Physical explanation of amp's break in?

Recently purchased Moon i-5, manual mention 6-week break in period, when bass will first get weaker, and after 2-3 weeks start to normalize. Just curious, is there ANY component in the amp's circuitry that known to cause such a behaviour?

I can't fully accept psycho-acoustical explanation for break-in: many people have more then one system, so while one of them is in a "break-in" process, the second doesn't change, and can serve as a reference. Thus, one's perception cannot adapt (i.e. change!) to the new system while remain unchanged to the old one. In other words, if your psycho-acoustical model adapts to the breaking-in new component in the system A, you should notice some change in sound of your reference system B. If 'B' still sounds the same, 'A' indeed changed...
"Just curious, is there ANY component in the amp's circuitry that known to cause such a behaviour?"

If I agree with Bomarc, would anyone be surprised?
My understanding of break in (of components and cables) is that current flowing in new circuitry is finding the path of least resistance through the lattice of molecules that make up conductors.
For components the highest concentration of conducting material is usually in the transformer(s) of the power supply.
Complete break in takes much longer than most manufacturers will admit. Typically, there is a noticeable improvement in the initial hours of operation with gradual further improvement. But in my experience full break in can take six months or longer.
I believe in "break in."

But, I also believe there is an emotional component to audio.

Your sense of hearing can change based on your emotions.

When you are stressed, certain frequencies can become subdued
while others come to the fore -- not a good thing if one is listening
to music and trying to hear the full range.

After purchasing a component, we often go through an emotional period. If one has splurged a little bit, bought an expensive piece of equipment, and any piece can feel expensive as one upgrades,
one can have unrealistic expectations, feeling that the new piece should be perfect, should feed the dog, make coffee, and make you feel like the musicians are giving you deep tissue massages
on their breaks.

Instead, because one is nervous and certain frequencies are
jumping out while others are subdued, the system can be extremely dissapointing. After awhile, you get used to the fact
that you spent the money, that the piece is not going to be healing wounds or raising the dead, and you go through a period of
acceptance. That's when your stress goes away and -- voila --
your new equipement sounds a LOT better.

On the other hand, you may have read that a number of "audiophiles" have used this particular cable and it made cardboard boxes sound like Wilson Watt-Puppies! In this case,
peer pressure over-rules any other stress and -- damn if you don't
plug those cables in and -- wow -- you can hear EVERYTHING!
Not only can you tell what kind of underwear the singer is wearing,
but you can even discern the brand of detergent in which they were washed -- you are ONE OF THE GANG!

What happens if one buys these cables and fails the underwear
and detergent test? Well, that's because the cales need to..... "BREAK IN!"

I believe some stuff does sound better after a break in period, but
I also believe there is an emotional element to all of this as well
as Maslow's hierarchy of needs. The need to belong can be intense, buyer's remorse is very real, the feeling that you were
duped into buying epensive gear can grab you like a pitbull once
you bring it home and listen with your stress altered auditory nerves.
Does it keep on breaking-in until it breaks down or does it stop exactly at the zenith of this process? Do you hold to the theory that the component unlearns this molecular path of least resistance trick if not used and has to go back to "conductivity class". Does a component reach a point where it should be tossed out because this prime molecular path is too worn to be of any use? As the other fellow on the other site puts it "inquiring minds want to know". Thanks.
Resistors shift value, diodes will alter their point of conduction, transistors will alter their point of conduction and their gain curves, the dielectric in capacitors are forming, etc... All of these things do this on an individual basis on their own schedule and the differences between new and "broken in" might seem quite small on their own. When all of these "shifts" are added up and combined though, both the measured and sonic results can be quite different for the entire circuit.

Just bare in mind that stressing any given component, whether it be due to amplitude of signal, thermal changes, etc.. will cause further shifting of value on some components. This can have a domino effect as the newer shifts in value can cause other circuitry to respond differently. As such, it is possible for a device to change even further ( measurably and sonically ) after you think that it is "fully broken in". This is especially true if you start running it harder or in a very different manner than what you used to.

In extreme cases, these "value shifts" for individual parts can be significant enough to cause the unit to operate erratically or not at all. The fact that components do shift in value is what causes them to "wear out" and need repair. I have even seen where a 6" piece of wire inside of a unit developed a resistance of appr 50 ohms. While i could not explain how this happened, it did. To be quite honest, this threw me for a loop for quite a bit of time too. The last thing that one would ever expect would be resistive wire in a low voltage / low current circuit, yet stuff like this happens.

