AUDIO RESEARCH VT100

Second-hand, in good condition, it has some scratches (see pictures). Supplied with its original package.

The VT100 is a 100W per channel stereo amplifier that uses four pairs of Svetlana 6550 output tubes and shares with the VT130SE the ultralinear-configured output stage, combined with partial cathode coupling designed for low output impedance and high current delivery. According to Audio Research's Chief Engineer, Rich Larsen, these circuits run the screens slightly hotter than conventional pentode operation but still offer higher efficiency with less signal loss than triode designs.

The fully differential, direct-coupled input and driver stages, derived from the Reference 1 preamplifier, use 6922 dual triodes with FET constant-current sources designed to achieve a more accurate differential balance. The output tubes are mounted on vertical circuit boards, one for each channel, running along the left and right interior chassis walls. This results in a virtually dual-mono layout all the way back to the power transformer (with shared secondary winding), with independent, distributed energy storage and very short signal paths.

Technical specifications:

• Power output: 100 watts per channel continuous from 20Hz to 20kHz. Approximate power at clipping: 120 watts.
• THD: Total harmonic distortion at 1kHz (typically 0.3% at 100 watts and below, 0.03% at 1 watt).
• Power bandwidth: 12Hz to 60kHz (-3dB at 1 watt).
• Frequency response: 1Hz to 80kHz (-3dB at 1 watt).
• Input sensitivity: 1.7V RMS (balanced or SE) for rated output (24.3 dB gain balanced into 8 ohms).
• Input impedance: 200k ohms balanced, 100 ohms single-ended.
• Output taps: 8 ohms, 4 ohms.
• Overall negative feedback: 15dB.
• Slew rate: 8 volts/microsecond.
• Rise time: 4 microseconds.
• Hum & noise: less than 0.2mV RMS, 103dB below rated output (IHF weighted, input shorted).
• Power supply energy: approximately 540 joules.
• Power requirements: 105-125 AC 60Hz (210-250 VAC 50 Hz); 650 watts at rated output, 800 watts maximum, 440 watts at idle.
• Tubes required: (4) matched pair 6550C; (4) 6H30.
• Dimensions: 19" W x 8.75" H x 19.5" D; handles extend 1.5" forward.
• Weight: 66 lbs.