Maybe how "burn in" started
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bigshot

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I don’t doubt there is a short term shift on big woofers, what have you got on headphones, DACs and amps?
 
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protoss

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I noticed a very important factor here,

"Revisions" (first edition drivers to present updated drivers)

Heard more R10s than normal people, and some swear that all R10s sounds the same, Others saying nope 2 versions, bass lite and Heavy and others saying 'nope' All same drivers with just marking of productions #, and finally just age, and burn-ins.

We must be careful here about, revisions affecting the judgment of headphones instead of calming it is a burn-in effect.

For example, Hifiman, Audeze are the worst at revisions, one pair can have 100hrs of burn-in and the other pair will have the newer revision drivers. And people will argue back and forth that it was the burn-in that did this change, instead of anything else.

So, we must be sure that no revisions are put into this mix.

Another thing I found out is,

"Placebo effect" plays another important role in burn-in. For example, L3000 (500 units) L3000G (50 units) people will argue that the green version is different, but actually it is the exact same headphone, but because one only has 50 units worldwide, people claim they hear unicorns from the green instead of the brown version.
 
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bigshot

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Headphones generally have a manufacturing tolerance for response of up to +/-5dB. That means that two sets of the exact same model might sound quite different. But they probably sound just as different at hour 1 as at hour 300.

I had the chance to talk at length with the designer of Oppo's PM-1s. He said that their tolerance for the PM-1s was +/-1dB, which is *very* precise. He said every set of cans was tested before shipping and if they didn't meet that spec, they were rejected. I asked him if they were coming up with a lot of units that didn't meet that standard. He said yes. I asked what they did with all those out of spec headphones. He said he didn't know. That wasn't his department.

And then they released the PM-2s for considerably less... Wanna bet the reject PM-1s ended up being put in a slightly different housing and sold as PM-2s?
 
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protoss

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Ha,

That is exactly like the R10 history. Sony R10 division nearly went bankrupt in trying to create the R10 matching drivers. Hundreds to thousands of garbage drivers were tossed because they couldn't properly match them exactly the dB range they wanted too.

I believe that, this is where the Bass lite and Bass Heavy comes from. For example, the Bass Heavy was more slightly more bass with less detail and Lite has more detail and less bass. This could have been the leftover drivers of not matching them exactly how they wanted to.

The first 200 units were all 100% bass lite and afterward, from #200 to #1300 it was a scatter of bass-heavy and light. It is funny that after Unit number 1000 they have given up and went the cheaper weaker drivers of the CD3000 into the R10.

:nerd:

... I am surprised you like PM-1. The company let me borrow it for over a month. I found it amazing but the dang earpads were killing my ears. Narrow crystal sound is all I remember :)
 
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bigshot

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The PM-1s came with a leather pad and a velvet pad. They both work fine for me. During the pre-release testing, I thought the clamping pressure was too tight, but I still have that set of cans and now it feels perfect. It might have broken in (as opposed to burn in!) Later iterations didn't clamp quite so tight. Were you in the pre-release forum too? I wish I had capped some of the stuff they posted there. That Eastern European fellow was really forthcoming and knew his stuff inside and out.
 
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hodgjy

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What always gets me on the whole burn in myth is why it always makes the sound better. Why is it never the other way around? This has to be confirmation bias.

How do designers take into account burn in when they are designing their products? It seems quite odd to me that a designer would carefully spec together whatever it is they are designing and then say, "Oh hell, it'll sound even better after 100 hours!" How can they even accurately predict those changes? This also seems incredibly inefficient during the design process, and in the business world, time is money.

And why does burn in only apply to audio gear? Why don't we need to burn in our Blu-ray players? Toaster ovens? Water heaters? Garage door openers? Usually, all of those items degrade over time, but somehow audio gear only gets better.
 
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What always gets me on the whole burn in myth is why it always makes the sound better. Why is it never the other way around? This has to be confirmation bias.

