Battery Biasing and Forming the Dielectric
Just one look at Vandersteen’s Model 5 crossovers (either outboard or the ones built into the
speaker) and you will notice something weird. There are a bunch of Duracell
batteries in there! Has Vandersteen lost his mind?
Not yet. The batteries are there to provide a voltage to the capacitors in the crossover. The idea is
to eliminate the "warm up" period needed for equipment (in this case, speakers)
to sound its very best. One of the main reasons your stereo doesn’t sound as
good at turn on as it will an hour later is that the capacitors in your
components and loudspeaker crossovers are "un-formed" at turn on. The longer it
has been since you last had a signal flowing through those capacitors, the
closer to brand new they are and therefore the worse they will sound.
It’s the dielectric, or insulation, in the capacitors that needs to be formed. As a signal travels
through a capacitor, it suffers a certain amount of degradation, most noticeably
at the boundary between the dielectric and the conductors. This degradation gets
reduced more and more the longer the capacitor has a charge on it. When
"un-formed" the capacitor will sound hard, closed-in and unclear compared with a
"formed" capacitor. The batteries in a Vandersteen crossover keep the capacitors
formed all of the time by providing a charge all of the time. This ensures that
the crossover will sound its best any time you want to listen.
As for Vandersteen’s choice of the Duracell brand of batteries, I’ve always preferred Energizers
myself. I’ll do some experimentation and get back to you. Just kidding.
Battery Biased Cables?
On a similar note, Audioquest has plans to introduce a new line of battery biased
cables. A bias charge is presented to the cables' dielectric whenever a battery
is connected. The concept applies to the insulation layers in a cable just as
described above with a capacitor.
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