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.
The unit is multitimbral, and has 128 ROM slots and 32 RAM slots. The RAM slots were rarely utilized due to the quality of the original patches and the difficulty of programming new sounds with the limited front-panel interface. Among the presets is the famous LatelyBass, one of the most popular presets in synthesizer history. Producer Babyface at one point had two units in his studio, both of which he kept set to the preset, one detuned from the other. This expanded version of the preset became a part of his signature sound.
Some say the prevalence of the TX81Z's presets was also because of the difficulty in creating new patches. Creating new sounds from the unit's front panel is possible, but numerous nested parameters must be navigated by way of 11 buttons and a backlit 16 character, 2-line LCD. However, several personal computer-based editing applications have been developed since its release.
The TX81Z was released as a low-cost FM machine and has always been relatively inexpensive compared to most other FM synthesizers. For this reason, it became popular with many producers on a tight budget, and is still used by part-time house and acid house producers. Eliot Kennedy uses it for one purpose, a "classic dancefloor bass sound.". Units are still fairly common and can often be found at pawn shops, second-hand music retailers, and internet auction websites.
The TX81Z is backwards-compatible with sound patches developed for Yamaha's DX21, DX27, DX100, and FB01 synthesizers. It is also very similar to the DX11 synthesizer, which is essentially a TX81Z with a velocity and pressure-sensing keyboard, and a pitch envelope.