How do designers take into account burn in when they are designing their products? It seems quite odd to me that a designer would carefully spec together whatever it is they are designing and then say, "Oh hell, it'll sound even better after 100 hours!" How can they even accurately predict those changes? This also seems incredibly inefficient during the design process, and in the business world, time is money.

And why does burn in only apply to audio gear? Why don't we need to burn in our Blu-ray players? Toaster ovens? Water heaters? Garage door openers? Usually, all of those items degrade over time, but somehow audio gear only gets better.
Or televisions, or computers, or what about cars?

I think this is another good point towards just how in denial most audiophiles are - its so glaringly obvious that "burn-in" makes zero sense, yet otherwise intelligent people refuse to acknowledge that fact.
 
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jagwap

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Burn is only a myth in some products. Putting the myths aside, and looking at the ones where there is little debate in the industry: speakers. Why do these only get better after burn in? There are two factors.

Firstly, as the parts flex during the burn in period, they become more flexible, allowing easier movement. This is mostly found in the spider, but kevlar and other woven materials can take a pummeling before they act as intended. This sounds better when combined with the second factor...

Then there is the fact that as the product is tuned, through crossover, cabinate, port and absorbant material adjustments, this is almost never finalised on a brand new unit, as the process takes hours (if you actually measure and listen to do this as you should). So the final decisions on balancing the final system sound happens on well burned-in drivers. This ensures that any burn-in on production units on avarage head towards the intended final sound.

Simple really. However it seems to cause so much anger here when it goes against peoples previous assumptions.
 
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hodgjy

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There have been numerous studies posted all over that measured speakers pre and post burn in. While it’s true there are usually small measurable differences in air movement, SPL, and frequency response, they’re inaudible by the human ear. If burn in changes the sound of the speaker to the point a person can detect it, it’s time for new cones and surrounds.
 
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bigshot

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I think the term "break in" is better for speakers. Anything with a mechanical excursion like a big woofer is going to be a bit stiff when it's first manufactured. It shouldn't take long to break in, and I imagine it depends on what kind of surrounds the woofer has. But for headphone rigs, I can't see any sort of break in happening unless it's a volume pot being a little sticky at first.
 
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jagwap

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There have been numerous studies posted all over that measured speakers pre and post burn in. While it’s true there are usually small measurable differences in air movement, SPL, and frequency response, they’re inaudible by the human ear. If burn in changes the sound of the speaker to the point a person can detect it, it’s time for new cones and surrounds.
I have worked in this industry, and by that I mean designing audio equipment, for nearly 30 years, and I have yet to meet an acoustic engineer who does not, know for sure, that speakers need burn/break/run in. This is in consumer, budget & esoteric hi-fi and pro-audio. It is standard practice, with a new speaker that is going to be evaluated, you let it run overnight or more first.

All this debate by armchair experts aside, the industry has moved on.
 
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bigshot

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You should leave any piece of equipment on overnight when you first get it. If it's going to fail, it will likely do it sooner than later. Better to run it a few hours so it will fail right away when you can still box it back up and ship it back for a refund.
 
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IEMusic

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My 2c.

The truth...we don’t know if burn-in exists on certain products, speakers aside. I can’t prove to you that burn-in, say on orthodynamic headphones, exists, b/c I can‘t measure it. But no one has proven to me that it doesn’t exist. My pet peeve is when so-called “scientific minds” state that “there is no evidence of X” as an argument to prove that X doesn‘t exist. Lack of evidence for something, is NOT the same as evidence against that something. Now granted, to prove the absence of something would involve a huge study, as the N would have to be a large population, so it’s rarely worth it. It is also true that the burden of proof is on the person trying to support a hypothesis. However, in the absence of proof for or against a hypothesis, the answer is...we don’t know. It is absolute hubris to think that just because our current science can’t prove something, it must not exist. I personally just so happen to not believe in ghosts/hauntings, but I can’t prove that it doesn’t exist, so if someone else believes in it, that’s perfectly fine with me, and I will not dismiss them as an “un-scientific fool”. The reality is “the more I know, the more I know that I know nothing”. When there is lack of proof, evidence is just anecdotal, and ultimately comes down to personal experience and belief. A debate is interesting, and in some cases necessary, but face it, any NEED to convince the opposition of our position is simply pride/arrogance.

