High Quality Content by WIKIPEDIA articles! The Yamaha TX81Z is a rack-mounted (keyboard-less) frequency modulation music synthesizer, which was released in 1987. Unlike previous FM synthesizers of the era, the TX81Z was the first to employ a range of oscillator waveforms other than just sine waves, giving it its unique, grating timbre. The TX81Z has better digital-to-analog converters than many of its keyboard cousins, and has a reputation for producing more powerful bass sounds than similar vintage Yamaha synthesizers, such as the DX11.