audio research

Integrated tube stereo amplifier.

From the ARC website

With an unbeatable combination of great sound, cool packaging and affordable pricing, the VS55 and VS110 amplifiers have been garnering rave reviews and enjoying brisk sales around the world. We are very pleased to inform you of an addition to the series, the VSi55 Integrated Amplifier. With a rated output of 50 watts per channel and a reasonable price, a remarkable level of performance, build quality and value is now available to a much wider group of music lovers.

Physically, the VSi55 is 14" W by 8" H x 16" D, making it 1" taller and 2" deeper than the VS55. The milled, anodized natural top plate is 1 1/2" deeper and has the larger inset Audio Research logo used on the VT series of power amps. In place of the power switch and silkscreening found on the front of the VS55 is a slightly recessed area (mimicking the shape of the engraved line found on our front panels), with function and volume LEDs on the left and back soft touch buttons on the right, like the layout of the SP16. The supplied remote controls all functions including power, muting, stereo/mono, input select, and volume up/down. (There is no processor pass-thru or 12V trigger.)

The rear of the chassis has five pairs of single-ended inputs labelled CD, Tuner, Video, SE1 and SE2, a (full-range) mono subwoofer output, voltmeter test points for setting bias, 0-4-8 ohm five-way binding posts, and detachable 14-gauge AC line cord. An optional perforated cage-type top cover, specific to the VSi55, is available.

The control section of the VSi55 is passive, utilizing microprocessor-controlled relays. The high performance input relay paths are especially short, the same as those in the REF2 MKII. The microprocessor control remembers the last input selected and the stereo/mono setting when it is powered down. Upon turn-on there is an automatic 30-second warmup mute, with the volume control reset to zero to avoid possible unwanted surprises. The active circuitry is essentially that of the VS55, but with 7dB more gain for greater sensitivity (.38V). The VSi55 utilizes the same Class A input (with regulated DC heater supply) and driver stages utilizing three 6N1P tubes, and partial cathode-coupled Class AB output stages with two pairs of 6550EH output tubes. The simplicity and purity of this audio circuit has proven itself both sonically and in its reliability.

Musically, the VSi55 is a joy to listen to, with great tonality, resolution and dynamics. You will have to keep reminding yourself that the VSi55 is reasonably priced because other products sound colored and lifeless in comparison. There is no bandwidth limiting, and the robust power supply allows music to flow with remarkable dynamic life. The VSi55 is pure, harmonically right, and lets music bloom. Pair the VSi55 with a great CD player and loudspeakers and you can have a compact system which defies expectations and gets to the heart of the music.



In 2007, VSi55 had their tubes changed from 6550EH (Electro Harmonix) to 6550C (Svetlana) at the production line. The output tube bias was changed to 55mV, providing better sonics and improved reliability.

Perforated cage-type top cover ($250).

MSRP (US new retail)
$2,995. Increased to $3,495 on December 1st 2005.


Power output 50 watts per channel continuous from 20Hz to 20kHz. Approximate actual power available at "clipping" 52 watts (1kHz)
Power bandwidth (-3dB points) 12Hz to 90kHz
Frequency response (-3dB points at 1 watt) 1.0 Hz to 100 kHz
Input sensitivity 0.5V RMS Single-ended for rated output. (32 dB gain into 8 ohms)
Input impedance 50K ohms Single-ended
Output taps Five way binding posts for 0-4-8 Ohm
Output regulation Approximately 1.5 dB 8 ohm load to open circuit
Overall negative feedback 10 dB
Damping factor 5
Distortion 1kHz total harmonic distortion typically 1% at 50 watts, below .05% at 1 watt
Slew rate 10 volts/microsecond
Rise time 2 microseconds
Hum & noise Less than 0.14mV RMS - 103dB below rated output (IHF weighted, input shorted)
Power supply energy storage 166 joules
Power requirements 100-125VAC 60Hz (200-250VAC 50Hz) 320 watts at rated output, 500 watts maximum, 205 watts at "idle". 0.5 watts power off.
Tube complement (2 matched pairs) 6550EH power output, (3) 6N1P input and driver
Other Maximum input: 3.5V RMS (any input). Optional 6dB pad for CD use.
Output polarity: Non-inverting (any input).
Mono subwoofer output: 1V RMS at rated power.
Power supplies: Electronically regulated Low and High Voltage supplies for input stages. Automatic 30 second warm-up/brown-out mute, with the volume control reset to zero.
Voltmeter test points for bias.
Detachable 14 gauge power cord.
Dimensions 14"(35.6 cm) W x 8"(20.3 cm) H x 16"(40.6 cm) D. Rear connectors extend .88" beyond chassis
Weight 34 lbs. (15.5 kg) Net; 40 lbs. (18.2 kg) Shipping.