Burning in... (a question from a novice)

[mtrycraft]

but what can it hurt?

Only the thruth.

[mtrycraft]

Could there in fact then be a fairly noticiable difference - to the overall sound of ones system - when you add up all the small variations of all the products? Seems possible to me.

Seems possible? Yes. All this is testable though. No such evidence out there. Why don't the component makers who recommend this have the data, even the measured changes?

Most, if not all, high-end manufaturers suggest a certain break in peroid for their components. These are the same manufacturers that make some of the best sounding and quality built products out there.


Ah, you think there is a cause and effect here? Not so fast. The evidence is just not there to support you on this.

I would rather own, say Mark Levinson gear, than Denon.

That is a choice.

I believe that not only does the Levinson gear sound better but it is built to a much higher standard and quality.

Both can be tested. One may or may not effect the other, sonically though. Again, the evidence is not available.

Now is it worth the price difference, perhaps not, but that depends on your pocket book, and in may cases ones ego!

Yes,

[mtrycraft]

but if it works then do it.

IF, is the key. You make such claims, you support it beyond hand waving that it works.

Nevermind definitions. They mean nothing in the real world.

Maybe that is the problem, in the real world, according to you, nothing matters, has no meaning, just what you imagin it to be, right?


What really does matter if perception.

Actually, that can be dangerous. They lock people up for their perception when it gets out of hand.


[b]Do anything to achieve the right sound.
Whether it be putting a penny on the headpiece of your tonearm or changing your tubes. It doesnt matter because its all subjective. An art not a science. BTW...to EVERYONE who thinks science is proving stuff...please dont misunderstand...science is a process of disproving.

[/QUOTE]

One can just imagine then.

[92135011]

what is there to sell?
everyone is saying that breaking in is a commercial trap.
I dont understand why it would be because there is nothing to gain from it.
The fact of matter is that some people notice a difference. Thats good for them. Doesnt really do much really...Those people who do notice differences go to an audition with the assumption that the products are burned in. Those who dont think there is a difference dont really care about any burn in factor anyways so it doesnt matter to them.

Im not going to argue with you on the science or art issue.
science to obtain an art vs art inspired science. Matter of perception. no better - just different.

[mtrycraft]

[QUOTE=lumiere]. Everything changes. /QUOTE]

Some slower than other things.

[Haoleb]

Im not going to join in on this nonsense but, if you want to have your speakers settle in, face them twards eachother (to canel out soundwaves, as to not bother you) and play some real music at moderate levels.

I would NOT suggest leaving stuff on while on vacation. bad idea. If you have tubes thats a just plain stupid idea.

Who really cares what it is, or what happens. If you want to think it will make a difference, or not then thats great. No need to get into a big argument over it... One of the reasons why i dont like this forum, among others. Too much audio nonsens and arguing.

[92135011]

Im not going to join in on this nonsense but, if you want to have your speakers settle in, face them twards eachother (to canel out soundwaves, as to not bother you) and play some real music at moderate levels.

I would NOT suggest leaving stuff on while on vacation. bad idea. If you have tubes thats a just plain stupid idea.

Who really cares what it is, or what happens. If you want to think it will make a difference, or not then thats great. No need to get into a big argument over it... One of the reasons why i dont like this forum, among others. Too much audio nonsens and arguing.

good call.

[skeptic]

Your posting is absurd to the point where it hardly deserves a reply but since I have nothing better to do at the moment.....

Shoes are expected to wear out from day to day, even hour to hour. Comparing shoes which undergo constant mechanical stress that is fully expected to eventually destroy them and are usually manufactured with the understanding that they need to be broken in by the user because of the cost of mechanically flexing every pair in the factory until they soften up would be too expensive is a rediculous comparison to an electronic component.

Reputable manufacturers conduct all types of destructive and non destructive tests including life cycling tests to simulate aging. If the materials they use or the way they are manufactured are so unstable that performance drifts beyond acceptable limits called tolerances within a specified period, they have to modify the design, the materials, or the manufacturing methods. This is even more true today than it was 40 years ago. Some manufacturers like AR made the mistake of using foam surrounds which deteriorated and need repair after only a decade or two. Others like KLH used cloth surrounds which have held up during all this time. Mine are at least 40 years old and show no physical or audible signs of deterioration. Speakers whose performance drift within a matter of days or weeks are definitely to be avoided. Once the product leaves the factory, it is beyond the manufacturer's control and there is no way to predict what it will perform like or where it will stabalize, or even if its performance will ever stabalize. This is not the same as product failure such as the deterioration of foam surrounds. Under those conditions, you have no idea what you are getting for your money and neither does anyone else.

