There is not really such a thing as break
in. Sorry to dispel all these myths that writers who get paid by the word
have put in your head; but let's examine the parameters one by one.
After studying what I call "audio
anthropology" for 55+ years, here's my take on break-in, especially
as it applies to speakers.
The few other
valid and measurable effects are the "forming" of electrolytic
capacitors, and changes to batteries, which because of their continuing
and changing chemical action are more organic than anything else, and therefore
exhibit all sorts of subtle and not so subtle operational changes. We all
know batteries drain, and therefore their entire mode of operation is continually
changing - their voltage for example. That's easy.
OK, then there are tubes. Since the thermionic
emission of tubes means that electrons are boiling off the cathode, as time
goes by the cathode gets depleted, and various other subtleties take place,
and so yes, you might say that tubes 'change'. You could theoretically consider
this 'break-in' if you were to also say that the reference point would not
be reached until the tubes were operating for 100 hours. What if your reference
point were at zero hours? Then from that point on, the circuitry would get
But for essentially everything else, the
effect is more human than a phenomena of physics.
The psychoacoustic truth is that nearly
anything will sound correct if you listen to it long enough; it becomes
the new baseline (pun almost intended) of your reference, and then "other"
things will then sound wrong, or at least different.
When you listen to a new unknown for awhile,
its physical characteristics fill slots in your auditory mental library
that may or may not line up with your auditory notions, pre-conceived notions,
or expectations. For instance, if you play one brand of piano for a long
time, when you play a different one it seems "wrong" for a "certain
amount of time". As you become more adjusted to it it might not seem
so "wrong" but it will still seem "different". The entire
mechanism of your hearing, including the vagueness of your auditory memory
"learn" the complex frequency and phase characteristics of the
overall sound and stamp that impression onto your admittedly soggy notions.
Very few people can listen to a Steinway, then a Bosendorfer, then a Yamaha,
then a Young Chang and come back 6 weeks later and pick them out again.
Of course YOU may think you are in the minority and are able to do this.
That's what being an audiophile is all about. (!)
If you go back and forth between driving
an 18-wheeler, a sports car, and a squishy sedan, each seems like a "wrong
fit" for a little while until the new proprioception reference points
settle in, then eventually the vehicle you are in becomes the "norm".
In essence your nervous system and its inherent feedback loops are micro-phaselocking
to all the physical and spatial reference points, and there is a "fit"
between your body-mind loop and its operating environment. While you are
IN the truck you may long for the tight feel of the sports car, but the
truck is still your current reference set, and then the NEXT vehicle you
are in, no matter what it is, is referenced back to your last reference
point, the truck. This is the same phenomena as with speakers. You notice
it because speakers are mostly so different from each other.
Besides, all speakers are of course designed
and tested "new" --- with new parts. No one designs and tests
speakers with used drivers, with the surrounds loose and worn out, etc.
Yes, sure everything has a downward curve.
Speakers, like people, start getting worn out from the moment they're born.
So you might say that speakers never get better, they only get worse over
time; the surrounds get looser and less able to mechanically snap back to
their original center position; the magnets get weaker, although only a
tiny fraction.. and so on. Of course the phrase "over time" may
typically mean MANY, MANY years, just like people. There is no technical
change over a few hours or days... but as a human you might have a perceptual
change over a few minutes, few hours or few days.
Yes, there are also the issues of temperature
and humidity, but for these purposes we will assume a moderately stable
"living room" set of measurements.
The new(er) driver technologies such as
those used (and often invented) by such companies as JL Audio are light
years ahead of the stuff that so many of us might have enjoyed in "college".
From the early 70's on many manufacturers used the worst if not the cheapest
drivers available to both (a) make a buck and (b) ensure that with a reasonable
amount of smog and a reasonable amount of frat house partying, the most
owners of these subs would "use up" the drivers and therefore
they would require reconing or replacement. Under the thinly veiled guise
of "better sound" the manufacturers used the worst and therefore
most absorbent paper cones; the worst and therefore most smog/pollution-sensitive
'foam' surrounds, (often called "foam rubber", but not rubber
at all, actually a urethane) and so on. The resistance to humidity, ultraviolet,
temperature cycling, pollutants, thermal effects of the coil and magnet,
and so on was somewhere between non-existent and minimal.
