breaking in audio components

sometimes you get lucky, and a dealer or direct manufacturer enable you to audition a component for a trial period, after which you may return it, or get a refund if you paid for it initially.

sometimes the trial period is 10 days, usually no more than a month.

you place the component in your stereo systems, listen to "test" recordings and try to evaluate its contribution to the sound of your stereo system.

there is the issue of break-in. a component may or not break-in during your trial period.

what criteria do you use to determine that a component has broken in ?

you might ask the dealer or manufacturer how long it takes to break in the component, or how many hours of signal transmission is necessary in order to fairly evaluate the component.

there is always the possibility that the component has not completely "settled" sonically, while in your possession.

there is the chance that if you buy the component, its sound may change after the trial period ends.

is it always a crap shoot when buying components, or has your experience taught you when to tell that any further changes in sound will be minor and not affect your overall sentiment toward the component ?
break-in is never dramatic. its your brain that adjusts. like going from full range speakers to mini monitors....after some time the bass sounds deeper
There has been no noticeable change in my system since I bought them 8 months ago. I have logged probably 500 hours and they still sound the same. I don't think it is gonna happen.

This is what I have experienced with my current amps and speakers.
It depends on the equipment.

Speakers such as Dynaudio Temptations, Dali Megalines, Kharma Exquisite and Sound Lab Ultimates all go through big changes with break in. Electronics vary by brand and design as do cables.
I have experienced break in difference with a new pair of Paradigm Studio 60s. A noticeable improvement after a month or so. I seriously thought the speakers were faulty out of the box but smoothed out nicely. Can't say I've noticed it with any other component or cable.
I feel that if you don't like the sound of a component from the get go, breaking it in will not necessarily transform it into a giant killer although there will be some audible improvements.
I had a new Arcam Alpha 10 integrated amp that would totally disgust the deaf for the first 12 hours or so, with other products the changes have been either less dramatic or non-existent.
I am very skepitcal as most of you know. But speaker suspensions do loosen up over a short period of time and will produce more bass. We often have to re-adjust subs once they have broken in because the bass increases.
I'm positive my underwear fits me much better now then when I first bought them seven years ago.
I worked in the electronic component manufacturing field for 10 years making ceramic capacitors. I can tell you capacitors change value over time and the change is logarithmic - so the largest change is when the component is "new". Some of the high end military contracts required burn-in for each individual component before we shipped them. This was to insure the component value was sound and therefore the circuit it was in was far less likely to fail due to changes in capacitance value. It's nice when you are shooting missiles if they don’t fail. The change in value had to do with how the material changed electrically (capacitance increase or decrease) as electricity was applied to it. After a certain amount of time - the change was negligible. I could go on an on and boar you to tears but I can tell you burn in is legitimate ... if you don’t believe me check out AVX, Kemet, Vitrimon, Kyocera web sites ... they have tons and tons of engineering data for circuit designers. You will want to look at life test data sheets. They might be a little hard to discern if you don’t have a lot of experience reading them but you will notice they are on a logarithmic scale.

You look at how the dielectric changes over time and the design your circuit accordingly. That’s probably why the sound improves significantly over a short time and less as time goes on – the person that designed your linestage calculated it that way. I don’t think I’m going out too far out on a line to assume most conductive materials change electrically in some way over time. If you can calculate this rate – you can design around it.

Any Material Science or Ceramic Engineers out there? Chime in now please …

The Horse
if your dealer doesn't know what the break-in time is, he's not a very good dealer!
p.s. count me in the "believes break-in is real" group
gentlemen, the point of this thread is to determine audibly if possible, what are the signs that a component has "broken in" sufficiently, so as to make a judgment as to whether you like it or not and/or wish to purchase it or not ?

are there any aspects of frequency response or soundstaging that one might listen for to be confident that much or most of the break in has already occurred ?
I'd have to side with people saying they DO notice differences after break in. And with components, speakers, and cables (IC's, speaker, and PC's). Granted, some are more subtle changes, but some are more noticeable (in this hobby of "splitting hairs"). Probably the only things in my system I don't notice "breaking in", are the isolation tweaks I've used.
Gunbei, LOL! Horseface, thanks for the info. Nice to learn a new fact that can explain burn-in from a scientific point of view.

Mrtennis , my rule of thumb is that by 72 hours, you will be able to tell the sonic signature of the gear; improvements will continue, but the essence of the sonics will be known. See Horseface's post.

The most obvious improvements that I have heard are a removal of "grain" or edginess of the highs, a tightening of the bass, and an improvement dynamic "punch", and more detail in the micro-dynamics [resolution and separation of very soft passages from the louder passages]. The treble is the easiest improvement to hear, and the bass improvement the next so.
Sometimes a dealership will loan out a demo which is probably the same one loaned for other customers & no doubt already broken in. I would then have to agree with Musicslug, that an informed dealership should know his products and the required break-in period. Aside from new component break in I know that my system always improves after an hour warmup.