[Audie Oghaisle]

Is your belief system on shaky ground? Does the mere thought of rational debate cause a fit of paranoia? How else could you explain the following:

You respond to a statement by saying definitions don't count in the real world...

I counter by asking if you really believe that...

You ask if that is some sort of personal attack?

According to your line of reasoning, anything can mean whatever anyones choses it to mean, with little or no regard for accepted practice...does that mean a cow isn't quadruped ungulate that chews its own cud?...Is it a breadbox?...a steamship?...a jolly comfortable Chesterfield? Things are defined by the parameters involved...co-opting an accepted term to give an air of authenticity to a dubious practice is self serving and misleading...

Audie

[92135011]

Audie, if I responded to that then this thread will last forever.
HaoLab is right. This is the reason why people don't like forums.

[poneal]

No matter what you say you are only fooling yourself if you really belive that audio equipment needs a breakin period. I can only sit here and laugh.

[mtrycraft]

what is there to sell?
everyone is saying that breaking in is a commercial trap.
I dont understand why it would be because there is nothing to gain from it.
The fact of matter is that some people notice a difference. Thats good for them. Doesnt really do much really...Those people who do notice differences go to an audition with the assumption that the products are burned in. Those who dont think there is a difference dont really care about any burn in factor anyways so it doesnt matter to them.

Im not going to argue with you on the science or art issue.
science to obtain an art vs art inspired science. Matter of perception. no better - just different.

It is the idea of believeing stuff because a maker tells you it is so, or a friend tells you it is so. No wonder the marketplace is so full of voodo, mythology, bs. Not enough skeptics and inquiring minds out three to question the nonsense of the marketplace.

You are confusing what science created and what art creates. Art creates the music with instruments. That is art. The reproduction aspect is all science. But that is here nor there for this discussion, immaterial.

[Soundbro]

Digital electronics do not change with time unless they are no longer working. There are arguments that old tubes would change with age, but even those remained fairly constant until burnout. Speakers contain a mechanical system that moves air waves. All mechanical systems are highly susceptible to variance and performance changes with use. There is a mild settling in speaker sound as the moving parts begin to wear and fatigue slightly allowing them to move more freely. This can increase speaker sensitivity and relax high frequencies as the tweeters become less difficult to move. Think of it as a car accelerator pedal that sticks a little. When you apply enough pressure to overcome the resistance, all the force releases at once causing you to rev the engine even though you did not intend to. When the resistance is not present, there is no sudden release of force. The idea of leaving your stereo system on for weeks to accelerate this process is absolutely ridiculous. Reducing the life of your electronics is the most you can hope to accomplish. Granted, I said a noticeable difference will occur in the speakers, but not enough of one to justify rushing the process. Normal listening over time will gradually affect the speakers. It should be noted, speakers like everything else are made with materials that have distinct properties. Someone who keeps their home at 65 degrees will have a different sound than someone who keeps their home at 80 degrees and this will also affect your burn in time and success. All in all, it's a hugely hyped up phenomenon that holds little significance to all but the most critically bored.

[maxg]

Completely anecdotal but for your amusement as follows:

Last night a friend came round with a brand new set of speakers he just built. We connected them to my amp and started to play them. Hardly any bass - tiny amounts of air coming out of reflex port.

Leave them playing for a while (Candy Girls - a greek pop thingie that is fairly bassy and a hit with my daughter). Bass appears to be improving. More air is coming out of the port. Switch to my speakers - way more bass - switch back - play another hour - bass still seems to be increasing.

Go out - walk the dogs - leave the speakers playing and my daughter dancing.

Get back - more bass than we remembered.

Go back to mine - much less of a difference (same damn song - it is beginning to wear me down).

Volume was not touched suring the process - it was set at "loud". All amps and cables same. Not burn in? What then? If it were simply that we were getting used to the sound (eminently possible) but why the apparent reduction in difference compared to my speakers?

To be fair they didnt get to the level of my speakers' bass at all. Sadly a fuse blew on my amp so testing was cut short (we must have touched the speaker wires together without reducing the volume during one of the changes). Of coruse I didnt have the right spare - picked that up this morning (pack of 10 for 60 cents - in other words 6 cents worth of fuse brought the whole show to a grinding halt). Typcial!!

I'd also put new feet on my TT and was looking forward to testing them out for sonic differences after all this speaker testing - that will have to wait for the weekend now - typcial again!!

