Burn in. What does it actually do? And other various questions. - Page 2

Hirsch,

in the audio circles i spend time in (pretty much other reviewers), burn-in is accepted as fact. to some extent this is true for the only other audio board i frequent (audioasylum) as well.

in this example, psychoacoustics isn't a variable... but you do raise an obvious next question: how do you know the component has broken in? following your logic you haven't gotten used to how the component sounds in your system before break-in, so can you compare sound after the process?

after break-in i assume? then psychoacoustics has now become a variable.

once again, i do and have experienced burn/break-in with many, many, many components. however, just as i accept that there isn't any conclusive scientific explanation for it (what've we got, dielectric theories? sketchy electromagnetic theory?) i also accept that it's possible (note the word possible) that it's all in my head.

i think we'd both agree that it's what a person hears that's important, it's the most sensitive measuring tool we have. Wes hears differently than anyone else. same for everyone on this board (hobby, planet, whatever). i hear break in, so do you, so do a lot of people... but a hell of a lot of people believe a lot of things. it's still subjective, not absolute truth.

best,
carlo

carlo,

I don't really mean to say that burn in effects are imaginary in any sense that implies they do not exist. We are talking about perceptions, and what one perceives, one perceives. There is no higher authority on what a person perceives than that very person. He may perceive differently on another occasion and may interpret the causes of the original perception differently, but none of that negates anyone's experiences.

What I do mean to suggest is that there is something maybe more fairly described as a learning curve, an adaptive process, as one uses an new piece of audio gear. That we learn to hear and interpret the sound of a particular piece just as we get used to seeing through our eyeglasses.

With one's first bifocals, it's a little messy and distracting to see some fuzzy patches where there used to be more clarity. After a bit, one no longer notices, and its as if your continuous visual field were still there. If you attend again to what you are "really" seeing, you can restore the sensation of the fracture in your visual field, but the natural state when you are not concentrating on your glasses is a lot like it seemed before you wore any at all. (Hirsch, was that the explanation you were looking for?)

So that's my analogy for what is reported--absolutely reliably--by all believers in burn in. Because of their (seemingly) simpler structure, no one (so far) has been tempted to think that their eyeglasses are changing with use. But it is just marginally possible that there are some such effects not yet noticed, isn't it? (I've gotta start marketing those premium eyeglasses soon, you know, the Personal Light Paths with the falcon-leather nose pads.)

I am not sure that I hear anything so differently from the rest of you (although I may). Rather I would say that I interpret it, especially its causes, differently. I readily agree that every new piece of audio equipment that I listen sounds different on first encounter than it does later, but I attribute that to a redistribution of my attention to the artifacts of the equipment (and away from the music) and to the freshness to me of whatever differences there are compared to the previous experience.

It is good to know that at least one headphone manufacturer confirms that his product changes over time. Maybe it's a marketing problem for headphone producers to get into that concept for what tends to be a mass market product. The non-audiophiles might get upset if they read that their new purchase is going to be doing something they did not expect.

Tomcat,

The AT burn in enthusiasm is a special case indeed. Could it be the wood? Possibly, but then the expectation of seasonal variations would be warranted as puck suggests.

In fact, if I had a new product that burned in so much and so persistently, I would begin to worry that it was inherently unstable and might keep on burning in right past its prime. But the Team AT seems not to worry that their phones are like other organic things, like a flower, for instance, that they purchased as a bud, that now is blooming beautifully but soon will wither.

Doesn't anyone think that burn in can go too far and become deterioration? If that is not entertained even as a possibility, then it looks like once again as if the effects are likely to be subjective. (Which is not to say that they do not exist.)

*jumps anxiously as he hears the ghostly galloping sounds of wooden headphone enclosures in pursuit*

Yes break-in is real, it's natural process of USING it!

I'm not a materials engineer, but the properties of elastomers do change over time, and the curve of change is probably not a straight line -- I bet there are usually two sharp changes in slope -- one shortly after the item is brand-new, and the other when it's near or at the end of the useful lifespan. Think of the springs and rubber used in a car suspension or a mountain bike fork, or the leather and foam padding used in your shoes. Rubber and metal change as they're stressed. The surround and diaphragm in speaker drivers are made of elastomers and composites of different materials, so they can be flexible in some ways and inflexible in others.

