An
analog (or
analogue)
synthesizer is a
synthesizer that uses
analog circuits and
analog signals to generate sound electronically. The earliest analog synthesizers in the 1920s and 1930s such as the
Trautonium were built with a variety of
vacuum-tube (thermionic valve) and electro-mechanical technologies. After the 1960s, analog synthesizers were built with a variety of
operational amplifier (op-amp)
integrated circuits, along with
potentiometer (pot, or variable
resistor) to adjust the traits of the sound that is produced. Analog synthesizers also use
low-pass filters and
high-pass filters to modify the sound. While 1960s-era analog synthesizers such as the
Moog used a number of independent electronic modules connected by
patch cables, later analog synthesizers such as the
Minimoog integrated them into single units, eliminating patch cords in favour of integrated signal routing systems.