Burn in nonsense

Interesting read. For me the burn exists, but you might argue it's just in your head..... at the end it's about the enjoyment, and it seems from your post that you have achieved a satisfying level.

My most amazing burn in experience was my 252 which to my ears had a special bump after 5 or 6 months of having it in the house. I couldn't belief my ears,,,.....but just accepted it as a very nice effect. The airiness, soundstage of my 252 improved by the way.....

For all who don't belief in burn in, you just can argue that I am Dutch and that I apparently smoked to much of this certain stuff.........

I have also been there many many years ago

It's real my 500dr sounded poor...after dr ing ...and it took 3 months for it to start really opening up..... 

...& I doubt you will be the last.

The only explanation I can offer is that the influence of an electrical current may 'polarise' electrons in the conductors and in doing so 'lines them up'. I also have first hand evidence of some materials being polarised, changing from insulators to diodes under certain conditions.

It definitely happens, as far as I'm concerned. I witnessed the gradual change with my 52, then my 552 (although that was pretty good right from  the start), most definitely with my pair of 500s (I was about to sell them... my 300s had seemed much better... and then after a couple of months, wow!) and now with Super Lumina which gradually did something magical to my system.

Nothing to do with the ears, I'm certain. The gear definitely changes.

Maybe not the ear, but perhaps the brain. In a way similar to its ability to recognise hidden images in an apparently arbitrary array of dots, perhaps.

Whatever the reason, though, the effect seems real enough to me.

Adam Meredith posted:

perizoqui posted:

It occurs to me that my ears have burned in, rather than the amplifier. There's a definite explanation for that, and a well known one in the research community.

NOT this again!

I am a ear-doctor person of so much experience that it embarrasses me and (should) intimidate you.

The human ear is no more capable of 'burning-in' than ........... Oh god, I've lost the will to live (again).

 

At the risk of driving Adam to drink, might the burn-in effect be a combination of physical change (the electronics) and pysiological (ear/brain) change or rather adaptation in the case of the latter. I am no expert, far from it, but I would suggest the physiological change I refer to (if indeed it exists at all) would be related much more to the brain's ability to adapt, or rather the interaction between ear and brain.

Whatever your view, there does seem to be significant number of individuals (on here anyway) who have experienced and described burn-in from a personal perspective.

l shall remain neutral for fear of being burnt as a witch should I confess all.

There probably is some degree of placebo effect going on, but my Nait 3 takes about 10 days to sound its best.

Clive 

I can't offer an explanation but I can say post a service my 552 sounding pretty poor but some  4 months down the line it is now singing - I can't figure out why but glad I persevered.

Gary

Adam Meredith posted:

The human ear is no more capable of 'burning-in' than ........... Oh god, I've lost the will to live (again).

By burn-in when it comes to the ear, people are (or at least I am) talking about learning and memory in the brain. As I'm sure you'd expect people learn music they hear often. A number of folks, beginning with Elizabeth Strickland here at Purdue University, have found that the cochlea dynamically adjusts the length and thereby gain of the hair cells in response to expected signals. In other words, you hear better when the sound is expected. If you google her name and Purdue you'll find her webpage with all the peer-reviewed papers you may require to satisfy your intellectual curiosity. Anyhow, ears can be trained to hear "better" when they become "used to" particular sources of sound. I'm calling this "burn-in."

Cheer up butter cup, there's still reason to live 

fathings cat posted:

I can't offer an explanation but I can say post a service my 552 sounding pretty poor but some  4 months down the line it is now singing - I can't figure out why but glad I persevered.

Gary

Same here, noticed it more than i ever have on any other equipment I've owned. 

I wouldn't have said it was poor but maybe wouldn't have spent out the money for it if i hadn't had the pleasure of demoing a very well used example at home beforehand.

Burn in does exist and I suspect it will have something to do with the how the signal travels and modulates through natural materials. Water will make a path over a landscape and find it's own route, I am sure something is going on....

perizoqui posted:

"....  I'd love to do a side-by-side of a new vs "burnt-in" 300. Anyone done this? ..."

 

That's a good question. I would think Naim dealers might perhaps be best placed to comment on variations heard between brand new and burnt in examples of the same equipment. Anyone?

perizoqui posted:

A number of folks, beginning with Elizabeth Strickland here at Purdue University, have found that the cochlea dynamically adjusts the length and thereby gain of the hair cells in response to expected signals...

