Burn-in

[microstrip]

Burn-in. This should must one the most polemic subjects in hifi. But having gone recently through two long phases of burn-in (the Audio Research Anniversary preamplifier and Kimber KS1136 cables) I am clearly in position to say that the sound of these components changed a lot during the first 500 hours. And I am sure it was not me who adapted to a new type of sound – a few friends who listened after and before without exposition to the system meanwhile also noticed it.
I measured some classical technical parameters (noise, frequency response and THD) of the preamplifier before and after burn-in. They did not change within the resolution of my system.

Even Wikipedia recognizes that the effect is not without discussion:
“There is another use of the term by some audiophiles, who leave new audio equipment turned on for multiple days or weeks, to get the components to achieve optimal performance. However, many debates have arisen about the benefits of this practice” End of quote.

But I would never have bought the KS1136 if I had to make my mind from the sound of the virgin cables – they sounded sterile taken from the box. Very defined, great bass and detailed, but uninteresting sound. Only after 300 hours of burn-in they are now sounding great in my system.

The Anniversary preamplifier improved a lot during burn-in, but even taken out of the box with 60 minutes warm-up sounded a lot better than the Ref5.

 

[Steve Williams]

My personal experience with Audio research gear having owned the Ref600 Mk ll, Ref2 Mk ll and Ref 3, is they sound terrific out of the box but then tend to muddy up for the next several 100 hours before they burn in

 

[nsgarch]

burned--out!

My personal experience with Audio research gear having owned the Ref600 Mk ll, Ref2 Mk ll and Ref 3, is they sound terrific out of the box but then tend to muddy up for the next several 100 hours before they burn in

I don't know about the "next several 100 hours" part, but what you're describing is primarily a phenomenon of tube gear, not all gear.

"Burn-in" has become one of those meaningless terms (like "love" or "boredom") in that it really doesn't describe anything specific -- and (hopefully) never involves fire!

A better term would be "steady-state equilibrium". Not sexy, but more descriptive. Except for vacuum tubes, some cable insulation materials (NOT the metal conductors), and large power supply capacitors, other parts of electronic gear do not for the most part change physically due to exposure to heat or electrical current -- they do their jobs the same after an hour as after a year. Almost all solid state devices (IC chips, transistors, rectifiers and diodes) do not exhibit audible performance changes over time. One day, they just die (or self-destruct ;--)

Things that MOVE are another story altogether. Speaker cones/diaphragms, belts, and cartridge suspensions all need some time to "limber up" a bit. While metal bearings and other contacting parts will develop improved tolerances and quieter operation after a short while.

 

[Gregadd]

IME equipment I that have purchased new without exception has sounded horrible out of the box to the point of my thinking I had been ripped-off or received a bad sample. Often driving me into deep short term depression. I have referred to some as listenable right out of the box. Without exception those components improved significantly over time. Some improved so much that I went on to rave about it. As an end user I don't have to explain what happened. If I had convinced myself that there is no break-in as some have tried to do(See http://www.dagogo.com/View-Article.asp?hArticle=748) Audiophile Law#6 and Now my good friend Neil whose opinions I respect greatly, I would have returned those products for cash or store credit. That truly would have deprived me of some very good music. I should also point on many occasions the sound changed but was still awful. They enjoyed a short stay in my system.

I guess I'll let the scientist debate over what happened. I'll just enjoy the music.

 

[Gregadd]

If you doubt me consider my purchase of the Allnic L1500. I purchased it used from Audiogon. It sounded horrible. I thought it needed a reubeN contacted Hammertone Audio about a possible retube. Dave had the local distributor call me. After asking where I had obtained the unit and informing me that a retube might be prohibitively expensive, inquired where I obtained the unit. It turned out the unit was not used but was sold a customer who had traded up and had barely plugged the unit in. Proper break-in yielded a glorious sounding unit. If I did not believe in break-in i would have resold the unit on the Internet.

