The Akai PRO-601 is a synthesizer module produced by Akai Professional in the 1980s. It is a monophonic analogue synthesizer known for its unique sound and versatile capabilities. The PRO-601 features two voltage-controlled oscillators (VCOs) with various waveforms, a low-pass filter, two envelope generators, and a modulation section. It also has MIDI capabilities, allowing it to be controlled by external devices. The PRO-601 is highly regarded among musicians and synthesizer enthusiasts for its powerful sound and programmable features.