Other than that, anybody that tells you that components don't break in or "settle" is either uneducated about the subject at hand and throwing out a guess at your expense ( IF you believe them ) or knows better and is blatantly lying to you. When it comes to subjects like this, you either know what you are talking about based on book smarts and education and / or first hand experience or you are talking out of the top of your hat. Given the fact that i've been making money by troubleshooting / repairing / modifying / designing electronic circuitry for 25 years now should give you some idea of where i'm coming from in terms of experience. Sean

PS... I'm sorry if this comes across as "confrontational" to some, but when you try to pass off bullshit or a personal opinion that can't be verified in any way, shape or form as fact, i have little room for compassion.
Pbb: you bring up valid questions that i addressed above. We were probably typing at the same time and our posts "crossed in the mail". Sean
Thanks Sean. Indeed, first time I see so professional and practical *positive* opinion on that matter. I would highly appreciate your opinion about cables break-in: cables are generally simpler 'devices', which offers less room for 'combining'...

I think both emotional and psycho-acoustical components take their part here as well, but as I mentioned in the original post, there are some aspects that cannot be explained just by "delusive perception".
It takes a little while for the electrons that have been randomly thrown into the amp to get together and sing Kumbaya.

It also takes them a bit to see the arrows on the shielding of the cables. A confused electron is a terrible thing.
Sean - Excellent response! From those of us who are ee and still use our test equipment, brains, and ears, thank you. Keep preach'n, even if only to the choir.
As always, just one man's opinion.
Dmitrydr: I know nothing of metalurgy. I can't explain what happens to cables scientifically using test bench equipment taking measurements either or tell you how / why cables "settle" in terms of theory. I do know that i can hear a difference before and after "burning" cables on the various "cooking" devices that i have though. I will not try to pass this off as fact as it is strictly my opinion that i've stated here a dozen times before. Evidently, some people share this point of view while others don't.

Some folks have sent me cables to burn for them and then done A/B comparisons between identical cables ( burned vs un-burned ) once they returned. The differences before and after burning were always quite audible. Some of the identical cables being compared were fresh out of the box whereas other cables had hundreds / thousands of hours of actual use on them. In each comparison, the cables that were cooked were deemed to sound more natural with improved harmonic structure. I've never had anybody tell me that the results of "burning" the cables were anything less than beneficial.

Having said that, those that have an opposing point of view never seem to want to put their money where there mouth is or learn from experience. That is, i've offered to burn cables for them free of charge several times and not one of the "nay-sayers" has ever contacted me once. As such, my guess is that they prefer to spout off rhetoric without doing any form of research on the subject or seeing for themselves what others are talking about. Instead, they chatter away with no personal experience to support their point of view rather than experiment / find out for themselves what the "real deal" is. Kind of hard to argue / debate with someone that refuses to view evidence contrary to their point of view. Actually, it's more than hard to argue or debate with someone like that, it's more like talking to a brick wall. Sean

PS... My offer still stands to those that are interested. If you really want to see / hear the differences for yourself though, just be prepared to go without the interconnects for several weeks. I can "burn" them for however long you want, but my experience with most cables is that the longer that they are on the burner, the bigger the differences are.
there is no break in...its you getting used to the sound
Sean is right, as a piece ages, the components inside it change value. Resitors changes value, electrolytic caps start to dry out and ALL of them will eventually fail if used long enough, substances such as plastics used as dielectrics change especially when they get hot, and it is indisputable that tubes change as they are used.

I have rebuilt numerous tube guitar amps over the years and the change in sound is quite amazing when the carbon resistors that have risen in value and the old, dried out electrolytics are replaced.

Electronic components have a rated lifetime but they don't have an instantaneous change in value at the end of their life. They change gradually over a period time until finally they are stressed past the point they can withstand or the circuit they are in no longer functions properly.

Solder joints are a very good example. There have been numerous studies about this and volumes of data that support the fact that these joints change over time.

Whether you want to call this "breaking in" or not is up to you. Whatever you call it it is very real.
"Recently purchased Moon i-5, manual mention 6-week break in period, when bass will first get weaker, and after 2-3 weeks start to normalize. Just curious, is there ANY component in the amp's circuitry that known to cause such a behaviour?"