 

[MylesBAstor]

Burn-in. This should must one the most polemic subjects in hifi. But having gone recently through two long phases of burn-in (the Audio Research Anniversary preamplifier and Kimber KS1136 cables) I am clearly in position to say that the sound of these components changed a lot during the first 500 hours. And I am sure it was not me who adapted to a new type of sound – a few friends who listened after and before without exposition to the system meanwhile also noticed it.
I measured some classical technical parameters (noise, frequency response and THD) of the preamplifier before and after burn-in. They did not change within the resolution of my system.

Even Wikipedia recognizes that the effect is not without discussion:
“There is another use of the term by some audiophiles, who leave new audio equipment turned on for multiple days or weeks, to get the components to achieve optimal performance. However, many debates have arisen about the benefits of this practice” End of quote.

But I would never have bought the KS1136 if I had to make my mind from the sound of the virgin cables – they sounded sterile taken from the box. Very defined, great bass and detailed, but uninteresting sound. Only after 300 hours of burn-in they are now sounding great in my system.

The Anniversary preamplifier improved a lot during burn-in, but even taken out of the box with 60 minutes warm-up sounded a lot better than the Ref5.

I always found this information useful about equipment burn-in when it relates to Teflon caps. This appeared a while back from a poster on AA who actually works for a company that manufactures Teflon caps. Some Teflons such as the V-caps sound dreadful for the first 100 hrs! All the cj gear equipped with Teflon caps takes at least 300 hrs.

Teflon caps have some unique characteristics. Electrically they are about as perfect as can be, but Teflon has the mechanical properties of a liquid and therefore flows slowly when under pressure. In the case of Teflon caps, the actual value and the microphonic properties (probably the biggest drawback of Teflon caps) change over time when a DC voltage is applied. The value goes up and the microphonics go down, because the Teflon settles under the force of the electrostatic field in the cap.

So when a Teflon cap is used in AC only applications such as filters, the break-in effects are very small and can take years. However, if a Teflon cap is used as a coupling cap between the anode of a tube and the output of the amp, for instance, the break-in effects are significantly larger and it also goes a lot faster. (Months or weeks depending on the DC voltage applied.)

For that reason I would recommend if you use Teflon caps to keep the anode voltage of your amplifiers switched on all the time and only switch off your filament voltage to spare your tubes when not in use.

 

[MylesBAstor]

I don't know about the "next several 100 hours" part, but what you're describing is primarily a phenomenon of tube gear, not all gear.

"Burn-in" has become one of those meaningless terms (like "love" or "boredom") in that it really doesn't describe anything specific -- and (hopefully) never involves fire!

A better term would be "steady-state equilibrium". Not sexy, but more descriptive. Except for vacuum tubes, some cable insulation materials (NOT the metal conductors), and large power supply capacitors, other parts of electronic gear do not for the most part change physically due to exposure to heat or electrical current -- they do their jobs the same after an hour as after a year. Almost all solid state devices (IC chips, transistors, rectifiers and diodes) do not exhibit audible performance changes over time. One day, they just die (or self-destruct ;--)

Things that MOVE are another story altogether. Speaker cones/diaphragms, belts, and cartridge suspensions all need some time to "limber up" a bit. While metal bearings and other contacting parts will develop improved tolerances and quieter operation after a short while.

Neil:

I think the burn-in process actually describes two separate phenomena.

1. Equipment burn in
2. Organisms adapatation to the stress/sound.

There is a wealth of information beginning with Canadian endocrinologist Hans Selye on the human bodies response eg the HPA axis (hypothalamus-->pituatary-->adrenal) to different stressors eg. resistance, temperature, etc. For instance, if I dropped you into the Artic, you would shiver for a couple of weeks at which time your body would eventually adapt to the low temps.

Selye broke the process into either eustress (beneficial) or distress (detrimental) and three separate periods of adaptation: alarm, resistance (adaptation) and exhaustion of adaptive reserves (overtraining). Basically, what Selye describes is an initial period where the bodies reacts to the stress and performance decreases followed by a period of the body adapting to the stress and getting stronger in one case. (the same happens for heat with the bodies synthesis of molecular chaperones eg. heat shock protein-that interesting are induced by a number of different agents including lack of oxygen, ROH, heat, trace metals, etc.) I think this phenonema also applies to sound/music stressors and our bodies reaction to the sound and is one of the arguments I think pertain to why short term listening tests have a problem.

