VT100 MkIII

About the VT100 MkIII

The Audio Research Corporation VT100 MKIII is a stereo tube power amplifier introduced around 2004, rated at 100 watts continuous per channel into 4 or 8 ohms. It features a Class AB differential circuit design using four matched pairs of 6550C output tubes and four 6H30 driver tubes. Key upgrades in the MKIII version include a built-in 12VDC remote turn-on circuit, active cooling fan, balanced/single-ended input switch, increased negative feedback to 15dB, larger 540-joule power supply, and improved performance metrics such as lower THD (0.3% at 100W), better SNR (103dB), and refined frequency response. It employs ultralinear output transformers with partial cathode coupling for enhanced efficiency, lower output impedance, and superior drive into various loudspeaker loads. The amplifier supports both single-ended and balanced inputs, with output taps for 4, 8, and 16 ohms in some descriptions. Discontinued as noted in forums around its production period, it is praised for robust bass, deep soundstaging, excellent imaging, dynamics, neutrality, and detail.