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If You Believe in Burn-in, Clap Your Hands

ejr

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For all you technical types, if you believe that audio equipment must be "burned in" before use (or to get accurate measurements), I am wondering if there is any objective technical data to support that supposition.

I recently purchased an Eversolo A6 Gen 2 streamer/DAC/preamp and liked it enough to buy a second one two months later. This gave me an opportunity that I have never had before -- namely, to test two identical pieces of audio gear, one that we could say had been "burned in" and the other which had not. My subjective impression, using only my ears, was that there was no difference that I could detect between the two, before or after the second unit could also be said to have been "burned in". My feeling is that, if there were any differences in audio quality, they were too small for my ears to notice.

Since then, I have been using my Loxjie D60 as an external DAC for one of these units, and I do hear a slight difference between the two setups. But it is not dramatic. I use the D60 primarily for my TV audio, but also route the output of the A6 through it to use the powered speakers or its headphone amp when I just want to listen to music (because streaming Amazon Music sounds better with the A6 as a source than Amazon's Roku or Google TV apps and is less buggy).
 
There is a difference between warm up (components settling to an optimal operating point) and break-in.

Settling-time is the time equipment needs to reach optimal performance (several minutes after power on) think tubes or SS needing to reach operational temperatures.
Burn-in is a process where a new device undergoes a duration test to weed out early defects.
Break-in is a process where mechanical components can change to reach their designed properties (drivers for instance)
Brain-in is a process where the brain gets used to a 'presentation' and starts to accept the deviations.
 
I like the term "brain-in", that's where the answer, and the problems lie :)
 
Clap clap :)

Me thinks everything that is built needs burn-in. Question is how long is the burn-in time. ;)

* apartment at the higher floors of a new building needs about 6 months burn-in time for the hairline cracks to stop growing, building settles, then one can paint over the hairline cracks.

* every morning my car need about 5 mins burn-in time, coz it behaves a bit cranky the in the first few minutes during burn-in.

* my old class-A amplifier needs around 15-mins burn-in time before it makes the speakers sings with sweetness

* my DAC probably needs a few seconds of burn-in time to be it’s best.

* my cables need … hmm … 0 secs burn-in time … coz i suspect the electrons inside the cables only takes a few femto seconds of burn-in to get their butts moving.



;)
 
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Anything built from scratch needs break in, five minutes to form capacitors, so their leakage settles etc. Once done it's done. Then all anything needs is warm up, a few minutes for ss amps, dacs with tcxo or ocxo can take longer to settle, but it's unlikely to be audible after a few minutes.

I build a pretty fancy discrete phono stage that takes about 70 hours to burn in. There's a bunch of large value caps on the current mirrors that feed the gain stage, these only see tiny current flow and you can watch the dc offset at the output settle from a couple of hundred mV to sub mV over that 70 hours.

The difference in sound is clearly audible from the 100s to sub 10 mV, the sound seems to wander from speaker to speaker. Below that I can't tell by ear.

It takes about ten minutes to settle from subsequent start ups, it has a pair of class A shunts that feed the current mirrors that stabilise over that time as they come up to temp.

Sounds like a lot of hassle, but theres few MC phonostages with snr in the high minus 80db at 2v out and 64db gain.

It's easy to talk in genralities, of should and shouldn't, does and doesn't, but there's always edge cases. We just shouldn't get carried away with them.
 
I'm reminded of the almost religion which surrounded a particular UK amp maker, their disciples claiming to need up to three weeks for the products to 'break/burn in.' Truth was that at the time, the amp circuits had some idiosyncrasies and drifted all over the place, eventually drifting way off spec after a year or three left powered 24/7 as was recommended and needing an expensive recap and service to pull them back into line.

Another UK brand had a preamp which was also recommended for 24/7 running. The case was unventilated, well sealed and the twin mainboard mounted regulators with small attached heatsinks ran VERY hot. After a few years of 24/7 running, the circuit board sometimes suffered burn-out and needed to be scrapped as unrepairable economically I remember. I still have one of these preamps, bought cheap to use as a phono stage from the tape outputs and absolutely NO warm-up is actually needed, so when needed, I turn it on and set the record output, use it and switch off afterwards! Later preamps used smps and it's these that cook and fail I gather...
 
What about the ECU in a car? It performs the same from the day the car leaves the factory until either the car or the ECU dies.

No burn in required.

And it works in extreme temperatures (cold or hot) as well.

Why should audio equipment be any different?
 
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Simple fact:if you listen to music, systems sound better over time.

If you listen for defects, they get more prominent over time.

Critics and reviewers and engineers probably listen for defects. And that’s okay for the rest of us.

Mechanical devices, including speakers, might limber up over time. If this is necessary, it should be done at the factory.

Just a stray thought, but since the advent of synthetic oil, new cars no longer require a 500 mile break-in.
 