I do hear a break in period with ss gear as well though one might hypothesize its less due to less caps say in the signal path.

And certainly speakers have break in periods that depends to a large extent upon the speaker. For instance, Magnepan talks about a one month break in period for their speakers.

 

[mep]

I wonder how much of the 'Burn in/Break in" effect is really the user adjusting their ears to the new component that replaced something else in their system. When you first install something new, it will sound different than what it replaced in most cases. You might not like that something new until your ears adjust to it. I think if something sounds "horrible" out of the box, it probably is horrible. As for steady-state equilibrium, I think the term is really thermal equilibrium. Components need to heat up to the temperature they are used at in the circuit. I always thought SS sounded better if it was never turned off.

And one other thing, a great circuit design built with less than the "best" parts will sound way better than a crappy design that uses the "best" parts. The ideal of course is to have the a great design with great parts.

Mark

 

[MylesBAstor]

I wonder how much of the 'Burn in/Break in" effect is really the user adjusting their ears to the new component that replaced something else in their system. When you first install something new, it will sound different than what it replaced in most cases.

I always thought SS sounded better if it was never turned off.


Mark

See above.

Or turned on

 

[Gregadd]

I think if something sounds "horrible" out of the box, it probably is horrible.

That of course would be the logical conclusion. However if that is true than it would be the greatest thing that ever happened to me. I could go to the Bose outlet store buy a self equalizing HT system and wait for my inevitable delusion to set in. Moreover I would never have found anything to be horrible over the long run. There must be another explanation.

 

[nsgarch]

If you doubt me consider my purchase of the Allnic L1500. I purchased it used from Audiogon. It sounded horrible. I thought it needed a reubeN contacted Hammertone Audio about a possible retube. Dave had the local distributor call me. After asking where I had obtained the unit and informing me that a retube might be prohibitively expensive, inquired where I obtained the unit. It turned out the unit was not used but was sold a customer who had traded up and had barely plugged the unit in. Proper break-in yielded a glorious sounding unit. If I did not believe in break-in i would have resold the unit on the Internet.

Greg, your comment indicates that perhaps you missed my point. I was not negating the experiences of so many (including myself) that the sonic performance of audio hardware sometimes changes after its initial power-up or installation. I was simply pointing out that the parts, materials, components, and devices responsible when these sonic "changes" occur are relatively few, and that they age, or cure, or settle-in, for different reasons. And that, except for tubes, burning is (hopefully) not involved! -- and so the term "burn-in" disturbs me because, even in the case of tubes, it does not describe the many changes going on inside a tube when it's first fired up.

Your "Allnic experience" illustrates my point perfectly: it is a TUBE unit, after all, and pre-owned, so you (understandably) assumed a nominal amount of mileage. Unless it was sold with a new tube set, why would it occur to a second owner that the tubes had zero time on them -- hello?! Ditto the power supply with its tube voltage regulation! Your reaction naturally was "If this as good as it's going to get, then send the damn thing back!" I would have been thinking the same thing!

On the other hand, it's always been pretty easy for me to predict which (kinds of) products will likely require a period of "assimilation" and which ones won't (or shouldn't) As most audiophiles don't have the technical background to make that call, it's easy to to convince them that everything in audio needs to be "burned in"!

But we all make mistakes -- and the more experience one already has under their belt, the faster they'll figure out what they overlooked. For instance, I was recently outraged at the stated "burn-in" time of 300 hours for my new quad of Treasure Series KT88's. "Who are they kidding?", I snickered to myself. "Probably just trying to cover their asses when I decide they suck!" Well, like all new power tubes, they sounded crappy for the first 30 -- 40 hours, and by 50 hours they bloomed and smoothed out, just like most power tubes. But they didn't test very well initially (according to the published specs) and only a little better after 100 hours, so I sent them back. When I received the replacements, also well-matched like the first set, I decided not to test them out of the box; just checked them for shorts and leaks (they had to swim all the way from China!) and then I installed them and ran them, carefully logged, for a FULL 300 HOURS first! They kept improving sonically, and by 200 hours were really impressive! And when I pulled them to test after 300 hours, they exceeded the published specs!

