[Snake]

I guess nobody bothered to [actually] read the links I provided regarding materials stress.

Quote:

Originally Posted by rodbac [edited- I see what Snake is getting at] Snake- if I understand your point correctly, you're assuming that reproducing a 140Hz wave will require 2/3 of the available excursion from both drivers (using your example). What on earth leads you to believe that?

Because actual driver excursion is a computation of 2 factors - frequency and volume. A 140Hz wave can cause any driver to reach full excursion...if the amplification placed upon it demand it.


Quote:

The myriad factors that figure into design considerations to generate 100db 140Hz in a room versus the same in a headphone make your point pretty tough to grant.

As I said, I guess nobody bothered to look at the links provided. Even though I am not a materials analyst the (second) link provides explanation of elastic failures. Here is another:

http://www.trueaudio.com/about_3.htm

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We can see that the excursion response of this driver at its full rated power of 75 Watts goes over both the mechanical and linear excursion limits. At 50 Watts the excursion stays just under the mechanical limit but is over the linear limit at the lowest frequencies. At 25 Watts the system just hits the linear limit (Xmax) at the lowest frequencies.

All driver motor systems have a linear limit, the area where linearity in response starts to degrade. However, this limit is quite a bit less than absolute limit of excursion of any (and all) drivers - therefore driving any driver to a certain volume limit moves the performance outside the linear area.

http://www.meyersound.com/products/technology/qa.htm

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How does Meyer Sound ensure linearity in drivers and systems? (snip)

http://www.mcsquared.com/nsca98.htm

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Sensitivity, Power Handling and Output (snip)

Now plug all that into my first quoted links regarding elastic material deformation.

It should all be apparent once the ding! lightbulb of assimilation hits

 

[Snake]

Quote:

Originally Posted by 003 Driver burn in I can see. But solid-state amp burn in and cable burn in? Where is the reasoning behind that? What the heck is there in a cable that "burns" in? It's just basicly a wire that transfers an electric signal to it's destination.

Well, sold-state amp "burn in" also happens due to the heat/cool cycle implimented across the components, along with charge/discharge (as audio is AC). For instance, capacitors change and this, scientifically, is called "forming"

http://www.ieci.com.au/highvoltage/type_AB.html
http://www.repairfaq.org/sam/captest.htm

As this single component, the capacitor, is installed new into new devices they have not gone through any charge / discharge cycles to form oxides within the case (dielectric caps). "Burn in" on solid-state devices is when, again, the multiple components that make up the circuits "settle in" to their "worn" states, as capacitors do indeed wear.

Cable "break in"?...

That's another subject. I couldn't and won't say yea or nay absolutely, but IMHO maybe it's a combination of "relaxation" of the strands after installation (as most cables are shipped coiled but installed in any way other than this), plus some level of change regarding the wire's natural capacitance.

But I am NOT going to say for sure if cable "break in" is real.

 

[tomb]

Quote:

Originally Posted by dpippel Again, nothing but anecdotal evidence. There isn't a single bit of hard data here, just listener impressions.

Enough said - absurdity has met its match. Todd, Tyl, AKG, and Ultrasone will be glad to know your opinon of their "listener impressions." So will the University of Helsinki and all their hard data on headphone data. Apparently, they had another HATS (Head And Torso Simulator) they didn't know about.

P.S. No offense, but if you choose not to materially participate in a discussion, you are better off not posting at all.

P.S.#2 - No, Snake - none of these guys are reading the resources. There is no interest except in repeating arrogant prejudice - might as well stick fingers in ears and yell, "nannie-nannie-boo-boo." Our time is probably better spent somewhere else - I know mine is.

 

[Alu]

Quote:

Originally Posted by tomb Enough said - absurdity has met its match. Todd, Tyl and Ultrasone will be glad to know your opinon of their "listener impressions." So will the University of Helsinki and all their hard data on headphone data. Apparently, they had another HATS (Head And Torso Simulator) they didn't know about. P.S. No offense, but if you choose not to materially participate in a discussion, you are better off not posting at all.

I meant to reply earlier to your post, but I chose not to. Nonetheless I agree with dpippel. Your post does not include any hard evidence, except for one remark in the wiki about the K701 with the diaphragm (still not being very detailed), and the one with Ray Samuels in the 6moons review about the "huge filter capacitor's dielectric".

