ST-150

About the ST-150

The VTL ST-150 is a stereo power amplifier designed to provide an engaging and true-to-live listening experience. It features a tetrode/triode switchable design, delivering 120 watts per channel in tetrode mode for wide dynamic response and bass punch, and 60 watts per channel in triode mode for delicate, detailed, and intimate sound suited to vocal and small instrumental ensembles. The amplifier uses 8 x 6550 tubes, 2 x 12AT7, and 2 x 12BH7 tubes, with individual bias settings for each 6550 tube. It is hand-built with audiophile-grade components including film and foil capacitors in the signal path and proprietary output transformers. The ST-150 offers a very low noise floor with a specially designed grounding scheme and a high energy storage power supply exceeding 200 joules. It is well-suited for smaller electrostatic panels and dynamic speakers with efficiencies of 92dB/1W/1m or higher. The amplifier has an extruded aluminum front panel available in black or silver, and measures 19 x 12 x 9 inches, weighing approximately 85 lbs (38.6 kg). Power consumption is 240W idle and 800W at full power. Input sensitivity is 0.880V at 100V mains and 1.0V at 120/240V mains, with an input impedance of 130K ohms and an output load range of 2 to 8 ohms. Signal-to-noise ratio is -95dB at 120Hz, and total harmonic distortion is less than 3% from 20Hz to 20kHz at rated power. The amplifier includes appropriate ceramic fuses for mains and B+ circuits.