It didn't take me long to figure out why they required such a long time to reach their peak performance. The Treasures' carbon polymer coating (think 'resin') has never been used in vacuum tubes, and it apparently takes (a long) time to "cure". This also explains why the factory can't really match/measure these (premium) tubes right off the production line, as with conventional power tubes; not unless they want to run them for 300 hours themselves. So "conventional wisdom" didn't apply in this case, but without a statement/explanation from the manufacturer (good luck with that!) I just assumed someone was pulling my leg (about the 300 hour requirement) until I figured out it was legitimate.

 

[MylesBAstor]

I think if something sounds "horrible" out of the box, it probably is horrible.

That of course would be the logical conclusion. However if that is true than it would be the greatest thing that ever happened to me. I could go to the Bose outlet store buy a self equalizing HT system and wait for my inevitable delusion to set in. Moreover I would never have found anything to be horrible over the long run. There must be another explanation.

It's hard to generalize here but my general impressions are that if a component sounds "bright" out of the box, this artifact will diminish in magnitude with playing (or is the ear adapting?) but usually never completely go away. OTOH, many components, cables, amp, cartridges, sound dynamically compressed or frequency limited out of the box-- and that definitely improves with time --to different levels. Now the difference between the two examples is that I can't live 'brightness' and that affects my reaction and perception.

 

[RogerD]

Burn-in 500 hours was not enough

I purchased a Accuphase C200 preamp used, plugged it in and it sounded horrible. So I recapped it totally,all the electrolytics were blackgate N &NX series,films were Nichicon.

Plugged it in and sounded much better,after 250 hours better still, after 500 I quit counting. It has turned out stunningly,but it was one pain in the butt.

Over the years I have had equipment sound better after 50 to 100 hours. Usually the longer it morphs the better it sounds. YMMV

 

[nsgarch]

It's hard to generalize here . . . . . . .

. . . . and not really instructive either. So why bother? All the academic attributions, and historical anecdotes about human auditory perception and adaptation, fail to address 'why' equipment can sound 'wrong' at first, 'why' it sometimes changes, and 'why' sometimes it doesn't! That to me is useful and interesting information! Anecdotal reports detailing another individual's subjective impressions may be cathartic for them, but of no value to me, unless I asked them (probably out of politeness!)

The point I made earlier was that audio equipment, if/when it does require some 'run in' time, can require it for a variety of different reasons. I'm not insisting everyone be as curious as I am about WHY things do what they do (or don't do what they're supposed to do;--) but as I see it, everything else, as Rabbi Hillel put it, " . . is just commentary" I wish he'd said, "meaningless commentary" but he was a Holy Man, and I'm not!

 

[MylesBAstor]

. . . . and not really instructive either. So why bother? All the academic attributions, and historical anecdotes about human auditory perception and adaptation, fail to address 'why' equipment can sound 'wrong' at first, 'why' it sometimes changes, and 'why' sometimes it doesn't! That to me is useful and interesting information! Anecdotal reports detailing another individual's subjective impressions may be cathartic for them, but of no value to me, unless I asked them (probably out of politeness!)

The point I made earlier was that audio equipment, if/when it does require some 'run in' time, can require it for a variety of different reasons. I'm not insisting everyone be as curious as I am about WHY things do what they do (or don't do what they're supposed to do;--) but as I see it, everything else, as Rabbi Hillel put it, " . . is just commentary" I wish he'd said, "meaningless commentary" but he was a Holy Man, and I'm not!

Actually I did talk about why sound may change because of equipment parts. See #6.

And the reason that I wrote what I did was that I'm somewhat confused as to break-in. Some characteristics fade but never totally go away; others do seem to go away with playing. What are these due to?

