Lee de Forest
Historical value of the Lieben valve is debatable. According to Reiner zur Linde, it was not an invention but a development of existing designs and ideas of John Ambrose Fleming, Lee de Forest, Arthur Wehnelt and others. Nevertheless, Linde agreed it is a milestone in telephone technology; Lieben and his associates created the electronic amplifier, a working, low-distortion alternative to the carbon microphone repeater.