Krell's Massive Attack Part 2
Tucked within the madness of the "Zoo," as the Las Vegas Convention Center is called by its inmates, Krell assembled a temple of high-end heavy metal. Jon Iverson, Stephen Mejias, and I steered Primedia's Greg Nevins over to the monoblock Evolution One 450W power amplifiers ($50,000/pair) and Evolution Two preamplifiers ($40,000/pair), assuming they were Krell's newest additions. Au contraire, Todd Eichenbaum assured us, Krell was introducing 10 (!) new models at the show—a new line called EVO, which replaces the CAST line with components containing trickle-down technology from the Evolution flagship products.
The EVO power amplifier all feature Active Cascode Topology, which Eichenbaum explained, eliminates global negative feedback by employing only nested local feedback within the individual gain blocks. In addition, the signal path employs both Krell Current Mode and CAST circuitry, which means that when used in a complete EVO system from source to output connected in CAST, the number of voltage gain stages is reduced to one, "the minimum." Huge power supplies, extensive magnetic and electrical shielding, microprocessor control, and internal line conditioning circuitry combine to make the EVO amps so quiet they "approach the theoretical limit of technology," Eichenbaum opined. The EVO amplifiers are: EVO 402, stereo 400Wpc ($15,000); EVO 403 , three-channel 400Wpc ($20,000); EVO 600, 600W monoblock ($15,000); and EVO 900, 900W monoblock ($20,000).
EVO preamplifiers feature 1.5 MHz open loop bandwidth in a zero feedback, balanced circuit incorporating Current Mode and CAST. The EVO pres don't need no negative feedback—Krell says open-loop distortion is typically less than 0.005% (50 parts per million). The volume control is a trick 16-bit balanced resistor ladder. The preamplifiers' power supplies are housed in separate chassis and use electrical and magnetic shielding to prevent interference with preamplifier circuits. The two chassis EVO222 is $10,000; the four chassis dual mono EVO 202 is $15,000.