The properties of wood change as the wood ages, too. While the cherry used in the AT cans is supposedly preaged and stable, it is being subjected to vibration across a wide spectrum, and as the musical instruments referred to above, that has an effect apart from age alone. Wood is a natural composite -- and the modern version, carbon fiber, is used by Senn for the HD-600.

Audio Technica pointedly notes the break-in phenomenon in their website literature about the wooden phones. Sennheiser talks about this, too, when they laud the virtues of their new diaphragm material.

For electronics, the break-in phenomenon is probably related to chemical and electrical changes occurring in componentry as they age in the presence of heat generated by use. For the mechanical components used in things like CD players and turntables, there has to be wear involved as well, and that wear also involves heat. Metal-to-metal contact, or any physical contact, causes frictional wear on both surfaces -- microscopic polishing.

The best example of break-in is something old in audio and not used by too many people here -- cartridges for vinyl playback. They're very tiny motors, electrical generators, using frictional forces via diamond contacts and elastomers and coils to create electrical energy; and many have wood bodies! They too can change dramatically as they age.

Wes,

I was going to quote your first two paragraphs but i figure that'd be a waste of space... that's a nice post. i think in essence we're agreeing to disagree, yet it's great to do so with someone who raises very legitmate and thought out arguments. i'm sorry if my choice of words (ie: "imaginary", "in my head") weren't the best - i meant it in the interpretive sense. i think your points on perception pretty much sums up everything about the hobby, life, etc. i've enjoyed this exhange quite a bit.

*wondering if Wes is only perceiving that people are out to get him*


audio&me,

expand your mind, man. if the musical/electrical signal is breaking in your stuff, how would different music affect it? how about white noise, or xlo's burn in track? does the signal need to reach different frequencies or is any signal fine? if it is due to dielectric behavior will it keep those characteristics after, say two weeks of non-use? how about nordost's cable burn in device and bob crump's cable cooker? make a point instead of a statement.

JML,

what makes the cartridge example a little easier to visualize is that it has a mechanical property (stylus riding on the groove). what gets a touch more interesting is if the coil in the cartridge and the cabling used to connect it to the tonearm wire breaks in as well.

the aspect of this that goes past (currently) measurable techniques is why/if specific electrical components (ie: cabling, resistors, etc) break-in. it could be heat, i don't know. i recall one of the first things a professor said in a class on kinetic-molecular theory: "keep in mind we used to all believe in caloric." there's a lot of things we don't know.

regards,
carlo.

I created test tones, white and pink noise, and frequency sweeps. I left it looping for a few days, I did notice a difference, it made it (HD600) sound softer. After a week of back to normal music, the sound tightened up... Weird ****.

My statement was a simple acknowledgement of the reality of burn in.

My, quite a discussion has broken out since I last posted!

Well wes, your initial contention that there is no friction to speak of in the headphone system is patently false. Friction is a fact of the world we live in, thanks to the ever present thermodynamics. There is a stable unit, that has a moving part inside of it. This moving part generates the frequencies we hear. There is going to be friction in this interface. Even if the the parts were being held suspended between other, there is still 'magnetic friction' from the constantly changing fields interfereing and adjusting one another.

The engine is decidedly more crude than the headphone element, and the effect of breakin is more dramatic (you can actually damage the engine if you exceed certain rpms during break-in), but I think the principle is the same. We still have several new parts, that are going to be forced to work in synergy with one another, that will, through thermodynamics, begin to 'homogenate' to work together.

I think such comparisons like going to a hi-fi store, and testing a brand new pair of headphones, against an identical pair of broken in headphones, using a model you've never owned before, show that the breakin has an effect that isn't just your mind getting 'used' to the sound.

Maybe we need to do some double blind tests. Choose a pair of headphones that someone has never listened too before, take an identical pair, and break it in. Then, give them one to listen too, then the other, let them go back and forth a bit, and then have them decide if they sound different, and if so, then have them identify the 'best' and the 'worst' sounding pair, and then have them guess which is the 'broken in' pair and the 'out of the box' pair. We could see what people think. You could even throw in controls like have them evaluate two identical pairs that are both brand new, or try two broken in pairs against each other, etc.

Sounds fun

peace,
phidauex

Kurt,
It might be both. Isn't it even said that a Stradivari violin needs to be played from time to time in order to preserve its tone?

Wes,
That is a possibility, definitely. But I wouldn't hold my breath if I were you.

