Burn in question and evaluation before burn in


We all experienced sound transformation before and after a new equipment or cable is burned in, however, I am wondering if there is a general rule as to which direction any burn in would be heading? Specifically, I am interested to know would sound generally go smoother/darker or brighter/more transparent after burn in? I am thinking if there is such a rule, it would be valuable to know for evaluating products.
wenrhuang
Right on the money Albert! And any good designer will voice his equipment with the presentation of the components AFTER stabilization in mind. Hopefully- transparency will be their goal.
Albert,

I never said break in was not real. I just prefer components that are engineered to be precise and that do not drift dramatically with time. It is a simple design choice to place a capacitor in the signal path or not. It is a simple design choice to either place a capacitor in a passive crossover (where it adds distortion) or use a line level x-over filter. One can also design circuits so that they drift less with age and temperature through careful selection of components and design. I could go on about driver design as well -many drivers change dramatically with use due to thermal compression - every track the speaker may perform differently in some typical poor designs.

My point was to simply challenge the idea that burn-in that sounds greatly different is a good thing . It often implies overly simplistic designs that are commensurate with a goal of "purest signal path". Unfortunately, the engineering reality is quite the opposite - through added design complexity one can dramatically increase precision and robustness of product performance from changes in temperature, ground loops, cables, interconnects, power, noise, component aging etc.
Thanks for the responses. Shadorne, your point is well taken, actually, what prompted me to ask the question was that I was frustrated that my new solid state preamp sounded good at first install, but became too bright, and strangely, the tight bass was gone too after a week. I know I had only like about 30 hours playing time on it, so it is not fully burned in yet, but I wish I can be assured that further play time would kind of reverse the initial burn in direction, if that is at all possible.
Just curious if you bought your equipment without an audition. I would think that if you bought this new and auditioned a completely burned in one at a dealer, you would have an idea of how it will eventually sound. In my experience cables are a different animal, but usually there is even some information as to the burn in process and the overall sound qualities that can be expected when it's completely burned in. I don't have Thor electronics, but most of my experiences are the same as Thorman's, but I am pretty certain that others have had different experiences. Shandorne raises a question that I thnik we all are a bit fearful about and that is that the results of the burn in procees do not meet our expectations.
Mr W- I've had passive and active components that went through 4 or 5 changes in presentation before reaching stabilization. Some sounded ridiculous at times. Be patient(at least 200 hrs) before listening critically, and deciding whether you like the component's presentation or not. The best capacitors and cables use high grade dielectrics(ie: polypropylene/polystyrene/Teflon) that don't absorb/discharge energy as quickly. That means "burn-in" takes longer too. (http://www.national.com/rap/Application/0,1570,28,00.html) Also look at the paragraph about Dielectric Absorption here: (http://www.sbelectronics.com/application_notes/cterminology.htm)