Krell

The Evolution 600e monaural amplifier sits in the middle of the Evolution e Series. Powerful enough for almost any application, the Evolution 600e is the amplifier choice in many stereo and home theater systems worldwide. This power capability is coupled to a new green operating mode that reduces standby electrical draw to a mere 2 Watts. As with all Evolution amplifiers, the Evolution 600e development began with a question, "What is the most difficult scenario this amplifier will face?" The answer is a 2 Ohm speaker load. When the final design is complete, and the amplifier is presented with a typical 8 Ohm speaker, it practically coasts. This amplifier simply sings with this stress-free load connected. Outputting a daunting 600 watts of power and coupled to Krell Evolution e Series circuit technology, the Evolution 600e is a velvet hammer.

Power Supply

The Evolution 600e is equipped 2 2,200 VA transformers and 108,000 µF. This power source is the backbone for the output of the Evolution 600e. With this foundation, the Evolution 600e delivers 600 watts into 8 Ohms, 1,200 watts into 4 Ohms, and 2,400 watts into 2 Ohms. 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 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 new 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 600e 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.

Frequency response
20 Hz to 20 kHz +0, -0.18 dB
<0.5 Hz to 120 kHz +0, -3 dB
Signal-to-noise ratio
>110 dB, wideband, unweighted, referred to full power output
>119 dB, "A"-weighted
Gain
25.4 dB
Total harmonic distortion
<0.02% at 1 kHz, at 600 W, 8 Ohms
<0.15% at 20 kHz, at 600 W, 8 Ohms
Input impedance
Single Ended: 100 kOhms
Balanced: 200 kOhms
CAST: 70 Ohms
Input sensitivity
Single Ended or Balanced: 3.72 V rms
CAST: 3.72 mA rms
Output power
600 W RMS at 8 Ohms
1200 W RMS at 4 Ohms
Output voltage
196 V peak-to-peak
69 V RMS
Output current
49 A peak
Slew rate
100 V/µs
Output Impedance
<0.030 Ohms, 20 Hz to 20 kHz

Damping Factor (referred to 8 ohms)
>270, 20 Hz to 20 kHz
Transformer

Two 2200 VA (4400 VA total) for audio circuitry
One 10 VA for digital control circuitry
Power Supply Capacitance
108,000 µF
Power consumption
Standby: 2 W
(High-current standby: 260W) Idle: 410 W
Maximum: 3800 W
Heat Output
Stand-by: 7 BTU/hr. (High-current standby: 890 BTU/hr.
Idle: 1400 BTU/hr.
Maximum: 5500 BTU/hr.
Inputs

1 single-ended via RCA connector
1 balanced via XLR connector
1 CAST via 4-pin bayonet connector
Outputs
1 pairs Krell binding posts
Dimensions
17.3 in. W x 9.8 in. H x 22.1 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

 

Hi Fi Critic Review
"The overall quality is so well balanced and so even over the frequency range, it's easy to underestimate how good this amplifier is, and one only finds out what might be missing when substituting other references."
Read more...

Home Theater Review
"It is hands down the best amplifier I've ever heard and the new benchmark..."
Read more...

  • Evolution 600e
  • Evolution 600e
  • Evolution 600e
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