None of the effects Sean noted are known to cause the behavior Dmitrydr asked about. Hence my original answer.
Sean is absolutely correct--all of the phenomena he mentioned do in fact occur. While electronics changes are perhaps more subtle and gradual than changes in speakers, they happen and are audible for one who has the ears to hear it. His reference to changes in use patterns was particularly interesting. I used a pair of $300 bookshelf speakers for 2 years while looking for new ones. I began pushing them harder and harder as I got closer to replacing them, and listening one day, I had to admit that even after 2 years, they had undergone a major change in sound, and up till then were not truly broken in. I've had my Magnepans for well over a year now, and even with extensive hard use, I have no trouble believing that they are still undergoing changes. In short, believe it!
A few points that were mentioned in the above post and responses:

- manual mention 6-week break in period for the unit (SimAudio)
- component values shift over time (known fact,though this aging process is much longer than six weeks)
- break in or "settle" (Sean) VS breaking-in until it breaks down (Pbb).

The last one is definitely worth my 2 cents. Personally, being an EE, I prefer the term "settling time". And our ears settle to the unit's sonic signature long before any radical change in any passive component value (active components, being bias dependent, are excluded). Of course, no break-down is ever desirable.
Sean...I doubt that the normal changes over time/use of resistor and capacitor values can explain what you claim to hear. These changes are trivial compared with the value tolerances of the components (2% is typical for resistors and 20% is common for capacitors). Circuits are designed with such tolerances in mind. Also, if values change, why should they preferentially change in such a direction as to improve audio performance?

Now, about that 6" wire that went to 50 know that this wasn't normal It had broken strands or the like.
If it was solid wire, and it wasn't the terminations that were bad, I hope you sent the wire to some research agency for analysis. You discovered the "Sean effect"!

There are obvious reasons for speakers and phono pickups to change with age/use, so those items ought not to be a part of this great ongoing breakin debate.
Eldartford, your logic is flawed. Even though it is true that components are rated at some value plus/minus some percentage, it does not follow that a different value will sound the same even though it is within the rated specification. For example, if you built a crossover with all caps that are + 20% and another with all caps that are minus 20%, they would have decidely different cutoff frequencies and they would sound different.

As to the original weaker bass, stronger bass question, this could have something to do with the capacitors in the amp. The dielectric does change over time as voltage is applied to it. This affects the capacitance as well as the effective series resistance. I have no idea what the topology of this amp is or what type of caps are used, but I would not rule this out. Sean has given sound scientific explanations for his response, Bomarc, I would be curious to hear the reasoning behind your "nope."
Herman....Capacitors that are in frequency-sensitive circuits like a crossover, are selected to tighter tolerances, like 1%. In the usual power amplifier interstage coupling application, capacitors are specd to a much higher value than necessary so as to pass the lowest frequency of interest, so that even a 20% low item will be perfectly acceptable.

If you believe that the circuit is sensitive to exact values of components (that would not be a good design) the difference from unit to unit would be much greater than any variation of a particular unit over time and use.

And how about my question: How do the electronic components know which way to change so as to improve, rather than degrade, performance.
Herman, can initial change of new components be predictable? Meaning, for example, that for a specific type of capacitor, it's value goes down 0.2-0.4% on first X hours of use?
Eldartford, you are correct. Components are ignorant, but designers are not. They listen to their creations after everything has settled in, if it sounds worse than when they began they attempt to find out why. This is the same reason amps, etc. sound better when they are warmed up, that is how the designers listened to it when they finalized the design.

And yes, the circuits are sensitive to the value of componenets. Maybe not "exact" values, but there has to be some point at which the change is audible. Otherwise there would only be one value of resistor, capacitor, etc. Why does Levinson use laser trimmed resistors in some of their circuits? Because they believe that the exact value at that point in the circuit is critical.

Dmitrydr, I am not a capacitor engineer so I don't speak with great authority on how capacitors change over time, but I don't find it unreasonable to assume that if one was to apply a certain signal to a certain material that it's reaction would be predictable. So I would say yes to your question.
Part of the problem with measuring or "charting" component settling is that audio is a very dynamic signal. As such, there is little consistency in amplitude, frequency or duration of the signal being passed through these devices. On top of this, one might listen for a few hours on Monday and then not have the chance to put the system to use until the week-end. Once the week-end comes around, the system gets a good work-out. As such, the duty cycle and consistency of use also come into play.

The reason that i bring this up is that i've had people come in with units that were 10 years old but were never used much at all. When i put them on the bench, they operate like brand new units. Within a matter of minutes or multiple hours ( depending on the specific unit ), i can sometimes see HUGE differences in how the circuits perform. In effect, those 10 year old but barely used units are going through break-in just like a brand new unit would.

