Four-lamp super is the most common type of broadcasting receiver, since with this number of lamps it is already possible to fully realize the main advantages of a superheterodyne receiver: good selectivity, greater sensitivity with the ability to automatically adjust it, reception stability and sometimes the ability to receive distant stations on a room antenna. Automatic sensitivity control (APC) in the receiver reduces its sensitivity when receiving loud signals. This reduces the susceptibility of the receiver to local interference and protects the detector of the receiver from overload and associated distortion. Making a four-lamp super, due to the relative simplicity of its circuit, is simple and affordable for a medium-skilled radio amateur.