EDIT: Snake, your contributions are excellent and will be read as a whole after my exams. I looked over them quickly, also your explanations seem very comprehensive to me.

 

[alfie]

Quote:

Originally Posted by tomb No, Snake - none of these guys are reading the resources. There is no interest except in repeating arrogant prejudice - might as well stick fingers in ears and yell, "nannie-nannie-boo-boo."

Do you understand that for every single reference you post here people con find ten claiming the complete opposite, from well respectable sources as well? "define prejudice" -> "a partiality that prevents objective consideration of an issue or situation". Huumm it sounds like could be applied to both factions.

 

[Zoobies]

Contrary to popular audio belief, capacitors do not take hundreds of hours to form.

 

[Snake]

Quote:

Originally Posted by alfie Do you understand that for every single reference you post here people con find ten claiming the complete opposite, from well respectable sources as well? "define prejudice" -> "a partiality that prevents objective consideration of an issue or situation". Huumm it sounds like could be applied to both factions.

Only if you find mathematical engineering analysis discountable.

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If the loading process shown in Figure 2 is continued from -smax to +smax, then a hysteresis loop will result as shown in Figure 3. The hysteresis loop defines a single fatigue cycle in the Strain-Life method. Note that the stress and strain amplitudes are 1/2 the total stress and strain ranges. The area within the loop is the energy per unit volume dissipated during a cycle. Figure 3: Typical Cyclic Stress-Strain Curve When subjected to strain-controlled cyclic loading, the stress-strain response of a material can change with the number of applied cycles. If the maximum stress increases with each successive cycle, the material is said to cyclically harden. If the maximum stress decreases with the number of cycles, the material is said to cyclically soften. If the maximum stress level does not change, the material is said to be cyclically stable. *Transient material behavior tends to stabilize after a relatively small number of cycles - typically less than 10% of the total life.* (emphasis mine)

From http://www.engrasp.com/doc/etb/mod/f...life_help.html, Copyright © 2001-2005 Engrasp, Inc. All rights reserved., quoted without permission.

This website is not an audiophile website - it is the "Engineer's Toolbox" for rapid computations of material specifics needed for statistical solutions:

"Welcome to the EngineersToolbox (ETBX), a graphics-based rapid analysis tool for engineers. ETBX provides fast, interactive solutions to a wide range of engineering problems using an integrated library of computational modules."

The mathematical computations used by engineers during the analysis of elastic material deformation takes cyclically softening, hardening and stability into account...

what we, in the audiophile world, have labeled "break in".

Unless the math used to compute the strength, or weakness, of everything from concrete to steel is non-verifiable - which means that the buildings we are in, the cars that we drive, and general high-tech life all around us - is wrong...

I think it's safe to say that their math can be trusted!

Note the emphasized quote:

"Transient material behavior tends to stabilize after a relatively small number of cycles - typically less than 10% of the total life"

10% of total life. "Break in", in a nutshell. How much is 10% of the lifespan? It can vary depending upon the design and construction materials used.

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Mean Stress Effects Most basic S-N fatigue data collected in the laboratory is generated using a fully-reversed stress cycle. However, actual loading applications usually involve a mean stress on which the oscillatory stress is superimposed. For details on the parameters used to define a stress cycle with both alternating and mean stress, see the Stress-Analysis module. The effect of mean stress on the strain-life curve is shown schematically in Figure 5. Mean stress primarily affects component life in the high-cycle regime, with compressive means extending life and tensile means reducing it. In the plastic regime, large cyclic plastic strains cause mean stress relaxation, and any mean stress tends towards zero. Morrow was the first to propose a modification to the baseline strain-life curve to account for the effect of mean stress. His approach was to alter the value of the fatigue strength coefficient in the elastic component of the stress-strain relationship: where is the mean stress. In this equation, tensile mean stresses are positive (s0 > 0), and compressive means are negative (s0 < 0) . In terms of the strain-life relationship, the Morrow Mean Stress Correction can be expressed by: where the mean stress s0 is positive for tensile stress and negative for compressive stress. Figure 6 illustrates the effect of a tensile mean stress in modifying the strain-life curve using the Morrow equation.

Again, from http://www.engrasp.com/doc/etb/mod/f...life_help.html, Copyright © 2001-2005 Engrasp, Inc. All rights reserved., quoted without permission.

Pease read the links I have provided regarding materials, drivers et al.

