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Headphones burn-in question - Page 2

post #16 of 67
Quote:
Originally Posted by nanaholic View Post

 

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.

Your point is valid. I did try out of the box K701 and I did not like them - and do not believe that they can change so much for me to start liking them. I have a friend who got them about a month ago - and will try to listen to this pair in say half a year. Do not think anything will change enough though.

 

Carbon nanotubes are an entirely different case. 20 dB difference measured is a night and day difference. But it could never be achieved by using music of whatever genre alone - even at an infinitely long burn in.

post #17 of 67
Quote:
Originally Posted by jaddie View Post

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.


Point taken.

 

Nonetheless, if the headphone driver is not the cause of changes in bass response, I would look to the acoustic coupling between the headphone chamber, earpad, and head as the main culprit. I think we can all agree that earpads will deform and "break-in" after a period of use. And since headphones get most of their bass output from the acoustic coupling to the head, I would expect this to cause a significant change in bass response and overall sound.

 

Anecdotally, I can say that when I first got my headphones they seems bass-shy with a thin-ish midrange. After a week or so of wear, the bass seemed to really gain presence. When I replaced the earpads, they went back to sounding bright again until I had a chance to wear them in.

post #18 of 67
Quote:
Originally Posted by analogsurviver View Post

 

Carbon nanotubes are an entirely different case. 20 dB difference measured is a night and day difference. But it could never be achieved by using music of whatever genre alone - even at an infinitely long burn in.

 

I'm interested in reading about the carbon nanotubes case as yes, 20dB difference is more than a significant amount and would certainly qualify as "night and day difference".  You wouldn't happen to have links to the measurements would you?

post #19 of 67
Quote:
Originally Posted by nanaholic View Post

 

I'm interested in reading about the carbon nanotubes case as yes, 20dB difference is more than a significant amount and would certainly qualify as "night and day difference".  You wouldn't happen to have links to the measurements would you?

As I said - I OWN those measurements, had to pay local Bruel & Kjaer representative to make them. I have had it with the claims burn in is not real. Due to misunderstanding a report was done in our, Slovene language - and you know what gibbetrish coms out of computer translators. Will try to get it online ASAP - wit a help from my "computer" friend.

 

Busy with other things at the moment - like finishing mods to my recorder ( see my profile ) and further research into turntables and phono cartridge. This is something I can do without the Bruel & Kjaer ( or at least comparable ) rig used for measuring headphones - it would be nice to own such a rig and thus have the possibility to try perfecting the headphones. Those JVC nanotubes really are good, but have a couple of "sore thumbs" - nothing not possible to at least ameliorate, but without permanent acces to measuring equipment to verify the listening impressions this is unfortunately impossible. It is crazy how pronounced is the effect of a seemingly very small modification - and although it can be predicted what will happen, the magnitude has to be verified and finely tuned by measurements. 

post #20 of 67
Quote:
Originally Posted by analogsurviver View Post

As I said - I OWN those measurements, had to pay local Bruel & Kjaer representative to make them. I have had it with the claims burn in is not real. Due to misunderstanding a report was done in our, Slovene language - and you know what gibbetrish coms out of computer translators. Will try to get it online ASAP - wit a help from my "computer" friend.

 

Busy with other things at the moment - like finishing mods to my recorder ( see my profile ) and further research into turntables and phono cartridge. This is something I can do without the Bruel & Kjaer ( or at least comparable ) rig used for measuring headphones - it would be nice to own such a rig and thus have the possibility to try perfecting the headphones. Those JVC nanotubes really are good, but have a couple of "sore thumbs" - nothing not possible to at least ameliorate, but without permanent acces to measuring equipment to verify the listening impressions this is unfortunately impossible. It is crazy how pronounced is the effect of a seemingly very small modification - and although it can be predicted what will happen, the magnitude has to be verified and finely tuned by measurements. 

You have to understand that when you say there's a 20dB difference after burn-in, and nobody else is showing that, there's going to be a little disbelief.  Did you, for example,have a "control" pair that were tested at the same time as the burned-in pair to show there was not change in the test setup?  Or was there some other way used to verify the test setup had not changed? Any way to post the graphs?

post #21 of 67

The problem with giving your headphones to someone to do the measurements pre and post break-in is that you're measuring lots of different things. Lots of variables... Different placement causes large changes. Slight changes in seal can completely ruin low-end response. Different wear of the pads causes measurable changes. Even temperature difference can show up in measurements. IIRC, Tyll said that even a truck driving by changes his measurements. Maybe you even damaged the driver..

