3. Thermal Compound, depends on which compound to be used. "Then the compound thickens slightly over the next 50 to 200 hours of use to its final consistency designed for long-term stability. "
Yeah, but I believe almost all of this "burn In" effect is occurring in our brain.
When we walk in a old church, we immediately notice the long echo, but by the time we leave there, we usually forget about it.
I think the reason why it takes more time for our aural system to accustomed to the audio system is, our brain have not trained for those unnatural sound. When we go to audio show or someone's audio room, our brain start ignoring the room artifact in very short time (in a few minutes?), but to be accustomed to audio equipment takes much longer time, I believe. Well, I know this is my own Pseudo Science.
I think the reason why it takes more time for our aural system to accustomed to the audio system is, our brain have not trained for those unnatural sound. When we go to audio show or someone's audio room, our brain start ignoring the room artifact in very short time (in a few minutes?), but to be accustomed to audio equipment takes much longer time, I believe. Well, I know this is my own Pseudo Science.
I note that you have not actually disagreed with the three statements which I made, particularly the last one.
I don't doubt your ability to perceive and eliminate the 'distortion hardness' you encounter while setting up a new or reworked amplifier. You appended your own suggestion as to the origin of this distortion with the question "or something like that?", thus encouraging me to make my contribution.
Is this 'initialising' something that a purchaser might catch when auditioning their new amplifier and, if so, how long does the process take?
Why do the believers in 'burn-in' only state that an amplifier or system sounds distorted or horrible on first switch-on.?
Why does it never sound superb but degrades with time?
Surely this is equally possible !!
Andy
As you see, peoples experiences vary, sometimes probably due to exposure, some aren’t aware , others have encountered , making it even more interesting
What if the only people hearing burn-in are those expecting it and experiencing some strong congnitive bias (which bias I'll leave people to choose from this list of established human biases :List of cognitive biases - Wikipedia) >
Then only those with the bias will be "exposed" to it .
To then say some are exposed to it and some are not requires to already believe in its existence. How can one be exposed to something if it possibily doesn't exist?
I guess you won't hear anything until you believe harder!
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Warm-up is obvious, it is room temp when switched on, and after some time it is (a lot) hotter. Class A more so than others, but all will warm up to some degree ;-)
But why would that lead to audible differences?? If it does, you are allowed to say it is badly designed.
Sometimes I get the feeling that changing sound with temperature is regarded here as something good. But it is only a sign of incompetent design.
Jan
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Hahaha. Changing sound with temperature is regarded as a sign of good equipment is very audiophile thinking. I think I know where that feeling is coming from: "Since there is no perfectly designed amp, the designer has to compromises somewhere, and temperature more unstable amps should have less compromise in sound." It would be a ridiculous idea, but maybe would not be completely unreasonable.
I wish my amp would sound the same right after turn on and after 10 minutes, off course!
I wish my amp would sound the same right after turn on and after 10 minutes, off course!
I don't see a lot of variation of opinion in the posts received so far. The majority question the existence of burn in as a legitimate phenomenon..
My phono preamp takes about 30 minutes (more in winter when ambient is lower) to warm up. The most noticeable difference is a slight increase in gain as it warms. Starting from cold one or two LP sides gets it to the stable point, and of course if I left it powered on it would stay that way. The mechanism is well understood and could likely be overcome with a CCS in the input stage, for a slight noise penalty. I am happy to turn the volume down a couple of clicks after the first fouple of records.
The only Burn In I have ever experienced was in the early 1980s while working for Texas Instruments in the Industrial Controls Division.
We had the entire back of one manufacturing module fitted with "Burn In Racks" inside temperature controlled chambers.
Newly manufactured products would be mounted on racks and power cycled at elevated temperature for 7 days (60C IIRC) with a new design to determine the time for infant mortality to be established. After the initial characterization, products usually only were burned in for 24 Hrs.
This was to eliminate component defects which resulted in early failure (which at the time were very high) before products were shipped to customers.
The defects were not shift in component value of discrete components, but rather failure of integrated circuits.
We had the entire back of one manufacturing module fitted with "Burn In Racks" inside temperature controlled chambers.
Newly manufactured products would be mounted on racks and power cycled at elevated temperature for 7 days (60C IIRC) with a new design to determine the time for infant mortality to be established. After the initial characterization, products usually only were burned in for 24 Hrs.
This was to eliminate component defects which resulted in early failure (which at the time were very high) before products were shipped to customers.
The defects were not shift in component value of discrete components, but rather failure of integrated circuits.
Is that really so ? Wouldn't a good design be such that it sounded best at it's mean temperature, the one it will operate at for 99% of its time? Wouldn't one have to spend a lot of time to either re-design components so they didn't change spec at different temps or have to make loads of inefficient work-arounds to counter the effects?
Unless you're saying that off the shelf components don't change spec (I don't actually know if they do or not but have always assumed they do.. I'm open to learn differently) then it would surely be a more efficient design that thought ahead to spec changes and incorporated them - if people just wait for it to warm up.
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