Along those same lines, i work on many units right out of the box. After a reasonable warm-up period, i calibrate and align the circuitry and send them out the door. It is VERY common for a customer to come back in with a unit a month or two later with that same unit and it measures and performs very differently. Since i told them that this would happen and i cover this under warranty, i re-align the unit again from top to bottom. Once i do this, it will typically hold these settings much better / more consistently than if it were brand new. It may require further adjustments later on down the road, but not with the drastic shifting that it underwent during initial use. That is because most of the parts had fully "settled in" but a few others were still shifting at a reduced rate.

For the record, i get to watch digital "phase locked loop" and "quartz locked" circuitry drift all over the place every day of the week on multiple units a day. While these types of circuits are supposed to be "rock solid", and that's why they use them for generating reference frequencies and speed control stability, some designs are MUCH better than others. Some circuits are right on the money in a matter of minutes whereas some take several hours of actual use to stabilize. The funny thing is, some of those that are the least stable can be found in some of the more expensive gear. Like anything else, you don't always get what you pay for. Unfortunately, not every audiophile or consumer electronics enthusiast know and realize this.

The only thing that you can be assured of when you buy electronic componentry is that it WILL "settle" at least a small amount. That is why each individual component that went into making the assembled component and the assembled component itself is alloted a specific "tolerance" for normal operation. If the unit does not meet spec and is out of tolerance, that is because parts have "settled" or "shifted" further out of tolerance than they should have. As mentioned above, this typically happens due to thermal or amplitude stress in most cases. Sean

PS... I'm done on this subject pretty much forever. If someone can't follow along with the information presented in this thread or in the archives, so be it. They are either too dumb to comprehend the subject at hand or are too stubborn to admit the truth. I don't think that you'll find ANY Electrical Engineer or service technician with any amount of experience that will argue with any of the points that i've brought up. That should tell those that challenge the "theories" that were presented here where they really stand.
Thanks a lot, Sean!
Sean has pointed out that the change which occurs with initial use is a DETERIORATION, and he needs to readjust circuitry to make it work right. Tuned, adjustable circuits (which appear to be what he refers to) can be shifted away from optimum adjustment by the small changes of component electrical characteristics. This is not the same thing as saying that a power amplifier circuit improves with use.

The original posted question sought to find a scientific explanation for "breakin" improvement, but somehow the thread has degenerated into a debate as to whether such a thing happens. Frankly, I remain to be convinced, but my comments have been directed to pointing out that some of the theories put forward are, from an engineering perspective, obviously wrong, and detract, rather than add, to the pro-breakin point of view.
Sheesh... As the components shift to their natural point of settling, the sound or performance of a circuit typically improves as the circuit itself reaches its' natural "plateau" of operation. In other words, the circuitry finds its' own "groove" and settles there. Since the device is now running at a point that it has reached via normal use and is no longer changing values during normal operation, the presentation tends to sound more natural and relaxed due to increased circuit stability. Everything is done shifting and is now working together. This is kind of like "neighbors" that have had time to become fully familiar with one another and know what to expect out of each other. If the relationship between any given components are pushed beyond the point of initial settling, deterioration and / or "re-settling" takes place but this is usually not without good reason. If pushed to an extreme, damage occurs and the circuit is no longer usable as is. Sean

By the way, the brand new units that come back in for "re-alignment" after a few months typically work better than they did when i took them out of the box and aligned them the first time. I am not talking about small incremental improvements in selected areas of performance, but "better" in most every aspect once they've been "dialed in" after "breaking in". Sean
Eldartford, It is really very simple.

1. a prototype is built
2. it is allowed to burn in for an extended period of time
3. the sound is evaluated
4. adjustments are made
5. it is burned in, evaluated, adjusted
6. it is burned in, evaluated, adjusted
7. etc. until the design is finalized

The final design is based on components that are burned in.

A new unit has not been burned in for this extended period. It does not sound like the one that was the final design until it has been.
Once again, I believe there *is* such a thing as "break in." I believe I have heard amplifiers change over the first few weeks
and they also sound better if you leave them on, never turning them off. But, I also believe manufacturers have become hip to the fact that buyers are often stressed by a new purchase and that, not only does the component "break in" but the buyer's ears return to
normal after a period of acceptance. And, this is just another good
reason to tell buyers to give the unit 300 hours to "break in."
Whatever...In the missile guidance system business we have learned over several decades that circuits ought to be configured so that they are not sensitive to exact values of their electronic components. It can be done. The necessity for items like lazer-trimmed resistors, except in particular applications like an A/D or D/A, indicates (in our experience) sloppy circuit design. Maybe that's what we have in the audio business.