Properly designed and made drivers,
with stable materials, still look the same in measurements before and after
they are "exercised". We can take a driver at room temp, check
its parameters, then exercise it by driving it right to its xmax limits
for hours, then measure it again, and the amount of change is small, and
mostly due to coil temperature. More stable materials are just that
-- more stable. As soon as the coil temperature goes back to ambient, the
measurements are the same.
And besides, the most difficult thing to
do in all of speaker manufacturing (besides getting it right in the first
place, the subject for at least one long book) is consistency! We want a
finished speaker (that means speaker cone, speaker driver, and finished
product in a box, including amplifier, crossover, and adjustments) made
today to sound the same - within incredibly tight limits - as one made last
week, or last year -- or next year! And we also want 6 of them made today
to sound the same, and to measure to within a hair of a reference manufacturing
To dispel any
myths about manufacturing tolerances, everything has a tolerance. If you
machine 2 pieces of metal which then have to fit together, they each have
a + or - mechanical tolerance. So here's the surprise: if you purchase 6
tweeters (or mid range drivers, etc.) from a manufacturer and connect them
up to a rotary switch and feed them white noise, you will hear 6 different
sounds as you rotate the switch. That's a sad fact of life. Amazing! There
is simply almost no such thing as "the same" ! They are all
close perhaps, but all somewhat different. Your ears may be able to discern
that difference... or maybe not. Here's why:
To touch on specs and frequency response
for a moment, many if not most mfgs spec response as + or - so many dB,
i.e. ±3dB. Therefore you can have 2 drivers sitting on the test bench
connected to the aforementioned rotary switch, and one driver might
have a bump of 2.5 dB batween 2k-4k and the other might have a dip
of 2.5 dB between the same frequencies and they are both "within spec"
yet to a human, switching back and forth between the two, they sound rather
different. Perhaps very different. (they are 5 dB "apart") But
the overall point of this article is not manufacturing tolerances, but "change(s)"
Of course over a VERY long period (15-25
years) some parts can degrade, especially capacitors. If the wrong solder
is used it can craze and the connection can get bad and turn into a noisy
rectifying junction. Carbon resistors can change a % or so here and there...
well you get the idea. Those changes are subtle and occur over time.
You might say that the magnet [in the speaker]
weakens MICROSCOPICALLY over time, perhaps a few percent in many years.
Some magnetic materials - and much about magnetism still borders on alchemy
and magic - change their strength and other properties permanently when
exposed to temperature abnormalities.
There is the phenomena of "driver
compression" which changes with temperature, and an issue with temperature
in general. For example, if you start out with a subwoofer in a cold room
and the coil heats up until it is "hot" then the sound from that
driver will be a little 'different'. But at the same time, your own hearing
and perception will be different than when you started because since
you have been exposed to these loud sounds your thresholds will change,
therefore you cannot base your perception on a fixed point because your
perception of your perception is continually changing!
Do not confuse "break-in" with
"burn-in". Burn-in is a factory procedure when after a unit is
built it gets connected and operated (often into a rated load, for example
a power amp connected to a load resistor) to determine if anything will
fail - an infant mortality test for all the components if you will. This
has nothing to do with running the equipment so it gets "better"
and therefore the manufacturer has "saved" you some "time
and effort", although sadly, some manufacturers or after-market snake
oil vendors will try and sell you on this idea.
And last but hardly least, the absurd myth
about 'break-in' with wire and cable (ahem... 'interconnects') During my
time at a private laboratory division of Hughes Aircraft I had many opportunities
to witness and partake in various discussions about various devices being
tested in the most amazing ways: everything from electron microscope examinations
of hard and floppy disc surfaces to cloud chambers where transistor junctions
were being tested to determine the extent of cosmic ray bombardment, to
changes in different alloys undergoing thermal changes (from nearly liquid
state to near absolute zero) and scientifically, no one has ever been able
to determine anything happening technically that would change the sound
of an RCA cable the first few hours, weeks, or months you play it. The rest
of this discussion about the manufacture of wire is the next huge topic:
So there you have it.
Bottom line: enjoy your speakers.
If you need a laundry list of other things to worry about
(besides "break-in") I can supply that for you.