Training Example: Jeff Rowland Design Group – Review the Data, Give Your Score & Compare to the Real AI Evaluation

ENGINEERED DAILY

MAGIC

[H2] The 1500 W Daemon Super Integrated
Music of the gods… from whatever source you choose.
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[H2] Letter from Jeff Rowland
Introduction to 735
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[H2] Join Us in the Gallery
See HD video and pictures of the current products, manufacturing process, and behind-the-scenes.
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[H2] Current Product Reviews
Find reviews of the Model 725, Model 625, Corus Preamplifier, Aeris DAC, and more…READ MORE
[H2] More Power Deeper Engagement
With virtually no distortion, the redesigned Model 625 S2 unlocks the magic between the notes.
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STEREO AMPLIFIER

MODEL 625 S2

[H2] Model 625

The 625 Series 2 incorporates many of the same technical features of the 725 amplifiers. Similar to the 725, the 625 S2 signal circuitry is built upon a Rogers ceramic circuit board laminate material for lower dielectric absorption and energy storage. The 4-Pole filter capacitors used in the 725 power supply have also been included in the S2, significantly reducing power supply output noise. The maximum output power has been increased from 300 to 325 watts per channel at 8 ohms.
Precision LED based current sources have been implemented throughout the amplifier circuitry, along with 0.1% thin film SMD resistors for more stable operating points and lower noise. Custom designed Lundahl input transformers are implemented with a higher turns ratio and wound with Cardas high purity copper wire.
Input circuitry includes an additional linear phase 2 pole filter to effectively attenuate all out-of-band signals from any source, including DSD spurious noise.Cardas gold/teflon/rhodium XLR input connectors are carried over from the 725. Newly developed error-correction circuitry has been incorporated around the entire amplifier, making a total of three independent error-correction techniques used to decrease all forms of distortion throughout the entire audio bandwidth.
The Model 625 S2 delivers a sensuous grain-free musicality of unparalleled transparency and low level resolution that blossoms from a rich velvety silence and blossoms into the pure enjoyment of your listening experience.

FEATURESSPECIFICATIONSBACK PANELMANUAL
[H2] Features

[H4] Machined Aluminum Chassis
Precision-machined chassis with integrated heat-sinks, milled from a solid block of aircraft grade aluminum, provides exceptional thermal heat transfer/dissipation, RFI/EMI shielding, and resonance control.
[H4] Composite Circuit Architecture
Unique composite circuit architecture incorporating separate Class AB voltage and current gain blocks with no overall negative feedback, delivers a sensuous grain-free musicality of unparalleled transparency and low level resolution.
[H4] Balanced Topology
Inherent cancellation effects of balanced topology implemented throughout all power and input/output circuits ensures greatly reduced distortion and noise under dynamic signal conditions.
[H4] High-Current Copper Bus-Bars
High-current, dual polarity, ultra low impedance copper bus-bars distribute both power supply input current and signal output current, virtually eliminating intra-circuit EMI signal contamination, greatly reducing internal wiring, while increasing circuit board rigidity.
[H4] High Precision Surface Mount Components
Extensive use of Lead (Pb)-free, low temperature coefficient, active and passive surface-mount components results in significantly smaller loop areas, reduced circuit capacitance and inductance, and introduces less noise than conventional leaded components.
[H4] Transformer-Coupling and Isolation
Transformer coupled input circuitry provides universal component compatibility and virtually eliminate ground loop noise and RFI/EMI. Transformer coupling ensures identical amplifier overall gain when using unbalanced input adapters.
[H4] Power Factor Correction
Power Factor Correction (PFC) in the power supply reduces AC line harmonic noise pollution and increases AC line power utilization to 99%.
[H4] High-Efficiency Switch-Mode Power Supply
Highly efficient, compact, light weight, 1500 watt DC switch-mode power supply provides optimum voltage regulation for all circuits and operating conditions, and allows for quiet operation over a wide range of AC mains power sources.
[H4] Dual-Position Speaker Terminals
Dual CE approved speaker output terminals, in both horizontal and vertical orientation, require no tools for secure, low resistance connections, and allow for easy bi-wiring applications.
[H4] Flexible 20 Amp AC Power
20 amp AC power inlet accepts a wide variety of after-market high-performance power cables.
[H4] Front Panel Standby Button
Illuminated front panel push-button switches the amplifier into standby mode (<1 watt consumption).
[H4] Rear Panel Remote Jack
12V 3.5mm jack on rear panel permits amplifier power on/standby switching in remote and home theater applications.
[H4] Self-Leveling Supports
Removable 3-point self-leveling Delron chassis supports provide high frequency mechanical noise isolation.

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[H2] Specifications

Output Power
325 watts @ 8 ohms / 600 watts @ 4 ohms
Frequency Response
10 Hz – 150 kHz, -3 dB
S/N Ratio
95 dB, ref. 1.0 watt @ 8 ohm load
Output Noise
< 100 µv, A-wtd
Crosstalk
> 91 dB @ 1 kHz, 74 dB @ 20 kHz
Input Impedance
40k ohms
THD + Noise
< 0.001% @ 1 kHz, 8 ohms
Damping Factor
> 200, 20 Hz – 20 kHz
Overall Gain / Bal. or Unbal.
26 dB
Common Mode Rejection Ratio
> 90 dB, 20 Hz – 20 kHz
Absolute Phase Non-inverting
Pin 2 Positive
Inputs
1 pair balanced (XLR)
Outputs
2 pair parallel binding posts per channel
Power Consumption Idle
100 watts
Power Consumption Standby
< 0.5 watt
Amplifier Weight
54 lbs. / 24.5 kg
Amplifier Shipping Weight
64 lbs. / 29 kg
Amplifier Dimensions (h/w/d)
5.75” x 15.5” x 16.25” / 146mm x 394 mm x 413mm

