Illusion Preamplifier

The Illusion preamplifier extends the Krell tradition of separating the power supply from the audio circuitry in our 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.

 

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

The Illusion II is the perfect centerpiece for a world class digital and analog 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.

 

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 Preamplifier
Specifications
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

Download the "Quick Set-up Guide"
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


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

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:
  • 17.3 in.W x 3.8 in. H x 18.3 in. D
  • 43.8 em W x 9.7 em H x 46.4 em D
Power supply only:
  • 17.3 in. W x 3.8 in. H x 17.7 in. D
  • 43.8 em W x 9.7 em H x 44.8 em D
Preamplifier and power supply:
  • 17.3 in. W x 7.6 in. H x 18.3 in. D
  • 43.8 em W x 19.2 em H x 46.4 em D

Weight
  • Shipped: 61 lbs., 27.6 kg
  • Preamplifier only: 18 lbs., 8.1 kg
  • Power supply only: 28 lbs., 12.7 kg


Illusion II Preamplifier
Specifications
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

Download the "Quick Set-up Guide"
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)


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)
  • Singleended: 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

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:
  • 17.3 in.W x 3.8 in. H x 18.3 in. D
  • 43.8 em W x 9.7 em H x 46.4 em D

Weight
  • Shipped: 38 lbs., 17.2 kg
  • Preamplifier only: 23 lbs., 10.4 kg