Isn't that what perception bias is? If you are aware of which 'phone you are listening to then you will expect a difference at least, if not an improvement.
Is burn in real or placebo?
- Thread starter Hifi Man
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Well, what do you do with the second unit? Do you keep it, return it, or sell it? Do you keep the one that sounds better? And which one sounds better, the one you ran for two weeks, or the one that sat in the box? Does the store give you a refund for the unit you bring back? I am amazed that you would have enough money sitting around to buy two of everything and run this little test on them all. Many times.
As fascinating as this sounds, I'd be very surprised if you could "tell the difference" just by listening to a device after two weeks. Your memory of that sound isn't going to last that long. Sorry my friend, but our ears and our memory just aren't that good.
My personal experiences with this phenomenon can be read in a little review I did a short time ago here:
http://www.head-fi.org/t/676593/budget-fi-comparison-schiit-magni-vs-bravo-v2-with-schiit-modi-vs-pure-i-20
You can skip down to the conclusion, epilogue, and last post, for the point, which is this: simply swapping around the amps, dacs, and headphones of two setups I was accustomed to listening to, totally skewed my perceptions of their sound quality. No burn in occurred. No changes in the gear at all. After I finished the comparison, the sound of my M+M stack had changed. A couple weeks after letting my ears re-adjust to the original setups, they started sounding good again. That change was all in my ears and my mind. The gear hadn't changed at all.
Solid state devices do not burn in. There is nothing to burn in, as it were. People have been mis-using the term that is really only properly used when describing part of the tube manufacturing process, for probably a long time, so it has now become an urban myth. What you are hearing is a change in perception within your ears and your mind.
Well, what do you do with the second unit? Do you keep it, return it, or sell it? Do you keep the one that sounds better? And which one sounds better, the one you ran for two weeks, or the one that sat in the box? Does the store give you a refund for the unit you bring back? I am amazed that you would have enough money sitting around to buy two of everything and run this little test on them all. Many times.
As fascinating as this sounds, I'd be very surprised if you could "tell the difference" just by listening to a device after two weeks. Your memory of that sound isn't going to last that long. Sorry my friend, but our ears and our memory just aren't that good.
My personal experiences with this phenomenon can be read in a little review I did a short time ago here:
http://www.head-fi.org/t/676593/budget-fi-comparison-schiit-magni-vs-bravo-v2-with-schiit-modi-vs-pure-i-20
You can skip down to the conclusion, epilogue, and last post, for the point, which is this: simply swapping around the amps, dacs, and headphones of two setups I was accustomed to listening to, totally skewed my perceptions of their sound quality. No burn in occurred. No changes in the gear at all. After I finished the comparison, the sound of my M+M stack had changed. A couple weeks after letting my ears re-adjust to the original setups, they started sounding good again. That change was all in my ears and my mind. The gear hadn't changed at all.
Solid state devices do not burn in. There is nothing to burn in, as it were. People have been mis-using the term that is really only properly used when describing part of the tube manufacturing process, for probably a long time, so it has now become an urban myth. What you are hearing is a change in perception within your ears and your mind.
ferday
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solid state devices do indeed "burn in"! particularly the caps, there are even MIL specs requiring cap burn in before use. this is often called a smoke test (also see bathtub curve). a bit of an internet search will even show up measurements of cap changes, here is one document that i quickly found (i'm lazy beyond that) that lists the MIL specs and offers some explanation. my experience conducting smoke testing is usually 96 hours at elevated temperature. these are not necessarily applicable to all types of caps, all the time, mind you.
1. the vast majority if not all consumer products are smoke tested before sale. they are generally ran at higher temps than normal use and often higher current. the "burn in" is a failure test, not a "burn in" as noted by the audio community
2. the "changes" are very unlikely to be audible, as the changes are magnitudes lower than that of dynamic changes (micro cracking of spiders, stretching of diaphragms, etc) which are already measured to be not likely audible....not to mention that the slight change in voltage may not even affect the rest of the circuit in any way at all!
3. it has been shown that the amount of change depends on the construction of the cap. some caps will "degrade" slowly over time, but can be refreshed with a shot of high temp. some caps are temp compensating.
if one replaces the caps in their equipment with brand new units, it is likely that a measurable (using intense equipment) change might occur during the burn in. my skepticism is the audibility of the change (or even that the change will affect the rest of the circuit in any way, particularly as it moves down to the end of the signal chain), and for pre-built consumer units, they have all been burned in already and as such will not exhibit change over time.
solid state devices do indeed "burn in"! particularly the caps, there are even MIL specs requiring cap burn in before use. this is often called a smoke test (also see bathtub curve). a bit of an internet search will even show up measurements of cap changes, here is one document that i quickly found (i'm lazy beyond that) that lists the MIL specs and offers some explanation. my experience conducting smoke testing is usually 96 hours at elevated temperature. these are not necessarily applicable to all types of caps, all the time, mind you.