You mean to say that there is hope for my boldy head?

perizoqui posted:

...I thought it would be interesting to post in this forum, in the hopes that those with engineering knowledge might offer me an explanation I haven't thought of (I haven't been able to think of any), for the physical basis that might underlie burn-in for a solid-state amplifier. Google searches haven't turned up much beyond annoying arguments of "burn in is real!" followed by "no, you're an idiot!" replies. I'm hoping that doesn't happen in this generally much more sophisticated forum. Rather I'm hoping for an engineering discussion on the underlying mechanisms for burn-in at the solid-state amplifier level. I know how it works in my ears and in the brain. I know how it works in mechanical devices like speakers and headphones. I know how it works in tube amplifiers. But I don't for the life of me know how it might work, if it works, in my 300.

But I do know this: my 300 sounds just spectacular. Best I've ever heard recorded music. It sounds far better than it did one month ago, and I think there's more to it than my ears getting used to it because every new piece sounds spectacular, not just the ones I've been listening to all month. Anyway, thanks in advance for taking the time to share your knowledge and thoughts.

Best,

---Pedro

I know you've asked for an engineering explanation and nobody has yet obliged.  I'm not going to either, as I don't have the expertise.

What I do know is burn in real.   I experienced it with my NDX, and am currently experiencing it with my SuperNait 2.  I won't bother with the details, but with my NDX, it got better, then worse, then better again.  I thought that the people who described that chain of events were imaging things, but I experienced it as well.

I too would love a scientific explanation because it interests me, but beyond that I don't much care.  I know what I hear, and that's enough for me. 

One of the explanations that's always trotted out by the blind testing brigade is confirmation bias.  It's a nice way to dismiss the real world experiences of individuals, but it doesn't actually provide a satisfactory explanation for people's reactions to audio gear, particularly on this forum, where many will argue that some of the less expensive equipment (relatively) is better than the more expensive gear.  Confirmation bias would suggest that whatever's more expensive is better, but there's plenty of disagreement about what sounds good around here.

I find it fascinating that so many people (and this isn't directed at you, Pedro) are willing to discount the actual experiences of people listening to music, but I don't hear anyone ever call for blind (no pun intended) testing of TVs.  Someone in Stereophile, probably Michael Fremer, has suggested that this is due to most audio writing in newspapers and magazines these days being done by tech writers.  I suspect that he's right.  That and the fact that very few people actually sit and listen to music these days, so are content to accept whatever explanation "makes sense", rather than actually investigating for themselves.

Lastly, and I know this is a very long post, you asked who has done comparisons between new and broken in equipment.  I'm sure many dealers have, and certainly Naim.  And they mention it right in their user manuals.  

Jeff

Side by side comparison of new vs burnt-in?

Different component values, different assembly, different circuit track lengths, different conductor composition, different wire insulation, what's the definition of new, how long to be burnt in, different manufacture dates, way the amp was stored, humidity, match with speaker cable, temperature..... not sure there would be enough control over the the variable to be meaningful. Wish there was.

After forty years in engineering and academia I fully understand how much I think I know of how little we understand about the things we think we know (?).

s.

Naim manufacturers the equipment, so why not simply ask them the question?

They are the experts and know their products...... if burn in is a reality, they will confirm it. If not, then perhaps we can finally establish that it is simply placebo.

Ardbeg10y posted:

You mean to say that there is hope for my boldy head?

Yes. If you own and listen to the Naim Statement preamp and amp, your hair will grow back. Sure thing. Those who say this isn't true, do not own said gear. Those who own said gear have a luscious full head of hair.

Mr Frog posted:

Naim manufacturers the equipment, so why not simply ask them the question?

They are the experts and know their products...... if burn in is a reality, they will confirm it. If not, then perhaps we can finally establish that it is simply placebo.

 

They'll probably just say RTFM, which says

OK, I am an engineer (OK, well I was).

Some electronic components do show small long term changes going from unpowered storage conditions to long term powered condition, but principal among these are electrolytic capacitors.  Their leakage currents, noise and series resistance all decrease over a period of time when power is applied after a period of unpowered storage.  This effect reaches an asymptote, before eventually the ageing process of the components starts to reverse these beneficial changes and the unit then needs to be serviced (principally a 'recap') to restore previous performance.  The effect in the components may be small and subtle, but it is quite audible due to the amazing discrimination of the human ear/brain combination.