So, in summary, the best explanation offered above was that of Danvetc, who suggests that the newly awakened electrons are disorganized and take a while to get together and sing "Kumbaya".

Over and out..:) Ed
In a missile guidance system, are the components simply responding and looking for a signal that acts as a command / response arrangement or is the quality of the signal being quantified and judged along with the basic data being provided ? This is where the difference lies between data devices and how our brain interprets sound impulses.

I'm assuming that the guidance system has some type of system that checks in and verifies data and responds accordingly, doing this on a phenomenally frequent basis. As such, this would be akin to high quantities of negative feedback in an amplifier circuit. While the system measures phenomenally well and does everything it is supposed to in terms of measured data and responds promptly to changes in detected signal, it just so happens to sound like hell. All of the bench tests in the world can't tell us why ( at this point in time ), but the computer aided test equipment connected between our ears that deciphers such input makes this all too clear.

I hope that at least some of you get the point. That is, we don't know everything there is to know about everything : ) Sean

Missile guidance systems ???????????? Are you seriously comparing the performance of missile guidance systems to that of audio circuits? If you insist on taking your experience in controlling the flight of giant bullets and using it to explain the function of audio circuits, then I fully understand your inability to grasp these concepts.

If I had known we were discussing two entirely different worlds, I would never have refuted your original position.

I too am "over and out" on this one :>)
Herman, et al....My experience with audio circuitry goes back to about 1953, when we built our own equipment, often from raw electronic parts, sometimes from kits, and also did a bit of circuit design on the side. My bread and butter job, as opposed to hobby, was in the missile guidance business. (Retired now but consulting part time). Because we may disagree, don't characterize my position as inability to grasp concepts. I am familiar with all the arguments put forth above. Although some facts cited are true (eg: component values settle with use) the conclusions drawn (eg:the amp sound better) just doesn't follow. Note that I did not say that the amp didn't sound better...just that you have not correctly identified the reason. I encourage you to think up some new explanations for review.

My comments on circuit design relate to philosophy and are general in nature and applicable to most if not all types of circuitry. You might consider study of the work of Genichi Taguchi, a Japanese disciple of W Edwards Deming (the "Father of Modern Quality Control") who was very influential in the development of superior products by Japanese industry following WW2.
Holy crap! this sounds like a threat i would be involved in.

anyways, Hey Sean, Thanks for the great info, its completly one of those "Gee Duh" type things, simple to understand and why diddnt i think of that?

hell, i wish i thought of the pet rock. i would have one hell of a stereo from that cash cow.

ANyways, Sean, i hate to get in this heated post with a seperate question, but you made several references that you would burn in the non-believers cables? (sounds almost like a biblical smite in a way huh?) Well, how do you do it, besides letting slow roast for months on end in my rig?

better yet, "Ahem, Sean, You sir, do not know jack from shit"

Now, when i get new cables, can ya burn em in for me? :)
Bottom line:

If you buy a new amplifier, give it some time before drawing a conclusion as to its sound. If you hear
improvement, it may be because it "broke in," it might
be because your ears returned to normal after a period
of stress related to buying new equipment, it might be
some combination of both, or it may be that there really was no change at all -- you just imagined it, were
influenced by the power of suggestion, peer group
pressure, or by the need to feel you made a good purchase. On the other hand, if you hear no difference,
it may be because you have tin ears or it might be
that you are the type of individual who isn't swayed by
emotions, stress, peer group, or any other kind of pressure.

Have I left anybody out?
Good points Ed (Eldartford), Bomarc and Charlie.

Sean, I have a couple of questions. You claim or at least imply that you know what you are talking about. I don't see any evidence for that in the words you throw together. If I may ask, what is your educational background? Do you have an EE degree? Advanced degree? What professional experience do you have in designing audio equipment? Really, it isn't the same thing as repairing TV's.

Everyone I know who has an EE and has designed components that have actually been marketed by big well known companies agrees with Bomarc and Eldartford.

I claim to know nothing, but based on my own experience listening to a variety of hi-fi components over the last 35 years, I think that, except for phono cartridges and loudspeakers, components do not burn in. And I wouldn't want them to. They should perform as designed, period.

