Krell Evolution 222 Stereo Preamplifier

1.5 MHz open loop bandwidth in a zero feedback, balanced, Krell Current Mode design terminating in Krell CAST. All signal gain is realized in a surface mount topology using proprietary multiple-output current mirrors with nearly 500 times the open loop linearity of other designs. Zero negative feedback is used anywhere in the preamp, nor is it necessary. Open-loop distortion is typically less than 50 parts per million. A complete Evolution (source, preamp, amplifier) system, connected in CAST, reduces the number of voltage gain stages to the minimum, one. The resulting noise floor is approaching the theoretical limit of technology. The volume control is realized with a 16-bit balanced resistor ladder -- bandwidth and transient response of the preamp circuitry are virtually unaffected by the volume setting. 150 VA toroidal transformer drives four 6-amp bridge rectifiers and 19,800 microfarads of filter capacitance. Krell designed digital control circuit monitors and optimizes the preamplifier's operating parameters.

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 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 a 2-conductor 3.5 mm connector 1 preamplifier link via an RJ-45 connector Control outputs 2 individually programmable 12 VDC trigger outputs via 2-conductor 3.5 mm connectors (500 milliamps maximum per output) 1 preamplifier link via an RJ-45 connector Power output 1 phono power output (+/-20 VDC) for KPE via a 9-pin D-subminiature connector Input impedance CAST: 45 Ohms Balanced: 95 k Ohms Single-ended: 47.5 k Ohms Output impedance CAST: >1 M Ohms Balanced: 50 Ohms Single-ended: 25 Ohms 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 CAST: 14 mA RMS Balanced: 14 V RMS Single-ended: 7 V RMS Output overload CAST: 16 mA RMS Balanced: 16 V RMS Single-ended: 8 V RMS Frequency response 20 Hz to 20 kHz +/- 0.02 dB 0.1 Hz to 1.5 MHz +0, -3 dB Total harmonic distortion plus noise Balanced Output: 99 dB "A" weighted: >108 dB Power consumption Standby: 60 W Power on: 65 W Power on, with KPE: 75 W Dimensions 17.3 in.W x 3.8 in. H x 18.3 in. D 43.8 cm W x 9.7 cm H x 46.4 cm D Weight Shipped: 37 lbs., 16.7 kg Preamplifier only: 22 lbs., 10 kg