 

[tomb]

Yep - Engineer's Tool Box is a great site - use it all the time. I know I said I was through, but had to commend the real Engineering.

This one is good, too - http://www.eng-tips.com/, but it's a true forum, and perhaps a little thick for non-Engineers.

Alu - sorry to disappoint, but the Wiki reference is a ringer. I included for illustration purposes about what you guys consider anectodal vs. valid empirical evidence. Wiki is notorious for free edits from anyone - that was simply copied from another individual's review that you can find in several places on the Internet.

Alfie - prejudice is meant as Engineering prejudice - those that only believe what a measurement may tell them (or not believe anything in the absence of such measurements). Real Engineering is not as precise as that in many instances. If someone such as Tyl, Todd, or even mfrs such as AKG suggest a burn-in is needed, an Engineer would be a fool to discount that as his initial position.

Edit: Put another way, a customer who quickly discards a new headphone - simply because he/she doesn't believe in burn-in - may be be missing out on a lot.

 

[Snake]

Quote:

Originally Posted by Zoobies Contrary to popular audio belief, capacitors do not take hundreds of hours to form.

You are probably correct. But it may take quite a while for an individual capacitor to stop forming - that is, completely and utterly settle into it's stable nature.

Multiply the number of individual components used to manufacture any quality piece of modern electronics by the stability factor and you get a sum = "quite a while", in order to stop sensing changes, as each component is exposed to different levels of AC signal during the "break in" operation.

 

[PinkFloyd]

Quote:

Originally Posted by Duggeh Just to offer my input to this thread, I do personally believe in burn in. However I believe that burn in of the "wait for 300 hours" or the "you need to let them run in for at least 18 yeard while playing Mr Osio" Kind of burn in is nonsense. Burn in is a first 24 hours kind of thing, just the driver getting into its stride. The Equivilant of a new car engine needing a couple of hundred miles of run-in before you open up the throttle. Not the "run the car for 5K miles before judgement" kind of thing. JM2C.

Bed in...... "bed in" everything that moves beds in whether it be a pair of 'phones, a piston, a leather belt, a pair of shoes, a pair of gloves, a pair of speakers or a door hinge they all need usage to bed in and find their groove.

 

[PinkFloyd]

Quote:

Originally Posted by Zoobies Contrary to popular audio belief, capacitors do not take hundreds of hours to form.

What about the electrons forming a path? You think that happens instantly and is not constantly changing?

 

[alfie]

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Originally Posted by Snake Only if you find mathematical engineering analysis discountable. ... Pease read the links I have provided regarding materials, drivers et al.

I'll will tomorrow, but I have a small idea what it is talking about, which is not that easy to apply so confidently to explain burning-in in headphones; as many times stated, even if some sort of modification can happen on a phone during burning in, it must be audible. Note that I have no opinion about, I was just replying to a post I found a little bit harsh.

 

[Zoobies]

Quote:

Originally Posted by PinkFloyd What about the electrons forming a path? You think that happens instantly and is not constantly changing?

Electrons forming a path? Current flows or it doesn't. It doesn't "kinda flow" or "sort of flow." I'm not sure I understand what you are getting at.

 

[Snake]

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Originally Posted by alfie I'll will tomorrow, but I have a small idea what it is talking about, which is not that easy to apply so confidently to explain burning-in in headphones; as many times stated, even if some sort of modification can happen on a phone during burning in, it must be audible.

That is certainly true, and why "burn in" is noted between different individuals and between different gear / situations.

Sometimes it will be a notable difference, "wow, this thing really burned in!", and other times "burn in didn't happen / is fake". Many variables persist.

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Note that I have no opinion about, I was just replying to a post I found a little bit harsh.

No problem

 

[tomb]

Quote:

Originally Posted by alfie I'll will tomorrow, but I have a small idea what it is talking about, which is not that easy to apply so confidently to explain burning-in in headphones; as many times stated, even if some sort of modification can happen on a phone during burning in, it must be audible. Note that I have no opinion about, I was just replying to a post I found a little bit harsh.

No harshness intended, and it certainly wasn't in reply to anything you posted. I probably let my frustration show at someone's insistence of essentially claiming to know more than the headphone mfrs and suppliers themselves.

Prejudice exists in many technical discussions. It is also an accurate way to describe consumer preferences about headphones, for instance. It wasn't meant in any way outside of that context.