The problem is Neil, that I see the world in shades of grey, not black or white. Too often in audio, we look at phenomena and put forth correlations as cause-effect. In reality, there are multiple variables involved and ascribing the changes with break-in to one or even two things, is probably way too simplistic; It's like the old less filling, no great taste commercial.

 

[The Smokester]

I think it is interesting, and perhaps telling, that "break-in" is mostly reported as being beneficial.

 

[Bigfish8]

I think it is interesting, and perhaps telling, that "break-in" is mostly reported as being beneficial.

Yes, I must agree with your comment that it is interesting! Some of my audio friends won't listen to a new piece of gear until they have establish a couple hundred hours of play time on it. Personally, I can never wait for a piece of gear to get 200 hours on it before listening to it. I have determined if I do not like the way something sounds brand new I am not going to like it after "break-in."

Ken

 

[nsgarch]

Actually I did talk about why sound may change because of equipment parts. See #6.

A specious example at best; in any case, I thought I already made that point?

And the reason that I wrote what I did was that I'm somewhat confused as to break-in. Some characteristics fade but never totally go away; others do seem to go away with playing.

OK, but what part of that reality confuses you? It's just how things are; and if a product doesn't live up to your expectations or the manufacturers claims, (especially after allowing it to BURN-in, if that's what you think it needs) then like Greg sugggests, just return it!

What are these due to?

Well now, that IS the question, isn't it ;--)) A question that has excellent answers if one cares find them; and as I already said, I don't criticize those who don't care to know. However, throwing up one's hands and citing "multiple variables" and "shades of gray" as if to say "it's all just too complex, and not worth trying to understand" sounds arrogant/pretentious to me.

There is a delightful article/interview in today's New York Times, on the subject of "unknown unknowns" (stupid bank robbers ;--)) that addresses this issue in a more dynamic way:
http://opinionator.blogs.nytimes.com/2010/06/20/the-anosognosics-dilemma-1/?hp

 

[MylesBAstor]

Personally I don't think anyone I know of has talked about what goes on with Teflon caps and why they take hundreds of hours to break in. The issue with capacitor microphonics is also interesting since Dave Wilson years ago talked about the sensitivity of caps in crossover to vibrations; ergo, teflon caps in speakers could be at a disadvantage.

Now as far as the reasons, no its not arrogance, it's just plain science. There's a difference between cause-effect and correlations.

It's like those who look at the metabolism and effect of doxorubicin (a chemotherapy agent) and one camp says it kills cells via free radical driven mechanism while other researchers say acts through DNA intercalation. The bottom line that I learned in biochemistry--and it applies to most things in life including our hobby--is that it's near impossible to change one parameter without affecting 5 others. Talk to high end designers and they will tell you about all the tradeoffs that exist in the circuit and if they improve A, it affects B and C. Sorry but reductionism just doesn't work. Like it too, but sorry it doesn't.

 

[mep]

Yes, I must agree with your comment that it is interesting! Some of my audio friends won't listen to a new piece of gear until they have establish a couple hundred hours of play time on it. Personally, I can never wait for a piece of gear to get 200 hours on it before listening to it. I have determined if I do not like the way something sounds brand new I am not going to like it after "break-in."

Ken

Ken-I agree with your comment. I can't recall a single component that I thought sounded horrible when I first got it and it ever became anything better. If it doesn't sound at least really good when I use it for the first time, it goes away. A good circuit is always going to sound good. It might sound better after "break in," but it should always show its promise right out of the box. I think most of us agree that transducers take more time to settle in than electrical devices. However, even with cartridges and speakers, I have never bought any that I didn't enjoy right out of the box. Did they get better with time? Yes. The point is, I thought they sounded pretty damn good when they were brand new.

And by the way, I bought an hour meter to keep track of my new GL KT-88 output tubes in my Jadis Defy 7 MKII. They sound really good right now with less than 10 hours on them, but they are not blowing me away in comparision to the SED 6550 tubes they replaced. We shall see what happens after more hours.