Krell
Krell Pre-Amplifiers
The Illusion II is the perfect centrepiece for a world-class digital and analogue audio system. Added to the normal selection of balanced and single-ended inputs are five digital inputs. The digital module features AES/EBU, coaxial, and optical digital inputs for use with streaming devices or other digital sources.
Illusion Pre-Amplifier
The Illusion preamplifier extends the Krell tradition of separating the power supply from the audio circuitry in their flagship preamplifiers. 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.
Illusion Preamplifier
The optional crossover functionality 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.
Crossover Highlights
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.
Circuitry Highlights
The Illusion preamplifier is a dual monaural circuit design with the left and right channels afforded 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 bandwidth in a zero feedback, balanced, Krell Current Mode design terminating 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.
Power Supply Highlights
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 e 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 Preamplifier
Circuitry Highlights
The Illusion II preamplifier is a dual monaural design with the left and right channels afforded their own power supply regulation and individual circuit boards. All signal gain is executed with surface mount technology using proprietary multiple-output current mirrors with nearly 500 times the open loop linearity of other designs. Featuring 700 kHz bandwidth in a zero feedback, balanced, Krell Current Mode design, the Illusion II shares the same design philosophy as its bigger brother, the flagship Illusion preamplifier. 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. The headphone circuitry is identical to the main circuitry, offering private listening with the same performance as speaker playback.
Digital Module Highlights
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.
Power Supply Highlights
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.
Illusion I Pre-Amplifier
Inputs | : | 2 pr. CAST via 4-pin bayonet connectors, 2 pr. balanced via XLR connectors |
: | 3 pr. single-ended via RCA connectors | |
Tape Input | : | 1 pr. single-ended via RCA connector |
Main Outputs | : | 2 pr. CAST via 4-pin bayonet connectors, 1 pr. balanced via XLR connector |
: | 1 pr. single-ended via RCA connector | |
Control Outputs | : | 2 individually programmable 12 VDC trigger outputs via 3.5 mm connectors |
: | 1 preamplifier link via an RJ-45 connector | |
Power Output | : | 1 phone power output (±20 VDC) for KPE via a 9-pin D-subminiature connector |
Input Impedance | : | CAST: 25 Ohms, Balanced: 40 k Ohms, Single-ended: 20 k Ohms |
Output Impedance | : | CAST: >1 MΩ, Balanced: 250Ω, Single-ended: 125Ω |
Gain | : | 12 dB (CAST or balanced output), 6 dB (single-ended output) |
Volume control | : | Balanced, current-mode, 16-bit, discrete R-2R ladder |
Input Overload | : | Balanced, current-mode, 16-bit, discrete R-2R ladder |
Output Overload | : | CAST: 16 rnA RMS, Balanced: 16 V RMS, Single-ended: 8 V RMS |
Subwoofer Outputs | : | 1 pr. balanced via XLR connector |
: | 1 pr. single-ended via RCA connector | |
Tape Outputs | : | 1 pr. single-ended via RCA connector,buffered |
Control Inputs | : | 1 RS-232 input via a 9-pin D-subminiature connector |
: | 1 remote IR detector input via a 3-conductor 3.5 mm connector | |
: | 1 12 VDC trigger input via 3.5 mm connector | |
: | 1 preamplifier link via an RJ-45 connector | |
Frequency Response | : | 20 Hz to 20 kHz ± 0.02 dB, 0.35 Hz to 720 KHz +0, -3 dB |
: | Single-ended: 8 V RMS | |
Total Harmonic Distortion plus noise | : | Balanced Output: <0.003%, 20 Hz to 20 kHz, 4 V RMS or 4mARMS |
Signal-to-noise ratio | : | 4 V RMS balanced or 4 mA RMS CAST output |
: | Wideband, unweighted: >100 dB | |
: | N' weighted: >109 dB | |
Power Consumption | : | Standby: 60 W, Power on: 65 W, Power on, with KPE: 75 W |
Dimensions - Preamplifier only: | : | 43.8 x 9.7 x 46.4 cm D (WxHxD) |
Dimension - Power supply only: | : | 43.8 x 9.7 x 44.8 cm (WxHxD) |
Dimensions - Preamplifier and power supply: | : | 43.8 x 19.2 x 46.4 cm (WxHxD) |
Weight | : | Shipped: 27.6 kg (shipping weight) |
: | Preamplifier only: 8.1 kg | |
: | Power supply only: 12.7 kg |
Illusion II Pre-Amplifier
Analog Inputs | : | 2 pr. balanced via XLR connectors |
: | 3 pr. Single-ended via RCA connectors | |
Digital Inputs | : | 1 AES/EBU via XLR connector |
: | 2 coaxial via RCA connectors, 2 optical via Toslink connectors | |
Main Outputs | : | 1 balanced via XLR connectors |
: | 1 pr. Single-ended via RCA connectors | |
Input Impedance | : | Balanced: 40kΩ, Single: Ended 20kΩ |
Output Impedance | : | Balanced: 310 Ω |
: | Single-ended: 155 Ω | |
: | Headphone: <3.0Ω | |
Gain | : | Balanced: 12.0 dB |
: | 6 dB (single-ended output) | |
: | Singleended: 6.0 dB | |
: | Headphone: 5.1 dB with 32 Ω load | |
Volume control | : | Current mode, 12-bit, discrete R-2R ladder |
Input Overload | : | > 7.0 V RMS balanced or single-ended |
Output Overload | : | Balanced: >16 V RMS |
: | Single-ended: >8.0 V RMS | |
: | Headphone: >3.0 V RMS, 32 Ω load | |
Headphone Output | : | 1 via 3-conductor 6.35 mm (1/4 inch) connector |
Control Inputs | : | 1 RS-232 input via a 9-pin D-subminiature connector |
: | 1 remote IR detector input via a 3-conductor 3.5 mm connector | |
: | 1 12 VDC trigger input via 2-conductor 3.5 mm connector | |
Control Outputs | : | 2 individually programmable 12 VDC trigger outputs via 2-conductor 3.5mm connectors (30 mA maximum per output) |
Frequency Response | : | 20 Hz to 20 kHz +0, -0.02 dB |
: | 0.25 Hz to 1.2 MHz +0, -3 dB | |
Total Harmonic Distortion plus noise | : | Balanced Output: <0.003%, 20 Hz to 20 kHz, at 4.0 V RMS |
: | Headphone: <0.09%, 20 Hz to 20 kHz, 2.0 V RMS, 32 Ω load | |
Signal-to-noise ratio | : | 100 dB wideband, unweighted |
: | 107 dB "A"-weighted, both referred to 4.0 V RMS balanced | |
Power Consumption | : | Standby: <2 Watts |
: | Power on: 40 Watts | |
Dimensions - Preamplifier only: | : | 43.8 x 9.7 x 46.4 cm (WxHxD) |
Weight - Preamplifier only | : | 10.4 Kg |