Krell just announced their flagship Illusion and lower-cost Illusion II stereo preamplifiers. The $15,000 Illusion preamp separates the power supply from the audio circuitry, while the $7,000 Illusion II adds digital inputs and eschews the separate power supplies. Sharing the new Class A iBias power amplifier aesthetic and featuring Krell CAST technology, the Illusion preamplifier is the ideal match for the new Solo 375 and Solo 575 power amplifiers.
“Separate power supplies for our top preamplifiers has always been featured by Krell,” Bill McKiegan, president of Krell Industries, said. “Now we’ve created a pair of preamplifiers for all audiophiles supporting the new esthetic established by the Foundation preamp processor and our new iBias amplifiers.”
An optional crossover function offers the ability to use a subwoofer/satellite speaker arrangement and still maintain the highest quality sonic performance. Previous to the Illusion preamplifier, this system configuration would require signals to pass through a subwoofer’s lower quality crossover circuitry. The Illusion preamplifier is the centerpiece of a world-class audio system where space is at a premium.
Owing to Krell’s work in the Modulari Duo Reference loudspeaker, the unique crossover feature is a highly sophisticated option. When the optional board is present, additional crossover menu items become available. Definable parameters include independently assignable crossover frequencies and filter types for the high and low pass sections. Choices include 40Hz, 55Hz, 75Hz, and 100Hz crossover points with 12dB, 24dB, and 48dB Butterworth or 24dB Linkwitz-Riley style filters. The high pass section of the crossover uses the full Illusion preamplifier circuitry for its output stage.
Illusion – Circuitry
The Illusion preamplifier is a dual monaural circuit design with the left and right channels afforded by their own power supply regulation and individual full chassis sized boards. All signal gain is realized in surface mount topology using proprietary multiple-output current mirrors with nearly 500 times the open loop linearity of other designs. 1.5 MHz open loop circuit bandwidth in a zero feedback, balanced, Krell Current Mode design terminates in Krell CAST. A complete Krell system (source, preamp, and amplifier) system, connected using CAST interconnects reduces the number of voltage gain stages to the minimum, one. The resulting noise floor approaches the theoretical limit of technology. Negative feedback is not used anywhere in the preamp, nor is it necessary. Open-loop distortion is typically less than 0.003%. The volume control is realized with a balanced resistor ladder – bandwidth and transient response of the preamp circuitry are virtually unaffected by the volume setting.
Illusion – Power Supply
The Illusion audio circuits receive power from a Krell Current Mode analog power supply housed in its own dedicated chassis. The power supply avoids the common integrated circuit topology used in many preamplifiers and instead mimics the design topology of Krell Evolution Series amplifiers. The circuitry is completely discrete giving it the ability to respond quickly to current demands and also be unaffected by all but the most severe AC voltage power fluctuations. Oversized for a preamplifier, the power supply features a 290 VA transformer and 41,600µF of capacitance. Locating the power supply in its own chassis presents the ideal configuration for isolating stray electrical and magnetic interference from the critical preamplifier signal path. Capable of delivering current and voltage swing for any musical event, the Illusion power supply is gentle on AC requirements when not in use. A new eco-friendly design reduces standby power draw to 2W.
Illusion II – Digital Sources & Module
The Illusion II offers five digital inputs. The digital module features AES/EBU, coaxial, and optical digital inputs for use with streaming devices or other digital sources. The digital module supports up to 24 bit/192kHz LPCM. All digital signals are fed to an ESS Sabre DAC and then sent to Krell’s Current Mode, discrete, balanced analog circuitry.
Illusion II – Power Supply
Oversized for a preamplifier, the power supply features a 95 VA transformer and 40,000 µF of capacitance giving it the ability to respond quickly to musical demands. The large power supply improves noise rejection and renders the Illusion II impervious to all but the most severe AC voltage power fluctuations. A new eco-friendly standby mode reduces power consumption to 2W.
Pricing and Availability
The Krell Illusion Preamplifiers will ship late March 2014 at the following prices:
- Krell Illusion stereo preamplifier with separate power supply → $15,000
- Krell Illusion II stereo preamplifier with digital inputs → $7,000