What makes CD/SACD players "burn in"?
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Leo V

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"Burning-in" headphones is easier to understand: they have moving parts, which loosen up, improving sound quality (as posted in these forums).

But people report improvements on CD/SACD players as well. I wonder how this could happen. I mean, a DAC converter has no moving parts, right? Does this mean that "burning in" is an electrical process, as well?

Taking no chances, I created a 30-second pink noise CDRW using CoolEdit, and my Sony NC650V is playing it in a loop. I'm fairly confident that sound quality improved since I got it 2 days ago. But to play devil's advocate: what if it's ME who was "burned-in", getting better used to the player?

Any comments appreciated!
Leo
 
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dariusf

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Many manufactures themselves recommend burn in of their equipment. For example in my Creek OBH-11 SE amplifiers manual its stated that the burn in is necessary for best sound. Now if you actually do this before listening or just use it and have it burn in over time is your call. But definitely the sound improved quite a bit in the case of this amp. I'm sure its not exception. I used to be skeptical about things like this. But after all I read about it and tried it myself now I'm a 'believer'
 
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dariusf

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The way I actually tested this was I listened to my setup with the new Creek for about 20 min, then I let it burn in for about 72 hours (yes, it was VERY hard to resist) and then I listened again after it was supposed to be burned in. Its hard to compare with out A/B switching but the deference was quite evident. Was it suggestive? I'm sure a little, after all I was expecting a change, but I don't believe it would account for the total deference in sound.
 
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andrzejpw

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Although I'm also still unclear about the whole how cdps burn in, I THINK it may be something with the electron pathways getting used to electrons flowing through them. Don't take my word for it though: I'm probably just spouting wrongs.
 
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Leo V

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Well, here is what I found.

"Only within the last decade have designers of high fidelity equipment begun to admit that their equipment does indeed improve sonically after the first hours of operation. Capacitors, it was said, underwent changes as signal was applied over a period of time. The process of "forming" the capacitor changed its sonic characteristics, to a degree, improving the ability of the part to convey the more subtle aspects of music. The more we learn, the more the feeling grows that virtually every signal carrying part in the unit undergoes a conditioning routine, not just capacitors. From resistors to transistors, to wire and transformers, every item seems to reveal some capacity for improvement after use."

Also, some company PR here:

"playing music is not the most effective means of burning in a system. It does not deliver every frequency with the same intensity or consistency, and could even result in a sonic "signature" on the capacitors in your system by playing only the same type of music. Playing music only will also do nothing to help the inevitable residual magnetism building up on the components themselves."

Don't know about the credibility of it all...
 
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fredpb

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My tiny two cents.

Even CD players have mechanics. The do need to loosen up a bit, to minimize tracking errors, error correction, and jitter.
Vibration CAN effect CD performance. For most of this, VIBRAPODS are ok.

Ignoring differences in engineering and design, components do need to settle in.

Mainly capacitors and dynamic components, like IC's and transistors, and of course, tubes.

Capacitors especially. They need to "form", as they use "electrolye" between "plates". This ages, and forms with current and voltage.

For some items, just having the unit powered up can burn things in. But things that use the dynamics/signal path need a signal to burn in. Volume levels and frequencies do make a difference.

Don'to go paranoid about it. Right now I am burning in my Cambrigde Audio D500SE CD player for my bedroom. It had a sticker on it that said leave it playing for 32 hours before critical listening. I believe that. RIght now, it's about on hour 36.

That burn in time will also allow you to find out if the player has any defects, too. Constant playing will heat things up and maybe show up some defective mechanics.

As with my philosophy, enjoy the music, enjoy the toys. Toys like players and headphones give you satisfaction, music can give you emotions and joy.

 
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Jeff Guidry

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CDP's are also mechanical devices, and much like a new hinge on a door can be a little stiff until they have been used for a while.

I think that the transport must be played for a while until all the lubrication put on the unit at the factory has a chance to really work its way evenly on the whole unit and insure smooth rotation of the spindle. Likewise, I think the laser must go up and down its path several times before the lubrication for it has been evenly distributed and can smoothly and flawlessly track. For that reason, I think it is better when burning in a player that you play on repeat a CD that is as long as possible, so that the laser can go throught the full length of its tracking. You should do this from time to time anyway, especially with portables, so you can knock off bits of dirt and such that can get on the track.