Best regards,

Paulwp: I have posted a small portion of my background in an Agon thread entitled "Who R U". For further info, you can also read this thread over at AA's "General Asylum". I only mention this as it gives further information as to my background in the field of electronics that i didn't mention in the Agon thread.

While you're over at AA, you can search for a post that i made within the last few months that publicly challenged any EE / designer / product manufacturer to post commentary pertaining to the effects of "break in" / measurable parts value shift NOT taking place in new components. I have done a search for it but can't find it, otherwise i would have provided a link.

Either way, there was not ONE response posted to that "challenge" because everyone that works on / uses gear for a living knows that it is the truth. Most of the engineers / designers / manufacturers that read and post on AA are "hands on" kind of folks and know what is really going on. Since they know the truth, they didn't bother to respond. It is only the "desk jockeys" that design gear and never use it that think that things always work as they should in theory.

As far as the EE's that you talked to and bought their schpiel, i make my living working on the products that they design. By "working on", i mean repairing the failures in under-designed circuitry that wasn't well thought out to begin with and / or modifying that same circuitry so that it performs in a more optimized manner.

Other than that, you can believe / trust whom you want to. Whether you want believe or disregard my opinions, that is up to you. Having said that, the wide bandwidth scopes, $15,000 signal generators, $35,000 spectrum analyzer, etc... that i have and use on a daily basis are basically impartial witnesses to my testimony. The results that i've obtained using this test equipment and past experiences with hands-on use are what i've based many of my opinions on.

Other than the opinions of others that you've repeated here, do you have any first hand experience or technical references that explain what YOU base YOUR thoughts about the subject on ? I think that i've more than explained how parts shift / circuits change over time and use and done so in an easy to understand manner. Sean
I guess you answered my questions about your educational background. You aren't an EE. You've said you know what you are talking about because you repair things. I told you my firsthand experience is I have listened to an abundance of amps and have never heard one change from day one. That's all I claim.

A pretty silly grade school rhetorical device to ask someone for a technical explanation of why an imaginary event doesn't occur. As far as I know, the only thing that can happen is degradation, and that should be measurable.

Btw, I think I saw a reference to Carver amps in the AA thread. Do/did you like the Lightstar II?
Paulwp...Don't give sean a hard time! Although I don't always agree with him, I find his comments interesting/informative. Although I am primarily an academic-type engineer, I have always been known as one who likes to get his hands dirty, and I must say that some of my best theoretical insights (over a 40-plus year career) have come about as a result of screwing around in the lab.

My view in a nutshell is that things you see (or hear) in the lab ought to be confirmed by scientific expanation. Until that is accomplished, you can't be sure that you weren't fooled in some way.
pheeew...i thought i was the only one that didn't believe in break-in of amps, cables, and CD players...well, i guess i'm not alone anymore...thank you guys!
What's funny here, people tend to consider this as something to "believe in", instead of "know". To believe because "somebody told me", or "he must have MSc in EE to know"... LOL! Here you've got an opinion based on a practical experience and professionally measured data, not just a simplified theory. Instead of asking "educational background" :) , it would be more appropriate to provide a data, acquired on a similarly professional level (not "personal thoughts"), that would just prove the opposite... Should be easy, right?
The problem, Dmitry, is there are no profesionally measured data evidencing burn-in. It is a belief based on what people think they hear, based on what people expect to hear. I didn't ask about educational background to support the position taken on the issue of burn-in, but to support the assertion above that he knew what he was talking about.
Here's my last post to this thread.

I am not an EE, nor have i ever claimed to be. I will only add that i have almost 2500 posts on this forum and who knows how many at AA. Having said that, there have been less than a handful of those posts that an EE posted something contrary to what i had referenced when talking on strictly technical terms. To take that a step further, some of these disagreements have been due to poor wording on either my part or theirs and we really were in agreement when all was said and done.

As such, one does not have to have a piece of paper to tell you what they know or don't know. On the other hand, having that piece of paper simply means that someone knew enough to respond correctly to specific questions on tests. This does not give them practical experience when trying to design electronic circuitry or deal with real world problems and situations that arise in such circuitry.

