What Exactly Does "Burn In" do for Electronics?

To those who don't believe in, or who haven't heard a difference, with burn in:

- please sell me that brand new bad sounding $2500 phono cartridge with only 10 hours on it for 40% of what you paid for it

I can't even count the number of cables or electronic pieces or capacitors or other parts of all types that have continually changed with "burn in" use over time. The change isn't subtle from start to finish, though it can be subtle in degrees. 20-50 hours isn't usually enough time to get to the end of that change. More like 100-200 hours.

All I can think is ... if you can't hear it then maybe your system isn't as resolving as you think.

"06-16-14: Ptmconsulting
To those who don't believe in, or who haven't heard a difference, with burn in:

- please sell me that brand new bad sounding $2500 phono cartridge with only 10 hours on it for 40% of what you paid for it"

In all fairness to some of the other posters, I believe they were mainly talking about cable break in. Typically, a new phono cart breaks in more than any other component. To me, they sound broken when they are new. Cable break in is usually much more subtle (but it definitely happens). But they're not all the same. For example, I don't notice that much break in with my AQ cables. There is some, but they get to where they should be fairly quickly. I have some Cardas cables that take forever. 100's of hours.

06-16-14: Zd542
I have some Cardas cables that take forever. 100's of hours.

ZD, as I'm sure you realize I have great respect for your experience and your sonic perceptions. But a question: How do you know that the improvement you are perceiving after 100's of hours is due to the cables, and not to something else in the system that has changed in the meantime? Or, for that matter, something that has changed in the AC power, or even the temperature or humidity of the room?

My question is prompted in particular by reports I have seen here from others about cables and power cords requiring seemingly absurd burn-in durations, e.g., 800 hours or more. Unless, and perhaps even if, that is done independently of operation of the system, such as with a cable cooker, or in a different system, or by using a power cord to power a refrigerator, etc., I don't see how any such changes can be distinguished from effects that may be occurring elsewhere in the system or its environment.

And even if the burn-in is done via one of those alternative methods, given that 800 hours represents more than a month of 24/7 operation, it would still seem very possible that some unrelated effect might occur in the system or its environment in that period, that could be responsible for the perceived change.

Best regards,
-- Al

06-16-14: Almarg

06-16-14: Zd542
I have some Cardas cables that take forever. 100's of hours.
ZD, as I'm sure you realize I have great respect for your experience and your sonic perceptions. But a question: How do you know that the improvement you are perceiving after 100's of hours is due to the cables, and not to something else in the system that has changed in the meantime? Or, for that matter, something that has changed in the AC power, or even the temperature or humidity of the room?

Best regards,
-- Al

Yes as Al has pointed out this this greatly overlooked.
Take any hybrid ESL speaker for instance, they are tuned for a certain sound by the factory.
The esl panel on a day when the humidity is 70%-100% can loose as much as -3db efficiency, making the balance sound bass heavy as the dynamic bass driver has not lost this -3db.
I have measured it on my new panels, dry day 5kv bias charge and on a humid day 3kv-4kv bias charge, I tend not to do any evaluations or serious listening on days when the humidity is above 70%. Or if I have to, I can with some trouble turn down the gain of the bass electronics by the appropriate amount so all is balanced again.

Cheers George