Aurora One Tube Line Preamplifier & Buffer
Class-A Line Preamplifier
High Gain, Low Gain, & Bypass Modes
The Aurora One Line Preamp and Buffer is your answer for a highly flexible tube analog input preamp.
The unique on-board gain matching is specifically tailored to today's audio systems where audio sources can have a wide variety of input signal levels and output routing needs.
$4,999.99
All Tube Signal Path...
The Class-A all tube signal path utilizes the finest new production tubes for extremely low noise with a neutral yet authoritative response into even those difficult to drive power amplifiers.
All tubes are matched in house at their operating conditions across 4 key parameters; gm, u, Rp, and Ia (transconductance, gain plate resistance and current).
The Aurora One offers 3 modes of operation; Low Gain, High Gain, and Bypass. These modes can be pre-programmed by the user for each of the 6 inputs. When a specific input is selected, the preamp will automatically recall the user-programmed mode and display the status via the indicators on the front panel. This unique feature allows for better volume matching between inputs with different signal strengths. Not only does the user not have to continuously tweak the volume, you no longer have to worry about going deaf by accidentally switching to the wrong input!
Aurora One Features
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SHIPS WITH 6H30PI AND E88CC GOLD PIN TUBES
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IN-HOUSE MATCHING OF TUBES ACROSS GM, MU, RP, & IA
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6 PAIRS OF RCA INPUTS
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2 PAIRS OF RCA OUTPUTS
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INDEPENDENTLY BUFFERED
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INDEPENDENT MUTE CONTROLS
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HIGH GAIN, LOW GAIN, AND BYPASS MODES
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PRE-PROGRAMMABLE FOR EACH INPUT
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ALPS BLUE VELVET VOLUME CONTROL
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DUAL MONO REGULATED POWER AND FILAMENT SUPPLIES
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TIME DELAY OUTPUT ACTIVE CIRCUIT FOR POP-FREE STARTUP AND SHUTDOWN
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CUSTOM-DESIGNED LOW FLUX DENSITY EI TRANSFORMER
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PRP PRP9372 US-MADE METAL FILM NON-MAGNETIC AUDIO GRADE RESISTORS
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SOLEN FAST COUPLING CAPACITORS
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MOGAMI W2330 COAXIAL SHIELDED AUDIO SIGNAL WIRING
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EXTRA THICK FR4 PRINTED CIRCUIT BOARDS
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ALUMINUM CHASSIS WITH STEEL DIVIDER FOR LOWEST NOISE
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SORBOTHANE® FEET FOR VIBRATION ISOLATION
Aurora One Typical Specifications
Gain
14dB (High Gain)
8dB (Low Gain)
0dB (Bypass)
Channel Balance (With Volume knob set to -6dB)
0.01dB (High Gain)
0.01dB (Low Gain)
0.2dB (Bypass)
THD +N (1V RMS Output)
0.03% (High Gain)
0.06% (Low Gain)
0.01% (Bypass)
THD +N (2V RMS Output)
0.05% (High Gain)
0.08% (Low Gain)
0.01% (Bypass)
Frequency Response (-3dB down)
<10Hz and above 175KHz
Input Referred Noise (A-weighted)
1.9uV / -112.2dBu (High Gain)
3.5uV / -106.9dBu (Low Gain)
8.1uV / -99.6dBu (Bypass)
SNR 2V RMS Output (A-weighted)
-106dB (High Gain)
-107dB (Low Gain)
-108dB (Bypass)
Rated Output
10V at 0.5% THD+N
Input Impedance
50KΩ
Recommended Load (Output)
10KΩ or greater
Tubes (Tested and Matched in House
2x 6H30PI Electro-Harmonix Gold Pin
2x E88CC JJ Gold Pin
Voltage
Available in 115-120VAC or 230-240VAC
Power Consumption
70 Watts
Dimensions (includes faceplate and feet)
17.5" x 14.25" x 4.5"
Due to the open loop design of this amplifier, actual performance will vary depending on vacuum tube quality. Specifications subject to change.
Features
The Aurora One is designed with a time delay start sequence to ensure all operating voltages are stabilized and the preamplifier is ready to play audio before the output is active. This removes the chance of any pop and noise during power on and off. The Aurora One can be turned on and off without any need for power sequencing with other equipment. The “Active” indicator on the front panel shows the status of the power on sequence. The preamp output will be active approximately 25 seconds after power on.
While High Gain, Low Gain, and Bypass Modes can be pre-programmed for each input using the DIP switches on the back panel, the modes can also be overridden by switches on the front of the unit to help determine the correct settings or for experimentation.
High Gain: 14dB
Low Gain: 8dB
Bypass: 0dB
In Bypass Mode the internal gain stage is not used for 0dB gain from input to output. The user still has control of the overall volume and the output is buffered just like in Low Gain and High Gain modes. This mode is perfect for sources that already have high signal levels.
A pair of independently buffered stereo outputs...
With 2 sets of independently buffered stereo outputs, the Aurora One was designed to drive your main speaker system while simultaneously driving active subwoofers or another system all together.
Since each output has an independent mute switch on the front, a wide range of flexibility is offered. The robust tube output buffer has the capability to drive long interconnects and difficult loads without signal degradation.
Construction
An aluminum chassis with stainless steel hardware houses the circuitry for superior shielding to minimize magnetic coupling from external sources. Inside the chassis, the power supply is isolated from the sensitive amplifying stages with an extra thick cold rolled steel baffle. The ferromagnetic baffle keeps any magnetic noise and interference out of the signal path.
The chassis design allows the Aurora One to achieve superior noise performance without the added cost, complexity, and space requirements of a dual chassis design. Top and bottom venting keeps the Aurora One running cool for long tube life while Sorbothane isolation feet reduce mechanical vibrations.
The circuit is built on extra thick FR4 PCBs for high reliability and lowest noise. All connectors are mounted on a separate back plane PCB with relays for input switching. The use of relays minimizes audio path lengths and are service free. No contact cleaning required for noiseless switching.
Like the Kaskode One, The Aurora One uses an open-loop zero global feedback design in addition to a wide bandwidth, low noise, and low distortion performance circuit to provide superior sound and transient response. This approach provides a significantly more natural "in the room" experience compared to other preamps utilizing sub-optimal circuit designs with hefty doses of negative feedback to bring the performance back into acceptable levels.
Why not just start with the best possible circuit design?
Because it takes time and expense to design, test and manufacture a product in the manner, which is what Bandwidth Audio strives on!
In High and Low Gain Modes, initial amplification is taken care of with new Electro-Harmonix 6H30PI gold pin tubes. This robust high drive strength tube is used in a special circuit configuration for low noise and high linearity. We use this tube to its strengths running it at its optimal power point with significant current flow. Peddling these tubes at anything less is undesirable.
E88CC gold pin triodes are used as output buffers to drive a pair of independently buffered RCA outputs. This offers robust drive capability for consistent sound quality even with long interconnects.
Power is sourced from a custom designed low-noise and low-flux density EI core transformer. Compared to a toroidal transformer, the EI core is extremely forgiving to power quality for consistent sound. Power is sent to calibrated dual mono power supplies using precision discrete high voltage regulators and filament supplies to remove crosstalk. Extensive filtering is used throughout for extremely clean power.
Premium components are used throughout for the utmost performance, sound quality and longevity.
The Circuit