It’s that time of year!
recently had the privilege to sit down with Todd Eichenbaum who has been with Krell for 20 years, and serves as Krell’s Director of Engineering where he’s led the design
efforts for over 50 Krell products including every preamp, power amp and
loudspeaker they’ve designed over the past 12 years.
latest creation, the Vector HC Power Cord, is a departure for both Krell and
Todd, however as I found out the leap from making amplifiers to power cables
isn’t as great as one would think.
President, Bill McKiegan, said, “that with few exceptions most power cable
manufacturers haven’t made a power amplifier so they don’t fully understand
what is needed in a power cord.” I thought that was an interesting comment
and as I understand it the Vector HC is your baby, so how did it come about?
TE: My earliest
inspiration was born of frustration. I’ll explain. About four years
ago, not long after we launched the Evolution 900 monoblocks, one of
our salespeople got a call from an irate customer. His 900s weren’t
working properly; the microprocessors were indicating that one or more rail
voltages were out of spec. Typically this is an indication that something
is very wrong with an amplifier, but these were brand new, and
furthermore, sometimes they worked OK. After many phone calls and much
head scratching but very little success, we happened upon a juicy tidbit of
information: the customer was using aftermarket power cables. When he
removed them and reinstalled the very plain but quite functional cables that we
supplied with his 900s, the amps worked perfectly. So, in fact, the
customer’s ultra-expensive, super-exotic power cables were starving the 900s
for current to such a degree that their power supplies were coming out of
Looking at this from
my perspective, I found it infuriating that a company would design a power
cable that was failing at its most basic purpose–to provide enough power to
the component to which it was connected–and then to have the audacity to
charge top dollar for it. A power cable is not a particularly complex
piece of equipment; designing one properly simply involves knowing what it
needs to do well, which is to provide a secure, reliable, safe, low resistance,
and low inductance pathway from the wall outlet to the audio component.
At the end of the
day, the Vector HC really was born from power amplifiers.
AR: You started with CAST and now you have
the Vector HC power cord. Is Krell quietly trying to get into the cable
not making a conscious effort to expand into the cable business, quietly or
otherwise. Rather, we’re filling what we see as gaps in current
offerings. For example, the CAST concept started as a more accurate means
of interconnecting audio components, not as a vehicle for selling cables.
In fact, several other companies now offer CAST cables that, frankly, we prefer
to our own CAST cables. With the Vector HC, we felt there was a need for
a product specifically designed to work well with electronics that place heavy
demands on the AC mains–in particular, our amplifiers.
How is Krell differentiating themselves from other high-end cable
TE: By the design
of the Vector HC cable itself, which has been optimized for what we, the
designers of large amplifiers, know to be of greatest importance in
providing AC power to such devices.
cable had to offer low resistance. Of course, the larger the cross
sectional area of the conductors, the lower the resistance; however, AC
connectors do have a limit as to how large the conductors themselves and the
finished cable can be. We determined that the largest conductor we
could comfortably work with was #11 AWG. That’s twice as large
as the #14 wire used in many premium cables, and still larger than the #12
wire used in many ultra-premium cables. We also specified oxygen-free
copper for its improved conductivity, which further reduces the resistance
of the conductors regardless of their size.
inductance, by definition, opposes rapid changes in the flow of current,
and since we want the audio component connected to be able draw whatever
current it needs instantaneously from the AC mains, the cable needed to have
low inductance. We are able to accomplish that by twisting the two
primary conductors together.
Third, we wanted to
reduce the amount of high frequency electromagnetic noise that could enter
or leave the cable. As luck would have it, twisting the conductors
also increases their capacitance, and increasing the capacitance between the
primary conductors helps filter high frequency noise. In this
case the “capacitor” is formed by the two primary conductors behaving
as its plates and the wire insulation as the dielectric between them.
Since we want to maximize the capacitance over a wide frequency range (to
minimize noise), we specified a Teflon derivative–the highest quality
dielectric available–for the wire insulation. In addition, the two
primary conductors are wrapped with a copper foil shield, also to reduce the
noise entering or leaving the cable. We selected foil instead of braided
wire because it works more effectively at the frequencies likely to be
encountered by audio equipment in the home. The shield is connected to
ground only at the wall plug, so any electromagnetic noise is shunted away
from the audio component and into the earth ground. Since the shield is
not connected to the component plug, however, no ground current can flow through
the shield. Rather, a third conductor, located outside the shield, makes
the ground connection between the component and the wall plug. Noise on
the ground conductor cannot penetrate the foil shield.
The connectors we use
are not unique to our cables, but they are unique. The mating surfaces
are rhodium plated. Rhodium is a noble metal, very resistant to
corrosion and extremely expensive, but much harder and more resistant to
scraping than gold, which makes it especially well suited to connectors
that might be inserted and removed many times over the life of the
product. Internally, we terminate the conductors with gold plated
spade lugs, which are then screwed into the connectors. Because the
internal connections are not subject to repeated wear, we chose gold for
its higher conductivity.
AR: A lot of people feel cables,
especially power cables, have little to no effect on a system’s sound, what do
you say to those people?
TE: Those people
should listen to their systems with different power cables installed. If
they still believe there to be no effect, or if the effect they hear is not
enjoyable, or if it is enjoyable but not worth an additional $2000 or $4000 or
whatever, then they should put their stock power cables back in their system
and start listening to music again. Honestly, we at Krell heard
differences we didn’t think we’d hear, so it’s likely that others will
have that same experience.
AR: I’ve experimented with and currently
own many high-end power cables and find the Vector HC to be among (if not the
most) pliable and easy to use in tight quarters even though it’s one of the
thickest power cords in my system-how did you manage to pull this off?
TE: This was one of
the design objectives for the Vector HC from the very beginning. There
were some materials that were either intrinsically pliable (such as the
finely-stranded oxygen-free copper conductors) or that we could specify to be
flexible (such as the clear PVC jacket over the wire) without any adverse
effects on performance, so we did that wherever possible.
The Teflon-based insulation on the conductors is not particularly pliable;
however, it does not need to be terribly thick to perform its job either.
In addition to protecting the conductors and giving the cable its unique
appearance, the helically-wrapped fiberglass cords afford good flexibility.
AR: Is the Vector HC built in house or are
some of the parts outsourced?
TE: The Vector HC
uses connectors and terminals sourced from Furutech in Japan, and the cable
itself is custom made to our specifications by a specialty wire house right
here in New England. We selected the Furutech connectors for two very
simple reasons: first, the materials and build quality were impeccable, and
second, they were approved by all the necessary safety agencies. When we
discovered later how wonderful they sounded, that was an added bonus, but it
was not what initially drew us to them. The finished cables are built to
our specifications by a company (also in New England) that specializes in
assembling high-end audio cables. They have the tools and the know-how to
do this better than we can ourselves, so we outsource it.
AR: Can you tell me about Krell’s future product
TE: No. You’ll just
have to wait and let us surprise you…