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Author Topic: Interesting link on burn-in  (Read 2325 times)

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Anaxilus

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Re: Interesting link on burn-in
« Reply #10 on: February 06, 2014, 09:36:29 PM »
Quote from: shipsupt on February 06, 2014, 09:30:42 PM
Quote from: Anaxilus on February 06, 2014, 09:02:37 PM
Mechanical wear is so obvious when discussing things like the modulus of change in elasticity, it's amazing to me such things are even questioned. 

Just depends on things like construction and design.

Yep, and the engineers designing this stuff know about it too. The good ones are going to pick materials appropriately to keep changes to minimum, or at best to an expected calculated quantity.

Using engine wear as a valid comparison just doesn't work for me.  The mechanical wear and failure modes in engine parts are simply not that comparable to the changes that occur when a speaker is exercised.

I wasn't using engine wear anywhere in there.  But since you bring it up I completely disagree.  I can take apart a Honda motor apart with 250,000 miles on it and find less wear within thousandths of an inch on journals compared to the massive wear on an aging butyl surround that is disintegrating or paper cones shot to shit.  I can look and touch some speaker surrounds and judge them whereas a well made import motor requires me to pull out a micrometer. 
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Anaxilus

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Re: Interesting link on burn-in
« Reply #11 on: February 06, 2014, 09:39:16 PM »
Quote from: shipsupt on February 06, 2014, 09:30:42 PM
Yep, and the engineers designing this stuff know about it too.

You are giving them god powers.  Engineers pray at the altar of Accountants who don't want your purchase to last.  Bad for business.  If I could find a list of transducer engineering priorities I'm pretty sure longevity would be pretty low on the list if at all.
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shipsupt

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Re: Interesting link on burn-in
« Reply #12 on: February 06, 2014, 09:47:36 PM »
I was referring to the original post.

I'm not talking about the amount of wear, I'm talking about the type of wear. 

While elasticity and stretch are certainly design criteria we consider when designing engines, generally it's not the issue we are worried about in the long term operation.  On the speaker side you don't have much in the way of material on material wear or materials that are easily susceptible to vibration fatigue (at least I'd like to think not, just seems like it would have to be poorly designed since you're definitely getting many duty cycles as part of the inherent design, but I'll be the first to admit I know more about designing an engine than I do about speakers!)

Maybe I'm not being clear, I can easily see mechanical parts in speakers that will be changed when cycled, but the mechanical changes are very different than those we see in engines because of different materials and different operating environments.

I just think there must be a better comparison to use to make the point.



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Yeah, well, you know, that's just, like, your opinion, man.

shipsupt

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Re: Interesting link on burn-in
« Reply #13 on: February 06, 2014, 09:52:42 PM »
Quote from: Anaxilus on February 06, 2014, 09:39:16 PM
Quote from: shipsupt on February 06, 2014, 09:30:42 PM
Yep, and the engineers designing this stuff know about it too.

You are giving them god powers.  Engineers pray at the altar of Accountants who don't want your purchase to last.  Bad for business.  If I could find a list of transducer engineering priorities I'm pretty sure longevity would be pretty low on the list if at all.


Uh, that's a little stretch on what I said, but OK...

What I meant was that just like you are surprised that the issue is questioned, I took it further to say I'm surprised that we wouldn't consider the engineers take this into account when designing.  No doubt that they are not given free reign to pick any material they want... I never said that all their designs are perfect, or even good!  Making money, or trying to, can have many interesting effects on design and products that make it out the door...

I actually think we're on the same page here...
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Yeah, well, you know, that's just, like, your opinion, man.

OJneg

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Re: Interesting link on burn-in
« Reply #14 on: February 06, 2014, 09:54:05 PM »
I'm not suggesting anything actually, just posing a question to those that might be better informed than myself. If anyone has done tests similar to the one in the original post but with headphones, I would be very interested to see.

Let's keep in mind that most headphones do not use a spider or a surround, which are attributed as the major factors of woofer burn-in. And like you mentioned Anax, the excursion and power going through a headphone load is not nearly as great as that of a woofer. So it would be interesting to see how exactly a conventional domed diaphragm or small voice coil (the two major variables left I suppose) would change during the burn-in period. Maybe we should be looking at what sort of burn-in exists for tweeters instead of woofers.
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frenchbat

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Re: Interesting link on burn-in
« Reply #15 on: February 06, 2014, 09:59:59 PM »
From Tyll's website :
http://www.innerfidelity.com/content/evidence-headphone-break

Quote from: OJneg on February 06, 2014, 09:54:05 PM
I'm not suggesting anything actually, just posing a question to those that might be better informed than myself. If anyone has done tests similar to the one in the original post but with headphones, I would be very interested to see.

Let's keep in mind that most headphones do not use a spider or a surround, which are attributed as the major factors of woofer burn-in. And like you mentioned Anax, the excursion and power going through a headphone load is not nearly as great as that of a woofer. So it would be interesting to see how exactly a conventional domed diaphragm or small voice coil (the two major variables left I suppose) would change during the burn-in period. Maybe we should be looking at what sort of burn-in exists for tweeters instead of woofers.
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Anaxilus

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Re: Interesting link on burn-in
« Reply #16 on: February 06, 2014, 10:03:57 PM »
Gotcha ship!   

Thx for clarifying OJneg.

