[dirtrat]

I'm glad you are open to the possibility that there are exceptions, because there are:

All transistors have very wide gain (the order of 80-350). Even the Hfe gain band selected types. This does not tend to affect burn in much, but is the main resdon for their being a finite warm-up time in amplifiers. It also can change the amplifier's audio stability if the amp is driven hard, particularly into clipping, taking sometimes minutes to recover. Their bandwidth, input capacitance, Vbe (on voltage), and many other parameters vary wildly between samples and temperatures. This is why discrete audio design involves experience and knowledge.

Electrolytic capacitors are far from tight tollerance. The best available are 10% in terms or their capacitance, these are rarely used. +/-20 % is commonly considered high quailty, and low cost gear uses +80/-20% tollerance, which if used with abandon will result in very lose consistancy between unit. However a little known and certainly overlooked factor is that a key characteristic of theirs: ESR (Electrical Series Resistance), or how closerly they represent a low impedance at higher frequencies, changes over time. Now it is well known by professional electronic engineers that is goes up over time slowly, as the componant wears out. This is VERY slow, and generally you will only noticed the effect when you find someone whop can change these components out for new parts, say 20-40 years of use. (don't worry, the 1% capacitors that should be in you RIAA phono stage are different and super stable, if the designer knows anything.)

However, what is less common knowledge, is these same parts go through a rapid change of ESR over the first few 10s of hours after the unit is switched on. The ESR goes down as the electrolyte settles to its working voltage, which improves their performance. The change is quite significant, and I would not be surprised if some equipment it could be audible.

A competant audio designer needs to design out these factors as much as possible. However you can only attenuate the effect, and it often cost money to do so. So this can be why high end gear gets expensive, but consistantly good.

Belief is a wonderful thing, but in Sound Science it should give way to repeatable results and scientific measurement.

I'm not buying your explanation but that's fine, we are all entitled to our OPINIONS. What's funny is I don't remember people talking about burn in much back in say the 1970's. I guarantee component tolerances are made to a higher standard now especially very high-end audio equipment. I know Resistor tolerances are better today and power supplies and voltage regulation can be built to much better standards. Many times, parts are hand selected and matched. Again, as far as I know there is no widely accepted definitive scientific study that proves beyond a shadow of the doubt that burn-in is a real phenomenon that greatly improves the sound quality. Like I said before I'm guessing there are exceptions to this, I'm sure but again I can't prove anything!

 

[castleofargh]

1/There is inevitable change over time. chemical, mechanical, dark energy made of quantum gremlins.

2/Then there is the question of when those changes get audible. That will only make a portion of the changes. Portion made even smaller when considering how many of the clearly audible changes using direct switch, would go unnoticed when stretched over a long period of time.

3/Last but not least, there is the question of finding out how many of the audiophile testimonies about driver burn-in have something to do with it. Personally, I'd be absolutely amazed if even 1% of the testimonies were correct. By correct I mean, memories and impressions in line with the actual sound change, and that change actually being caused by driver burn-in.

 

[bigshot]

If a clearly audible change occurs in a relatively short period of time, I’m going to assume it’s due to a defect in manufacturing and return the item. If burn in is real, I want them to do that at the factory before the transducers are matched, not after I’ve bought the headphones. I expect tight response tolerances.

 

[old tech]

I'm glad you are open to the possibility that there are exceptions, because there are:

A competant audio designer needs to design out these factors as much as possible. However you can only attenuate the effect, and it often cost money to do so. So this can be why high end gear gets expensive, but consistantly good.

Belief is a wonderful thing, but in Sound Science it should give way to repeatable results and scientific measurement.

My last purchase of active speakers cost nearly $3k, and that was direct from the manufacturer no middle men taking a cut. The company does not engage in marketing bs or embellishment. The manual that came with the speakers specifically states no burn in is required and goes on to explain why this belief is a myth.

 

[bigshot]

Burn in is a way to get consumers to burn through their return window.

 

[jagwap]

If a clearly audible change occurs in a relatively short period of time, I’m going to assume it’s due to a defect in manufacturing and return the item. If burn in is real, I want them to do that at the factory before the transducers are matched, not after I’ve bought the headphones. I expect tight response tolerances.