[H2] Back Panel
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[H2] Daemon Integrated

Jeff Rowland Design Group launched the 1500 WPC Daemon Super Integrated Amplifier at Munich High End 2015. Named after the ancient Greek word for the power of “creative genius” and the spirit of “scientific inspiration”, the Daemon represents a technological leap forward as Jeff Rowland’s fifth generation of integrated amplifiers.
“Designing the integrated amplifier is one of the most challenging tasks in audio. To achieve perfect synergy of all components while entirely eliminating cross component interference is a black art,” says founder and president Jeff Rowland. “When done well, the results can be spectacular. The Daemon is one of our most sophisticated products to date. You’ll see much of its DNA expressed in future products. ”

FEATURESSPECIFICATIONSBACK PANEL
[H2] Features

[H4] MACHINE-ALUMINUM CHASSIS
Precision-machined chassis with integrated heat-sinks milled from a solid block of aircraft grade aluminum, provides exceptional thermal heat transfer/dissipation. RFI/EMI shielding, resonance control, and minimizes micro-phonically induced micro-vibrations from any source.
[H4] BALANCE TOPOLOGY
Inherent cancellation effects of balanced topology implemented throughout all power and input/output circuits ensures greatly reduce distortion and  noise under dynamic signal conditions
[H4] HIGH-PRECISION SURFACE COMPONENTS
Extensive use of Lead (pb)-free, low temperature coefficient, active and passive surface-mount components results in significantly smaller loop areas, reduced circuit capacitance and inductance, and introduces less noise than conventional leaded components.
[H4] THIN FILM RESISTORS
All resistors are low noise, 0.1% thin-film type for extremely low thermal noise which complement the low-noise characteristics on the active circuitry.
[H4] TEFLON COATED WIRES
All signal carrying input and output wires are teflon coated, also for low dielectric energy storage, further ensuring that each audio note reproduced naturally decays into the deeper silence of the music.
[H4] TRANSFORMER-COUPLING AND ISOLATION
Transformer coupled input circuitry provides universal component compatibility and virtually eliminate ground loop noise and RFI/EMI. Transformer coupling ensures identical amplifier overall gain when using unbalanced input adapters.
[H4] ACTIVE POWER FACTOR CORRECTION
A Power Factor Correction (PFC) integrated into the power supply reduces AC line harmonic noise pollution and increases AC line power utilization to 99%.
[H4] HIGH-EFFICIENCY SWITCH MODE POWER SUPPLY
Highly efficient, compact, light weight, 1500 watt DC switch-mode power supply provides optimum voltage regulation for all circuits and operating conditions, and allows for quiet operation over a wide range of AC mains power sources.
[H4] BINDING POSTS
CE approved speaker output terminals require no tools for secure, low resistance connections.
[H4] FRONT PANEL STANDBY BUTTON
Standby button is part of the three buttons on the front of the DAEMON .
[H4] REMOTE ON/OFF
(3.5mm) mini plug connector on rear panel permits amplifier power on/standby switching switching in remote and home theater applications.

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[H2] Specifications

Max. Power Output
8 Ω: 1500 WPC / 4 Ω: 2500 WPC
Frequency Response
10 Hz – 70 kHz
THD+N (20 Hz – 20 kHz )
< 0.05%
Intermodulation Distortion (CCIF)
18 kHz +19 kHz, 10 W, 8Ω 0.001%
Peak Output Current
30 A
Absolute Phase
Non-Inverting
Analog Inputs
3x RCA Unbalanced / 2x XLR Balanced
Digital Inputs
2x RCA SPDIF / 2x BNC SPDIF / 1x AES/EBU / 1x USB / 3x TOSLINK
Volume Control Range
99.5 dB
Weight
99 lbs / 45 kg
DIMS (h/w/d)
9.25” x 17.5” x 17.25” / 235 x 445 x 438 mm

[H2] Back Panel
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STEREO PREAMPLIFIER

CORUS

LEGACY PRODUCT

PRODUCTION SUSPENDED

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[H2] 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.

FEATURESSPECIFICATIONSBACK PANELMANUAL
[H2] Features

[H4] 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.
[H4] Diamond Sculpted Front Panel
Matching front panels precision-machined and sculpted with a diamond tipped cutting tool into a uniquely elegant prismatic curved design.
[H4] 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.
[H4] Free of internal signal pollution
Control subsystem taken completely offline after each command execution to maximize sound purity.
[H4] 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.
[H4] 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.
[H4] 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.
[H4] Dual zone preamplification
Separate 2nd gain stage for record outputs sports own OPA-1632 modules and independent volume.
[H4] 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).
[H4] 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.
[H4] Unity gain inputs
All main input configurable as unity gain bypass for compatibility with theater processors.
[H4] Phase inversion
Independent signal phase inversion control on left and right channels for optimum speaker setup and system checks.
[H4] Channel balance
Hi resolution (1.0dB) panning of stereophonic image (channel balance) for a maximum +/-20dB shift.
[H4] 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.
[H4] Remote sensor
Wired remote sensor milled from Aluminum billet enables Corus’s control while housing preamplifier in closed cabinet enclosures.
[H4] 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.
[H4] IEC
Grounded 15 Amp female IEC AC power connector.
[H4] 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.

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[H2] 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)

[H2] Back Panel
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