Equipment burn-in: am I deluded?

[maxxevv]

If anyone is serious about testing the burn-in hypothesis, just buy 2 identical NEW copies of any device that are so said to benefit from it.

Follow the burn-in protocol recommended for one set, while keeping the other new-in-box, unmolested.

After the supposed burn-in completion for one set, test out the 2 side by side. If the so said benefits exists, it should manifest itself there and then.

Its not difficult at all is it ??

 

[amirm]

I'll throw some links to some articles I had seen a while ago focusing on the headphone realm.

The problem with headphone testing is that the pads can deform differently, throwing off any such analysis.

Here is a test I ran showing the frequency response differences with no pressure and some pressure on the pads to compress them more:

That is quite a difference and likely heck of a lot more than any break in of the drivers.

 

[Kal Rubinson]

Its not difficult at all is it ??

Not if you do it in a proper controlled, double-blind trial.

 

[jhaider]

Speakers can take seconds to hours or more to "burn in" due to mechanical consider

Even there, the resonance and compliance changes generally offset each other, leading to the same performance when the driver loaded in a given enclosure.

 

[maxxevv]

Not if you do it in a proper controlled, double-blind trial.

The opportune word here is "if". And for things like transducers, frequency response changes should be measurable.
Similarly for electronics, when transmitted as output via a " seasoned " set of transducers.

 

[maxxevv]

The problem with headphone testing is that the pads can deform differently, throwing off any such analysis.

Here is a test I ran showing the frequency response differences with no pressure and some pressure on the pads to compress them more:

View attachment 17819

That is quite a difference and likely heck of a lot more than any break in of the drivers.

Franz has documented that on his anthology of HD650 mods too.

 

[Headphonaholic]

The problem with headphone testing is that the pads can deform differently, throwing off any such analysis.

Oh yes absolutely. You're changing the surface of the pads, the volume of the space inside of the pads as well as changing the distance of the driver to the ear. Lots of variables, even a slight repositioning of the headphone will result in measurable differences.

I was merely providing some more articles I had seen of people discussing burn in as food for discussion . I think the last article they did a single blind test and claimed they could definitely pick out the burned in headphones.

 

[amirm]

Oh yes absolutely. You're changing the surface of the pads, the volume of the space inside of the pads as well as changing the distance of the driver to the ear. Lots of variables, even a slight repositioning of the headphone will result in measurable differences.

I was merely providing some more articles I had seen of people discussing burn in as food for discussion . I think the last article they did a single blind test and claimed they could definitely pick out the burned in headphones.

My apology. I was not disagreeing with your post but rather, using it as a jumping point to share my point of view.

 

[Headphonaholic]

My apology. I was not disagreeing with your post but rather, using it as a jumping point to share my point of view.

Oh my bad, I couldn't tell . Was that your first use of the ears rig? I have one as well! I need to practice using it more so I can do tests of different pads and what not.

 

[amirm]

Oh my bad, I couldn't tell . Was that your first use of the ears rig? I have one as well! I need to practice using it more so I can do tests of different pads and what not.

No, I had used it before but gave up in frustration. Could not get any results resembling any other measurements out there. Then again the measurements out there did not agree with each other either.

 

[solderdude]

There is also the point of circuits needing to get at the correct operating points (usually heat related) but this would happen every time you switch it on and not go away after 1 or 2 times of usage. Idle currents being one of them.

Often 'forming' of caps is used as an excuse for wet electrolytics but usually isn't a problem unless it was never powered up (and then only for the first few seconds) or when caps are old and have not been used for many many years.

Pads (wear/compliance) is the most common sound changing aspect of headphones along with positioning on the head.
The few headphones I measured burn in with react so little little it is impossible to hear and certainly not 'night and day' difference or bass or treble level/quality changing noticeable.

