Mark IV

About the Mark IV

The Dynaco Mark IV is a single-channel (mono) tube amplifier introduced in 1960 by Dyna Co. (Dynaco) of Philadelphia, USA. It delivers a nominal output of 40 watts continuous power with a peak rating of 90 watts. The amplifier uses a circuit derived from the Dynakits Mark II and Mark III, featuring a 7199 tube as a pentode high gain voltage amplifier directly coupled to a cathodyne phase inverter, which requires no adjustment for tube aging. The output stage uses two EL-34 tubes operated below their maximum ratings with a fixed bias arrangement set by the patented Dyna Biaset for optimum linearity and minimal distortion. The power supply includes a GZ-34 tube rectifier and selenium rectifier. The amplifier has a frequency response of 20 Hz to 20 kHz, total harmonic distortion of about 1%, damping factor of 15, and a signal-to-noise ratio of 90 dB. It supports speaker loads from 4 to 16 ohms. The Mark IV was originally95 or assembled for , and modern special order versions are When used in pairs, the Mark IVs provide true stereo separation with each amplifier having its own power transformer and rectifier. The amplifier is praised for its quiet, transparent sound with strong bass and detailed midrange and treble, making it a favorite among audiophiles. Dimensions are approximately 14 x 6.5 x 5 inches, and it weighs about 20 pounds.