A classic amp from Audio Research. The Mark II is considered by many to be the best version of this classic amp; as it is all tube.I am the second owner. I have had this amp since 2001. It has received very light use. The tubes probably have a fair amount of life left in them, but I am selling this at a low price with the assumption that the next owner will be replacing the tubes. This amp is in very good cosmetic condition, but there are some minor smudges of the finish on the faceplate visible only under certain lighting conditions and up close. One of the screws that holds the top cover in place is stripped. There are some marks on the rear of the amp, and minor marks on the handles.
None of these defects are readily visible from more than 2 or 3 feet away, if at all. Please see my feedback on Audiogon under the name “abind”. Paypal please add 3%. Available for local pickup in the San Francisco Bay area. Thanks for looking.
Serial # 40092007 From the manufacturers web site: The VT100MKII is a new all-tube, balanced stereo power amplifier that draws upon the advanced technology of the flagship Reference Series models. Rated at 100 watts continuous output per channel, the VT100MKII is a Class AB, differential circuit design using two matched pair of 6550 output tubes in each channel, along with four 6922 twin triodes per channel for input and driver stages. A fully regulated, 540-joule power supply is distributed between two separate, isolated output circuit boards for short signal paths and true "dual mono" operation back to the massive main power transformer. Constant-current sources in the input stage help maintain stable drive
characteristics and differential balance under the dynamic conditions of music reproduction.
Ultralinear output transformers and partial cathode coupling to the output terminals give the VT100MKII higher efficiency and lower output impedance than conventional designs for better drive into a wide variety of loudspeaker loads. Inputs include both single ended and balanced. Output terminals are custom-machined, heavy duty, gold-over-brass posts. A spacious chassis and single cooling fan help maintain conservative operating temperatures.
Specifications
Power output 100 watts per channel continuous from 20Hz to 20kHz. Approximate actual power available at "clipping" 110 watts (1kHz)
Power bandwidth (-3dB points) 15Hz to 80kHz
Frequency response (-3dB points at 1 watt) 1Hz to 100 kHz
Input sensitivity 1.9V RMS (Bal or SE) for rated output. (23.5 dB gain into 8 ohms.)
Input impedance 200K ohms Balanced, 100K ohms Single-ended.
Output taps 8 ohms, 4 ohms
Output regulation Approximately 0.8dB 8 ohm load to open circuit
Overall negative feedback 10 dB
Damping factor 11
Distortion 1kHz total harmonic distortion typically 1% at 100 watts, below .05% at 1 watt
Slew rate 15 Volts/µs
Rise time 3 µs
Hum & noise Less than 0.5mV RMS 95dB below rated output (IHF weighted, input shorted)
Power supply energy storage VT100: 270 joules.
VT100 MKII/III: 540 joules
Power requirements 105-125VAC 60Hz (210-250VAC 50Hz) 585 watts at rated output, 750 watts maximum, 380 watts at "idle"
Tube complement VT100: (4 matched pairs) 6550 power output, (8) 6922
VT100 MKII: (4 matched pairs) 6550C power output, (4) 6922 driver, (4) 6922 input.
VT100 MKIII: (4 matched pairs) 6550C power output, (4) 6H30
Other
Dimensions 19" (48.3 cm) W x 8.75" (22.2 cm) H x 19.5" (49.5 cm) D. Handles extend 1.5" (3.8 cm) forward
Weight 65 lbs. (29.5 kg) Net; 83 lbs. (37.7 kg) Shipping.
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