For the LAST time, it does not affect frequency repsonse. The things it affects, like complience, are not practically measurable on the production line. The gear to do it is prohibitively expensive for production test equipment, and only lives in R&D labs. But the manufacturers of that test gear, Klipple, have published data on burn-in, which I have linked to here before.

If burn in takes 100 hours, do you expect speaker manufacturer making thousands a week to have them running at high power levels in a giant sound proof warehouse before shipping? This is an expense that most customers would not want to absorb.

 

[bigshot]

If it isn’t measurable, then how could it be audible? Clearly audible changes in sound in a short period of time is a red flag. It isn’t something you should expect.

 

[jagwap]

I'm not buying your explanation but that's fine, we are all entitled to our OPINIONS. What's funny is I don't remember people talking about burn in much back in say the 1970's. I guarantee component tolerances are made to a higher standard now especially very high-end audio equipment. I know Resistor tolerances are better today and power supplies and voltage regulation can be built to much better standards. Many times, parts are hand selected and matched. Again, as far as I know there is no widely accepted definitive scientific study that proves beyond a shadow of the doubt that burn-in is a real phenomenon that greatly improves the sound quality. Like I said before I'm guessing there are exceptions to this, I'm sure but again I can't prove anything!

There were no opinions in my explanation.

 

[jagwap]

If it isn’t measurable, then how could it be audible? Clearly audible changes in sound in a short period of time is a red flag. It isn’t something you should expect.

It is measurable by Klipple, as they explain in the paper I link to YOU before.

"There is nowt so daft that will ne listen"

 

[bigshot]

You talk in circles. Is it clearly audible?

 

[CoryGillmore]

In my experience, the sound of gear does change, sometimes drastically, over the course of the first day, week, month(s). Whether it's new or used. Yeah, new or USED. This tells me it's all in our heads. I mean yeah it IS real, relatively.
You see people all the time who claim drastic frequency response changes over the course of "burn-in". Yet, as far as I know, no one has ever measured these "drastic frequency response changes" before and after.
Audiophiles hate admitting their mind is playing tricks on them. But that's exactly what is happening. You're just acclimating to a new sound. I go through the same damn thing every time I switch to one of my other headphones after using something else for a while.
Or if I just listen to my 2-channel system for a while all of my headphones sound like trash.

 

[dirtrat]

There were no opinions in my explanation.

Your right, it just wasn't a good one and explained nothing! It's all good, after all, this is what I expected when I jumped into this topic. Nobody's opinion on this subject is any more relevant than anyone else's including mine. Believe what you want and enjoy the music.

 

[jagwap]

You talk in circles. Is it clearly audible?

In speakers it is clearly audible and measurable (By speakers I mean hi-fi, pro audio and other transducers with some resolution. Built in speakers in a laptop are unlikely to be audible to any noticable extent I think). It varies depending on material as to the extent of change, and the number of hours it takes. When you work in the industry you have access to multiple examples of the same product at different stages of burn-in, it is regularly evident.

When you are a arm-chair expert you either except the people working on this daily, or stick your fingers in your ears so that you cannot hear anything that disagrees with your entrenched point of view.

I do not talk in circles, unless it is chasing your ever increasing circles or selective memory. You are either blinkered, or trolling.

 

[jagwap]

In my experience, the sound of gear does change, sometimes drastically, over the course of the first day, week, month(s). Whether it's new or used. Yeah, new or USED. This tells me it's all in our heads. I mean yeah it IS real, relatively.
You see people all the time who claim drastic frequency response changes over the course of "burn-in". Yet, as far as I know, no one has ever measured these "drastic frequency response changes" before and after.
Audiophiles hate admitting their mind is playing tricks on them. But that's exactly what is happening. You're just acclimating to a new sound. I go through the same damn thing every time I switch to one of my other headphones after using something else for a while.
Or if I just listen to my 2-channel system for a while all of my headphones sound like trash.

Why can't both effects exist? Working together or separately? Physical burn in AND acclimatizing to the new sound?

I have stated above, in transducers, it is not frequency response that is affected, but mostly the driver's compliance (springiness curve).

 

[bigshot]

In speakers it is clearly audible and measurable

And it doesn't affect frequency response... Then it must affect amplitude across the entire frequency range. We're talking about dynamics, right?

I'm guessing by the way you're phrasing things that there's no evidence that this applies to headphones, correct?