My business partner, who does have his degree, has stated many times over that school taught him the basic fundamentals of theory but most of his knowledge of how things operate has come from hands on experience. My personal opinion is that many EE's will share that opinion as they are smart enough to realize that wisdom and knowledge come with experience. Anybody can read books ( as i did ) but applying that knowledge in a real world scenario is what seperates those that have "book knowledge" and those that can solve real world problems. Having said that, I don't know of any College that issues degrees in "common sense", "problem solving" and "application of knowledge". What College degrees do verify is that someone understands the basics of the subject at hand and that the College that issued the degree is willing to put their name behind that fact. What someone does with that basic level of understanding is up to them. Having that piece of paper does not necessarily mean that they know everything that there is to know about the subject at hand. It simply means that they knew enough to graduate. Mind you, one can graduate with an "A" or a "D-" average also.

Other than that, here's a thread on AA that discusses this very subject. An EE and i both come to the same conclusions there, much as what we have done on many, many hundreds and even thousands of threads.

Hasta la vista, baby.... Sean
After reading a statement like this, "anybody that tells you that components don't break in or 'settle' is either UNEDUCATED [emphasis added] about the subject at hand and throwing out a guess at your expense (IF you believe them ) or knows better and is blatantly lying to you," is it unreasonable to ask the author about his education?

Personally, I wouldn't care if someone never got past grade school if he could reference test measurements or a controlled study to support his argument.
Paulwp, I hope you accept the fact that components do initially shift their values, in predefined tolerance range? You don't have to call it break-in and it doesn't automatically assume any sound improvement. But if the same kind of components will tend to settle in the same direction, and to achieve their natural point of settling after about the same hours of use, where do you see a contradiction that during design period an "already settled" prototype is evaluated and being worked on, so the aim of the designers is not how it sounds just assembled, but after known and measured period, specifically for the parts used?
Sim Audio amps all have a notoriously long break-in period, 600 hrs minimum. Also after you power them on from a cold state they take a couple of days to settle in. Look at it from the manufacturer's perspective. If it wasn't true and borne out by experience then why would they state it in their documentation again and again. There is no upside to fabricating something like this.
SimAudio's components seem to take a long time to burn in. This was detailed in a review of the Magnum Dynalab 208 Receiver in Stereophile (Jan. 2001). SimAudio designed both the pre and power amp section for the MD208. The reviewer felt the sound was changing and not that great. Here's a snippet of the review. SimAudio's designer himself, Vince Stables, speaks to it himself. If you are going to believe someone, believe the guy who designed it and is most familiar with it.

from Stereophile's Review.....
"I'm glad I didn't, but for a while I experienced the symptoms of aural indigestion: amorphous bass focus, limited bass extension, incoherent soundstaging, a lack of high-end extension, poor low-level resolution, and, most notably, a limited volume range. There seemed to be an optimal volume setting at which the MD 208 evinced a realistic, coherent tonal balance and dynamic range; below that, the presentation lacked presence, body, and tonal coherence; above it, the tonal balance seemed to go out of kilter, as everything seemed a touch too loud and glary.

Vince Stables of Simaudio concurred, and seemed to be making a mental check mark next to each symptom as I detailed them over the phone. "Yeah, it takes a long time because there's a lot of Teflon used on the internal wiring in the preamp stage, those 4oz copper tracings on the PC board take forever to burn in, and you hear it all because there's no filter caps acting as sonic Band-Aids, and no corrective feedback save at the output stage. So it's much more revealing of nuances in the burn-in process as things charge up; eg, transformers, the power-supply section. And it doesn't harmonically sound right—it sounds sort of outside the music. The soundstage starts off very small and it doesn't permit a lot of microdynamic detail. It's almost like it's one step behind the speaker. If you turn the volume up, you won't be able to play as loud because it sounds out of sync from the music. And then, after about a month or a month and a half, as it warms up, it starts to jive and everything becomes more cohesive."

For those users who have never heard an amp change sound over time from new to burned in......some can hear it and some don't. But please don't tell us who have heard it though, that it doesn't happen.
No, I don't accept it as a fact, not do I deny it. Theories to justify the belief in burn-in are of no interest to me. I can't think of a less interesting subject actually, but I suppose I would pay attention to some test measurements. An amp had better perform to specs when first plugged in by the buyer. Then, so long as it continues to do so, it shouldn't sound different from day one. That's been my personal experience of using amps, though of course, I havent done a controlled analysis.

Take two identical amps. Do a DBT to verify that you can't tell them apart. Break one of them in. Then do a DBT to see if you can tell them apart. Do this with a significant number of listeners or a significant number of times. Come back and tell me the results.

Or, show me some bench test measurements in the range of audibility.

