Headphones burn-in question
Mar 9, 2013 at 11:30 PM Post #3 of 67
It really all depends on your headphones. My Shure SE215 sound started changing with in the first hour. However I had a bunch of Senn HD428's (now HD439) because I kept returning them and getting new headphones due to the terrible cable. Anyways I would say that they took a good 40 hours to get 'settled' in. I would not keep your headphones at a high volume just in case
 
Mar 12, 2013 at 10:39 AM Post #5 of 67
There's still no proof of the large burn-in changes reviewers talk about, so it seems mostly to be in their head.
 
Also keep in mind that playing loud tones (especially full-scale sine waves) for many hours on end can cause damage to the headphone drivers.. that will definitely cause audible changes.
 
Mar 13, 2013 at 12:43 AM Post #6 of 67
If burn in is a myth, then it's a harmless placebo. Costs nothing and makes you feel music better, sounds like a good bargain no? Honestly I too scratched my head as to why my S500 and DR150 sounded better after burning in.
 
You should go attack those $20,000 cable manufacturers.
 
Mar 13, 2013 at 9:45 AM Post #7 of 67
Quote:
If burn in is a myth, then it's a harmless placebo. Costs nothing and makes you feel music better, sounds like a good bargain no?

It's just that there is an undefined line between burn-in and burn-up... Just not sure there's any improvement once you cross it, and the harmless becomes harmful. And since we don't know where that line is, why chance it if it's only placebo?
 
Quote:
You should go attack those $20,000 cable manufacturers.

 
Don't worry, we do.
 
Mar 16, 2013 at 11:55 AM Post #8 of 67
My understanding is that full-sized woofers do in fact "break-in". That is, the parameters such as Fs (resonance frequency), Vas (volume of the air which the driver is coupled to), and Q (damping) can change after some playtime. In tests, you can accelerate a woofer's burn in process by playing test tones. I think it's fair to say that this sort of change will manifest itself as "better bass".
 
http://www.gr-research.com/myths.htm
 
But Tyll at Innerfidelity has done tests that show the effect of burn-in with headphones is much less pronounced.
 
http://www.innerfidelity.com/content/measurement-and-audibility-headphone-break
 
His tests mostly consists of FR and CSD plots of the headphone before and after "burn-in". And they seem to be mostly concerned with the midrange and treble. I'd like to see how the headphone driver parameters change with time and how the bass will change in turn. Since "better bass" seems to be the most common claim that audiophiles make about burn-in anyway.
 
Mar 16, 2013 at 1:33 PM Post #9 of 67
Quote:
 
But Tyll at Innerfidelity has done tests that show the effect of burn-in with headphones is much less pronounced.
 
http://www.innerfidelity.com/content/measurement-and-audibility-headphone-break
 
His tests mostly consists of FR and CSD plots of the headphone before and after "burn-in". And they seem to be mostly concerned with the midrange and treble. I'd like to see how the headphone driver parameters change with time and how the bass will change in turn. Since "better bass" seems to be the most common claim that audiophiles make about burn-in anyway.

The concern with the mid-range vs bass is likely because we are far more sensitive to changes in the mid-range.  It takes much more significant changes in response at 20Hz to become audible.
 
Even with sub-woofer burn-in, the worst cases show less than 5 Hz change in Fs, and typically around 2Hz, which isn't enough to even alter box tuning audibly.  If that's what's happening with woofers with huge Xmax, the changes in headphone drivers with microscopic Xmax would be insignificant.
 
Mar 16, 2013 at 2:14 PM Post #10 of 67
Quote:
The concern with the mid-range vs bass is likely because we are far more sensitive to changes in the mid-range.  It takes much more significant changes in response at 20Hz to become audible.
 
Even with sub-woofer burn-in, the worst cases show less than 5 Hz change in Fs, and typically around 2Hz, which isn't enough to even alter box tuning audibly.  If that's what's happening with woofers with huge Xmax, the changes in headphone drivers with microscopic Xmax would be insignificant.

Headphone Xmax is of course smaller than for loudspeaker. Yet the extension into the bass does change more than with loudspeakers - it is perfectly possible to see with a naked eye the diaphragm of a 40 mm dynamic driver ( to be precise, reflection of light from the diaphragm being "modulated")  in  a headphone playing a large amplitude signal - like low frequency sine wave. From say half a metre - that is in no case microscopic movement.
 
One, admittedly extreme, example of large Xmax is AKG K1000 - IIRC, + - 2 to 3 mm, most definitely visible during low frequency reproduction.
 
Mar 16, 2013 at 5:32 PM Post #11 of 67
Headphone Xmax is of course smaller than for loudspeaker. Yet the extension into the bass does change more than with loudspeakers - it is perfectly possible to see with a naked eye the diaphragm of a 40 mm dynamic driver ( to be precise, reflection of light from the diaphragm being "modulated")  in  a headphone playing a large amplitude signal - like low frequency sine wave. From say half a metre - that is in no case microscopic movement.


One, admittedly extreme, example of large Xmax is AKG K1000 - IIRC, + - 2 to 3 mm, most definitely visible during low frequency reproduction.