[hawkton]

I honestly have no idea why a thread as simple as this one would start such intense heat.

But the truth is (as I believe) that science is a superficial process and can be considered blind (science is just a process of collecting and analyze data, it's the interpretation that truly matters). Science abserves behavior or patterns over time and establish THEORIES which may later evolve to become "rules" and "laws". I am a computer science and computer systems dual major, I'm well aware of sciencific and engineering processes. I'm not trying to argue that science is made of bull****, it's not. Science did lead us to prosperity and many marvelous inventions, but science cannot possibly provide explanation or justification to everything, it it did, the words religion and crime wouldn't be in the Merian Webster's dictionary, to say the least. For example, a glass that's filled half way is scientifically at 50% of capacity. That's a fair statement to make, right? But some will interpret that glass as half full while others interpret it as half empty. Definition is definition, it's dead. Our interpretation of it means much more.

I really would have to agree with 92135011's posts that this whole home theater thing is an art more than it is science. As long as it pleases you or you feel that it makes an improvement, do it. Consider this question, a person buys a pair of speakers and calls the manufacturer about "break-in" procedure. The service rep told the person that their speakers don't require "break-in". However, this person laters "finds out" that the speakers "sounded better" after 2 weeks of listening. What if it's your ears that's broken-in? Does it not justify the break-in procedure?

Human mind is not scientific, trying to apply scientific rules/laws on human is a lost cause. It doesn't matter if the so called "break-in" has scientific effects, it only matters whether or not you believe it. If you do, break-in will make a difference to you. If you don't, start using your speakers.

Tony

[CyberStoic]

Greetings hawkton;
you wrote:
"I honestly have no idea why a thread as simple as this one would start such intense heat.
But the truth is (as I believe) that science is a superficial process and can be considered blind (science is just a process of collecting and analyze data, it's the interpretation that truly matters). "


Indeed. That's exactly what Joseph Stalin and Hillary Clinton have said.... "it doesn't matter who collects the data, it is who interprets it that matters".....


you shared"
" Science abserves behavior or patterns over time and establish THEORIES which may later evolve to become "rules" and "laws". I am a computer science and computer systems dual major, I'm well aware of sciencific and engineering processes. I'm not trying to argue that science is made of bull****, it's not. Science did lead us to prosperity and many marvelous inventions, but science cannot possibly provide explanation or justification to everything, it it did, the words religion and crime wouldn't be in the Merian Webster's dictionary, to say the least."


Science is a *method* to attempt to find the truth. By using the scientific method, one can systematically rule out possibilities that are false, and continue to derive closer approximations to the truth. Hypotheses are constantly refined, new models are developed, when new data gives evidence to that. The theory is adapted to fit the data.
Science involves careful measurement and observation, is verified and reverified, peer reviewed..... even double blind testing (gasp!) Using science you can do all sorts of interesting things like build tall buildings, ride in a maglev locomotive, travel to the moon, and design a build nice sounding speakers.

Religion is a *belief* that one holds, often in the face of no evidence or contradictory evidence. There is either not concern for ascertaining the truth, or a need to suppress contradictory evidence that compromises the belief. Data is molded to fit and support the belief. Religion involves a leap of faith; going to the precipise of the unknown and leaping in hoping that one's beliefs are true and sustains them.

I have had clients who believed themselves Jesus (actually 2 different Jesus' at once; we used to have interesting conversations), I have had clients that believed strongly that Kadar the space alien injected thoughts into their head and wore foil in their hats to stop the "waves" that they were using. In fact, some people will actually fly airplanes full of people into buildings full of people with the righteous certainty of their beliefs all the while with smiles on their faces. Don't know how that fits into our conversation here.....


You wrote:
" For example, a glass that's filled half way is scientifically at 50% of capacity. That's a fair statement to make, right? But some will interpret that glass as half full while others interpret it as half empty. Definition is definition, it's dead. Our interpretation of it means much more."


Your interpretation is an inference and an appraisal. That is, from what has happened and your beliefs, you develop an inference as to what that might mean and then make an appraisal as to what that means *to you*. Your interpretation may be rational or irrational. If someone you know passes you in the hall, makes eye contact, and looks away, you will develop some form of inference such as "Joe is avoiding me". Then, like all people, you will make an appriasal, such as "he hates me", or " he must be really busy and cannot talk". These will almost always be based on your beliefs, unless you are actually mindful enough to see the beliefs and think through logically/rationally free of them.

