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post #61 of 76 Old 11-29-2012, 07:26 AM
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Yes, as since you're the one not believing me - you're the one who has to disprove me.
Uh, no. The scientific burden of proof always rests with the side making the positive assertion. In this case, that would be the claim of an audible difference. You can present evidence that people can hear these differences in adequately controlled listening tests (difficult to do), or you can present evidence that measured changes before and after break-in are of a magnitude that exceeds recognized just noticeable differences for those parameters.

I'm not saying you're wrong. I'm saying the ball's in your court. And blathering about glue drying isn't evidence of audible differences.

If you can't explain how it works, you can't say it doesn't.—The High-End Creed

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post #62 of 76 Old 11-29-2012, 08:31 AM
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Originally Posted by Nightlord View Post

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Originally Posted by arnyk View Post

Of course, and you are totally ignoring the totally correct way to settle this - actual facts.

Yes, as since you're the one not believing me - you're the one who has to disprove me.

Insofar as the evidence you provided, which was based entirely on your word and some unknown words uttered by some unknown authority, I'm way far ahead of you because I named my authorities. Press me, and I might even do you the favor of providing some direct quotes from AES papers by them.

But no, even though I'm already way ahead, I'll raise you one more, this time with a direct quote from yet another authority with absolutely impeccable credentials (total = 3)::

Floyd Toole: Sound.Reproduction.The.Acoustics.And.Psychoacoustics.Of.Loudspeakers.And.Rooms page 353:

"
In parts of the audio industry, there is a belief that all components
from wires to electronics to loudspeakers need to
“break in.” Out of the box, it is assumed that they will not
be performing at their best. Proponents vehemently deny
that this process has anything to do with adaptation, writing
extensively about changes in performance that they claim
are easily audible in several aspects of device performance.
Yet, the author is not aware of any controlled test in which
any consequential audible differences were found, even in
loudspeakers, where there would seem to be some opportunities
for material changes. A few years ago, to satisfy a
determined marketing person, the research group performed
a test using samples of a loudspeaker that was
claimed to benefi t from “breaking in.” Measurements
before and after the recommended break-in showed no
differences in frequency response, except a very tiny
change around 30–40 Hz in the one area where break-in
effects could be expected: woofer compliance. Careful listening
tests revealed no audible differences. None of this
was surprising to the engineering staff. It is not clear whether
the marketing person was satisfi ed by the fi nding. To all of
us, this has to be very reassuring because it means that the
performance of loudspeakers is stable, except for the known
small change in woofer compliance caused by exercising
the suspension and the deterioration—breaking down—of
foam surrounds and some diaphragm materials with time,
moisture, and atmospheric pollutants. It is fascinating to
note that “breaking-in” seems always to result in an
improvement in performance. Why? Do all mechanical and
electrical devices and materials acquire a musical aptitude
that is missing in their virgin state? Why is it never reversed,
getting worse with use? The reality is that engineers seek
out materials, components, and construction methods that
do not change with time. Suppose that the sound did
improve over time as something broke in. What then? Would
it eventually decline, just as wine goes “over the hill”? One
can imagine an advertisement for a vintage loudspeaker:
“An audiophile dream. Model XX, manufactured 2004,
broken in with Mozart, Schubert, and acoustic jazz. Has
never played anything more aggressive than the Beatles.
Originally $1700/pair. Now at their performance peak—a
steal at $3200!”
"

Besides as others have correctly pointed out, you are the person making the exceptional claims. That means that the ball is clearly in your court.

Game, Set, Match!
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post #63 of 76 Old 11-29-2012, 09:47 AM
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Case is simple, I told you what to look for if you're interested and you're not. I don't have a lab and even if I did I would not waste time re-prove something I have the best source available for. Case closed. If you want to go ahead and keep being impolite, that's up to you. Sorry for bothering to put more info on the table, I won't do that again.

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post #64 of 76 Old 11-29-2012, 09:49 AM
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Case is simple, I told you what to look for if you're interested and you're not. I don't have a lab and even if I did I would not waste time re-prove something I have the best source available for. Case closed. If you want to go ahead and keep being impolite, that's up to you. Sorry for bothering to put more info on the table, I won't do that again.