Regarding audio equipment specifically, why not let all products “burn-in” instead of coming to conclusions prematurely? The cost is negligible, you somewhat test if the product will fail (as others have mentioned), and if you believe that perceived changes are just “brain burn-in”, then let that occur before you come to a conclusion. Whether burn-in exists is just an interesting debate.

Lastly, there are so many variables within one type of product, say dynamic speakers, that one cannot make a rule that encompasses all such equipment. Personally, I have often not perceived any difference over time with a speaker’s burn in. A few times, however, I have perceived very significant changes. The speaker sounded horrible at first. Most of the time, it’s probably somewhere in between and I just don’t notice it.

....interesting topic
 
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Or televisions, or computers, or what about cars?

I think this is another good point towards just how in denial most audiophiles are - its so glaringly obvious that "burn-in" makes zero sense, yet otherwise intelligent people refuse to acknowledge that fact.
My personal issue isn't that burn in exists because in practice it's such a vague concept applied to fundamentally different domains(mechanic, chemistry, psychology), that something somewhere will happen and will make actual sense even if all the other stuff are made up.
Some electrical components are known to change over time, from batteries to capacitors. I don't know that this should be called burn in, but it's very real and well documented(the audibility of it is another story that would need case by case study).
As for bending stuff many times, some of the properties of the material will change. For example, how much a material resists the movement? for many, that will show a sort of logarithmic curve over time.

It wouldn't take much effort to consider the first period with a much bigger rate of change, as being the "burn in" period. And then the rest where the rate of change has slowed down significantly(at least compared to the start), as being the "stable" state.
So long as the definition isn't some vague crap to justify any and all subjective impressions from new gears, I can live with the idea that we should call those stuff "burn in".


what gets to me and sometimes drives me slightly mad, is that with burn in we have mostly guys discussing anecdotal uncontrolled subjective memories, and deciding that this is the needed and necessary stuff to prove the act of burn in, the fact of audible change, and the causal relation between the two.:confounded:
It blows my mind, considering that each underlined term is by itself a well documented reason to be skeptical and a strong warning against jumping to conclusion on a global and alleged objective phenomenon. I understand ignorance, and I know something about self delusions:blush::crown:. But the amount needed to get all this wrong and maintain the absolute confidence to come make claims about burn in on the forum, that's special.
You'll notice that on this paragraph discussing what pisses me off, audio gears are irrelevant and burn in just an afterthought. people piss me off, not whatever it is that really happens to a component.
 
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IEMusic

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You'll notice that on this paragraph discussing what pisses me off, audio gears are irrelevant and burn in just an afterthought. people piss me off, not whatever it is that really happens to a component.
That‘s exactly it! Whether or not burn-in exists, or whether a tight braid vs just twisted pairs is the holy grail of cable geometry, or whether that $2,000 copper 3ft power cord that you plug into your rusted outlet that’s part of a 50yr old house electrical system is the key to making your system “pop” with dynamism....that’s all irrelevant. It’s the arrogance of people in general. I agree that people making random claims, passing it off as fact, as insulting you if you don’t fully agree, are (insert noun of choice). But, those who just fully deny any and all claims, even simple ideas, from a wholly reasonable person, in an aggressive and demeaning manner, are the same. Fortunately, I still think (a belief) that the majority of people are quite reasonable, and that the truth, as is usually the case, rests somewhere in the middle of the extremes.

Would you be better with using a different term rather than “burn-in“ of a single component? Maybe give it time for your “system to mature, warm up, settle in”? Since all components are connected and add their own variables.
 
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