But here is a little audio story... I recently bought some speakers (some polk R50's for mains and R20's for surrounds replacing some KLH towers I had). I had just got them out of the box and hooked them up to my Onkyo 601 receiver. A friend of mine was helping me set them up and once done I turned them on, and they sounded wonderful to me. My friend, however, thought they sounded shrill and he proceeded to share with me that they needed to be broken in. He stated that I should place them facing each other and wire one of them out of phase and play white/pink noise through them for two days until they were broken in. I personally thought that odd, since you could just as easily just play music and they would just "break in" as you did so, and I told him so. He seemed distressed at my disbelief and proceeded to tell me of all the reasons I needed to break them in. I agreed to do so, just to get him to stop harping about it, and got more beer. In any case, work and family was so hectic, I didn't even touch the set up for 2 days. He stopped by 2 days later in the evening after work and wanted to hear the speakers. Mind you, they had not been touched at all, nor any music or anything else played through them during this time. I did not tell him this, and when he came in they were still sitting where he had placed them, facing each other in the middle of the living room. We placed them back where they were to go, exactly where they were before (I had duct taped the outline on the floor so they would go back where they should go) and we turned them on. He began telling me how wonderful they sounded and how much better they were since being broken in. I pondered whether or not to tell him they hadn't been broken in, and when I told him, he was shocked. Later when he left, he said (after previously saying they sounded "wonderful") that they still sounded shrill and really should be broken in.

So your point of interpretation is well taken. When he believed (there is that word again) that they were broken in, he interpreted that they sounded better, wonderful in fact. When he discovered that they were not broken in, he interpreted (i.e., believed) that they did not sound as good. There are some that say that beliefs are like rose colored glasses that color all that you see.


lastly you shared:
"Human mind is not scientific, trying to apply scientific rules/laws on human is a lost cause. It doesn't matter if the so called "break-in" has scientific effects, it only matters whether or not you believe it. If you do, break-in will make a difference to you. If you don't, start using your speakers."


I hope that applying science with humans is not a lost cause. Although it was the great Wei Wu Wei that once quipped that "people would endure all manner of suffering, give up their lives for causes both noble and foolish, but few would ever give up even one of the beliefs that caused their suffering". Beliefs give comfort......, certainty to life...., so that yourself, the world and others conform to your expectations. Neither here nor there, I suppose..... Albert Ellis, the developer/inventor of Rational Emotive Behavior Therapy, studied this extensively and determined that human beings have an innate tendency to be both rational and irrational. A truism, I think. And there is no limit to the irrational things that people will believe and tell themselves. And it is very, very easy to condition oneself to believe anything. All it takes is a willing attitude, some circumstantial evidence, a supportive peer group who reinforces the belief and soon you will not even remember that you never thought this way before.

But as for break in (back to the subject at hand), for me, the jury is still out. Perception is fickle, and beliefs seem to color what you hear. The new agers say "you create your own reality", and so one might speculate that if you believe it will make a difference, then it will, *for you*. Perhaps tomorrow I will waste some time searching the web to see it I can find some research on the break in phenomena.

Take gentle care;

Vinny

[hawkton]

Ok, maybe I went a bit too far in some of my statements in my previous post. I do have to agree that there are both rational and irrational tendency in the human thinking process.

I guess what I was trying to say is that humans cannot collect data the way scientific devices do. Humans also store information in a very different way from how computers do. Take pictures/images as an example. Computers see them as a 2-dimensional array of color pixels. But humans "store" images very very differently, in a way that scientist can't quite understand yet. What we do know that is any "stored" image, when recalled, is rendered by our brains. This is why 2 people may describe a different picture with different people at the crime scene while telling the truth. Human vision is focused on one point, the rest of what we "see" is actually rendered by the brain. This is why the same sound wave will sound different to 2 different people.

Cyber Stoic, It's also interesting that you mentioned Joseph Stalin and Hillary Clinton. I am not sure what you were trying to say. I guess you were trying to disagree with me. Are we to believe that my statement was wrong just because 2 public/historical figures who were judged "wrong" or "bad" agreed with my statements? Let's think about 2 thing: 1. When a person is judged wrong or bad in history for some doings, does that mean everything he's ever done or said is also wrong or bad?
2. This so called moral, is it absolute? Not even science is absolute over time (that's why theories or even laws are sometimes challenged and changed).
I still believe that interpretation is much more important. If you dig to the bottom of this concept, definition is an interpretation itself, isn't it?