JML,
That's an interesting point. Incidentally, that's what Audio Technica produced when they started out in the sixties: phono cartridges.

phidauex,
You are right, of course. I'd just like to add that we have to consider the dynamic properties of the entire headphone system. And in the case of the wooden ATs, the enclosures seem to play a bigger role than usual. I presume the sympathetic resonance of the wooden enclosures influences the driver's ability to move its membrane. It's still akin to an acoustic suspension design, but the spring effect of the enclosed air might be a little different.

If you want to learn some fascinating things, just do a Google search on "wood violin instrument age" -- one hit is http://www.smithsonianmag.si.edu/smi...all_aug98.html

From what I'm reading, if burn-in essentially makes materials in a mechanical object more "flexible," then wouldn't the "eternal improvement" of the Audio-Technicas be detrimental in the long-run? I imagine that, since metal will inevitably snap after a good amount of back-and-forth bending, then wood, something even more delicate and brittle, would deteriorate at some point due to this supposed "perpetual burn-in," right? Owners of Audio-Technicas had better hope that their cans have a finite burn-in period!

really interesting reads:

break-in

i'm looking forward to grow my knowledge of headphones on this board

At the risk of being a bore, one more question on this burning, as it were, issue:

Since the exact mechanisms at work in burn in are not especially well understood and since good quality imaging depends on carefully matched drivers, is anyone worried that they will burn their way into an imbalance?

Why do we assume that the burn-in will affect both parts of any stereo set up not only beneficially but also identically? Considering this, I would think one should strongly prefer burning in only with test tones or mono input so that the effects work out as equally as can be. Of course, if burn in is a never concluded process (Team AT, watch out!), then the risk of differential burn in can't be avoided except by listening only to mono.

Has anyone ever reported even a temporary imbalance attributable to differential burning in? Certainly, if two neighbors and co-workers both bought identical cars and made their usual trips to work with the usual variations in driving habits, shopping trips, etc., we would not be surprised to hear that their engines had rather performed differently as they broke in. You would expect, after a few thousand miles, that this divergence would mostly even out, but you would not expect even break in for both vehicles every step of the way. Isn't this analogous to a pair of headphone drivers encountering different signals in stereo burn in?

*peers cautiously out from under desk*

I don't think transducers have a memory effect. As long as they're exposed to relatively the same amounts of noise, it shouldn't matter if the two channels fluctuate, so long as the frequencies are exercised to a reasonably equal amount.

Is a baseball glove going to cry if you beat it in as supposed to gentle break-in through a year or two of wear 'n tear? No, you'll get the same result - smooth firm calloused leather, then eventually soften out.

Some say burn in tightens up the bass and extends the highs! That's not exactly a good thing. Too tight of bass leads to gross molested analytical sound, and that hf extention could lead to distortion and end up sounding forced.

Then again what do I know as I don't care about detail, only smooth warm enjoyment of music. Go team lo-fi!

Another solution might be to listen to everything twice, switching the cables every time. Or maybe we should do it at the original recording -- everyone should burn a copy of every CD they have, with the channels switched digitally.

Seriously. I liken burn-in to firemen in a fire brigade -- you know, the ones that have to pass water to each other in buckets. When they first get started, they don't know each other, and they're sloppy, and slow, and they spill drops. But as they work with each other, they get to know each other, and they adjust their rhythms with each other, maybe speeding up slightly, or slowing down slightly, so that the overall chain is more efficient.

There's also the "cutting a path through the forest" analogy, that I believe is on the Audioquest site somewhere...someone post a link if they find it...

I just thought that I would contribute my 2 cents to this subject...

mechnical effects of "burn-in" is definitely a factor that would contribute to a change in the sound of the headphone over time. This is not to say it will always improve the sound of the headphone, but the original tolerances of the headphone would definitely be changed (things such as range of driver excursion...etc.). From an engineering standpoint and from an empirical standpoint, I have found this to be true.

"Continuous burn-in" may in actuality be possible (in reference to the Audio Technica posts). Although one poster suggested that the components may eventually fatigue over time as the cycles increase, this is only true if the break-in forces take the material beyond its elastic range in to the inelastic. Within the elastic range of a given material, it is theoretically possible to subject it to "infinite" number of cycles without failure. Also, there's always the wood/resin factor mentioned...