[BlackbeardBen]

Your entire post is a pointless rant. You say yourself you're not an expert. You also tell me that I "need to measure it," when you already know that it's far too late for that. The manufacturer told me that burn in with their amps is a real phenomenon. Moreover, I heard the difference with my own ears. I think I'll go with the people who actually built the amp and with my own ears rather than a bunch of people who don't know what they're talking about. The people on this thread are quite scary: so wrong and yet so sure of themselves. If you don't want to believe that the amp improved its sound, then don't. You will just continue to be W-R-O-N-G. But don't feel bad about it; you have plenty of company on this thread. There are plenty of people here who are just as wrong as you are.

I'm not an expert on burn-in (no one is), but I am an engineer, and I understand the scientific method. Claims of burn-in are unsupported by published objective evidence of any kind. Without that evidence, you cannot make the claim that it has an effect on burn-in and assume it is unequivocally true without unbiased, objective evidence. If that were acceptable, we'd have all manner of ridiculous claims... Well, we do anyway.

I'm not saying that every end-user must measure burn-in - only saying that if one wants to prove that it is real, it must be measured. You can believe whatever you want - that in itself doesn't make something real, but it can have a large effect on what we perceive...

nick_charles is right - it would not be difficult at all for a manufacturer to take and publish measurements if they really had something to prove. Then, at least, there would be something for a neutral third party to confirm or refute with its own tests (as you can't be serious that manufacturers are unbiased).


Anyway, here's a more broad survey of many manufacturers regarding burn-in (of speakers):
http://www.matrixhifi.com/ENG_contenedor_rodajealtavoces.htm

Which one do you believe? There's no consensus... I know that's about transducers and not amplifiers - but speaker crossovers themselves contain many of the components that amps have - especially the all-important electrolytic capacitors.

 

[EthanWiner]

Quote:

Could you ask the amp maker to do some measurements, it would be trivial for them to take a freshly baked amp and measure its response and let it burn-in for a few weeks and then measure its response again, in fact if burn-in is so crucial why do they not do this as a matter of course since by their view the product is not ready when it is released!

I asked for that too a hundred-odd posts back.
 
--Ethan

 

[Heidegger]

Frankly, I would be embarrassed to ask them, especially since they already know who I am. But if you or Nick want to make the request, go ahead. I would be interested to know how they respond.
 
http://www.lehmannaudio.com/

 

[upstateguy]

Has any manufacturer ever made before and after measurements to demonstrate burn in?
 
 
Maybe this is something Tyll knows about from his headphone measurements. 
 
In all the measurements he made, he must have had the occasion to measure a well burned in pair of headphones Vs a brand new pair....   the same with headphone cables.  He must have measured headphones with new cables and the same headphones with well burned in cables......  At the very least, one would think that out of curiosity, he measured his own stuff before and after re-cabling and when they were new as and when they were burned in....
 
Perhaps we can get Tyll to weigh in on this.............
 

 

[Uncle Erik]

If burn in is real, why don't manufacturers offer it as a service? It'd be blindingly simple to set up a board where headphones could cook for a few hundred hours. It'd probably cost a dollar or two in electricity and then they could charge an extra $50 or $100 for a "factory burned-in" headphone.

You know some people would pay for that.

It would be a beautiful way to pad margins.

 

[maverickronin]

Do these abominations count?

 

[Willakan]

If burn in is real, why don't manufacturers offer it as a service? It'd be blindingly simple to set up a board where headphones could cook for a few hundred hours. It'd probably cost a dollar or two in electricity and then they could charge an extra $50 or $100 for a "factory burned-in" headphone.

You know some people would pay for that.

It would be a beautiful way to pad margins.

You could apply the same argument to headphone recabling. If it really makes such a difference, why don't manufacturers take advantage? Again, huge margins are possible. And you know how EVERY expensive headphone magically ships with a cable that makes it sound horrible until you replace it with a solid silver one, cryogenically frozen and soaked in yak's milk at a full moon.

How can the headphone manufactures sit by as they ship their horribly crippled headphones? We should start a petition or something.

 

[Prog Rock Man]

Quote:

If burn in is real, why don't manufacturers offer it as a service? It'd be blindingly simple to set up a board where headphones could cook for a few hundred hours. It'd probably cost a dollar or two in electricity and then they could charge an extra $50 or $100 for a "factory burned-in" headphone.

You know some people would pay for that.

It would be a beautiful way to pad margins.

Pay £15 and Russ Andrews provide a cable burn in service  Clicky
 
I cannot find the link, but in one of the burn in threads in Sound Science there is a link to an attempt to burn in a headphone and then ABX test it with one not burned in. They gave up when they found no two headphones measured the same when new. So each one is slightly different anyway and that was not audible.
 
Heidegger, please read/re-read the opening post of this thread. I have added more tests recently. That is a heck of a lot of evidence that people when using their ears alone cannot hear differences between a whole host of hifi. Here we ask for people to listen to the music and not look at the hifi when deciding if hifi maker and reviewer claims are correct or not.
 