 

If that's the case, claiming that you measured changes that are solely due to break-in is patently absurd. On the other hand, if you say some of the changes measured were due to break-in and there's no way to quantify those changes what was the point to do the measurements in the first place?

You're supposed to follow the evidence where it leads, not the other way around.

 

 

Now saying "I've had it with the claims burn in is not real" is another fallacy. Let's assume you've controlled all the variables above and indeed shown that the headphone with nanotube drivers change a lot after playing loud tones. All you've shown is that those kind of drivers change their characteristics after playing loud tones. To generalize that for all headphones makes no sense.

How many headphone with nanotube drivers are there? Two? How many of these are hi-fi headphones? Zero?


Edited by xnor - 3/18/13 at 9:19am
post #22 of 67
Quote:
Originally Posted by jaddie View Post

You have to understand that when you say there's a 20dB difference after burn-in, and nobody else is showing that, there's going to be a little disbelief.  Did you, for example,have a "control" pair that were tested at the same time as the burned-in pair to show there was not change in the test setup?  Or was there some other way used to verify the test setup had not changed? Any way to post the graphs?

Perfectly understandable. 20 dB is an enormous difference - but then again one has to know what signal can achieve true burn in.

 

No, the intent was to show exactly the same pair of JVC HA-S770 hps "before" and "after" the 48 hour burn in regime - using the very same measuring setup, documented down to serial # of artificial ear, analyzer , etc, etc. I will translate the whole thing proper and post graph for the right channel that survived - there is no way the software used can identify as "before burn in" and "after burn in", so they are labeled Left and Right in the graph - for actual measurements for the surviving right channel - before and after burn in.

 

I went to the trouble of having made these measurements by no less than Bruel & Kjaer because I really had it with people who do not believe in burn in and insist on precise measurements to verify it.  But I will describe how this change can be heard - with the exact tracks and comments what is wrong with hps out of box and how they behave once properly burnt in. It can be heard ( and FELT on ears ) - and the difference is dramatic indeed. I limit myself to "before" and "after" - there is any degree "in between" , so when you read that a certain hp "sounds after so and so many hours of playing so and so" - do not dismiss this as BS, the guy who wrote that just might be honestly trying his best to describe the sounds he is actually hearing.

 

That failure of the left channel was an unfortunate fluke - every hp listed in my profile went through the 48 regime and all but this pair sing happily ( and better... ) ever after.

 

Remember - factories can not afford to burn in hps ( save for exceptions, for example Stax - see the report on the visit of head-fi in Stax Japan ) - nor it is performed when third party measures them. First the knowledge to do it is needed, second time is needed for that, probably less than 48 hours regime I use, but I do not believe it can be done in say 8 hours - and 2 measurements have to be made -  all this combined is costly indeed. Were it not for the fact that the owner of the company that measured these phones was not an enthusiast himself and partially turned blind eye regarding actual time used for making measurements, all the extra and at first not agreed upon measurements would have costed me a small fortune. Normal bussines practice can not afford such luxury.

 

Burn in is thus left for the consumer to do. Depending on hp type and listener sensibilities, it can range from "no difference" to "dramatic" - be it due to pads getting slightly different shape with use, be it to driver change ( like I would like to prove ) , be it to listener's changed appreciation. It is much like new shoes - some really "fit like a glove", some will give you a blister or two before becoming really comfortable. I hope no one will dispute this last claim. It is the same with new car - for certain period or mileage, you are not advised to push it to the max, after certain mileage there is mandatory first service check up - to verify everything is as it should have been.

 

The only audio manufacturer I am aware of that readily offers and encourages such check up after initial burn in is Van den Hul - because every phono cartridge will change its mechanical parameters a little and final adjustments can only be made after burn in of say 50-100 hours of playing. Every other serious cartridge manufacturer will do the same if the cart is returned - I can speak for Benz first hand, because I used to work there.

post #23 of 67
Quote:
Originally Posted by xnor View Post

The problem with giving your headphones to someone to do the measurements pre and post break-in is that you're measuring lots of different things. Lots of variables... Different placement causes large changes. Slight changes in seal can completely ruin low-end response. Different wear of the pads causes measurable changes. Even temperature difference can show up in measurements. IIRC, Tyll said that even a truck driving by changes his measurements. Maybe you even damaged the driver..

