I purchased this new 25 years ago and it is still going strong. It has been my main workhorse amplifier for 13 of those 25 years. It blew a capacitor back in 1999 and I had all the caps and tubes replaced. Then it did it again almost ten years later in 2008. Again I replaced the caps and tubes. That is when I learned to adjust the bias to make sure that didn't happen again. It has been in the closet in a box for the last 7 year. I hooked it up this weekend and it still has that Audio Research sound. Not syrupy sweet like a SET and the bass is more controlled. Just a great 50 watt push-pull tube amp based on the 6550 tube.
Power output: 50 watts per channel continuous from 20Hz to 20kHz. Approximate actual power available at "clipping" 52 watts (1kHz).
Power bandwidth: (-3dB points) 15Hz to 40kHz
Frequency response (-3dB points at 1 watt) 3Hz to 40 kHz
Input sensitivity 1.05V RMS for rated output
Input impedance 100K ohms unbalanced
Output regulation Approximately 0.6dB 16 ohm load to open circuit
Overall negative feedback 19 dB
Damping factor 14
Distortion 1kHz total harmonic distortion typically 1% at 50 watts, below .05% at 1 watt.
Slew rate 7 V/µs
Rise time 10 µs
Hum & noise Less than 0.5mV RMS - 95dB below rated output (IHF weighted, input shorted)
Power supply energy storage 184 joules
Power requirements 105-125VAC 60Hz (210-250VAC 50Hz) 265 watts at rated output, 300 watts maximum, 175 watts at "idle"
Tube complement (2 matched pairs) 6550B, (2) 6922 driver, (1) 6922 input
Dimensions VT60: 14" (35.6 cm) W x 7" (17.8 cm) H x 13.3" (33.8 cm) D. Output connectors extend 1" (2.5 cm) to the rear.
Weight VT60: 32.7 lbs. (14.9 kg) Net; 48 lbs. (21.8 kg) Shipping.
VT60SE: 36 lbs Net.