[MrTwyst]

I absolutely believe in burn in and have experienced it.
 
First, from a scientific perspective, I can reason it this way. You're taking matter and vibrating it repeatedly for hours. As far as conductive material, you're running current through it for hours.
 
If you take a box of raisin bran and shake it up, eventually, the raisins go to the bottom. Think about molecules with either electric or vibrational forces affecting them in the same manner repeatedly over time.
 
Recently, I purchased Ultrasone Pro 900s. One song I listened to had a female vocalist with a particularly high voice. When she'd hit an "s" in the song, the sibilance was completely unnatural sounding. I mean, NO ONE sounds that shrill, sharp and metallic. After several dozen hours, the harmonics flying off of her "s" were noticeably less. I'm still breaking the 900s in. If the trend continues (as I expect that it will), the unnatural sound of the "s" will be gone completely.
 
Doesn't the vibration/excitation and settling of molecules make sense to those who consider themselves to be scientific skeptics who don't understand the phenomenon?

 

[Kerry56]

Quote:

I had these cans and I ran them nonstop out of my home theater receiver for one full week.  Burn in did help.  While these cans aren't very good, they are far from hideous.  I gave mine away to my dad and he is happy to have them.
 


 

Thought I was being generous.  They went from two baggers to one baggers after burn in.  Or whatever the audio equivalent is. 

 

[hodgjy]

I see your point and agree mostly with the concept, but the molecules themselves don't move around raisins.  The density of materials can be reduced, crystalline structure cab break, and cohesion can be reduced (like stretching), but something as radical as molecules moving like raisins doesn't occur in solids.  Only in liquids.  But, I agree with the overall concept of what you said.  Things stretch and loosen, which will have an impact on sound.
 
Quote:

If you take a box of raisin bran and shake it up, eventually, the raisins go to the bottom. Think about molecules with either electric or vibrational forces affecting them in the same manner repeatedly over time.
 

 

 

[MrTwyst]

"but something as radical as molecules moving like raisins doesn't occur in solids."
 
Actually, it does. There is nothing, in reality, which is completely solid. You have a higher density of molecules in a solid, but there is still more space between the molecules of any solid than molecules themselves.

 

[hodgjy]

Well, we're just getting into semantics now, but while molecules may move, they don't move relatively as far or as disorganized as a raisin through a pile of flakes.  Molecules in "solids" vibrate, but they do not exhibit Brownian motion.
 
But, the details are not important.  Burn in has some merit. 

 
Quote:

"but something as radical as molecules moving like raisins doesn't occur in solids."
 
Actually, it does. There is nothing, in reality, which is completely solid. You have a higher density of molecules in a solid, but there is still more space between the molecules of any solid than molecules themselves.

 

 

[Coq de Combat]

Personally I believe in it, but I think that the changes that occur really aren't that big. I think that some people are more sensitive to hearing the changes than others, and I also believe that a part from the changes are due to getting accustomed to the new sound signature. I also have a feeling that some headphones (not different models, but the headphones themselves) might differ a bit when they come straight out of the factory.
 
Oh well, if we like the sound we get, no matter if it's pre- or post burn-in or brain burn in, that's the most important part, right?

 

[hodgjy]

Yep. 

  Personally, I think burn occurs between the ears and in the cans themselves.  Both are important.
 
Quote:

 
Oh well, if we like the sound we get, no matter if it's pre- or post burn-in or brain burn in, that's the most important part, right?

 

 

[MrTwyst]

Quote:

Well, we're just getting into semantics now, but while molecules may move, they don't move relatively as far or as disorganized as a raisin through a pile of flakes.  Molecules in "solids" vibrate, but they do not exhibit Brownian motion.
 


 

The vibrate. They move. They rearrange. No, it's not as drastic in a relative manner to raisins, because the molecules in most solids are in a a relatively uniform matrix. However, the energies hitting the solids will affect the density and arrangement of the molecules in a manner that is similar to shaking raisin bran. Or, if you would like, any analogous material where you get "settling," of the particles.
 
I don't think it's worth it to get into Brownian motion of particles suspended in gases and liquids in order to determine that solids are relatively form-retaining in comparison in order to diminish the relevance of the analogy.
 

 

[hodgjy]

Yes, I'm being nitpicky, but stretching/loosening the diaphragm is not the same as molecular rearrangement.  Just saying.
 
Quote:

The vibrate. They move. They rearrange. No, it's not as drastic in a relative manner to raisins, because the molecules in most solids are in a a relatively uniform matrix. However, the energies hitting the solids will affect the density and arrangement of the molecules in a manner that is similar to shaking raisin bran. Or, if you would like, any analogous material where you get "settling," of the particles.
 
I don't think it's worth it to get into Brownian motion of particles suspended in gases and liquids in order to determine that solids are relatively form-retaining in comparison in order to diminish the relevance of the analogy.
 

 

 

[MrTwyst]

Quote:

Yes, I'm being nitpicky, but stretching/loosening the diaphragm is not the same as molecular rearrangement.  Just saying.
 


 

;:O)

You do realize that if you're stretching something, you're changing the arrangement of the molecules, right?
 

 

[hodgjy]

Not like raisins cascading through bran.
 
Quote:

;:O)

You do realize that if you're stretching something, you're changing the arrangement of the molecules, right?
 

 

 

[MrTwyst]

If you want to find a better analogy, fine. But I will stand by this one because it's an analogy which gets the point across. There are forces placed on the molecules which cause the molecules to move and finally settle in as the effects of the forces diminish over time... much like shaking a box of raisin bran around. No, the movements of the molecules won't be exactly like the raisins, but you get the idea.

 

[Beagle]

Quote:

The vibrate. They move. They rearrange. No, it's not as drastic in a relative manner to raisins, because the molecules in most solids are in a a relatively uniform matrix. However, the energies hitting the solids will affect the density and arrangement of the molecules in a manner that is similar to shaking raisin bran. Or, if you would like, any analogous material where you get "settling," of the particles.
 

If they decide to continue to move and rearrange indefinitely, will one ever know what the actual sound of the headphone is?
 

 

[MrTwyst]

Quote:

If they decide to continue to move and rearrange indefinitely, will one ever know what the actual sound of the headphone is?
 

Molecules are always moving (unless you hit absolute zero). The thing is, in solids they move very little and, for all practical purposes, retain their shape until other forces are applied. There comes a point where some of the mild forces will have had their effects and then their effect diminishes... Like when you shake the box of raisin bran around, the raisins will settle to the bottom. After a point, no matter how much you shake the box, the effects will be minimal.

 

[MacedonianHero]

Just to add to the discussion:
 
http://www.innerfidelity.com/content/measurement-and-audibility-headphone-break