Corus

  • Corus Preamplifier

    Elegant main chassis milled from ingots of non-resonant aircraft-grade aluminum houses all delicate audio and control circuits.

    Ground-breaking AC power supply is segregated in its own handsome external milled aluminum unit.

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Corus Technology

The Corus’s refined sensuous musicality, sonic excellence, and trend setting usability features are derived from the Criterion’s, whose sophisticated architecture pushes the limits of today’s technological art. The Corus’s elegant topology is completely balanced in the input phases, in circuit, and output phases. An elegant main chassis milled from ingots of nonresonant aircraft-grade aluminum houses all delicate audio and control circuits, while the ground-breaking AC power supply is segregated in its own handsome external milled aluminum unit.

The preamplifier’s features fully isolated transformer-coupled balanced and single-ended inputs and outputs, military-grade 4-layer ceramic boards, as well as incredibly low noise and high gain differentially balanced OPA1632 audio amplifier modules at its core. These, together with a number of further trend-setting engineering solutions, are implemented into the most compact circuit topology of any Rowland reference preamplifiers to date.

Corus Features

Ultra Low Resonance Chassis

Balanced preamplifier design housed inside twin ultra-low resonance, structurally rigid chassis precision-machined from solid ingots of aircraft grade 6061-T6 aluminum, completely sealed for trouble-free operation, yield maximum electrical/EMI/RF isolation.

Diamond Sculpted Front Panel

Matching front panels precision-machined and sculpted with a diamond tipped cutting tool into a uniquely elegant prismatic curved design.

Functional isolation

Power supplies and microprocessor-based system control circuits confined inside control chassis. Sensitive audio circuits isolated in audio chassis. Left and right subsystems further isolated into individual milled Aluminum pockets in true dual mono design for ultimate RF and EMI shielding.

Free of internal signal pollution

Control subsystem taken completely offline after each command execution to maximize sound purity.

Multi-regulated AC SMPS

High speed switch mode power supply (SMPS) developed for aerospace applications incorporates passive power factor correction (PFC) for sonic performance so pure and musical that is virtually invariant to power cords.

Ceramic boards

Circuits implemented on military-grade 4-layer ceramic boards for minimum energy retention. Boards further sport numerous grounding points for extended internal star-grounding.

Shortest signal path

Gain stages based on ultra-low noise advanced TI Burr brown OPA1632 differential balanced audio amplifiers are implemented into shortest signal path of any Rowland reference preamplifier.

Dual zone preamplification

Separate 2nd gain stage for record outputs sports own OPA-1632 modules and independent volume.

Transformer-coupled

All inputs and outputs coupled to identical custom wound Lundahl transformers for maximum noise rejection and cross-component compatibility. Transformer coupling also ensures invariant gain for balanced and unbalanced devices. Flexible connectivity: 6 inputs (4 XLR balanced, 2 RCA unbalanced); 4 main outputs (2 XLR balanced, 2 RCA unbalanced); 2 record outputs (1 XLR balanced, 1 RCA unbalanced).

Input gain offsets

Hi resolution independently programmable gain offset on each main input ranging from -10dB to +10dB in 0.5dB increments--. Output offset: hi resolution programmable gain offset on main unbalanced input 2 with 0.5dB resolution.

Unity gain inputs

All main input configurable as unity gain bypass for compatibility with theater processors.

Phase inversion

Independent signal phase inversion control on left and right channels for optimum speaker setup and system checks.

Channel balance

Hi resolution (1.0dB) panning of stereophonic image (channel balance) for a maximum +/-20dB shift.

VFD

Long life graphic vacuum fluorescent display (VFD) for system control. Remote control: Highly ergonomic, custom remote control transmitter milled from Aluminum billet supports complete system control and duplicates front panel operations.

Remote sensor

Wired remote sensor milled from Aluminum billet enables Criterion’s control while housing preamplifier in closed cabinet enclosures.

Precision volume adjustments

Dual rate volume control allows precision level adjustments over nearly a 100 dB range. The volume control incorporates a permanently noiseless optical encoder that always maintain its tactile feel, accuracy, and channel balance at all settings. The volume can be adjusted from 0dB to 99.5dB from the multi-role control knob on the front panel, as well as from the multi-function remote control. Rapid turns of the control knob adjust the volume by 1.5dB increments. Slow turns of the control allow for very fine adjustments by 0.5dB increments.

Quiet power-up

Rocker switch on back panel coupled to timer relay, turns Criterion quietly on to full power after circuit test and stabilization.

IEC

Grounded 15 Amp female IEC AC power connector.

Green technology

Highly efficient circuits yield modest power consumption of mere 50 Watts in class A, resulting in cool operations, and permits constant power-up to eliminate warm-up time and maximize musical performance. The Corus can operate also enclosed inside an entertainment unit.

Corus Specifications

Overall Gain Independently Programmable 0 to 20 dB on each input
Gain Range 99.5 dB, 199 Equal Increments
Gain Resolution 0.5 dB, +/- 0.03 dB Over Entire Range
Frequency Response 10 Hz – 300 kHz, -3 dB @ 8 ohms
Maximum Input Level 13.5 volts (RMS) @ 0 dB Gain
Maximum Output Level 13.5 volts (RMS)
THD + Noise < .003% @ 2 volt (RMS) Output, 50 Hz – 20 kHz
Signal-to-Noise Ratio > 100 dB
Common Mode Rejection Ratio > 90 dB, 20 Hz – 20 kHz
Channel Separation 99.5 dB
Input Impedance 40k ohms Balanced or Unbalanced
Output Impedance 60 ohms Balanced or Unbalanced
Inputs 4 pair Balanced (XLR), 2 pair Unbalanced (RCA)
Outputs 2 pair Balanced (XLR), 2 pair Unbalanced (RCA) for Main Out, 1 pair Balanced (XLR), 1 pair Unbalanced (RCA) for Record Out
Power Consumption 15 watts
Power Supply Universal Voltage Input Power Factor Corrected Power Supply
Display 320 x 32 dot Vacuum Fluorescent Display (VFD)
Preamplifier Weight 22 lbs / 10 kg
Preamplifier Dimensions H/W/D 3.9” x 15.5” x 12.3” (99mm x 394mm x 311mm)
Power Supply Dimensions H/W/D 3.9” x 4.7” x 11” (99mm x 119mm x 279mm)

Corus Preamplifier

The Corus Stereo Preamplifier delivers the Jeff Rowland hallmark of a sensuous and grain free musicality, combined with astonishing transparency and low level resolution. A broad 3-dimensional sound stage materializes into the physical listening space, where instruments and vocalists assume the textured appearance of solid existence.

The preamplifier yields exceptional frequency extension and linearity, with magnificent bass definition, an extraordinarily complex exposure of harmonic structure, and a sweetly filigreed treble. The Corus yields amazingly nuanced low level detail and micro-dynamics, and outperforms every previous Rowland preamplifier with its transient speed, staggering authority, and breath-taking macro dynamics. Only the transcendent resolving musicality of the Criterion battery-powered Preamplifier ever yields an even superior listening experience.

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Corus Preamplifier Reviews
The Absolute Sound #228 - December 2012 - by Robert Harley
HiFi+ #83 - October 2011 - by Roy Gregory