There really is
no such thing as break-in. Sorry to dispel all these myths
that writers who get paid by the word and are often politically
connected to their suppliers have put in your head; but
let's examine all the parameters.
To start, 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.
First let's examine
what DOES "change".
We all know batteries
change. Because of their continuing and changing electro-chemical
action they 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. But you're not directly listening
to batteries - this is just an example.
Be aware there are MANY types of capacitors. Precision
wound mylar film caps are VERY stable. Chemical types
that have electrolytes - similar to a battery - are all
over the map, and if subjected to temperature changes
and high current flow they will tend to have a rather
short life - perhaps a very few years. Perhaps months.
There are "average"
caps and "audiophile grade" caps used in some
passive crossovers in speakers. There are instances where
they have a price ratio of 50 or 100 to one. Do not be
surprised if your speakers that cost $5000 have $3 caps
in their crossover. In addition, the % tolerance of the
large value caps used in crossovers is rather sloppy.
Expect +/- 10% or worse if you are lucky.
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 can easily 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 "worse".
But for essentially
everything else, the effect is more human than a phenomena
truth is that nearly anything will sound correct - and
become your personal "reference" - 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
loudness envelope, frequency, harmonic structure, 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. This exact same phenomena
happens in audio and the mechanism of your hearing.
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
old, used drivers, with the surrounds loose and worn out,
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.
New(er) driver technologies
are somewhat ahead of the stuff that so many of us might
have enjoyed in "college" years ago. From the
early 70's on many manufacturers used cheap 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 low freq drivers or 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 minimal. Did they "change"? Yes, but
not over a few hours or a couple of weeks.
Newer 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 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
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, with your own
hearing, 6 apparently 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") Spec sheets show "smoothed"
response curves. In real life, there may be +/- tolerances
of a few dB EVERY FEW CYCLES. But if they
showed you those unsmoothed curves you would never buy
But the overall
point of this paper is not manufacturing tolerances, but
what constitutes "change(s)" in parameters.
Of course over a
VERY long period (15-25 years) some parts can degrade,
especially capacitors, as mentioned above. If the wrong
solder or flux was used the connection can craze and turn
into a noisy or rectifying junction. Carbon resistors
can change a couple % or so here and there... well you
get the idea. Those changes are subtle and occur over
time, which means months and years.
You might say that
the magnet [in the speaker] weakens MICROSCOPICALLY over
time, perhaps a few percent in many many years. Some magnetic
materials - and much about our understanding of magnetism
still borders on alchemy and magic - change their strength
and other properties permanently when exposed to high
temperature abnormalities. The reasons there are essentially
no neodymium magnets in large woofers is twofold: first
that would be WAY too expensive, and second, the surprisingly
large temperature heating of the voice coil would tend
to weaken the magnetism.
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!
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 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) to ohm
meters with better than milliohm resolution 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.
So there you have it.
Bottom line: enjoy
your speakers and your system. If you need a laundry list
of other things to worry about in life (besides
"break-in") I can supply a very long list for