Mark IB

About the Mark IB

The Project/One Mark IB stereo receiver is a vintage HiFi unit characterized by a wood veneer case and a +/-30 volt power supply for the output stage. It uses SK3893 output transistors, which have a maximum output rating of 50 watts. The receiver is believed to deliver approximately 30 watts per channel into 8 ohms, similar in power supply design to the Pioneer SX-680, which is rated at 30 watts per channel. The Mark IB is a solid-state receiver from the 1970s, noted for its good looks and reliable performance. Users have reported repairing output transistors and other components to restore functionality. Detailed official specifications and bias adjustment data are scarce, but it is known to have a solid build and typical features of receivers from that era.