All of these and other factors make a difference between bits that get read and bits that don't, leading to error correction and reduced sound quality.
 
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Nadim

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Good question Leo. As someone reading all sorts of strange and not-so-strange claims floating around on audio forums, I've struggled with questions like these as well.

My initial opinions, formed of my skeptical nature and electrical engineering training, were that a lot of these claims were pretty much bogus. Really now, I stayed awake through, and did well in, solid state physics (and, IMO, that's not a feat to scoff at, either...). And never did I hear anything about transistors, resistors, and god forbid wire, "burning in". For capacitors...well, maybe over time the dielectric can build up some residual charge, but that would simply decrease their overall capacity, which for many applications would make them worse, not better. Now granted, eventually changes do occur, but as an engineer I call it "wearing out", and it's not supposed to be happening in the first few hours... In fact, since tolerances are achieved and tested for at the factory, logic (and my textbooks) would indicate that the best a circuit (and notice the word here....I'm not talking about moving parts that need lubrication, like a car engine or speaker diaphragm) will perform is when new. Over time, hopefully a lot of time, a circuit will degrade, as dielectrics break down, or thermal stress affects tolerances, or hysteresis affects affects transformers, etc.

Anyway, that was my initial take, but I know the feeling you're having. The more you read about people being able to hear differences, the more you wonder. The most insidious part of this is wondering if maybe your hearing just isn't up to snuff. This in turn causes the desire to hear these differences, leading in some cases to the death of objectivity.

Now, I am certainly not going to claim that there are no differences. Not only would that potentially start a flame war, but it would just be my opinion, and no more or less useful than anyone else's opinion to the contrary. You're going to have to decide for yourself. Before you read too much, though, and just "go with the flow", here's a link to an interesting piece that deals with marketing-speak and why you should be wary of certain claims:

http://www.sundial.net/~rogerr/truth.htm
(Check out the sections "A revolutionary new speaker system" and "truth and superstition in audio").

More to the point of your original question, though, I noticed you followed up with some quotes weighing in on the subject, including, *gasp*, some words written by a marketing department. Critical reading and thinking skills are a must, because one could easily quote plenty of contradictory opinions on this topic and plenty of others. For example, check out "The Burn-in Lie" section in this pdf document:

http://www.audioperfectionist.com/PD...watchdog10.pdf

In actuality, this section is written by someone trying to "debunk the debunking" of burn-in. However, when I read the passage, my own internal BS detector goes off far more on the rebuttal than the original quote he's trying to argue against. Note how the author of the rebuttal first simply attacks with useless generalities ("He'd have to be deaf to believe this drivel"), and then proceeds to "prove" the original author wrong by talking about the speaker case (specifically excluded from the original author's assertions), and about how warm circuits perform differently than cold ones (a fact that is easily provable with elementary thermo / solid state calculations, and has nothing to do with a "burn in" period). Anyway, enough from me, as I stated before, you should read critically and form your own opinion.

The most difficult thing about all of these opinions about what does and does not matter in audio is this: many, many people (well....not in the population at large, but in the population that posts on these types of forums) believe they can hear these differences. This seems to force someone reading these opinions to either of two conclusions: a) they really CAN hear a difference, or b) most people are liars.

I certainly can't accept option b...it just doesn't make any kind of sense (remember, opinions are free, but the equipment people buy isn't!). That seems to leave one with only a single choice. However, that's not necessarily the case. There's a third option. Namely, that most people truly believe that they can hear a difference. And, while there is a lot of debate on what differences truly are audible, and to what degree, there is a fair degree of consensus in psychology that people really do believe that they can perceive differences, when, in fact, testing shows that they can't. Note, again, in the first link in this post, under the section "Good amplifiers can sound the same". The author expresses a sentiment commonly found in double-blind testing, that they will swear, up and down, that they can hear differences between types of gear. Then, in the same exact environment, they score just around 50% right as soon as the testing goes "blind".

Combine this with the fact that distinguishing differences before and after a break-in period requires a) a long (days?) period between listenings and b) no ability to toggle back and forth between before and after states, and.....well.....you form your own opinion.