Criticizing people for not going on snipe hunts that they may have already fallen for once is not "putting more information on the table".
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post #65 of 76 Old 11-29-2012, 10:44 AM
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There was not so detailed information about the glue before in the thread, although it had been mentioned. I gave you that and you've just given me grief in return...
For me it's facts, for you it's unproven, but I can't see how anyone with a tecnical background could fault the possibility of a strong local heatsource being able to alter the material structure of glue and lacquer. I have no way of proving it, but anyone sufficiently interested and equipped could have a go.

Are we good?

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post #66 of 76 Old 11-29-2012, 11:37 AM
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Much as I hate to get into this... Nightlord, I have worked with high-temp epoxies for much different purposes so can believe the technical part of your response. I missed, and please forgive me if you already stated it as I was too lazy to wade back, if there was an audible difference? From what I think I recall of where you said the glue was, I suspect not, or was there?

IME, based on the measurements described earlier (listening tests were not a part of the testing I did), for conventional or electrostatic speakers there was no audible change after the first initial short runs. Now I wish I had (a) kept all the paperwork and (b) performed the mesaurements at much shorter intervals at the start of testing. The only signifcant change measured over any appreciable length of time was the planer Magnepans, and I do not quite recall the exact reasons they stated. I do have a fuzzy memory of B&W saying we might measure a change but implied it only took minutes. IIRC the change in the 801's response was significant enough to measure but deemed inaudible (maybe 1/2 dB at the low end).

Curious, thanks - Don

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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post #67 of 76 Old 11-29-2012, 12:01 PM
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I can't tell you if it's audible or not, I convey that at least the brand of elements in my speakers are to be burned-in. Myself, I don't have much trust in what I think I hear, we're too easily fooled, I prefer controlled experiments. What I believe I did state was that they guy who bought a previous pair from me had some initial concerns and it was brought to attention that I might haven't played them long and hard enough, which the guy did and his concern went away. I think that's about all I have intended to state.

I may be able to find out which kind of glue and where the effected bond in question was, but it requires quite som digging in old messages and I can't promise anything.

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post #68 of 76 Old 11-29-2012, 12:03 PM
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I also don't want to get on the wrong foot with interesting people, so that every other encounter in other threads are tainted by this one. I'm here for good, intersting conversation with interesting people and want everyone to be ok with me too. Hope that can be the case.

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post #69 of 76 Old 11-29-2012, 01:11 PM
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Originally Posted by Nightlord View Post

I can't tell you if it's audible or not, I convey that at least the brand of elements in my speakers are to be burned-in. Myself, I don't have much trust in what I think I hear, we're too easily fooled, I prefer controlled experiments. What I believe I did state was that they guy who bought a previous pair from me had some initial concerns and it was brought to attention that I might haven't played them long and hard enough, which the guy did and his concern went away. I think that's about all I have intended to state.
I may be able to find out which kind of glue and where the effected bond in question was, but it requires quite som digging in old messages and I can't promise anything.
I am under the impression that this thread is about audibility of so called speaker break-in, not what happens to cured glue when heated. Irrelevant to audibility unless it is the demonstrated cause of audibility.
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post #70 of 76 Old 11-29-2012, 01:28 PM
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I also don't want to get on the wrong foot with interesting people, so that every other encounter in other threads are tainted by this one. I'm here for good, intersting conversation with interesting people and want everyone to be ok with me too. Hope that can be the case.
If everyone took the same point of view, this place would be much more pleasant than the caustic atmosphere it has. Did Arny really say "game, set, match?"

Anyway, here is some data. There is a very nice super detailed paper from Kippel (the guys that make speaker measurement gear) published last year at Audio Engineering Society conference on the mechanical side of this topic:

Mechanical Fatigue and Load-Induced Aging of Loudspeaker Suspension
Wolfgang Klippel, KLIPPEL GmbH, Dresden, 01309 Germany

I will provide the abstract for a quick summary:

"The mechanical suspension becomes more and more compliant over time changing the loudspeaker properties (e.g.
resonance frequency) significantly. This aging process is reproducible and the decay of the stiffness can be modeled
by accumulating the apparent power supplied to the suspension part and using an exponential relationship. The free
parameters of this model are estimated from empirical data provided by on-line monitoring or intermittent
measurements during regular power tests or other kinds of long-term testing. The identified model can be used to
predict the load-induced aging for music or test signals having arbitrary spectral properties. New characteristics are
being introduced which simplify the quality assessment of suspension parts and separate mechanical fatigue from
the initial break-in effect. Practical experiments are performed to verify the model and to demonstrate the diagnostic
value for selecting optimal suspension parts providing sufficient long-term stability."