:)p5
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Solderdude

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Re: Interesting link on burn-in
« Reply #17 on: February 06, 2014, 10:44:05 PM »
Quote from: OJneg on February 06, 2014, 09:54:05 PM
I'm not suggesting anything actually, just posing a question to those that might be better informed than myself. If anyone has done tests similar to the one in the original post but with headphones, I would be very interested to see.

Let's keep in mind that most headphones do not use a spider or a surround, which are attributed as the major factors of woofer burn-in. And like you mentioned Anax, the excursion and power going through a headphone load is not nearly as great as that of a woofer. So it would be interesting to see how exactly a conventional domed diaphragm or small voice coil (the two major variables left I suppose) would change during the burn-in period. Maybe we should be looking at what sort of burn-in exists for tweeters instead of woofers.

I fully agree with what was written here, analogies are not applicable.
Woofers and headphone drivers really have nothing in common in construction, used materials, excursions, mass ... you name it.

The word 'burn-in' makes me sigh...  :-\
Woofers ? sure... headphones... some do, some don't (audibly IME).

Have modded many (cheap) HD681 and could compare new ones with 'burned in' ones.
Most sounded the same but every once in a while I got a new one in that severely lacked bass in the first few minutes.
and I don't mean slightly but difference from bass monster to bass shy.
On 2 occasions I could hear the lows come in within 1 song but one of them took about a half hour and never gave the same amount of lows as the others did.

Later I had 3x HD661 and 'burned' one in for 48 hours.
It played so loud I thought it may burn out during that test but had received 3 for free so took the risk.
Anyways NO audible difference when compared to the new ones (with my ears/gears).

The latest HD681-EVO I checked on a rig out of interest:

It came in cold (was just delivered and literally cold) and was measured shortly after it came in.
Then... 5 hours of blasting music so loud it distorted !
Headphone rig was clipping !
Music turned off after about 5 hrs.. and measured it directly after while it had been left sitting on the rig.
purple = 0 hours, green = 5hrs of bashing.
There is some difference (<1dB)
But.... the room temperature had risen and the headphone was warmer.
Maybe the measured difference isn't even caused by burn-in but may have been caused by the pads becoming more compliant (warmed up) and compressing slightly over those hours with the clamping pressure of the headphone (which was substantial).... who knows.
The question is would such a difference be audible ?
Could bigger differences be had when simply repositioning the headphone ?

Another one the Teufel Aureol Real:

just 4 hours of burn in... some changes in the highs.
Blue= directly out of the box, purple after 4 hrs.

Burn in of mechanical things... possible sure...
cab les ? resistors ? transistors ? op-amps ? ... yeah right... yet many claim these components also have to be burned in and swear they can hear it easily !

Just venting my viewpoint though.

« Last Edit: February 06, 2014, 11:00:30 PM by Solderdude »
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MuppetFace

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Re: Interesting link on burn-in
« Reply #18 on: February 06, 2014, 11:23:19 PM »
I don't for a moment doubt changes occur in headphones. After all, I don't think the drivers are immortal objects LOL. Where it becomes more questionable for me is the connotation of the word "burn in" which implies an audible change for the better. Just like the shoes example, the implication is they're uncomfortable until some period of time when they've loosened and molded to your foot more or less. The wear is almost always for the better in that context because they become personalized due to bodily contact. As Anax was saying WRT headphones, I've heard changes in headphones for the worse over time as well (Ultrasones and Grados).

Where it becomes tricky for me is the psychological factor, as I really do become mentally adjusted to certain headphones over time, so that it might seem like burn in, but returning to them later or after a "pallet cleanser" earphone / headphone yields different results. That's why it's often hard for me to really track changes in a headphone hour-by-hour like some people seem to do.

For me, the notion gets to be a little problematic when it's suggested as a requisite for liking gear. Especially in amplifiers, I find it does take a bit of time for them to settle, so that after say 100 hours or so they sound a little more effortless and natural (less tight-arsed). However I can pretty much tell if I'm going to like an amp. Even more with a pair of headphones: I have never experienced burn-in to the point of liking a pair of headphones I previous hated after 500 plus hours. At most, I've noticed a bit of added refinement and smoothness on the positive side or on the negative side the development of some honkiness and bloated bass.
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OJneg

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Re: Interesting link on burn-in
« Reply #19 on: February 06, 2014, 11:30:03 PM »
I agree that changes in the pads (mechanical clamping of the pad -> equivalent volume when the seal is made -> resistance to air flow) is probably the more significant factor in judging what most users perceive as burn-in. Most people's experience with regards to burn in tends to be improvements in bass response, which a better seal could easily explain. But a lowering of the Fs of the headphone driver (as shown in woofers) could be a part of the equation as well.

Explaining smoother treble might lie within the diaphragm itself. Hard to pin this down. As Tyll's measurements have shown, treble measurements are not terribly consistent. Or maybe we should look back and see how the treble qualities changes as the pad breaks in, seeing as how the pad effect is more accepted. Seeing how the treble energy radiates in the space of a changed headphone pad (instead of just looking at FR at a single position) might reveal some more significant differences.

I might try to measure how my TH02's impedance curve changes after some heavy use this weekend. It's not fresh out of the box at this point, but I expect the differences should be there after I expose it to some 40Hz tones headbang
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