Features
The Evolution 402e is the flagship stereo amplifier in the Evolution e Series
utilizes the same technological advances as in the larger Evolution monaural
amplifiers. The Evolution 402e is an extremely powerful stereo amplifier with
the distinct advantage of a smaller footprint. As in its larger siblings, the
Evolution 402e combines this power with a modest 2 watt power draw when in
standby mode. Perfectly matched with an Evolution 202 preamplifier for stereo
application, the Evolution 402e also shines as part of a home theater. In this
application, the Evolution 402e gets mated with the Evolution 707 Reference
Surround Preamplifier/Processor and an Evolution 403e Three Channel Amplifier
for ultimate home theater performance.
Power Supply
The Evolution 402e is equipped with two
2,200 VA transformers and 188,000 μF of capacitance. This power source is the
backbone for the output of the Evolution 402e. With this foundation, the
Evolution 402e delivers 400 watts into 8 Ohms, 800 watts into 4 Ohms, and 1,600
watts into 2 Ohms with all both channels driven simultaneously. The FTC mandates
that power ratings are quoted using a 1,000 Hz sine wave into a fixed 8 Ohm
resistor with final power specification stated at 1% distortion. Krell
engineering considers this specification too lenient and not indicative of what
an amplifier is required to provide. Krell designs to a much stricter standard.
Our power tests use a 20-20,000Hz signal into 8, 4, and 2 Ohm loads. Our power
tests use a 20-20,000Hz signal into 8, 4, and 2 Ohm loads with our final
specifications stated for .1% distortion.
Internal high-current line conditioning circuitry effectively blocks RF noise
entering via the AC line and compensates for any asymmetry or DC offset in the
power waveforms. The amplifiers' low level and gain stages are powered via multi
regulated rails that provide total immunity from supply fluctuations and assure
noise-free circuit operation. Primary rail voltages are quasi-regulated,
enabling an "on-demand" supply of power that is highly responsive to dynamic
load.
Circuitry Highlights
Krell's Active Cascode Topology™ is
a significant departure from traditional amplifier circuits where the positive
and negative rail voltages are each applied entirely across a single row of
transistors. High voltage swing and gain requirements dictate that the
transistors be "pushed" into non-linear operating regions and, in some cases,
dangerously close to breakdown. Krell topology divides the full voltage swing
across multiple rows of transistors, and all devices are active-biased (i.e.,
they all carry the audio signal). Because individual transistors in the cascode
array "see" only a proportional fraction of the rail voltage, they operate in a
region that provides optimum linearity, gain, and safety. And because the
devices are not being pushed to their limits, the amplifier runs cooler and more
reliably. The improved linearity and stability greatly reduces the need for
negative feedback, which is known to cause sonic degradation. Krell Evolution
power amplifiers use only 14 dB of feedback throughout the topology-a small
fraction of the amount implemented in typical designs.
Krell Active Cascode Topology™ offers several performance advantages. It
breaks through bandwidth limitations of conventional designs and delivers very
high current. The usable bandwidth of an Evolution 402e is 300 kHz; triple the
bandwidth of a typical high performance amplifier. The result is near perfect
performance in the audible range with no phase anomalies typical of lower
bandwidth designs. Because the "work" is spread across multiple devices, the
amplifier is more load tolerant. Open-loop output impedance is extremely
low-about one hundred times lower than with most power amplifiers-ensuring
exceptional speaker control. All of these performance gains are achieved while
maintaining a high rail voltage, which provides a beneficial "flywheel" effect-a
de facto regulation that enables the amplifier to better deal with sudden
changes in power requirement, such as those caused by large signal transients.
Evolution amplifiers feature Krell CAST technology. CAST is a unique circuit
and connection breakthrough that eliminates distortions inherent in voltage
based amplification. A complete Evolution (source, preamplifier, and amplifier)
system, connected with CAST interconnects reduces the number of voltage gain
stages to the minimum, one. The resulting noise floor is approaching the
theoretical limit of technology. Emanating from a completely black background,
music explodes from absolute silence moving the listener closer to the goal of
recreating the live musical event in the listening room.
제품 Specfications
Frequency response
20 Hz to 20 kHz +0, -0.17 dB
<0.5 Hz to 125
kHz +0, -3 dB
Signal-to-noise ratio
>108 dB,
wideband,unweighted, referred to full power output
>118 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 both channels driven
800 W RMS at 4 Ohms both channels driven
Output voltage
160V 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 8ohms)
>145 at 20 Hz, referred to 8 Ohms
>125, 20 Hz to 20
kHz, referred to 8 Ohms
Transformers
Two 2200 VA
(4400VA total) for audio circuitry
One 10 VA for digital control circuitry
Power Supply Capacitance
188,000 μF
Power consumption
Standby: 2 W
(High-current standby: 260W)
Idle: 390 W
Maximum: 3800 W
Heat Output
Stand-by: 7 BTU/hr.
(High-current standby: 890 BTU/hr.)
Idle: 1300 BTU/hr.
Maximum: 6400 BTU/hr.
Inputs
2 single-ended via RCA connector
2 balanced via XLR connector
2 CAST via 4-pin bayonet connector
Outputs
2 pairs Krell binding posts
Dimensions
17.25 in. W x 9.75 in. H x 22.05 in. D
438 mm W x 248 mm H x 560 mm D
Weight
Shipped: 150
lb., 67.9 kg
Unit Only: 135 lb., 61.1 kg