Tony

[RGA]

Your posting is absurd to the point where it hardly deserves a reply but since I have nothing better to do at the moment.....

Shoes are expected to wear out from day to day, even hour to hour. Comparing shoes which undergo constant mechanical stress that is fully expected to eventually destroy them and are usually manufactured with the understanding that they need to be broken in by the user because of the cost of mechanically flexing every pair in the factory until they soften up would be too expensive is a rediculous comparison to an electronic component.

Reputable manufacturers conduct all types of destructive and non destructive tests including life cycling tests to simulate aging. If the materials they use or the way they are manufactured are so unstable that performance drifts beyond acceptable limits called tolerances within a specified period, they have to modify the design, the materials, or the manufacturing methods. This is even more true today than it was 40 years ago. Some manufacturers like AR made the mistake of using foam surrounds which deteriorated and need repair after only a decade or two. Others like KLH used cloth surrounds which have held up during all this time. Mine are at least 40 years old and show no physical or audible signs of deterioration. Speakers whose performance drift within a matter of days or weeks are definitely to be avoided. Once the product leaves the factory, it is beyond the manufacturer's control and there is no way to predict what it will perform like or where it will stabalize, or even if its performance will ever stabalize. This is not the same as product failure such as the deterioration of foam surrounds. Under those conditions, you have no idea what you are getting for your money and neither does anyone else.

Hmm do I trust you on your word that every speaker manufacturer in the world today is nothing but a shill - since they ALL recommend a break in.

There is only one speaker I know of that was tested, the CDM 1NT, and it measured differently after a break in period - very slight maybe unnoticeable - no way to to do a DBT however, which would mean nill anyway. Since the next CDM 1NT may not have a measured difference one cannot conduct a test in that manner. And no not all CDM 1NTs are identical off the line otherise so would cars and thre would be no lemons.

Speakers like Tubes wear out and SLOWLY get worse --- or like shoes get more comfy because you get more used to them. Of course your hearing after 40 years also gets worse as time goes on which may make it all very unnoticeable.

Once again people avoid the most intelligent aspect of the issue...break in or not is irrelevant since you have to play the speakers ANYWAY. I am more apt to believe that it is the manufacturer wanting people to get USED to the speakers because most people are moving from some ghetto blaster or 25 year old Bose that had no high frequency response whatsoever.

The punchy bright crap they're trying to sell today sounds extremely screachy compared to to the no highs of older speakers. So you the BUYER need some time to adjust to this new so-called improved home theater speaker designed garbage of today. After a week or two you get accustomed to this and it begins to sound more acceptable -- OR the buyer who has been slammed with reviews for months and heavy marketing thinks he or she is wrong because some expert said the speaker was good and he (whoever he is) said X speaker is the best so you just live with it...who cares if after 3 months you never play music anymore. The manufacturer does not want to see returns after 2 hours of listening.

If you're naive enough to think there is absolutely NO CHANGE whatsoever or could be ANY change whatsoever in a moving pistonic item made of soft material like a speaker cone A) you're wrong because the changes have been measured and B) you're wrong in thinking that the slight changes somehow discredit the speaker's quality. You are the one who says SLIGHT frequency changes mean nothing - so if the CDM 1NT with it's miniscule change is now crap then you must assume speakers have the tightest tolerances of any products ever made on the planet. Engineers are not as stupid as you think they are (dense and can't see the big picture perhaps and arrogant and self righteous perhaps) but they sure can pick out a material and know the properties of its wear and compensate for the parts' maximum change co-efficient into their design so the speaker may fall within X and Y variance - they'll spec it at the worst number - less radical than a belt on a turntable going after a period of time. Two belts exactly the same one will last 10 years one will last 3 with the same number of hours of spining? Can you time it exactly as to how many hours you'll get from one? No!

I had a B&W DM 302 that made a few popping sounds for the first couple hours of use and then it was fine for the 3 years I had them. Problem? No! Break In? Well you tell me what it was? Sounded like a driver that needed to move out and in a few times to settle itself to me. My new speaker has required no such period and I have detected no change. I can hardly call the 302 a lousy speaker because of its first few hours. I doubt there is a better speaker for $300.00Cdn New then or since. I actually regret trading them.

[Debbi]

....since burn in is a fact...there is no rational reason to consider purchase of new speakers since I could only guess at the burn in stage while listening and could not make any determination as to whether I like the speaker in question.I might retire with a Lady and wake with a whore.....

