A monophonic, analog synth produced by PAiA. This is a basic but very usable synth consisting of two voltage controlled oscillators, one voltage controlled filter, one voltage controlled amplifier, two envelope generators, and a MIDI interface. (There is no LFO.) As is the case with many PAiA products, there are a number of money-saving design choices which create some limitations but also keep the product very affordable and a good value.
The two VCOs generate only a sawtooth waveform. They can be detuned relative to each other and mixed in a varying proportion. The VCF is a two-pole, low pass, OTA design (an unusual choice for this type of synth; a transistor ladder would be more typical for a small monophonic synth). The VCF and VCA each have a dedicated envelope generator; the VCF's is an AR type with switch selectable sustain. The VCAs is an ADSR with a "punch" switch that adds a short hold period at 100% level between the attack and decay phases, duplicating an inadvertent feature of the Minimoog's envelope generator which is often credited for its "punchy" bass sounds.
The MIDI interface responds to note, velocity, and pitch wheel messages. Velocity can be routed to the VCF and the VCA. As a money saving measure, and to make construction easier, the VCOs do not have exponential converters and hence have a Volts/Hz response; the MIDI interface does the conversion in software.
The Fatman was introduced in 1997, at the beginning of the late-1990s analog renaissance, and has sold well; it remains available as of January 2016. Like all PAiA products, it is sold in kit form only. The kit can be ordered with either rackmount or tabletop packaging, or purchased as a bare board for incorporating into other systems. A huge variety of modifications have been developed by customers and can be found online.