Oh, tube amps may change. I guess it takes tubes a few hours to settle in, and then they start downhill.

But, again, who cares? For me, it's like shoes. Do shoes break in? Of course. Should you go ahead and buy a pair that hurts hoping they will break in the right way? I never do. And I never keep a component that sounds wrong hoping it will break in.
Well, I guess sean has checked out, but just as I do not discount knowledge derived from practical experience, he should not discount what's learned in college. As he says,there are no degrees granted in "common sense, problem solving, application of knowledge" but there are most certainly courses in such subjects. Indeed, many specific facts learned in school become obsolete by the time one gets a job, and the real benefit of school is that it teaches you how to learn, which you should continue to do all your life. Also, having a degree does not prevent you from doing all the things that sean does to gain knowledge.

I mentioned Taguchi design philosophy previously: very quickly here is the jist of it.

You build a circuit (or anything else, like a camera lens system) and test it.
You find that some component, say R235, critically affects performance.
It's been suggested that the circuit designer should now begin to tweek R235, and other parts of the circuit to optimize performance.
WRONG! says Taguchi. Send the circuit designer back to the drawing board to modify the design so that R235 does not need to be tweeked.

The purpose of inspection and test of samples of a product as it comes off the production line is it make sure that the design and the production process are producing satisfactory results. If a problem is found, you don't fix the unit before shipping. (That was the old idea of quality control). You junk it, and fix the design or production process.
Until i can get people to stop putting words in my mouth, I'll never be able to get out of this thread : )

Let's clear things up here. I never said that i discounted a College ( or any other type of formal ) education. I have a great amount of respect for the majority of "educated professionals". Anybody that thinks differently has never read any of my posts where i've lauded praise on various designers / engineers / manufacturers or commented on specific products in a positive manner. It was Paulwp that ( effectively ) said that he discounted any form of knowledge outside of College that one doesn't obtain a degree for. His words were that if one doesn't have a degree, one doesn't know what they are talking about. I can't think of a more pompous comment ever being made here on these or any other audio / electronic based forum.

I also never stated that units that have "shifted value" or "broken in" would not meet spec before or after "shifting" or "settling in". Most specs are written in a manner that makes the unit look good on paper yet allows enough variance in production to let "less than optimum" performing units still get by quality control. Those companies that set tolerances phenomenally tight undoubtedly have a far higher amount of unacceptably products. Since the rejection rate goes up, the profit margin goes down.

Since most companies are more worried about the bottom line ( profitability ) rather than the ultimate quality of their products, specs and production techniques become a juggling act in terms of what can be made to pass without having a high quantity of rejects and monetary losses. The end result is that specs are typically "slightly loose" so as to let the majority of products manufactured fly out the door yet "tight enough" to maintain respectability by professionals in that specific field by weeding out the "lemons". As a side note, most of those "lemons" end up getting sold as "factory refurbished" units because most manufacturers don't want ANY loss in profitability. That is, if they can help it.

By the way, anybody that thinks that only tubes begin to deteriorate once they are fired up has very limited understanding of electronics and how / why parts and circuitry fail.

As to El's comments, how many manufacturers follow "Taguchi's rule of mass production and quality control" ? Just because he is aware of these guidelines does not mean that every manufacturer follows them or is even aware of them. Should anyone doubt this, please see the example sited above regarding specifications and factory refurbs. Sean
LOL. I said? My words? Hardly. You said in your first post above, Sean, that "anybody that tells you that components don't break in or 'settle' is either UNEDUCATED [emphasis added] about the subject at hand and throwing out a guess at your expense (IF you believe them ) or knows better and is blatantly lying to you." I ask again, was it unreasonable to ask you about your education with reference to your claiming to know what you're talking about? Not the question of burn-in, but of your claiming to know what you're talking about.

On the subject of burn in, I later said: "Personally, I wouldn't care if someone never got past grade school if he could reference test measurements or a controlled study to support his argument."

Now, absent any measurments or studies, I'll trust my own experience, my own ears. It does happen that I know an ee or two with experience designing and marketing amplifiers who tell me that I don't hear a burn-in effect because there isn't one, but in the end, it's my ears that count. Yours too.

What I take exception to is your statement quoted above. You are saying that, for one example, the designer of some pretty nice equipment is either "uneducated" (that isn't true, he has an ee degree), "throwing out a guess," (nope, wrong there, he has done controlled studies) or "is blatantly lying" (shame on you for saying something like that).

You never said if you were familiar with the Lightstar II.