1. the vast majority if not all consumer products are smoke tested before sale. they are generally ran at higher temps than normal use and often higher current. the "burn in" is a failure test, not a "burn in" as noted by the audio community
2. the "changes" are very unlikely to be audible, as the changes are magnitudes lower than that of dynamic changes (micro cracking of spiders, stretching of diaphragms, etc) which are already measured to be not likely audible....not to mention that the slight change in voltage may not even affect the rest of the circuit in any way at all!
3. it has been shown that the amount of change depends on the construction of the cap. some caps will "degrade" slowly over time, but can be refreshed with a shot of high temp. some caps are temp compensating.
if one replaces the caps in their equipment with brand new units, it is likely that a measurable (using intense equipment) change might occur during the burn in. my skepticism is the audibility of the change (or even that the change will affect the rest of the circuit in any way, particularly as it moves down to the end of the signal chain), and for pre-built consumer units, they have all been burned in already and as such will not exhibit change over time.
jaddie
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If you know which one you are listening to, your perception is biased by that knowledge. If there's something you even slightly prefer about that choice, even subconsciously, you'll hear a difference, even if there is none. If someone has told you that one is better for any reason at all, you can hear the difference, even if there is none. In a true double blind test, you won't know what choice you're listing to. The task will not be to determine the difference, but to match choice A or choice B with choice X which will be either A or B, but unknown to you. A statistically high score after a minimum of 16 to 20 trials in which X is scrambled for each indicates you can hear a difference without perception bias.
Quote:
Suggestion is far more powerful than you realize. The placebo effect is real, well documented, and unescapable.
If you know which one you are listening to, your perception is biased by that knowledge. If there's something you even slightly prefer about that choice, even subconsciously, you'll hear a difference, even if there is none. If someone has told you that one is better for any reason at all, you can hear the difference, even if there is none. In a true double blind test, you won't know what choice you're listing to. The task will not be to determine the difference, but to match choice A or choice B with choice X which will be either A or B, but unknown to you. A statistically high score after a minimum of 16 to 20 trials in which X is scrambled for each indicates you can hear a difference without perception bias.
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Suggestion is far more powerful than you realize. The placebo effect is real, well documented, and unescapable.
Baxide
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I use the 2nd unit in a different part of the house. In some cases I have several of the same item. Like 5 pieces of the SB Touch, or four of the same Sony TV. I do have a big place after all. As far as money is concerned, why do you assume I am poor and incapable of affording the nicer things in life? I can probably sell just my watch and use the money to buy the equivalent of your whole audio and video set up.
I am surprised that you are surprised that I can't hear the difference after two weeks. It's not a question of memory, but direct comparison between the two. You are obviously making excuses as you go along instead of paying attention on how to conduct your own test by direct comparison between two identical units.
I use the 2nd unit in a different part of the house. In some cases I have several of the same item. Like 5 pieces of the SB Touch, or four of the same Sony TV. I do have a big place after all. As far as money is concerned, why do you assume I am poor and incapable of affording the nicer things in life? I can probably sell just my watch and use the money to buy the equivalent of your whole audio and video set up.
I am surprised that you are surprised that I can't hear the difference after two weeks. It's not a question of memory, but direct comparison between the two. You are obviously making excuses as you go along instead of paying attention on how to conduct your own test by direct comparison between two identical units.
xnor
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DavidJ1973
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Before ever knowing what burn-in was, I remember a distinct point in time when my old Grados seemed to sound more balanced. I even took them off my head and looked at them quizzically. The highs were still there but the lows were deeper. I tried numerous different tracks from a bunch of different genres and they all seemed better. I didn't think much of it but about two years later came across a friend talking about burn-in with his Sennheisers. Placebo? Maybe. But I think I experienced it without even knowing it existed.
Quote:
I think you just made my point. 96 hours is a bit of a protracted test, but that's still on the order of a smoke check. One day, or a few days, is not much in terms of burn in. Even so, the process you're describing is a smoke check. That isn't burn-in. There's nothing in a capacitor to burn in. You're just making sure it works under full load for a longer period of time than most people would ever expose the device to. That by definition is a smoke check.
The process you describe does not do for a capacitor, what burn-in does for a vacuum tube. At this point I'm going to refer you to my earlier posts, because I don't care to repeat myself. The whole concept of burning in a vacuum tube is wholly unlike what you're talking about. What I tend to see being discussed on Head-Fi constitutes a confusion of what burn-in means. It isn't surprising really, because even today there are very few companies who make such devices. The number of people familiar with the process is very small. And I probably know many of them
When I made tubes, we burned them in for 1000 to 1500 hours. Of course, those were rather specialized tubes that lasted many years, in continuous usage (not like glass envelope vacuum tubes). That's 42 to 62 days, give or take a couple hours. But, the length of time isn't really the issue. What burn in does for a vacuum tube is a couple of things, mainly, continuing the outgassing of the materials in the tube that flashing the getter started, and stabilizing the output so that it becomes a reliable amplification device. It also confirms that the device will work as long as expected (in the case of a TWT, 15 years in continuous usage). Tubes that were faulty would either lose their vacuum, become unstable, or output power would slowly drop over the length of the burn in period.