And this list:

"Non-reversible changes which can be interpreted as an
“aging” of the suspension have the following causes:

 Initial exposure to mechanical load opens some
bonded joints in the impregnated fiber structure
(break-in effect).
 Accumulated mechanical load causes slowly
growing cracks, destruction of the micro-fibres
and other mechanical deformations (fatigue).
 High ambient temperature or voice coil heating
changes the suspension properties permanently.
 Humidity, direct water contact and reaction
with other chemicals change the material
properties.
 Gravity changes the geometry of the
suspension part and the coil’s rest position if
the loudspeaker is mounted in horizontal
position.
 Instability of the chemical compounds causes
decomposition over time.
 UV light promotes chemical reactions and
decay processes in diaphragms and surrounds."


There is no listening tests or frequency response measurements in the paper however. The graphs are all relative to changes in the driver characteristics.

This is not a field that I have studied but I did sit through the Harman/Dr. Toole presentation that Arny quoted. The frequency response measurement difference they showed was indeed minor.

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post #71 of 76 Old 11-29-2012, 02:12 PM
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Originally Posted by amirm View Post

Quote:
Originally Posted by Nightlord View Post

I also don't want to get on the wrong foot with interesting people, so that every other encounter in other threads are tainted by this one. I'm here for good, intersting conversation with interesting people and want everyone to be ok with me too. Hope that can be the case.
If everyone took the same point of view, this place would be much more pleasant than the caustic atmosphere it has. Did Arny really say "game, set, match?"

Anyway, here is some data. There is a very nice super detailed paper from Kippel (the guys that make speaker measurement gear) published last year at Audio Engineering Society conference on the mechanical side of this topic:

Mechanical Fatigue and Load-Induced Aging of Loudspeaker Suspension
Wolfgang Klippel, KLIPPEL GmbH, Dresden, 01309 Germany

I will provide the abstract for a quick summary:

"The mechanical suspension becomes more and more compliant over time changing the loudspeaker properties (e.g.
resonance frequency) significantly. This aging process is reproducible and the decay of the stiffness can be modeled
by accumulating the apparent power supplied to the suspension part and using an exponential relationship. The free
parameters of this model are estimated from empirical data provided by on-line monitoring or intermittent
measurements during regular power tests or other kinds of long-term testing. The identified model can be used to
predict the load-induced aging for music or test signals having arbitrary spectral properties. New characteristics are
being introduced which simplify the quality assessment of suspension parts and separate mechanical fatigue from
the initial break-in effect. Practical experiments are performed to verify the model and to demonstrate the diagnostic
value for selecting optimal suspension parts providing sufficient long-term stability."

You know there are always grade school kids who will sneak into the adult section of the library, read a book on deviant sexual behavior and want to try out some things they read there on their 9 year old girlfriends ASAP...

This slide from the presentation mentioned above at http://www.almainternational.org/assets/Documents/WinterSymposia/InvitedPapersWS2012/mechanical%20fatigue%20and%20load-induced%20aging%20effects%20in%20loudspeaker%20suspensions-klippel.pdf clarifies the purpose of this paper, in case the title wasn't clear enough.



Long story short this paper is not about breaking-in speakers, its about breaking speakers (as in making them stop working by the "Bop until you drop" method.

Irrelevant to the discussion so far...
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post #72 of 76 Old 11-29-2012, 02:45 PM
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Let's see the "non-relevant" points from the paper:

"Short break-in effect can be easily separated from the long-term fatigue effect."

Short break in is the same as failure mode? I think not.

"The mechanical suspension becomes more and more compliant over time changing the loudspeaker properties (e.g.
resonance frequency) significantly. "

Resonance frequency changing is an effect we worry about after the speaker has failed? I think not.

"Additional on-line monitoring of the voice coil temperature, displacement, ambient temperature and humidity of the air are required to explain temporary changes of the stiffness caused by varying ambient condition, voice coil heating [17], creep and other iscoelastic
effects."

We worry about temporary changes once the speaker has failed? I think not.