 

If that's the case, claiming that you measured changes that are solely due to break-in is patently absurd. On the other hand, if you say some of the changes measured were due to break-in and there's no way to quantify those changes what was the point to do the measurements in the first place?

You're supposed to follow the evidence where it leads, not the other way around.

 

 

Now saying "I've had it with the claims burn in is not real" is another fallacy. Let's assume you've controlled all the variables above and indeed shown that the headphone with nanotube drivers change a lot after playing loud tones. All you've shown is that those kind of drivers change their characteristics after playing loud tones. To generalize that for all headphones makes no sense.

How many headphone with nanotube drivers are there? Two? How many of these are hi-fi headphones? Zero?

I was present at both measurements personally and aided as much as I possibly could. I am aware of the seal problems in LF - artificial ear was used, as it gives more constant seal than possible with artificial head - which was not available in any case. Hp itself was held to the artificial ear using same set of rubbers - as it again gives the most constant seal. Setup was the same in both cases - down to the last cable and connector. Temperature is a known variable - it was held within certain limits, 23 +- 2 degree Centigrade. As was humidity and air pressure. Wear of pads was exactly for the said 48 hours - like it would have been under normal use for he same time. I am aware that vibration, caused by a nearby truck, train, etc can change measuring result. It was quiet and measuring setup does many measurements and presents only averaged result - so this is not likely to affect the result. I did everything humanly possible to insure that the conditions were the same for both measurements.

 

Every other hp to date behaved in similar fashion - to a lesser or greater degree. It can be heard, I did not do measurements, as it is that audible The region most affected is bass, say from 200 Hz all the way down.

 

The 48 hour regime was first devised for burn in of electrostatic drivers, which required too much time using music or pink noise to settle down to their final condition - 25 or so years ago. I believe Stax is doing similar - see report of head-fi visit of Stax. Both to weed out any drivers that might develop faults in the future as well as insuring that customer receives hps that will no longer appreciably change in sound from open box due to use - they have done that so that customer does not have to. 

 

The number of hps using nanotube drivers is growing slowly but steadily. I used nanotubes as they really stick out of normal requirements for burn in - they really sound different after being burnt in and require much more playing to achieve this than more conventional hps. Carbon nanotubes have much different mechanical properties than anything that went on before - some mechanichal parameters are order(s) of magnitude better - depending how and with which material they are compared with. 

 

After seeing the results for the JVC HA-S500, you can judge for yourself if it is hifi or not. You can also check Tyll's measurements on HA-S500.


Edited by analogsurviver - 3/18/13 at 3:43pm
post #24 of 67
Quote:
Originally Posted by analogsurviver View Post

Every other hp to date behaved in similar fashion - to a lesser or greater degree.

Wow, I would hope not greater. I'd be seriously pissed off if a pair of headphones I had changed their sound by over 20 decibels.

 

Before you translate these results, can you say what region this boost/recession occurred in?

post #25 of 67

I hope there are also pre/post THD+N measurements.

post #26 of 67

If a product changes 20dB in 48 hrs, there are a few problems.  

 

1.  The material used in the headphones may be unstable. That much change in that short a time may indicate that the material hasn't reached its final state yet. If some aspect of response showed a 20dB change after 48 Hours of undefined "conditioning", it's possible they will continue to change significantly for a very long time. The problem is, nobody would purposely engineer a product that would change beyond normally accepted tolerance of say +/- 3dB...and even that's a whole lot..for the useful life of the product.  That's just poor engineering and materials selection.

 

2.  The conditioning signal may have over-stressed the materials beyond design limits.  You could for example condition your headphones in a way that would result in a 90dB change, but that would be damaging them with high power.  We could be into the edge of that damaging area.

 

3.  There are only two data points here: the starting condition and the ending condition.  Two data points are not even enough to define a trend, much less any useful rate of change information.   For a proper evaluation of the effects of conditioning, there should have been periodic tests a regular intervals.  

 

4.  There was, as I mentioned before, no "control" to the experiment.  No means of verifying that the test or measurement conditions didn't change.

 

5.  There was no mention made of a measurement made after a significant period of "rest" or "cool down" after the conditioning.  The entire effect could have been the result of deep heating, and that test would have shown that effect.  Perhaps the headphones revert after a period of time.

 

6.  There was mention made of 3Hz and 1Hz changes, which are way out of the design parameters for any headphones.  If that's the area where these huge change occurred, they could be indeed related to material fatigue, but a 20dB change at 3Hz is well into the areal if inaudibility.  