I recently tested 'newer' Koss KSC75 against older ones and they measure differently but look exactly the same. Letting the new ones (that had less bass extension) burn in a long time brought no changes. I used the same pads on both (decay of Koss foamies is well known).
Silent revisions happen a lot in headphones as well.

Brain-in is what's the biggest reason for someone 'detecting' burn in. This is by far the biggest variable and those that feel they 'keep it into account' are mistaken. Placebo works at conscious and not conscious levels.

As for speakers... Most (good) speakers are designed using units that have been used tested many hours already. Tuning of filters/ports/enclosure thus is done using 'played in' speakers. So any freshly assembled speaker should end up closely to the intended performance. Product variances/tolerances set aside.

And yes, mechanical (moving) parts, electron tubes/valves do change but this is not 'burn-in' but wear.

 

[Wombat]

No matter how hard I try I cannot 'burn-in' to the widespread concept of burn-in espoused by 'audiophiles'. I guess my knowledge and understanding of the associated factors just damn-well get in the way.

 

[Theo]

Very good post you are referring to. So isn't the OP actually a severe case of brain-in? Or may I call it "ear burn in"?

 

[solderdude]

Very good post you are referring to. So isn't the OP actually a severe case of brain-in? Or may I call it "ear burn in"?

That's what I suspect. Could be mood related, could be different songs used, could be the expectation it sounds 'thin' as he experienced that earlier and thus heard more lows than before ?
One will never know unless it was measured both times.
I measured a lot of gear and never noticed roll-off on low and high extremes of its bandwidth to ever change.
Highly unlikely this happened to the OP but never in any lab.

I have seen a lot of 'reviews' where people 'upgrade' their system over time but kept the first purchase and re-visited that item later to find it performed much better than they remembered.
The brain is a very funny 'device' and a lot less reliable than electronics when it comes to repeatability (and a lot of other tasks).
Brain-in can be very stark.

 

[JJB70]

Beyerdynamic pretty much tell customers that headphone burn in is primarily in the mind:

https://support.beyerdynamic.com/hc/en-us/articles/201875262-Do-I-need-to-burn-in-my-headphones-

I agree on pads though, they do deform and change the initial stiffness and so over the initial few hours will bed in and feel different, and that will alter both the seal between the pad and your head and also the geometry between transducer and ear. However that tends to be something which happens very quickly.

 

[restorer-john]

Measurements Harman made showed that the driver does indeed change. However, once you put it in a speaker box, that difference becomes very small.

Next time you get a new pair of speakers, do an impedance sweep straight out of the box, another at 1hr and another at say 100hrs. Any change to the suspension/resilience etc will manifest itself in changes on those plots I would expect.

I've never done it, all my impedance plots are done well after the speakers have been run-in so to speak.

The KEF link seems to be a sensible description IMO.

 

[svart-hvitt]

And don’t forget product-by-product variance from factory

I would bet that audiophile brands have much more product variation than professional tool makers (does Audioprecision have variation...?).

So blind tests between new and old (burned in) audiophile gear could yield a difference simply due to unprofessional manufacturing, design etc.

This should not happen in serious audio tools however (cfr. AP), but is to be expected in audiophool gear.

 

[SIY]

No, I had used it before but gave up in frustration. Could not get any results resembling any other measurements out there. Then again the measurements out there did not agree with each other either.

The last sentence is key. The situation with headphone measurement is far less certain than measuring speakers.

 

[mansr]

Could we have a list of producers who claim burn-in of gear, so as to separate the wheat from the chaff, so to speak.

All high-end consumer brands will say burn-in is real. Some actually believe it, others say it just because their customers want to hear it. If you want anything resembling truth from manufacturers you'll have to look at the pro market.

 

[svart-hvitt]

All high-end consumer brands will say burn-in real. Some actually believe it, others say it just because their customers want to hear it. If you want anything resembling truth from manufacturers you'll have to look at the pro market.

I haven’t talked to «all highend consumer brands» and hence cannot verify your claim, but I guess you’re about right