Spring reverbs provide a relatively simple and inexpensive method for creating reverberation effects. The Hammond Organ Company was the first to create a compact reverb effect for their line of organs in 1960. The design was so successful, it was released as a separate piece of hardware dubbed the Accusonics Type 4 Spring Reverb. One of the first customers to make use of this was Leo Fender, who installed the first Accusonics tank in the 1963 Fender Vibroverb amp. In guitar amplifiers, the spring reverbs are usually enclosed in a metal box, called the reverb pan, which is attached to the bottom of the amp. The actual operation of a spring reverb is simple: an audio signal is sent to one end of the spring (or several springs) by a transducer and this creates waves that travel through the spring. At the other end of the spring, there is another transducer that converts some of the motion in the spring into an electrical signal, which is added to the dry sound. When a wave arrives at an end of the spring, part of the wave’s energy is reflected and stays in the spring. It is these reflections that create the reverb characteristic sound.