So, yeah. Burn in is for vacuum tubes. Solid state devices are smoke checked, and they don't change (which was, after all, the primary advantage of solid state devices when they first came out).
I think you just made my point. 96 hours is a bit of a protracted test, but that's still on the order of a smoke check. One day, or a few days, is not much in terms of burn in. Even so, the process you're describing is a smoke check. That isn't burn-in. There's nothing in a capacitor to burn in. You're just making sure it works under full load for a longer period of time than most people would ever expose the device to. That by definition is a smoke check.
The process you describe does not do for a capacitor, what burn-in does for a vacuum tube. At this point I'm going to refer you to my earlier posts, because I don't care to repeat myself. The whole concept of burning in a vacuum tube is wholly unlike what you're talking about. What I tend to see being discussed on Head-Fi constitutes a confusion of what burn-in means. It isn't surprising really, because even today there are very few companies who make such devices. The number of people familiar with the process is very small. And I probably know many of them
When I made tubes, we burned them in for 1000 to 1500 hours. Of course, those were rather specialized tubes that lasted many years, in continuous usage (not like glass envelope vacuum tubes). That's 42 to 62 days, give or take a couple hours. But, the length of time isn't really the issue. What burn in does for a vacuum tube is a couple of things, mainly, continuing the outgassing of the materials in the tube that flashing the getter started, and stabilizing the output so that it becomes a reliable amplification device. It also confirms that the device will work as long as expected (in the case of a TWT, 15 years in continuous usage). Tubes that were faulty would either lose their vacuum, become unstable, or output power would slowly drop over the length of the burn in period.
So, yeah. Burn in is for vacuum tubes. Solid state devices are smoke checked, and they don't change (which was, after all, the primary advantage of solid state devices when they first came out).
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Well now, there's no need to get obnoxious and pompous. If that's how you roll, then I'll just redirect your emotional vomit to /dev/null.
I doubt that there is any human being capable of remembering what something sounded like after two weeks. Now, if you had described a scientific method of testing your theorem, then I would have been impressed, and probably convinced by your argument. However, since all you offered was anecdotal evidence, then that is all I can presume about your test methods. You have no data to back up your argument. You didn't describe how you captured or recorded this data. If all you're talking about is your memory and your ears, then I suggest that both are flawed, and you really should reconsider whether you should be so confident in your conclusions.
Well now, there's no need to get obnoxious and pompous. If that's how you roll, then I'll just redirect your emotional vomit to /dev/null.
I doubt that there is any human being capable of remembering what something sounded like after two weeks. Now, if you had described a scientific method of testing your theorem, then I would have been impressed, and probably convinced by your argument. However, since all you offered was anecdotal evidence, then that is all I can presume about your test methods. You have no data to back up your argument. You didn't describe how you captured or recorded this data. If all you're talking about is your memory and your ears, then I suggest that both are flawed, and you really should reconsider whether you should be so confident in your conclusions.
jaddie
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Wow, so you made traveling wave tubes? Klystrons too? Did you work for Varian?
I had the opportunity to walk through the GE plant with the last remaining tube production line in 1983. There was an huge rack for burning in tubes, hundreds at a time, before final test.
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No. Varian was one of our primary competitors. I worked for Hughes Electron Dynamics (it's still there, but it's owned by L3 now, and called Electron Technologies Inc). We didn't make Klystrons. We made all the TWT's for commercial microwave amps, satellites, radar, ECM's, and other stuff that I can't discuss. The really big tubes were the exciting ones to work on (things that you needed a crane to lift, and a cart to move around). I worked with voltages in the 5-figure range for a while. Talk about exciting LOL. We learned that people who made mistakes usually only made them once. I was pretty lucky, I only got hit a couple times, once with 800 volts, and once with 3000 volts. I still have the entry mark on my arm (it went all the way through me).
Maybe that's why I have such an electric personality?
No. Varian was one of our primary competitors. I worked for Hughes Electron Dynamics (it's still there, but it's owned by L3 now, and called Electron Technologies Inc). We didn't make Klystrons. We made all the TWT's for commercial microwave amps, satellites, radar, ECM's, and other stuff that I can't discuss. The really big tubes were the exciting ones to work on (things that you needed a crane to lift, and a cart to move around). I worked with voltages in the 5-figure range for a while. Talk about exciting LOL. We learned that people who made mistakes usually only made them once. I was pretty lucky, I only got hit a couple times, once with 800 volts, and once with 3000 volts. I still have the entry mark on my arm (it went all the way through me).
Maybe that's why I have such an electric personality?
upstateguy
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Baxide
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Why? The issue in question is whether I am financially capable of being able to afford to have more than one of the same item for testing purposes to determine if burn in exists or not. Well I am able to afford the stuff and spend my hard earned wages whichever way I please. Nothing pathetic about that. More like jealousy from your end.
xnor
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