"Intermittent measurements performed at low amplitudes require an additional break and muting of the high amplitude stimulus for accelerating the aging process to give the suspension part sufficient time to find a thermal and mechanical equilibrium and to produce data which are comparable with the results of traditional small signal measurements."

We need break in period to accurately measure the performance of the driver after it has failed? I think not.

"The model supports the separation of the breakin and fatigue effects which is important for assessing the quality and stability of a suspension part."

So he talks about "break in" when he is only writing about what it makes the driver fail? I think not.

"This model developed here has been applied to the stiffness value provided by small signal intermittent testing and to the stiffness value at the rest position x=0 in the nonlinear stiffness characteristic K(x) provided by on-line monitoring."

So "small signals" lead to driver destruction? I think not.

And final paragraph in the paper:

"The new empirical model and the measurement technique developed in this paper are the basis for assessing the quality of the suspension parts from a macroscopic perspective. Further research activities on alternative materials and new processing techniques are required to provide new kinds of suspension systems giving the desired linear or nonlinear characteristic and sufficient long-term stability at low manufacturing costs."

"Long-term stability" relates to destruction of the driver? I think not.

So no, it is not about "breaking" or failure mode of the driver. It is about the effect of use and aging of the drivers and how it can be predicted. Just because "break in" and "breaking" rhyme together in English language does not mean that is what the paper is about. You should pay the $7 to buy the paper and read past Figure 1.

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post #73 of 76 Old 11-29-2012, 02:48 PM
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Oh, let me also make something clear: I personally do not believe in speakers needing to be broken in, or any other product for that matter. That should be done by the manufacturer if needed an I doubt that it is needed. My belief in this regard however doesn't entice me to paper over data such as it exists in that paper. We can't censor research and expect to be have our opinions then be credible....

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post #74 of 76 Old 11-29-2012, 05:44 PM
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Originally Posted by Nightlord View Post

I can't tell you if it's audible or not, I convey that at least the brand of elements in my speakers are to be burned-in. Myself, I don't have much trust in what I think I hear, we're too easily fooled, I prefer controlled experiments. What I believe I did state was that they guy who bought a previous pair from me had some initial concerns and it was brought to attention that I might haven't played them long and hard enough, which the guy did and his concern went away. I think that's about all I have intended to state.

I may be able to find out which kind of glue and where the effected bond in question was, but it requires quite som digging in old messages and I can't promise anything.

Thanks, audibility was the question I had. That is one reason listening was not part of my tests, just measurements (I have done all sorts of other listening tests, but this was not one).

No need to dig up old glue, I can look that sort of stuff up on my own!

Thanks - Don

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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post #75 of 76 Old 11-30-2012, 06:54 AM
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IME, based on the measurements described earlier (listening tests were not a part of the testing I did), for conventional or electrostatic speakers there was no audible change after the first initial short runs. Now I wish I had (a) kept all the paperwork and (b) performed the mesaurements at much shorter intervals at the start of testing. The only signifcant change measured over any appreciable length of time was the planer Magnepans, and I do not quite recall the exact reasons they stated. I do have a fuzzy memory of B&W saying we might measure a change but implied it only took minutes. IIRC the change in the 801's response was significant enough to measure but deemed inaudible (maybe 1/2 dB at the low end).

Citing David L Clark on this topic embodies a wealth of real-world experience that most may know nothing about. DLC developed a device called Dumax:



The speaker in the jig "DUT" is stimulated by controlled current passing its voice coil and also by means of an air pressure source (not shown very clearly - it was something like a Shop Vac). The cone's location is determined by the laser. Something like a dozen of these were built and sold to major loudspeaker manufacturers the world over.

Dumax driver measurements differ from Klippel measurements in that the Dumax measurements are direct, and in themselves do not presume a detailed model of loudspeaker operation much beyond a simple moving diaphragm activated by an electrical motor (voice coil).

Obviously if you go to all this trouble to measure the speaker so precisely, it is important that the measurements provide a reliable view of the driver's parameters. If break-in exists and is significant, this becomes a major issue. Literally thousands of drivers have been measured this way (the row of boards on the lower shelf are jigs for matching various speakers to Dumax), so there is a wealth of real world experience to back Clark's statements up.
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post #76 of 76 Old 11-30-2012, 11:25 AM
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Now, that is cool, warms this engineer's heart! I had totally forgotten about him.

Thanks Arny!

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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