 

[Prog Rock Man]

Quote:

Frankly, I would be embarrassed to ask them, especially since they already know who I am. But if you or Nick want to make the request, go ahead. I would be interested to know how they respond.
 
http://www.lehmannaudio.com/

Lehmannaudio have now been e-mailed with a link to this thread and asked, do you ABX test, do you thin there is burn in and could you share any evidence of such?

 

[nick_charles]

Quote:

Frankly, I would be embarrassed to ask them, especially since they already know who I am. But if you or Nick want to make the request, go ahead. I would be interested to know how they respond.
 
http://www.lehmannaudio.com/

 I have emailed them a question asking for the mechanics of burn-in and for their measurements.

 

[ryflmn]

So essentially, the best bang for the buck are speakers/headphones.  Would everyone agree that this is where the greatest difference lies?

 

[Tyll Hertsens]

Quote:

 
Maybe this is something Tyll knows about from his headphone measurements. 
 
In all the measurements he made, he must have had the occasion to measure a well burned in pair of headphones Vs a brand new pair....  
 
Perhaps we can get Tyll to weigh in on this.............
 

Aha! Well...this is timely.  I, in fact, just received a couple of pairs of Quincy Jones Q701s.  Last week I left a pair on the test system and measured them fresh out of the box, then played pink noise at 90dB SPL in them and measured them: a second time immediately after the first test: then at intervals of 5min, 10 min, 20 min, 1 hr, 5hr, 10hr, 20 hr, 40hr, 60 hrs and 100 hrs all without moving the cans at all. Next week I will be doing some subjective listening with those cans (which have been burning in more), and a fresh set out of the box. 
 
My guess is that one will not be able to tell the difference between the curves visually, but I will be able to difference the measurements one against the others and come up with a fairly sensitive set of curves showing the differences of burn-in over time. I still doubt well see much, but the data is in the can and awaits analysis.
 
Since I have not observed the data, it rests rather like Schodinger's cat on Excel spreadsheets awaiting the deterministic moment. Should anyone feel that they have a particular view at stake, I suggest now is the time to start praying about the situation, and possibly by force of will it's outcome can be shaped by your desires.
 

 

 

[Jack C]

So essentially, the best bang for the buck are speakers/headphones.  Would everyone agree that this is where the greatest difference lies?

I agree with that conclusion but would caution that the other parts of a system should deserve the proper amount of attention as well. When is something "adequate" is up to personal preferences, and these are different for each listener. Ultimately, I am a strong believer in placing the majority of a system budget into the speaker/headphone than other parts of the system.

Jack

 

[nick_charles]

Dialogue with Norbert Lehmann, reproduced with permission.
 
 
Quote:

My message

Hello, I have been interested in high fidelity audio for over 35 years, I have been reading much about the controversy about solid state burn-in recently. I understand from fellow audiophiles that you are a proponent of such burn-in. Would you be able to explain to me how this works with respect to your SS headphone amps. What elements are burning-in, what physical changes are occurring and how do you measure the effect of this burn-in i.e do you do before and after measurements ?

Sincerely

Nick Charles, PhD

 
 
 
Norbert Lehmann's reply Quote:

[size=11pt]Dear Dr. Charles,[/size]
[size=11pt] [/size]
[size=11pt]thank you for contacting me in this matter. I experience sound improvements in several aspects over time, at least for some weeks.  To me it does not matter where the effects come from. What I guess to be  very important is the overall thermal stability of the circuit. There are, however, _no_ differences to be measured at least with my Audio Precision ATS2  which is a very nice unit for production tests but no real state of the art unit like the 2700 type. [/size]
[size=11pt] [/size]
[size=11pt]This is a rather unacademic approach for an engineer - but it helps. Sorry that I can't  supply a more satisfying answer. [/size]
[size=11pt] [/size]
[size=11pt]With kind regards from Germany[/size]
[size=11pt] [/size]
[size=11pt]Norbert Lehmann[/size]

 
 
 
 
 
 

 

[khaos974]

Quote:

Aha! Well...this is timely.  I, in fact, just received a couple of pairs of Quincy Jones Q701s.  Last week I left a pair on the test system and measured them fresh out of the box, then played pink noise at 90dB SPL in them and measured them: a second time immediately after the first test: then at intervals of 5min, 10 min, 20 min, 1 hr, 5hr, 10hr, 20 hr, 40hr, 60 hrs and 100 hrs all without moving the cans at all. Next week I will be doing some subjective listening with those cans (which have been burning in more), and a fresh set out of the box.
 
My guess is that one will not be able to tell the difference between the curves visually, but I will be able to difference the measurements one against the others and come up with a fairly sensitive set of curves showing the differences of burn-in over time. I still doubt well see much, but the data is in the can and awaits analysis.
 
Since I have not observed the data, it rests rather like Schodinger's cat on Excel spreadsheets awaiting the deterministic moment. Should anyone feel that they have a particular view at stake, I suggest now is the time to start praying about the situation, and possibly by force of will it's outcome can be shaped by your desires.
 

Provided that measurement error margins aren't higher than a hypothetical difference in measures due to burn in