Something that can be burnt in can also be burnt out

In a similar vein, something that works can spoil
 
I didn't notice anything burning when I first turned on my amplifiers. How can I tell if something is "burning in"? Perhaps someone clever can develop a burn-in detector, but I love the term, which gives wild imaginations, like fire and smoke.
 
If I remember well, I saw on YT a visit of the FOCAL factory, they had dedicated containers outside to burn in some of their expensive speakers for 24 hours, I guess for the woofers.
It costs them time and money and it's not for show so they clearly see something to it.
 
If I remember well, I saw on YT a visit of the FOCAL factory, they had dedicated containers outside to burn in some of their expensive speakers for 24 hours, I guess for the woofers.
It costs them time and money and it's not for show so they clearly see something to it.
That would be burn-in, as described here:

No matter how good your processes, occasionally you're going to get a dry joint, or a faulty capacitor, or some-one was having a bad day when they put the device together. Burning stuff in during manufacture means you catch some of those problems, not the customer.
 
If I remember well, I saw on YT a visit of the FOCAL factory, they had dedicated containers outside to burn in some of their expensive speakers for 24 hours, I guess for the woofers.
It costs them time and money and it's not for show so they clearly see something to it.
The properties of a woofer change during the first few hours, this is measurable.
 
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The properties of a woofer change during the first few hours, this is measurable.
That would be break-in, as described here:

I think that post covers everything.
 
I am not knowledgable about the fine points of capacitors. But from first principles, the things that can be measured: capacitance, ESR, leakage, from a good manufacturer, should be stable. Japanese, German, and any American high volume capacitor maker, large enough to have an R&D and quality/failure analysis group and a good supply chain, is what you want.

I would not consider the post I made about giant paper, aluminum foil, and oil capacitor made in someone's kitchen to be a good manufacturer. A capacitor that requires burn-in is not properly made. Quality manufacturing requires volume by definition.

Manufacturers make capacitors to be stable over a long (but not infinite for electrolytics, and some other types) lifetime so the design is stable.

Inductors and resistors are very stable. Active components and systems are discussed in this post:


Multi-frequency capacitor meters aren't that expensive, so any ASR reader can buy or take the capacitor out of the circuit, build the appropriate conditioning jig to run it for hours, days, and weeks, and test the capacitor. Then you can look at the circuit and see if the signal goes through the capacitor or the capacitor only involves power filtering. Usually the power filtering is far overbuilt. Present day A to D / D to A converters with free software like Room Eq Wizard can easily test an electronic device with audio signals to see if it changes over time.

Here is another way to look at it. The final device maker will usually test at the board level on a bed of nails, then the finished device. The longer the time of the test, the greater the cost to the maker. No maker is going to want to test for more than 2 minutes. So a maker will not select a supplier where the capacitor has to be aged to spec.

As for speakers, the same general argument holds. The driver maker wants to sell a stable driver, so should be doing any break-in as part of the manufacturing process. With speakers, you have the elastomeric suspension, the cone or dome, possibly ferrofluid. The driver designer is going to select long lasting stable elastomeric materials, design the dome/cone to be unchanging with use within limits. Ferrofluid is pretty long lasting, 30 years.

Again with a calibrated microphone, you can test driver distortion over time. You could test it with a sweep, then run it for hours, days, and weeks with continuous sweeps, then measure the distortion to see if it changes. Any reputable speaker manufacturer would test that on at least one instance of the driver.

Hopefully you don't have dogs who have to listen to weeks-long speaker tests!
 
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I don't know about electronics (capacitors primarily) and to some extent mechanical (speaker and headphone membranes/suspension) but cables?!?!?
Do they need to be polished by electrons??
 
I don't know about electronics (capacitors primarily)
Film capacitors are thermally annealed (i.e., baked) at moderately high temperature during the manufacturing process. We used to bake polyester (mylar) capacitors around 120 deg. C. and polyproplyene capacitors somewhere around 110 deg. C. if I remember correctly (it has been 25 years so my memory is a little hazy). They are not going to noticably change during normal use, assuming they are not over-heated nor operated at extremely cold temperature (e.g., below -40 deg. C.).

High temperatures age electrolytic capacitors, though, which has a negative effect, not a positive one.
 
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Clap clap :)

Me thinks everything that is built needs burn-in. Question is how long is the burn-in time. ;)

* apartment at the higher floors of a new building needs about 6 months burn-in time for the hairline cracks to stop growing, building settles, then one can paint over the hairline cracks.

* every morning my car need about 5 mins burn-in time, coz it behaves a bit cranky the in the first few minutes during burn-in.

* my old class-A amplifier needs around 15-mins burn-in time before it makes the speakers sings with sweetness

* my DAC probably needs a few seconds of burn-in time to be it’s best.

* my cables need … hmm … 0 secs burn-in time … coz i suspect the electrons inside the cables only takes a few femto seconds of burn-in to get their butts moving.



;)
Electrons' butts may be tiny, but what they lack in size they make up for in sheer numbers.
 
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