[bturk667]

Not necessarily. I have never really heard a difference in a speaker after the so called "break in period." This is not to say that a certain speaker design/type, driver type, and driver complement can not sound slighly different while they mechanically "break in." I just do not think the sound would be life altering. You know, the whole lady whore thing.

For what it is worth, I owned my Snell's for @ ten years before getting new drivers. After the drivers were installed I really could not hear a difference. At least not one that was apparent across the board. The bass did seem a little tighter and focused, but, again, not in every recording. So I do not feel there was in fact any difference.

[Klipschnut]

This thread has moved from a simple question on a mechanical device into the realms of perception of reality and faith. It's neat how a common interest in something like audio reproduction can lead to such interesting conversation. As for those who are complaining about forums leading to arguments, there is a big difference between sharing opinions in the attempt to reach a mutual conclusion and simply arguing. There have been many intelligent and relevant statements made so far, and there's no reason to give up simply because you didn't change someone's mind. You might as well sit in a room alone the rest of your life, talking to yourself, if the thought of listening to other people's viewpoints irritates you. The invention of forums and the internet itself was conceived in order to share information, including personal opinions.

Science is a study of observed patterns, from which hypothesis can be derived. That's not from Webster's, that's just my personal opinion. I believe the best tool for forming hypothesis is communication. We all use our senses to collect data and make assumptions about our surroundings, and the best way to accumulate the data into collective knowledge is by sharing and comparing it with other perceptive devices (humans).

In regard to the initial question posed in this thread, it is true that any moving device will exhibit some degree of friction and wear. The extent of this may or may not be detectible by human sensory organs. The placebo effect has been proven in enough tests to consider it reasonably factual. One test was described by a previous poster involving 'tricking' a friend into believing he had witnessed a noticable difference, when there was likely no detectable change from the speaker sitting without use.

I strongly agree with the idea that getting used to an amp or speaker's "sound" will change the listener's opinion about the product, regardless of whether any "breaking in" of the equipment transpired. The human subconcious is a powerful thing, and can easily persuade our susceptible minds into believing one thing or another. This phenomenon is prevalent throughout the audio kingdom.

I would suggest to the initial poster that he or she conduct a test themselves, and decide their own opinion, as I have doubts that anyone reading or posting here can conclusively prove or disprove this phenomenon, or its effect on the limited perception that we possess.

[Garrardman]

OK, guys, here are a few facts from the speaker end of the chain written by someone who makes his living designing hi-fi speakers currently and car speakers previous to that -

A moving coil loudspeaker drive unit consists of a cone of whatever material, supported by a surround which is usually cloth, foam or rubber and this is what most of the conversation in this thread seems to have been about. However, underneath that cone is a suspension of flexible material that is normally made from cotton, conex or some other type of cloth, heavily impregnated with a resin to stiffen it. The type, hardness and quantity of resin is generally what sets the mechanical properties of the suspension and thus the drive unit.
I can assure you all that this suspension starts changing its physical properties as soon as you put a signal through it and it's behaviour changes drastically over the period of its initial operation and will have a profound effect on the sound of the speaker.

One of my customers when i was designing car speakers required a "break-in" of every sample we provided, which consisted of playing short duration pulses with peaks of up to 35V through the speaker for an hour to loosen things up - their reason for this was to replicate the behaviour and performance of a speaker that had been sat in a car for a year or so, operated and exposed to the variations in temperature and humidity.. One of the products I designed was a high performance 2 Ohm 9x6 subwoofer and it needed a quantity and density of resin that had never been required before by our suspension supplier, in order to pass all the necessary environmental validation testing - when one of these speakers was taken from the end of the production line and swept with a sine wave, you could actually hear the resin quietly cracking, flexing and loosening for 20-30 seconds before it stabilised! Measuring one fresh from the line and then later after the above mentioned break-in would show lower drive unit resonance, lower distortion figures and in the case of full range speakers, smoother frequency response, particularly at high frequencies.

In my current company we always run our prototype speakers in at least overnight and sometimes over a weekend before making any measurements or carrying out listening evaluations. We actually use exactly the same method mentioned previously in this thread (pink noise, speakers facing each other, one out of phase) and i can assure you it DOES make a difference, however it would not be practical to do this for every production pair from the point of view of both physical space and cost.

The loosening of loudspeaker drive unit components has nothing to do with perception, imagination or witchcraft - it is a physical fact and, whilst i can't vouch for other manufacturers, in both of the companies i have worked for we design our speakers to take into account how their behaviour and sound changes as they run in - it isn't rocket science!

Adam.