Break in period

Jeff sez

If the results are audible, shouldn't they also be measurable

Should be, I guess. BUT what would one measure? Once measured a diy phono equaliser with a friend (for other purposes) at ~2month intervals with a scope. Zilch.

Note however, that the caps had already been "treated" with a variac before they were mounted. Likewise with critical path resistors (components are important for the equalisation curve). Also, first measurement was well after first power up (a couple of hours or so).

Measuring break-in is not necessarily going to be very straightforward. You have to know what to look for. The basics don't change much. A lot of the obvious parameters measure the same before/after. That doesn't mean something hasn't changed. As Atmasphere mentioned, the best way to judge is by using your ears. It is quite apparent the change in many components.

The question is, what to look for? Let's take cables as an example. There is more than just RLGC parameters. Maybe the dissipation factor of the dielectric changes. Perhaps there is some contamination, impurity, or flaw in the refining or construction. I would look for the little things, like photoelectric, pyroelectric, thermocouple, electro-chemical processes, parasitic diode structures, etc. Copper-oxide is a semiconductor. It makes for a lousy diode. Dissimilar metals, junctions, crimps, solders, the list goes on. Could there be parasitic batteries embedded in a cable?

Note also, when a component undergoes manufacturing, it experiences many traumatic and often life changing events. Materials get melted, alloyed, refined, drawn, hammered, cast, extruded, gassed, separated, cooled, well you get the idea. Where exactly does the manufacturing process end? When the item has left the factory? Or when it has been conditioned and formatted for the application?

Examples? How about a battery? At least with NiMH and NiCd, you have to format them with an initial charge of 20+ hours. Really trickle it. If cut short, the result was a battery that would from then on hold much less charge. We did this test at Nokia, and a fully formed battery ended up with double the capacity. How about shoes? Don't they take a little time to break in? How about a violin? If a Stradivarius isn't played it loses its tone.

It might take more than a spectrum analyzer. But the answers are out there.

jh

Atmasphere,

Shadorne, are you saying IOW that you hear changes but you attribute them to yourself rather than the gear?

Often yes. Depending on the last time I had a cold the changes can be significant. Most often it is the result of focusing on something specific or different in a familiar repeated track. I suspect we get very accustomed to sounds and have a pretty good sonic memory (for example an actor's voice is instantly recognizable on a cartoon)...so changing a component as significant as a speaker can be quite disconcerting for several weeks as memory adjusts to the new way it sounds (versus previous familiar sound).

For example, when I upgraded mains from ATC 20's to ATC 100's I actually had to make an adjustment to the reduction in harmonic distortion in the extreme LF at higher SPL levels. Initially, it was disconcerting to me that a great big box speaker seemed to have less bass (but incredible clarity & punch) compared to a modest sized bookshelf with already a lean bass sound (compared to most fare). On the face of it, I had become accustomed to more bass warmth or harmonic distortion of the little driver when it was driven hard at higher SPL. (This effect cannot have been break in as the 100's were already well used).

when I upgraded mains from ATC 20's to ATC 100's I actually had to make an adjustment to the reduction in harmonic distortion in the extreme LF at higher SPL levels.

ATC 100 have less harmonic distortion at LF at high SP levels than ATC 20? Really

Did you measure distortion levels and how do you know it is harmonic distortions?

Did you measure distortion levels and how do you know it is harmonic distortions?

I did not make measurements but harmonic distortion is quite easily recognized for its warmth, woody or resonant sound.

I doubt ATC would make a more expensive big box speaker used in studio mix and mastering with higher distortion at "loud" SPL levels as a modest ATC book shelf near-field.

I could be wrong though. Neither speaker sounded harsh ( telltale signs of excessive odd harmonics ) except at excessive SPL levels that were beyond rock concert levels.

All speakers introduce lots of distortion. Given similar quality in design/drivers, bigger speakers tend to play louder cleaner (a general rule for all speakers and not just ATC).