7
Ensuring Maximum Performance
“My pursuit of excellence in sound reproduction and
my love of great musical performance has led me
to the Evolution One Amplifier, and fuels the ongoing
Evolution design effort at Krell.”
Dan D’Agostino
The Krell Evolution One Monaural Power Amplifier, built upon the foundation of
huge, regulated power supplies and output stages, is designed to drive any
loudspeaker with complete control. The product of breakthrough Krell technolo-
gy, this amplifier provides a sound that is supremely dynamic and musical.
Indeed, it is the sound of the music itself.
Core Technologies
Class A, Balanced, Current Mode Gain
Topologies from Input to Output
Audio signal voltages are converted to currents at the amplifier input, and the
audio signal remains in the current domain throughout the entire amplifier until
the output stages. All signal gain is realized in the current domain using propri-
etary multiple-output current mirrors with extraordinary open loop linearity. The
current mirrors in the final gain stages use 36 pairs of high voltage, high speed
transistors. Originally developed for demanding, high bandwidth video circuits,
these transistors help yield gain stages with superb accuracy and very low dis-
tortion. The signal path is fully complementary and fully balanced from input to
output. The driver and output stages use 28 pairs of 150 Volt, 14 Amp, 50
megahertz power transistors mounted on Krell-designed high efficiency heat
sinks.
All transistors operate in Class A mode. Independent complementary pre-
driver and driver stages for the positive and negative output transistors make
the output stages extremely fast and linear. The output stage develops 450
Watts into an 8 Ohm load, 900 Watts into 4 Ohms, and 1800 Watts into 2
Ohms. This unique circuit is impervious to low-impedance or reactive loads;
the Evolution One amplifier simply drives any loudspeaker with absolute confi-
dence, achieving the very best possible sonic results.
continued
