By 1959 the age of mono Hi-Fi was winding down as stereo was catching on.   Bogen made one last attempt with the RB140, which seems to have limited production runs only that year.   It was a very high quality receiver featuring 19 tubes and a 40 watt amplifier.   It was expensive - by the following year stereo receivers were coming out, such as the Bogen SRB20 and the Harmon Kardon Festival TA230, that were only a little more expensive, handily outselling the older mono units.