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Power amplifiers stereo — Audio Research Reference 80S
Description, images, technical data and specifications
Audio Research Reference 80S
Image source - (c) Audio Research
The Reference 80S is a stereo valve power amplifier in the Audio Research Reference line, built by hand in Maple Grove, Minnesota. The maker created it for owners who do not need the output of the larger Reference 160S stereo and 160M mono amplifiers, and outwardly it shares the dimensions of the 160M.
Key specs that matter
Each channel delivers 70 W continuous from 20 Hz to 20 kHz, and distortion at 1 W stays below 0.04%. Switching to Triode mode lowers the available power to 33 W per channel. Power bandwidth covers 7 Hz to 68 kHz at the 3 dB points, and response at 1 W extends from 0.7 Hz to 94 kHz. Rated output is reached with 1.4 V RMS balanced or 0.7 V RMS single-ended, which works out to 25.5 dB of gain into 8 ohms. Input impedance is 300k ohms balanced and 75k ohms single-ended. Speaker taps are provided for 16, 8 and 4 ohm loads. Overall negative feedback is 15 dB, slew rate 10 V per microsecond and rise time 4.0 microseconds. Output regulation is about 1.0 dB from a 16 ohm load to open circuit, a damping factor of roughly 8.
Engineering and use context
Like every Reference amplifier before it, the 80S is a fully balanced differential design. A four-layer circuit board gives a separate ground plane, a better layout and fewer point-to-point connections. Two matched pairs of KT150 output tubes work with two 6H30 gain stage tubes, and dual GhostMeters float in front of the output valves. A proprietary auto-bias circuit corrects for tube age and for mains voltage swings, the output tubes are fused and monitored, and an hour meter records tube use. Operation switches between Pentode and Triode from a front panel button. Rear connections include XLR and single-ended inputs, an RS232 port and 12 V trigger connections in both directions, and the auto-off function can be defeated. Cooling comes from a single shallow whisper fan in the bottom plate with switchable speeds. The all-aluminium chassis uses extruded panels for rigidity. It is 47 cm wide at the chassis and 48.26 cm at the faceplate, 26 cm high and 47 cm deep, or 53.3 cm with handles and connectors, and weighs 28.2 kg net.
Pairing
The trigger link lets a preamplifier with a matching output switch the 80S on and off. Power draw is 221 W at idle, 280 W in Triode mode and 420 W at rated output, with 3.6 W when off.
Alternatives
The Audio Research VT80 SE is a stereo tube amplifier rated at 75 W per channel with auto-bias and 8 and 4 ohm outputs.
Key specs that matter
Each channel delivers 70 W continuous from 20 Hz to 20 kHz, and distortion at 1 W stays below 0.04%. Switching to Triode mode lowers the available power to 33 W per channel. Power bandwidth covers 7 Hz to 68 kHz at the 3 dB points, and response at 1 W extends from 0.7 Hz to 94 kHz. Rated output is reached with 1.4 V RMS balanced or 0.7 V RMS single-ended, which works out to 25.5 dB of gain into 8 ohms. Input impedance is 300k ohms balanced and 75k ohms single-ended. Speaker taps are provided for 16, 8 and 4 ohm loads. Overall negative feedback is 15 dB, slew rate 10 V per microsecond and rise time 4.0 microseconds. Output regulation is about 1.0 dB from a 16 ohm load to open circuit, a damping factor of roughly 8.
Engineering and use context
Like every Reference amplifier before it, the 80S is a fully balanced differential design. A four-layer circuit board gives a separate ground plane, a better layout and fewer point-to-point connections. Two matched pairs of KT150 output tubes work with two 6H30 gain stage tubes, and dual GhostMeters float in front of the output valves. A proprietary auto-bias circuit corrects for tube age and for mains voltage swings, the output tubes are fused and monitored, and an hour meter records tube use. Operation switches between Pentode and Triode from a front panel button. Rear connections include XLR and single-ended inputs, an RS232 port and 12 V trigger connections in both directions, and the auto-off function can be defeated. Cooling comes from a single shallow whisper fan in the bottom plate with switchable speeds. The all-aluminium chassis uses extruded panels for rigidity. It is 47 cm wide at the chassis and 48.26 cm at the faceplate, 26 cm high and 47 cm deep, or 53.3 cm with handles and connectors, and weighs 28.2 kg net.
Pairing
The trigger link lets a preamplifier with a matching output switch the 80S on and off. Power draw is 221 W at idle, 280 W in Triode mode and 420 W at rated output, with 3.6 W when off.
Alternatives
The Audio Research VT80 SE is a stereo tube amplifier rated at 75 W per channel with auto-bias and 8 and 4 ohm outputs.
Specifications
Model name
Reference 80S
Input sensitivity (mV)
N/A
Input impedance (balanced) (Ω)
300 000
Input impedance (single-ended) (Ω)
75 000
Output impedance (balanced) (Ω)
N/A
Output impedance (single-ended) (Ω)
N/A
Max current (A)
N/A
Output power (8Ω) (W)
70
Output power (4Ω) (W)
N/A
Gain (dBu)
N/A
Frequency response low +/- 3dB (Hz)
0.7
Frequency response high +/- 3dB (Hz)
94 000
Signal to Noise Ratio (dB)
N/A
Total Harmonic Distortion + Noise (0% global feedback) (%)
N/A
Total Harmonic Distortion + Noise (100% global feedback) (%)
N/A
Max power consumption (W)
N/A
Damping factor
N/A
Dimensions (mm)
482.6 × 260 × 470
Weight (kg)
28.2
Official link
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