ChrisSU posted:

Mr Frog posted:

Naim manufacturers the equipment, so why not simply ask them the question?

They are the experts and know their products...... if burn in is a reality, they will confirm it. If not, then perhaps we can finally establish that it is simply placebo.

 

They'll probably just say RTFM, which says

"Naim equipment takes a considerable time to run in before it performs at its best. The duration varies, but under some conditions the sound may continue to improve for over a month. Better and more consistent performance will be achieved if the system is left switched on for long periods."

That seems to confirm that Naim equipment does benefit from a period of burn in or as they refer to it, "run in"

Huge posted:

OK, I am an engineer (OK, well I was).

Some electronic components do show small long term changes going from unpowered storage conditions to long term powered condition, but principal among these are electrolytic capacitors.  Their leakage currents, noise and series resistance all decrease over a period of time when power is applied after a period of unpowered storage.  This effect reaches an asymptote, before eventually the ageing process of the components starts to reverse these beneficial changes and the unit then needs to be serviced (principally a 'recap') to restore previous performance.  The effect in the components may be small and subtle, but it is quite audible due to the amazing discrimination of the human ear/brain combination.

Thank you Huge.

So you feel it's the passives rather than the semi-conductors? That would certainly square with my expectation where solid-state is concerned. Especially if the passives refers to the electrolytics rather than the resistors, inductors, or any ceramic caps in there. Just as you say. Interestingly, and I didn't know this but I'm sure you do, the ESR of the electrolytic caps lowers with temperature which would explain why the circuits sound better warm too. And of course semi-conductors are also very sensitive to temperature.

But for burn-in we're going with electrolytics (you're the only one who's ventured an answer, and I had none), I'm curious if there are others... but for now: According to wikipedia ESR goes up with time,  C goes down, and leakage current likewise goes down:

Lifetime changes all seems to be a result of electrolyte evaporation, which can be avoided by ceramic or supercapacitors. But the former don't have the energy density of electrolytics, and the latter don't have the ESR.

Presumably, Naim design their circuits to operate perfectly (R, C, and I_L are inarguably important in setting operating points, so when these change the rest of the circuit must change). When we're in the middle part of all the above curves, we must be in the ideal operating point. Which means they are out of their ideal operating point early and late in the product life-cycle. Hence burn-in and re-caping. I'll buy that! It also means they don't burn in and then stop, they continuously get better until they begin continuously getting worse. Unless there's some sort of compensation mechanism for the changes around the middle point...

Out of curiosity, when you re-cap a 300 or 500, do you send both boxes back or just the PS? Just wondering if they use electrolytics in the signal path or just the power supply. Of course, the PS is a signal path too, but I'm referring to the audio signal path here.

Anyway, thanks again. I feel like I can say I've experienced burn-in without feeling sheepish now. Curious if anyone else has thought of other (there might be more than one!) mechanism of action for what so many of us have apparently observed?

The charts you give are designed for determining the time to end of life of the capacitors under stress (i.e. time before they go out of tolerance at high temperature and near to maximum working voltage); they're not intended for assessing their 'in life' characteristics.  In practical applications, capacitors are run with much greater voltage margins and at lower temperatures - this is certainly the case for Naim amplifiers.

The plots above give failure time of 2000hrs (i.e. 2.73 months), I'd expect a Naim amp to last a LOT longer than that.  Naim recommend a service interval of 10-15 years, so taking the shorter, that's 87,000hrs.  In actual fact, the average life expectancy before the component goes completely out of tolerance is more like 25 - 35 years as Naim use a low stress environment.  The curves are a bit different for these conditions, starting with a small decrease in ESR and leakage (noise is mainly related to leakage and temperature).  In the plots above this can't be seen as it's all squashed over in the left axis due to the stress test conditions.  This initial change in electrolytic capacitors is referred to as 'forming' (or re-forming after a period of storage).

Huge posted:

The charts you give are designed for determining the time to end of life of the capacitors under stress

Makes sense. So in normal usage you'd expect to see a quick drop to a long flat stable point, followed by a reasonable further drop at the end. Like a battery discharge curve. Agreed.