Introduction Movie
buffs may remember the name Krell from the movie "Forbidden Planet,"
where the Krell were the most powerful race of an alien civilization.
Krell Industries, manufacturer of some the world’s most exotic AV
equipment, named its company after this superior species. Like Morbius,
another “Forbidden Planet” character who sat in front of the Krell’s
computer terminal trying to understand their science, I sit in front of
Krell’s amplifier, learning about its science.
The amplifier I’m talking about is the Krell FPB (Full Power Balanced)
400cx, Krell’s latest “mid-priced” offering in the FPB stereo amplifier
line-up, priced at $10,500. The 400cx is rated at 400 watts per channel
into eight ohms, 800 watts in four ohms and 1600 watts into two ohms.
Upon unboxing the Krell FPB 400cx, I was immediately struck by its
build quality. Weighing in at 110 pounds and measuring 19 inches wide,
10.3 inches tall and 19.7 inches deep, this doesn’t exactly make it an
easy amplifier to haul around - I hoped that what my back didn’t like,
my ears would love. The 400cx’s large black anodized face and three
small blue LEDs give the amplifier a very appealing, distinguished
appearance. The front panel also has an infrared sensor for remote
operation and interaction with other Krell products. The rear panel has
two pairs of speaker binding posts per channel for bi-wire
applications. These can be easily thumb-tightened, but they will not
accept bare wire, banana plugs or pins - only spade lugs will work. It
also offers both single-ended and balanced connections, as well as the
proprietary Krell CAST inputs, which I’ll cover later in this review.
The rear panel also includes the remote control Krell Link to turn the
amplifier on and off, a very substantial non-detachable power cord, as
well as a power breaker switch and a pair of handles to carry the beast
around. Set-up
I placed the Krell FPB 400cx on the bottom of my rack and connected it
to my Krell HTS 7.1 via the balanced inputs with my reference Cardas
Golden Cross XLR interconnects. I made the speaker connections using
the Cardas Golden Cross bi-wire speaker cables to my Martin Logan
Prodigies. I’ve found the Cardas Golden Cross cables are a great value
and work exceptionally well in my system. My Arcam DV-27 was used for
both the audio and video source of my evaluation and the analog outputs
were used for CD playback, while the DACs in the Krell HTS 7.1 were
used for all movie watching.
Features
The FPB 400cx is a Full Powered Balanced X Series Stereo Amplifier,
which is what Krell calls their latest iteration in circuit design. The
latest X Series Amplifiers use the Krell Sustained Plateau Bias III
microprocessor control system that maintains Class A operation
regardless of music or movie demands. Class A bias is the
most accurate method used to amplify musical signals, but has it’s
engineering challenges. Class A operation means that all transistors in
the amplifier draw current all the time. However, the large current
consumption gives us one of the benefits of Class A operation, namely a
distortion that is low and kind to our hearing. It’s a design that’s
neither cheap nor easy to engineer, but has obvious advantages. As I
mentioned earlier in the review, the FPB 400cx has its own proprietary
output design, called CAST Technology (Current Audio Signal
Transmission), or in this case, CAST II Technology, Krell’s latest
update. Krell claims the CAST II system improves every performance
area, including speed, precision, dynamic range, depth and width of the
soundstage, transient impact, tonal balance, harmonic distortion, and
more. Unfortunately, I’m not able to confirm this, because my reference
preamp, the Krell HTS 7.1, doesn’t include CAST outputs. With all the
benefits that Krell claims CAST II technology delivers, it seems to me
it would be a feature they’d want to include in their best and latest
A/V processor, or at least create a Class A Series A/V processor that
includes CAST technology. I’m always skeptical when a manufacturer
makes claims of superior technological or sonic advantages of any type,
whether it is Class A, Class AB, Zero-Feedback, Single-Ended Triode, or
anything else for that matter. My thought is that it is implementation
that rules the sonic world, rather than claims about technology.
Movie
buffs may remember the name Krell from the movie "Forbidden Planet,"
where the Krell were the most powerful race of an alien civilization.
Krell Industries, manufacturer of some the world’s most exotic AV
equipment, named its company after this superior species. Like Morbius,
another “Forbidden Planet” character who sat in front of the Krell’s
computer terminal trying to understand their science, I sit in front of
Krell’s amplifier, learning about its science.
