears. who knew I could burn in my device by violently dropping it on the ground. :wink:
    if I spent some time thinking I'm sure I could come up with other less significant but still measurable stuff, like plugs, being clean or not, being forced or not, and cables being mistreated, rolled over with a chair, torn on a door knob... those are changes occuring over time but I also have a hard time imagining that I should call it burn in.

    those are the most significant changes I have been able to observe objectively. not the membrane of a flexing and "breaking in", not the capacitors being brand new, not my cables being "cooked". doesn't means something can't happens. but I'd already be impressed if the driver of a headphone "burning in" for 300hours could show a change in signature bigger than someone taking his headphone off, and putting it back on. my small anecdotal experience trying to measure stuff tells me that much.
    sonitus mirus likes this.
  5. bigshot
    Auditory memory for similar sounds last a matter of seconds. Differences in volume level can make a big difference. How do you overcome this when there is 500 hours of "burn in" between the two sound signatures you're comparing? I think it's pretty safe to dismiss all claims that burn in is real that don't involve measurements. That pretty well eliminates all of them, because I've never heard of anyone ever measuring a change due to burn in. Bingo! Question is answered.
  6. PointyFox
    There is a not very controlled test of the burn-in on the MDR-Z1R here:

    If you compare the overall frequency response from each time point, there seems to be a trend where the frequencies converge slightly on the (assumed) harmonic frequencies of the headphones the longer they are burned-in. This is not proof of anything, but there is a chance that the drivers could be increasing in flexibility on the harmonic nodes, adding a little volume to the harmonics while decreasing others slightly. If this is actually occurring, headphones would tend to sound worse with burn-in, though if changes are the magnitude seen here, they shouldn't be audible. I would assume different driver materials to change the magnitude slightly if this is actually occurring. But who knows. The sample size is 1, we don't know how repeatable this is and we have no control samples.
    Last edited: Dec 29, 2017
  7. amirm
    I would think the headphone cushions would compress over that time, impacting what is measured given the closeness of the microphones to them. No?
  8. Danamr
    Someone earlier made some points. #2 was people tend to exaggerate.
    I think he hit the #1 problem with things like "burn in" and cables for example.
    While I am sure cushions compressing has a small affect on the sound of a headphone, I am also sure it's very small and almost impossible to measure. Keep in mind that unless you are wearing your headphones exactly the same way every time, you will be talking about the same kind of changes in relationship of the driver to your ears.
  9. PointyFox
    I would imagine people wouldn't be able to detect these differences, especially over any time longer than around 3 seconds.
  10. HotIce
    There has been studies (google for "subwoofer burn in") that showed that burn in altered the physical characteristics of the speaker.
    From there, to actually blind-testing folks on hearing differences, it's the usual "Ohh, hmm, meh, ...".
  11. Brooko Contributor
    Speakers have a Spider which does actually physically change over time. The dynamic drivers used in headphones typically don’t have one. The dynamics and BA units in IEMs definitely don’t have one. So comparing speakers to headphones/IEMs is like comparing apples to potatoes :wink:

    And the audible burn-in myth is continually perpetuated unfortunately.
  12. HotIce
    Which part of my post was stating that subwoofers behave the same as IEMs (or else)?
    Clearly in a sub the mechanical dynamics of the system are stretched to the max, and there it was shown that it was possible to measure them.
    Conventional HP drivers, in order to generate sound, they have to move, and in order to move, something has to give up.
    Is it measurable with the right tools? Maybe.
    Is it distinguishable in blind tests? "Ohh, Uhm, Meh, ..." :slight_smile:
  13. bigshot
    I am REALLY glad my sub didn't shift from when I got it. I calibrated it and I don't want it to go out of calibration.
  14. Danamr
    So your saying you buy subwoofer brand X with the expectation that what it sounds like out of the box is not what you expect it to sound in the future?
  15. HotIce
    Actually, I said the contrary, but maybe the "Ohh, hmm, meh, ..." did not convey clearly enough my skepticism.
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