-Nadim
 
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Leo V

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Thanks for a very insightful post, Nadim. You summed up the issue quite nicely: despite lack of scientific evidence, people actually report a range of specific improvements in their gear. The most forceful are reports of improved standing of the "broken-in" gear, relative to the owner's other (relatively unchanged) equipment. Maybe we should challenge people to perform blind comparisons between similar units, the way these folks compared MP3 decoders.

As for fredpb and Jeff's pointing out the mechanical aspects of CD players, these certainly sound like more reasonable sources of (potential) improvement. I went ahead and filled a 74-minute CDRW with 8 tracks of pink noise, and set my 650V to randomly shuffle between tracks.

The bottom line is: useful or not, I have a greater peace of mind doing this. Setting this up only takes a couple minutes of my time, so I don't lose anything from it.
--Leo
 
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Nadim

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No problem, glad I could help.

I truly wish that more people would do the sorts of tests that are becoming common with mp3 encoders and decoders, but the unfortunate fact is that it's a lot harder to set up a good double-blind test of hardware than it is of software. There is the classic ABX page, still maintained here, which contains some controversial (and very interesting, whether you agree or not) hardware test results, but sadly I haven't been able to find more recent, updated, or expanded results using a similar methodology. Even so, some things just can't be measured this way...like, say, headphones. I don't see how it would be possible to do a truly blind test to determine if one can tell the difference between two different cans, considering that just the feel of them on the head would give away which was which. Still, it would be nice if it was applied, in conjunction with more subjective approaches, where possible. I'd certainly be far more receptive to someone's statement that A sounds "much clearer, more dynamic, with better detailing, like night and day" than B, if they could demonstrate that they could, at least, tell them apart 10 times out of 10.

Regarding mechanical break-in of CD players, certainly I would expect that like any mechanical device, running them for several hours would help evenly distribute lubricant, smooth points of mechanical friction, etc. However, excepting cases where mis-reads occur and missing samples had to be interpolated, it shouldn't make a difference in the sound, as far as I am aware.

And one final thought on burn-in, of both mechanical and electrical devices. All sound quality issues aside, it's probably still not a bad idea at all to burn in new equipment, so that you catch defective devices before the warranty expires (and before, say, your CD changer goes south and eats 400 of your best CDs...).

Happy listening, Leo.

-Nadim

P.S. So, after all this, just out of curiousity....did you hear a difference after your pink noise burn-in period? And if so, about how great a difference would you say it made?
 
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fredpb

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Well, I also never heard things about burn in when going to school for any electronics or engineer. That's the way most engineers are, and those that can't, teach, as the saying goes.

I used to laugh at my friends and their Stereophile magazine, and their descriptive terms such as detailed, liquid, etc.

Cables? Sound different? Rubbish! I used to think.

I then had time to spare, and went out listening. Not at mass market shops, but at exotic shops with good salespeople.

I got the shock of my life. Stuff DOES sound different. As far a those who say "it ain't in the book", that's their opinion. It is quite possible they don't have the hearing ability or desire to hear a difference.

I did.

Break in on my new CD just for 40 hours made a big difference. Especially in the lows.

If you can't tell the difference, it's cheaper that way, and you can always buy your equipment at Radio Shack.
 
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jopi

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I don't know whether burn-in is psychoaccoustic or real. The part that makes me sceptical is, that I've never heart anybody claiming that burn-in made his or her equipment sound worse. I will believe, that the sound change with burn-in, but why getting better?
 
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andrzejpw

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Well, with headphones, I guess its because the membranes are getting loser. With new phones, they are stiff, and don't move as easily as they would broken in. . . or stuff.


For me, the biggest difference is when I try some phones on, brand new, burn them in for 2 or 3 days, not wearing them at all, and then put them on. I HEAR a difference. Now, whether this was psychoacoustic or not, I don't know.
 
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jopi

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Right, I've forgot to mention that I exclude mechanical components.
 
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mikeg

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I've always believed that burn in was a bunch of nonsense; i.e., until I got a Stefan AudioArt cable for my AKG K1000 headphone. The manuafacturer recommends a 72 hour burn in, but I compared it to the stock cable right away. The Stefan cable produced an absolutely dull sound when first connected and compared to the stock cable; i.e., the highs were really lacking. But, after the 72 hour burn in it sounded wonderful; i.e., just like the stock cable. But unfortunately, at this point I can't hear any difference between the Stefan and stock cables. Perhaps the Stefan cable will improve further when used for a longer period.
 
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