 

Just a few thoughts, not really meant to shoot down the test because we haven't seen the results yet.  But before I would place a whole lot of faith in the generalized concept of "conditioning", I personally would want to know a whole lot more.

post #27 of 67
Quote:
Originally Posted by chewy4 View Post

Wow, I would hope not greater. I'd be seriously pissed off if a pair of headphones I had changed their sound by over 20 decibels.

 

Before you translate these results, can you say what region this boost/recession occurred in?

It will always be where there is maximum amplitude occuring - the lower the frequency, the greater the amplitude ( amplitude goes up inversely to the frequency squared - that is to say, for the same acoustic output, at 20 Hz it is 4 times greater than at 40 Hz ). So, this means bass.

 

I do not believe you would be pissed off if change is from about - 20 dB to about flat response.

post #28 of 67

I have yet to encounter any reliable evidence of the break in effect.

 

I tried 'breaking in' a pair of IEM's very recently: the acclaimed, or at least well reviewed klipsch S4i. They sounded like junk out of the box. I broke them in for about 30 hours over the course of a few days at medium volume. They sounded exactly the same as they did out of the box: like junk. Absolute throwaways. 

 

What's more bizarre than the number of people who believe that headphones can be broken in (it's not a baseball mitt), are all of the positive reviews these horrid klipsch IEM's get. 

post #29 of 67
Quote:
Originally Posted by xnor View Post

I hope there are also pre/post THD+N measurements.

Unfortunately not. After one driver of HA-S770 failed, I reverted the remaining measurements to HA-S500. These were measured only "after" - after much listening that did not provide good enough SQ, after 48 hour burn in regime, after much normal use. THD+N measurements of HA-S500 are very good, the only exception is distortion below say 100 Hz at 100 dB SPL, which is to be expected from 40 mm driver. At 90 dB SPL they are low even in bass.I will try to make several more graphs to showcase this, as it is possible to make graphs for whatever frequency range in order to present the results with best resolution for that range. 

 

For reasons such as these, I noted I would like to have permanent acess to the measuring setup. Ring up any Bruel & Kjaer representative, learn how much it would cost, and it will be soon clear that for anything allowing real work purchase of the whole rig is the only real answer. Based on limited measurements made, it is rather safe to conclude that they still are more comprehensive than what manufacturers usually perform - let alone publish.

post #30 of 67

I bought two pairs of Rockit R50's one for me and on for a gift. That gave me an excellent opportunity to see how they changed in sound quality with break in. First both sets were compared over several different cd's and found to be very similar in sound. Then one set was set on a preamp playing classical music from cable at a moderately loud volume. Every 24 hours I compared the two sets.

 

I found both pairs to be a harsh in the high end and the low end to be constrained at the out set.

 

After 24 hours there was a noticeable improvement in the high end. It sounded less harsh but still had an edge to it. The low end opened up sounding less constrained and have a better bottom end.

 

After 48 hours the improvements continued along the same lines. The difference in enjoyment level between the two sets increased.

 

At 72 hours there was a slight improvement but not as much as the previous two days. The improvement in sound quality was along the same lines. 

 

At 96 hours I couldn't tell any change from 72 hours. 

 

The unbroken in set was still harsh sounding and had the constrained low end. The broken in set was smooth sounding in the high end with the harshness gone. The low end had opened up achieving more definition and better lowest end. The bass no longer sounded constrained. Over all the broken in set was much more pleasing to listen to with out causing fatigue when listened  for long periods.

 

I repeated the break in procedure with the other set comparing them every 24 hours. The sound changes were the same with the second over the 4 days.

 

At the end of 96 hours the two set were again very close to identical. 

 

The mid range in both sets didn't change in a way that I noticed during the break in period.

 

This opportunity to compare two set of IEM's during a break in process convinced me that the break in phenomena is quite real. The difference in my satisfaction level with these IEMs between pre and post break in is significant. In short I like the R50's a lot more after break in than I did when I first got them.

 

This was the second set of R50's I had. The first set had major differences in sound quality right out of the box which did not go away with break in time. The company replaced both sets quickly and without any argument when I sent them an email detailing the large difference in sound characteristics between the two sets. Since I didn't know what the R50's should sound like at that point I was unable to say which of the two sets was at fault. 


Edited by SteadyT - 3/19/13 at 1:09am
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