Krell Industries Evolution One - Manual (Page 12)

8
Impedance Advantage
The output impedance of the final gain stages is one hundredth that of the final gain
stage in most power amplifiers. This provides extremely wide bandwidth and very
high current capability. The amplifier does not employ global negative feedback—the
final gain stages use only 8 dB of local, nested negative feedback. This is one five-
hundredth the amount used in most solid-state power amplifiers. The result is an
extraordinarily open, liquid, effortless sound.
Robust Power Supply Regulation
For Absolute Voltage Stability
The rails powering the amplifier’s low level and gain stages are regulated twice
for total immunity from fluctuations in the AC mains and virtually noise-free out-
put. All the regulators use current-mode circuitry for wide bandwidth, low output
impedance, and complete immunity to varying load conditions. The high-current
regulators powering the amplifier output stages use fully complementary gain
stages and output drivers. The resulting wide bandwidth and low output imped-
ance of the Evolution One surpasses even the stringent demands of the amplifier
output stages.
The driver and output stages in the high current regulators use 14 pairs of the
same robust, high performance power transistors used in the amplifier output
stages. All the regulators are located in the amplifier chassis to provide ultra low
impedance supply rails for the audio circuitry.
Evolution Bias Control Systems
The new Evolution Bias system features 12 individual bias levels for optimum
performance and efficiency. Evolution Bias constantly compares the audio signal
at the input stage with impedance at the output stage, and adjusts the bias cur-
rent accordingly. In addition, a proprietary bias monitor continuously measures
and adjusts the output stage bias, eliminating the need for future adjustment or
calibration.
(SECTION ONE: About Krell continued)