5
A Letter from Krell Industries
Dear Audio Enthusiast,
Thank you for your purchase of a Krell Evolution e Series amplifier. No component in an audio
system contributes more to the full range of musical expression than a power amplifier. The
seemingly impossible tasks of simultaneously conveying music's subtle emotional cues and intense
dynamic passages rest squarely on its shoulders. In our quest for amplifiers that deliver absolute
truth in music reproduction, we present the Evolution e Series. This next generation of Evolution
Amplifiers, “e”, short for enhanced, represent a defining moment in Krell design, joining awesome
current capability with a newly refined, ultra-linear circuit topology and environmentally friendly
operation.
Krell amplifiers are best known for their ability to drive any loudspeaker to sound its best, without
regard to impedance, efficiency, or driver style. It is linearity, an amplifier's ability to output an exact
duplicate of the input signal, which is the ultimate measure of that amplifier’s worth. Krell designs
toward the common goal of linearity, through the rigorous application of Krell design principles that
focus our efforts on four major performance factors: distortion, bandwidth, output impedance and
current capability. The Evolution e Series excels in each of these areas, delivering supreme accuracy
from whisper level to astounding, awe inspiring amounts of power with grace and elegance.
BETTER SOUND
Building on the unique Active Cascode Topology foundation of the Evolution Series, the e Series
amplifiers feature more precisely balanced current sharing among the seven sets of Active Cascode
Quartets that make up the output stage. This greater precision elevates an already impressive
performance envelope and provides greater amplifier reliability. Audible at all volume levels, this
improvement is independent of load current. Although negative feedback in the Evolution amplifiers
was already extremely low, a mere 14 dB several orders of magnitude lower than other
manufacturers' power amplifiers modifications to the feedback circuitry allow for more ideal
operation completely independent of the signal level. The results are greatly enhanced inner detail
and micro-dynamics with smoother high frequency response.
An intense upgrade to the power supply includes a number of improvements. There is now a
separate transformer for the digital power supplies. Not only does this facilitate greatly reduced
power consumption in standby, but it provides still better isolation between the digital and analog
power supplies. The high-current and high-voltage analog supplies have additional noise filtration
circuitry to reduce high-frequency switching noise from the rectifiers. The high-current power
supplies also have more reservoir capacitance than before (anywhere from 10-50% more,
depending upon the model). Finally, the power supply circuit board has been redesigned for better
isolation between the incoming AC power and the DC power supplies.
LESS HEAT, LOWER ENERGY CONSUMPTION
A new green standby mode reduces standby power draw dramatically. Standby power draw for all
Evolution e Series amplifiers has been reduced to 2W. As an example, the Evolution 402e power
draw drops to 2W from 260W as compared to the Evolution 402 - a reduction of 99% in energy
draw and a huge drop in heat output. The power indicator ring now glows green to indicate the new
energy efficient mode.
We hope that you enjoy your new Evolution e Series amplifier.
Sincerely,
Krell Industries, LLC
