Krell's Todd Eichenbaum Talks Cables

AR-KRELL-INTERVIEW-IMAGE.jpgI 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.

Todd's 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.

AR: Krell 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 regulation.

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 business?

TE: We're 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.

AR:  How is Krell differentiating themselves from other high-end cable manufacturers?

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. 

First, the 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.

Second, because 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 plans? 

TE: No. You'll just have to wait and let us surprise you...

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