I'm confused at how you can say the above. Yes, just to move enough air to present 20Hz at high volume a headphone driver has to move a bit. But in no way can we say "the extension into the bass does change more than with loudspeakers". A woofer movement at 20Hz is quite a bit greater than any headphones.

Perhaps I misunderstood your point?
 
Mar 17, 2013 at 12:15 AM Post #12 of 67
Quote:
If burn in is a myth, then it's a harmless placebo. 

 
It isn't completely harmless.  For example if someone bought a pair of headphones which he/she didn't really like but thinking that burn-in will make a "night and day difference", which some people do claim happens for some headphones, then that person might have just wasted money.
 
Mar 17, 2013 at 5:28 AM Post #13 of 67
Quote:
I'm confused at how you can say the above. Yes, just to move enough air to present 20Hz at high volume a headphone driver has to move a bit. But in no way can we say "the extension into the bass does change more than with loudspeakers". A woofer movement at 20Hz is quite a bit greater than any headphones.

Perhaps I misunderstood your point?

I should have been clearer. You have said woofer Fs will not change more than by a couple of Hz with burn in - which is correct and in line with my experience.
 
I did run a controlled burn in testing for a headphone. I have Bruel & Kjaer certified measurements for it. What did puzzle me was the fact that resonance of that headphone was approx at 4-5 kHz - thus far removed from the bass region where I did suspect it to be. Still, burn in was most effective - be it from listening point or measurement. On open box, there was no reflection from headphone driver to be seen if fed with a very low frequency signal - say 5 ( five ) Hz. After 48 hour burn in, it could follow 1 ( in a word : one ) Hz signal .
 
I need to translate the whole report to English and prepare it in a form that can be displayed on head-fi - and I suck with computers, particularly as this report was partly made on a mac and that is above my capabilities - will have to ask a friend to help me. But the curve "before" and "after" is clear as a bell - there is reduced hump in the midbass around 100-150 Hz and extension in the low bass - at approx 30 Hz, there is "only" about 20 dB ( ! ) difference in level - which even the most cloth eared burn in Doubting Thomases would have hard time not noticing. I have print outs for frequency response before and after burn in for 20 Hz to 25 khz range and from 20 Hz to 1 kHz range - and will have to do one from 20 Hz to 100 Hz range to allow for proper presentation/resolution, because it is in this region most difference is - try as one might, ignoring 20 dB is hard. There are differences higher up, but nowhere the magnitude of the one below 100 Hz.
 
Burn in process I will describe was put to use more than 25 years ago - for my electrostatic earspeakers. It works with dynamic drivers just as effectively.
But there is a problem - if manufacturer of the dynamic transducer did not assemble the output wires from the coil to the outer world properly, leaving loop that allows for large amplitude, once the burnt in driver reaches enough freedom to respond to low frequency signal ( amplitude of the dynamic driver increases with the square of the inverse frequency reduction, for frequency twice lower the amplitude is 2 squared = 4 times greater ) - it may happen the too short output wire(s) will break. I never experienced this in practice before, but Murphy made it possible for the right channel of this pair to develop open coil in this way - there was no thermal overload, as all my other hps and left one of these that got Bruel & Kjaer measurement are perfectly OK. I was not exactly thrilled by this, still I prefer it to happen during burn in and not offer "fading out" performance during say monitoring of a recording - where I would have probably blamed everything else but headphones for "something wrong" - I need to rely on the equipment I work with and prefer to weed out as much of any possibility of this or similar to happen as humanly possible.
 
Mar 17, 2013 at 5:40 AM Post #14 of 67
Quote:
 
It isn't completely harmless.  For example if someone bought a pair of headphones which he/she didn't really like but thinking that burn-in will make a "night and day difference", which some people do claim happens for some headphones, then that person might have just wasted money.

Burn in effects in headphones vary in degree. One that is known to be extreme in this is JVC HA-S500 with carbon nanotube diaphragm. Judging this headphone on open box and dismissing it as not good based on the first impression would really be a mistake.  This material needs much more/longer burn in than anything else I came across.
 
The differences in other hps might be less pronounced, but are audible nonetheless.
 
Mar 17, 2013 at 8:54 AM Post #15 of 67
Quote:
Burn in effects in headphones vary in degree. One that is known to be extreme in this is JVC HA-S500 with carbon nanotube diaphragm. Judging this headphone on open box and dismissing it as not good based on the first impression would really be a mistake.  This material needs much more/longer burn in than anything else I came across.
 
The differences in other hps might be less pronounced, but are audible nonetheless.

 
So were the AKG K701/Q701 which was also known amongst "audiophiles" to requires hundreds if not thousands of hours of burn it for them to sound "right", Tyl's experiment had failed to show that to be the case.
 
Also the difference being audible doesn't mean "night and day difference" which some audiophiles (and you) claims to be the case, and again if someone was buying a pair of headphones based on the promise that the headphone will undergo a dramatic transformation due to burn-in they certainly run the risk of buying a pair of headphones which they don't like to begin with and thus it is not a harmless placebo which was my original point.
 

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