The Evolution Series continues to expand, and now offers seven powerful amplifier models. Stereo components include the flagship Evolution One, the new Evolution 302, and the Evolution 402 amplifier. The Evolution 403 is a three-channel amplifier and the Evolution 400, 600, and 900 are monaural amplifiers. Two monaural amplifiers are required for stereo operation. The Evolution 400 Monaural Amplifier has a compact chassis containing all the high power, wide bandwidth, and low noise characteristics designed into every Evolution Series amplifier.

FEATURES
Active Cascode Topology eliminates global negative feedback, only nested local feedback is employed around individual gain blocks. The result is an extraordinarily open, liquid, effortless sound.

The signal path incorporates Krell Current Mode and CAST circuitry using proprietary multiple-output current mirrors in a complementary and balanced arrangement for extraordinary open loop linearity.

Evolution circuit topology breaks through bandwidth limitations of conventional designs resulting in near perfect performance in the audible range.

A complete Evolution (source, preamplifier, amplifier) system, connected in CAST, reduces the number of voltage gain stages to the minimum, one. The resulting noise floor is approaching the theoretical limit of technology.

All Evolution amplifiers feature massive power supplies with the Evolution 402 and Evolution 600 equipped with a 5000 VA power supply and the Evolution 403 and Evolution 900 housing 6000 VA power supplies.

The power supply makes use of extensive electrical and magnetic shielding to keep radiated interference out of critical amplifier circuits.

Internal high current line conditioning circuitry filters RF noise on the AC mains, as well as compensating for asymmetric power waveforms and DC on the mains.
The rails powering the amplifiers' low level and gain stages are regulated twice for total immunity from fluctuations in the AC mains and virtually noise-free output.

Advanced microprocessor control monitors critical operational parameters.

Bias, load impedance, regulator output volta

Frequency response 20 Hz to 20 kHz +0, -0.18 dB <0.5 Hz to 120 kHz +0, -3 dB Signal-to-noise ratio >116 dB, "A"-weighted Gain 25.4 dB Total harmonic distortion <0.02% at 1 kHz, at 400 W, 8 Ohms <0.15% at 20 kHz, at 400 W, 8 Ohms Input impedance Single Ended: 100 kOhms Balanced: 200 kOhms CAST: 70 Ohms Input sensitivity Single Ended or Balanced: 3.04 V rms CAST: 3.04 mA rms Output power 400 W RMS at 8 Ohms 800 W RMS at 4 Ohms 1600 W RMS at 2 Ohms Output voltage 160 V peak-to-peak 57 V RMS Output current 37 A peak Slew rate 100 V/µs Output Impedance <0.055 Ohms at 20 Hz <0.064 Ohms, 20 Hz to 20 kHz

Damping Factor (referred to 8 ohms) >145 at 20 Hz >125, 20 Hz to 20 kHz Power consumption Standby: 370 W Idle: 570 W Maximum: 5000 W Heat Output Stand-by: 1270 BTU/hr. Idle: 1950 BTU/hr. Maximum: 7700 BTU/hr. Inputs 3 single-ended via RCA connector 3 balanced via XLR connector 3 CAST via 4-pin bayonet connector Outputs 3 pairs Krell binding posts Dimensions 17.3 in. W x 9.8 in. H x 26.1 in. D 438 mm W x 248 mm H x 662 mm D Weight Shipped: 190 lb., 86 kg Unit Only: 175 lb., 79.2 kg

 

Home Theater Review
"Krell has put their top technology into this amplifier and it really shows. This is undoubtedly one of the best amplifiers made."
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• Product Manual