I hope to aid in the understanding of break-in and what it does.
During my research into distortion, I was
forced to include the break-in phenomenon.
Mostly because the tiny distortion I was going
after was very similar to the size of the distortion reduced or removed by allowing
sufficient “break-in” time. This component behavior is something I am very familiar
with. There is no mystery as to how break-in affects sound reproduction. To understand
how the sound changes, you need to know exactly what happens during that time.
There are those that have sought guidance from
A-B tests done on capacitors from various manufacturers. An attempt is made to
ensure that it is a “fair” test. Capacitors are swapped out under the same
physical conditions (leads are held by screw terminal type connections). While
it seems fair on the surface – it is not the way to determine which capacitors
are better than others.
If you want it to be fair – you take the ten
samples and build them into ten copies of the same circuit.
Then after listening tests that include early (fresh)
and late (3 weeks) comparisons you will have your answer. Two capacitors from
the same manufacturer can sound different depending on where it is used in the
circuit. You have to know some history of the component even though it may be
new stock. Depending on how it is tested before shipping will affect the length
of time forming process will take.
In a nutshell: The capacitor will initially behave
as having non-symmetrical impedance. It is not exactly the same as having a
non-linear component. Current drawn by the charging cycle will not match the
current given up by the discharge cycle. This is due to the instantaneous state
of the dielectric. Therefore the impedance will be slightly higher in one
direction and lower in the other direction (until it is formed). We are not
talking about a big difference – in fact it is not measurable.
How then would I know that this is true? I
have worked with distortion products that are at or below the noise floor. Once
you reduce distortion down to extremely low levels (to where they don’t show up
on test gear) it then relies purely on theoretical analysis to go any further.
Since I was already down there – the break-in phenomenon
was right in my wheelhouse.
The mismatch in charge/discharge current causes the timing of the positive and negative wave-fronts to be askew. This detracts from the feeling of "live" that we naturally get when listening through air.
In fact if you want to see the difference just
the break-in can make, I received 2 reviews for the same gear by the same
person whose comments in the second (follow-up review) describe how the
equipment has morphed into a different experience. When the circuitry has very
low or no distortion, the break-in changes are much more noticeable because
their distortion product is larger in size than the circuit’s own distortion. Once
the forming is complete, a now clear path is recognized through the entire product.
You begin to hear the true purity of just the circuit.
Roger
